ENT-1906: Modify the DJVM to wrap Java primitive types. (#4035)

* WIP - sandbox classloading
* Fix handling of Appendable in the sandbox.
* WIP - Load wrapped Java types into SandboxClassLoader.
* Add explicit toDJVM() invocation after invoking Object.toString().
* Add simple ThreadLocal to the sandbox to complete AbstractStringBuilder.
* Add support for Enum types inside the sandbox.
* Simplify type conversions into and out of the sandbox.
* Small refactors and comments to tidy up code.
* Fix Enum support to include EnumSet and EnumMap.
* Fix use of "$" in whitelist regexps.
* Add extra methods (i.e. bridges) to stitched interfaces.
* Rename ToDJVMStringWrapper to StringReturnTypeWrapper.
* Support lambdas within the sandbox.
* Fix mapping of java.lang.System into the sandbox.
* Don't remap exception classes that we catch into sandbox classes.
* Remove unnecessary "bootstrap" classes from the DJVM jar.
* Ensure that Character.UnicodeScript is available inside the sandbox.
* Tweak sandboxed implementations of System and Runtime.
* Ensure that Character.UnicodeScript is loaded correctly as Enum type.
* Disallow invoking methods of ClassLoader inside the sandbox.
* Apply updates after review.
* More review fixes.

djvm/build.gradle

@@ -52,6 +52,20 @@ shadowJar {
     baseName 'corda-djvm'
     classifier ''
     relocate 'org.objectweb.asm', 'djvm.org.objectweb.asm'
+    
+    // These particular classes are only needed to "bootstrap"
+    // the compilation of the other sandbox classes. At runtime,
+    // we will generate better versions from deterministic-rt.jar.
+    exclude 'sandbox/java/lang/Appendable.class'
+    exclude 'sandbox/java/lang/CharSequence.class'
+    exclude 'sandbox/java/lang/Character\$*.class'
+    exclude 'sandbox/java/lang/Comparable.class'
+    exclude 'sandbox/java/lang/Enum.class'
+    exclude 'sandbox/java/lang/Iterable.class'
+    exclude 'sandbox/java/lang/StringBuffer.class'
+    exclude 'sandbox/java/lang/StringBuilder.class'
+    exclude 'sandbox/java/nio/**'
+    exclude 'sandbox/java/util/**'
 }
 assemble.dependsOn shadowJar
 

djvm/src/main/java/sandbox/java/lang/Appendable.java

@@ -0,0 +1,19 @@
+package sandbox.java.lang;
+
+import java.io.IOException;
+
+/**
+ * This is a dummy class that implements just enough of [java.lang.Appendable]
+ * to keep [sandbox.java.lang.StringBuilder], [sandbox.java.lang.StringBuffer]
+ * and [sandbox.java.lang.String] honest.
+ * Note that it does not extend [java.lang.Appendable].
+ */
+public interface Appendable {
+
+    Appendable append(CharSequence csq, int start, int end) throws IOException;
+
+    Appendable append(CharSequence csq) throws IOException;
+
+    Appendable append(char c) throws IOException;
+
+}

djvm/src/main/java/sandbox/java/lang/Boolean.java

@@ -0,0 +1,100 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.io.Serializable;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Boolean extends Object implements Comparable<Boolean>, Serializable {
+
+    public static final Boolean TRUE = new Boolean(true);
+    public static final Boolean FALSE = new Boolean(false);
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Boolean> TYPE = (Class) java.lang.Boolean.TYPE;
+
+    private final boolean value;
+
+    public Boolean(boolean value) {
+        this.value = value;
+    }
+
+    public Boolean(String s) {
+        this(parseBoolean(s));
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof Boolean) && ((Boolean) other).value == value;
+    }
+
+    @Override
+    public int hashCode() {
+        return hashCode(value);
+    }
+
+    public static int hashCode(boolean value) {
+        return java.lang.Boolean.hashCode(value);
+    }
+
+    public boolean booleanValue() {
+        return value;
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Boolean.toString(value);
+    }
+
+    @Override
+    @NotNull
+    public String toDJVMString() {
+        return toString(value);
+    }
+
+    public static String toString(boolean b) {
+        return String.valueOf(b);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Boolean fromDJVM() {
+        return value;
+    }
+
+    @Override
+    public int compareTo(@NotNull Boolean other) {
+        return compare(value, other.value);
+    }
+
+    public static int compare(boolean x, boolean y) {
+        return java.lang.Boolean.compare(x, y);
+    }
+
+    public static boolean parseBoolean(String s) {
+        return java.lang.Boolean.parseBoolean(String.fromDJVM(s));
+    }
+
+    public static Boolean valueOf(boolean b) {
+        return b ? TRUE : FALSE;
+    }
+
+    public static Boolean valueOf(String s) {
+        return valueOf(parseBoolean(s));
+    }
+
+    public static boolean logicalAnd(boolean a, boolean b) {
+        return java.lang.Boolean.logicalAnd(a, b);
+    }
+
+    public static boolean logicalOr(boolean a, boolean b) {
+        return java.lang.Boolean.logicalOr(a, b);
+    }
+
+    public static boolean logicalXor(boolean a, boolean b) {
+        return java.lang.Boolean.logicalXor(a, b);
+    }
+
+    public static Boolean toDJVM(java.lang.Boolean b) { return (b == null) ? null : new Boolean(b); }
+}

djvm/src/main/java/sandbox/java/lang/Byte.java

@@ -0,0 +1,129 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Byte extends Number implements Comparable<Byte> {
+    public static final byte MIN_VALUE = java.lang.Byte.MIN_VALUE;
+    public static final byte MAX_VALUE = java.lang.Byte.MAX_VALUE;
+    public static final int BYTES = java.lang.Byte.BYTES;
+    public static final int SIZE = java.lang.Byte.SIZE;
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Byte> TYPE = (Class) java.lang.Byte.TYPE;
+
+    private final byte value;
+
+    public Byte(byte value) {
+        this.value = value;
+    }
+
+    public Byte(String s) throws NumberFormatException {
+        this.value = parseByte(s);
+    }
+
+    @Override
+    public byte byteValue() {
+        return value;
+    }
+
+    @Override
+    public short shortValue() {
+        return (short) value;
+    }
+
+    @Override
+    public int intValue() {
+        return (int) value;
+    }
+
+    @Override
+    public long longValue() {
+        return (long) value;
+    }
+
+    @Override
+    public float floatValue() {
+        return (float) value;
+    }
+
+    @Override
+    public double doubleValue() {
+        return (double) value;
+    }
+
+    @Override
+    public int hashCode() {
+        return hashCode(value);
+    }
+
+    public static int hashCode(byte b) {
+        return java.lang.Byte.hashCode(b);
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof Byte) && ((Byte) other).value == value;
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Byte.toString(value);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Byte fromDJVM() {
+        return value;
+    }
+
+    @Override
+    public int compareTo(@NotNull Byte other) {
+        return compare(this.value, other.value);
+    }
+
+    public static int compare(byte x, byte y) {
+        return java.lang.Byte.compare(x, y);
+    }
+
+    public static String toString(byte b) {
+        return Integer.toString(b);
+    }
+
+    public static Byte valueOf(byte b) {
+        return new Byte(b);
+    }
+
+    public static byte parseByte(String s, int radix) throws NumberFormatException {
+        return java.lang.Byte.parseByte(String.fromDJVM(s), radix);
+    }
+
+    public static byte parseByte(String s) throws NumberFormatException {
+        return java.lang.Byte.parseByte(String.fromDJVM(s));
+    }
+
+    public static Byte valueOf(String s, int radix) throws NumberFormatException {
+        return toDJVM(java.lang.Byte.valueOf(String.fromDJVM(s), radix));
+    }
+
+    public static Byte valueOf(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Byte.valueOf(String.fromDJVM(s)));
+    }
+
+    public static Byte decode(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Byte.decode(String.fromDJVM(s)));
+    }
+
+    public static int toUnsignedInt(byte b) {
+        return java.lang.Byte.toUnsignedInt(b);
+    }
+
+    public static long toUnsignedLong(byte b) {
+        return java.lang.Byte.toUnsignedLong(b);
+    }
+
+    public static Byte toDJVM(java.lang.Byte b) {
+        return (b == null) ? null : valueOf(b);
+    }
+}

djvm/src/main/java/sandbox/java/lang/CharSequence.java

@@ -0,0 +1,21 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This is a dummy class that implements just enough of [java.lang.CharSequence]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+public interface CharSequence extends java.lang.CharSequence {
+
+    @Override
+    CharSequence subSequence(int start, int end);
+
+    @NotNull
+    String toDJVMString();
+
+    @Override
+    @NotNull
+    java.lang.String toString();
+
+}

djvm/src/main/java/sandbox/java/lang/Character.java

@@ -0,0 +1,481 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.io.Serializable;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Character extends Object implements Comparable<Character>, Serializable {
+    public static final int MIN_RADIX = java.lang.Character.MIN_RADIX;
+    public static final int MAX_RADIX = java.lang.Character.MAX_RADIX;
+    public static final char MIN_VALUE = java.lang.Character.MIN_VALUE;
+    public static final char MAX_VALUE = java.lang.Character.MAX_VALUE;
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Character> TYPE = (Class) java.lang.Character.TYPE;
+
+    public static final byte UNASSIGNED = java.lang.Character.UNASSIGNED;
+    public static final byte UPPERCASE_LETTER = java.lang.Character.UPPERCASE_LETTER;
+    public static final byte LOWERCASE_LETTER = java.lang.Character.LOWERCASE_LETTER;
+    public static final byte TITLECASE_LETTER = java.lang.Character.TITLECASE_LETTER;
+    public static final byte MODIFIER_LETTER = java.lang.Character.MODIFIER_LETTER;
+    public static final byte OTHER_LETTER = java.lang.Character.OTHER_LETTER;
+    public static final byte NON_SPACING_MARK = java.lang.Character.NON_SPACING_MARK;
+    public static final byte ENCLOSING_MARK = java.lang.Character.ENCLOSING_MARK;
+    public static final byte COMBINING_SPACING_MARK = java.lang.Character.COMBINING_SPACING_MARK;
+    public static final byte DECIMAL_DIGIT_NUMBER = java.lang.Character.DECIMAL_DIGIT_NUMBER;
+    public static final byte LETTER_NUMBER = java.lang.Character.LETTER_NUMBER;
+    public static final byte OTHER_NUMBER = java.lang.Character.OTHER_NUMBER;
+    public static final byte SPACE_SEPARATOR = java.lang.Character.SPACE_SEPARATOR;
+    public static final byte LINE_SEPARATOR = java.lang.Character.LINE_SEPARATOR;
+    public static final byte PARAGRAPH_SEPARATOR = java.lang.Character.PARAGRAPH_SEPARATOR;
+    public static final byte CONTROL = java.lang.Character.CONTROL;
+    public static final byte FORMAT = java.lang.Character.FORMAT;
+    public static final byte PRIVATE_USE = java.lang.Character.PRIVATE_USE;
+    public static final byte SURROGATE = java.lang.Character.SURROGATE;
+    public static final byte DASH_PUNCTUATION = java.lang.Character.DASH_PUNCTUATION;
+    public static final byte START_PUNCTUATION = java.lang.Character.START_PUNCTUATION;
+    public static final byte END_PUNCTUATION = java.lang.Character.END_PUNCTUATION;
+    public static final byte CONNECTOR_PUNCTUATION = java.lang.Character.CONNECTOR_PUNCTUATION;
+    public static final byte OTHER_PUNCTUATION = java.lang.Character.OTHER_PUNCTUATION;
+    public static final byte MATH_SYMBOL = java.lang.Character.MATH_SYMBOL;
+    public static final byte CURRENCY_SYMBOL = java.lang.Character.CURRENCY_SYMBOL;
+    public static final byte MODIFIER_SYMBOL = java.lang.Character.MODIFIER_SYMBOL;
+    public static final byte OTHER_SYMBOL = java.lang.Character.OTHER_SYMBOL;
+    public static final byte INITIAL_QUOTE_PUNCTUATION = java.lang.Character.INITIAL_QUOTE_PUNCTUATION;
+    public static final byte FINAL_QUOTE_PUNCTUATION = java.lang.Character.FINAL_QUOTE_PUNCTUATION;
+    public static final byte DIRECTIONALITY_UNDEFINED = java.lang.Character.DIRECTIONALITY_UNDEFINED;
+    public static final byte DIRECTIONALITY_LEFT_TO_RIGHT = java.lang.Character.DIRECTIONALITY_LEFT_TO_RIGHT;
+    public static final byte DIRECTIONALITY_RIGHT_TO_LEFT = java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT;
+    public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC = java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC;
+    public static final byte DIRECTIONALITY_EUROPEAN_NUMBER = java.lang.Character.DIRECTIONALITY_EUROPEAN_NUMBER;
+    public static final byte DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR = java.lang.Character.DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR;
+    public static final byte DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR = java.lang.Character.DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR;
+    public static final byte DIRECTIONALITY_ARABIC_NUMBER = java.lang.Character.DIRECTIONALITY_ARABIC_NUMBER;
+    public static final byte DIRECTIONALITY_COMMON_NUMBER_SEPARATOR = java.lang.Character.DIRECTIONALITY_COMMON_NUMBER_SEPARATOR;
+    public static final byte DIRECTIONALITY_NONSPACING_MARK = java.lang.Character.DIRECTIONALITY_NONSPACING_MARK;
+    public static final byte DIRECTIONALITY_BOUNDARY_NEUTRAL = java.lang.Character.DIRECTIONALITY_BOUNDARY_NEUTRAL;
+    public static final byte DIRECTIONALITY_PARAGRAPH_SEPARATOR = java.lang.Character.DIRECTIONALITY_PARAGRAPH_SEPARATOR;
+    public static final byte DIRECTIONALITY_SEGMENT_SEPARATOR = java.lang.Character.DIRECTIONALITY_SEGMENT_SEPARATOR;
+    public static final byte DIRECTIONALITY_WHITESPACE = java.lang.Character.DIRECTIONALITY_WHITESPACE;
+    public static final byte DIRECTIONALITY_OTHER_NEUTRALS = java.lang.Character.DIRECTIONALITY_OTHER_NEUTRALS;
+    public static final byte DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING = java.lang.Character.DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING;
+    public static final byte DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE = java.lang.Character.DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE;
+    public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING = java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING;
+    public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE = java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE;
+    public static final byte DIRECTIONALITY_POP_DIRECTIONAL_FORMAT = java.lang.Character.DIRECTIONALITY_POP_DIRECTIONAL_FORMAT;
+    public static final char MIN_HIGH_SURROGATE = java.lang.Character.MIN_HIGH_SURROGATE;
+    public static final char MAX_HIGH_SURROGATE = java.lang.Character.MAX_HIGH_SURROGATE;
+    public static final char MIN_LOW_SURROGATE = java.lang.Character.MIN_LOW_SURROGATE;
+    public static final char MAX_LOW_SURROGATE = java.lang.Character.MAX_LOW_SURROGATE;
+    public static final char MIN_SURROGATE = java.lang.Character.MIN_SURROGATE;
+    public static final char MAX_SURROGATE = java.lang.Character.MAX_SURROGATE;
+    public static final int MIN_SUPPLEMENTARY_CODE_POINT = java.lang.Character.MIN_SUPPLEMENTARY_CODE_POINT;
+    public static final int MIN_CODE_POINT = java.lang.Character.MIN_CODE_POINT;
+    public static final int MAX_CODE_POINT = java.lang.Character.MAX_CODE_POINT;
+    public static final int BYTES = java.lang.Character.BYTES;
+    public static final int SIZE = java.lang.Character.SIZE;
+
+    private final char value;
+
+    public Character(char c) {
+        this.value = c;
+    }
+
+    public char charValue() {
+        return this.value;
+    }
+
+    @Override
+    public int hashCode() {
+        return hashCode(this.value);
+    }
+
+    public static int hashCode(char value) {
+        return java.lang.Character.hashCode(value);
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof Character) && ((Character) other).value == value;
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Character.toString(value);
+    }
+
+    @Override
+    @NotNull
+    public String toDJVMString() {
+        return toString(value);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Character fromDJVM() {
+        return value;
+    }
+
+    @Override
+    public int compareTo(@NotNull Character var1) {
+        return compare(this.value, var1.value);
+    }
+
+    public static int compare(char x, char y) {
+        return java.lang.Character.compare(x, y);
+    }
+
+    public static String toString(char c) {
+        return String.toDJVM(java.lang.Character.toString(c));
+    }
+
+    public static Character valueOf(char c) {
+        return (c <= 127) ? Cache.cache[(int)c] : new Character(c);
+    }
+
+    public static boolean isValidCodePoint(int codePoint) {
+        return java.lang.Character.isValidCodePoint(codePoint);
+    }
+
+    public static boolean isBmpCodePoint(int codePoint) {
+        return java.lang.Character.isBmpCodePoint(codePoint);
+    }
+
+    public static boolean isSupplementaryCodePoint(int codePoint) {
+        return java.lang.Character.isSupplementaryCodePoint(codePoint);
+    }
+
+    public static boolean isHighSurrogate(char ch) {
+        return java.lang.Character.isHighSurrogate(ch);
+    }
+
+    public static boolean isLowSurrogate(char ch) {
+        return java.lang.Character.isLowSurrogate(ch);
+    }
+
+    public static boolean isSurrogate(char ch) {
+        return java.lang.Character.isSurrogate(ch);
+    }
+
+    public static boolean isSurrogatePair(char high, char low) {
+        return java.lang.Character.isSurrogatePair(high, low);
+    }
+
+    public static int charCount(int codePoint) {
+        return java.lang.Character.charCount(codePoint);
+    }
+
+    public static int toCodePoint(char high, char low) {
+        return java.lang.Character.toCodePoint(high, low);
+    }
+
+    public static int codePointAt(CharSequence seq, int index) {
+        return java.lang.Character.codePointAt(seq, index);
+    }
+
+    public static int codePointAt(char[] a, int index) {
+        return java.lang.Character.codePointAt(a, index);
+    }
+
+    public static int codePointAt(char[] a, int index, int limit) {
+        return java.lang.Character.codePointAt(a, index, limit);
+    }
+
+    public static int codePointBefore(CharSequence seq, int index) {
+        return java.lang.Character.codePointBefore(seq, index);
+    }
+
+    public static int codePointBefore(char[] a, int index) {
+        return java.lang.Character.codePointBefore(a, index);
+    }
+
+    public static int codePointBefore(char[] a, int index, int limit) {
+        return java.lang.Character.codePointBefore(a, index, limit);
+    }
+
+    public static char highSurrogate(int codePoint) {
+        return java.lang.Character.highSurrogate(codePoint);
+    }
+
+    public static char lowSurrogate(int codePoint) {
+        return java.lang.Character.lowSurrogate(codePoint);
+    }
+
+    public static int toChars(int codePoint, char[] dst, int dstIndex) {
+        return java.lang.Character.toChars(codePoint, dst, dstIndex);
+    }
+
+    public static char[] toChars(int codePoint) {
+        return java.lang.Character.toChars(codePoint);
+    }
+
+    public static int codePointCount(CharSequence seq, int beginIndex, int endIndex) {
+        return java.lang.Character.codePointCount(seq, beginIndex, endIndex);
+    }
+
+    public static int codePointCount(char[] a, int offset, int count) {
+        return java.lang.Character.codePointCount(a, offset, count);
+    }
+
+    public static int offsetByCodePoints(CharSequence seq, int index, int codePointOffset) {
+        return java.lang.Character.offsetByCodePoints(seq, index, codePointOffset);
+    }
+
+    public static int offsetByCodePoints(char[] a, int start, int count, int index, int codePointOffset) {
+        return java.lang.Character.offsetByCodePoints(a, start, count, index, codePointOffset);
+    }
+
+    public static boolean isLowerCase(char ch) {
+        return java.lang.Character.isLowerCase(ch);
+    }
+
+    public static boolean isLowerCase(int codePoint) {
+        return java.lang.Character.isLowerCase(codePoint);
+    }
+
+    public static boolean isUpperCase(char ch) {
+        return  java.lang.Character.isUpperCase(ch);
+    }
+
+    public static boolean isUpperCase(int codePoint) {
+        return java.lang.Character.isUpperCase(codePoint);
+    }
+
+    public static boolean isTitleCase(char ch) {
+        return java.lang.Character.isTitleCase(ch);
+    }
+
+    public static boolean isTitleCase(int codePoint) {
+        return java.lang.Character.isTitleCase(codePoint);
+    }
+
+    public static boolean isDigit(char ch) {
+        return java.lang.Character.isDigit(ch);
+    }
+
+    public static boolean isDigit(int codePoint) {
+        return java.lang.Character.isDigit(codePoint);
+    }
+
+    public static boolean isDefined(char ch) {
+        return java.lang.Character.isDefined(ch);
+    }
+
+    public static boolean isDefined(int codePoint) {
+        return java.lang.Character.isDefined(codePoint);
+    }
+
+    public static boolean isLetter(char ch) {
+        return java.lang.Character.isLetter(ch);
+    }
+
+    public static boolean isLetter(int codePoint) {
+        return java.lang.Character.isLetter(codePoint);
+    }
+
+    public static boolean isLetterOrDigit(char ch) {
+        return java.lang.Character.isLetterOrDigit(ch);
+    }
+
+    public static boolean isLetterOrDigit(int codePoint) {
+        return java.lang.Character.isLetterOrDigit(codePoint);
+    }
+
+    @Deprecated
+    public static boolean isJavaLetter(char ch) {
+        return java.lang.Character.isJavaLetter(ch);
+    }
+
+    @Deprecated
+    public static boolean isJavaLetterOrDigit(char ch) {
+        return java.lang.Character.isJavaLetterOrDigit(ch);
+    }
+
+    public static boolean isAlphabetic(int codePoint) {
+        return java.lang.Character.isAlphabetic(codePoint);
+    }
+
+    public static boolean isIdeographic(int codePoint) {
+        return java.lang.Character.isIdeographic(codePoint);
+    }
+
+    public static boolean isJavaIdentifierStart(char ch) {
+        return java.lang.Character.isJavaIdentifierStart(ch);
+    }
+
+    public static boolean isJavaIdentifierStart(int codePoint) {
+        return java.lang.Character.isJavaIdentifierStart(codePoint);
+    }
+
+    public static boolean isJavaIdentifierPart(char ch) {
+        return java.lang.Character.isJavaIdentifierPart(ch);
+    }
+
+    public static boolean isJavaIdentifierPart(int codePoint) {
+        return java.lang.Character.isJavaIdentifierPart(codePoint);
+    }
+
+    public static boolean isUnicodeIdentifierStart(char ch) {
+        return java.lang.Character.isUnicodeIdentifierStart(ch);
+    }
+
+    public static boolean isUnicodeIdentifierStart(int codePoint) {
+        return java.lang.Character.isUnicodeIdentifierStart(codePoint);
+    }
+
+    public static boolean isUnicodeIdentifierPart(char ch) {
+        return java.lang.Character.isUnicodeIdentifierPart(ch);
+    }
+
+    public static boolean isUnicodeIdentifierPart(int codePoint) {
+        return java.lang.Character.isUnicodeIdentifierPart(codePoint);
+    }
+
+    public static boolean isIdentifierIgnorable(char ch) {
+        return java.lang.Character.isIdentifierIgnorable(ch);
+    }
+
+    public static boolean isIdentifierIgnorable(int codePoint) {
+        return java.lang.Character.isIdentifierIgnorable(codePoint);
+    }
+
+    public static char toLowerCase(char ch) {
+        return java.lang.Character.toLowerCase(ch);
+    }
+
+    public static int toLowerCase(int codePoint) {
+        return java.lang.Character.toLowerCase(codePoint);
+    }
+
+    public static char toUpperCase(char ch) {
+        return java.lang.Character.toUpperCase(ch);
+    }
+
+    public static int toUpperCase(int codePoint) {
+        return java.lang.Character.toUpperCase(codePoint);
+    }
+
+    public static char toTitleCase(char ch) {
+        return java.lang.Character.toTitleCase(ch);
+    }
+
+    public static int toTitleCase(int codePoint) {
+        return java.lang.Character.toTitleCase(codePoint);
+    }
+
+    public static int digit(char ch, int radix) {
+        return java.lang.Character.digit(ch, radix);
+    }
+
+    public static int digit(int codePoint, int radix) {
+        return java.lang.Character.digit(codePoint, radix);
+    }
+
+    public static int getNumericValue(char ch) {
+        return java.lang.Character.getNumericValue(ch);
+    }
+
+    public static int getNumericValue(int codePoint) {
+        return java.lang.Character.getNumericValue(codePoint);
+    }
+
+    @Deprecated
+    public static boolean isSpace(char ch) {
+        return java.lang.Character.isSpace(ch);
+    }
+
+    public static boolean isSpaceChar(char ch) {
+        return java.lang.Character.isSpaceChar(ch);
+    }
+
+    public static boolean isSpaceChar(int codePoint) {
+        return java.lang.Character.isSpaceChar(codePoint);
+    }
+
+    public static boolean isWhitespace(char ch) {
+        return java.lang.Character.isWhitespace(ch);
+    }
+
+    public static boolean isWhitespace(int codePoint) {
+        return java.lang.Character.isWhitespace(codePoint);
+    }
+
+    public static boolean isISOControl(char ch) {
+        return java.lang.Character.isISOControl(ch);
+    }
+
+    public static boolean isISOControl(int codePoint) {
+        return java.lang.Character.isISOControl(codePoint);
+    }
+
+    public static int getType(char ch) {
+        return java.lang.Character.getType(ch);
+    }
+
+    public static int getType(int codePoint) {
+        return java.lang.Character.getType(codePoint);
+    }
+
+    public static char forDigit(int digit, int radix) {
+        return java.lang.Character.forDigit(digit, radix);
+    }
+
+    public static byte getDirectionality(char ch) {
+        return java.lang.Character.getDirectionality(ch);
+    }
+
+    public static byte getDirectionality(int codePoint) {
+        return java.lang.Character.getDirectionality(codePoint);
+    }
+
+    public static boolean isMirrored(char ch) {
+        return java.lang.Character.isMirrored(ch);
+    }
+
+    public static boolean isMirrored(int codePoint) {
+        return java.lang.Character.isMirrored(codePoint);
+    }
+
+    public static String getName(int codePoint) {
+        return String.toDJVM(java.lang.Character.getName(codePoint));
+    }
+
+    public static Character toDJVM(java.lang.Character c) {
+        return (c == null) ? null : valueOf(c);
+    }
+
+    // These three nested classes are placeholders to ensure that
+    // the Character class bytecode is generated correctly. The
+    // real classes will be loaded from the from the bootstrap jar
+    // and then mapped into the sandbox.* namespace.
+    public static final class UnicodeScript extends Enum<UnicodeScript> {
+        private UnicodeScript(String name, int index) {
+            super(name, index);
+        }
+
+        @Override
+        public int compareTo(@NotNull UnicodeScript other) {
+            throw new UnsupportedOperationException("Bootstrap implementation");
+        }
+    }
+    public static final class UnicodeBlock extends Subset {}
+    public static class Subset extends Object {}
+
+    /**
+     * Keep pre-allocated instances of the first 128 characters
+     * on the basis that these will be used most frequently.
+     */
+    private static class Cache {
+        private static final Character[] cache = new Character[128];
+
+        static {
+            for (int c = 0; c < cache.length; ++c) {
+                cache[c] = new Character((char) c);
+            }
+        }
+
+        private Cache() {}
+    }
+}

djvm/src/main/java/sandbox/java/lang/Comparable.java

@@ -0,0 +1,8 @@
+package sandbox.java.lang;
+
+/**
+ * This is a dummy class that implements just enough of [java.lang.Comparable]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+public interface Comparable<T> extends java.lang.Comparable<T> {
+}

djvm/src/main/java/sandbox/java/lang/Double.java

@@ -0,0 +1,163 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Double extends Number implements Comparable<Double> {
+    public static final double POSITIVE_INFINITY = java.lang.Double.POSITIVE_INFINITY;
+    public static final double NEGATIVE_INFINITY = java.lang.Double.NEGATIVE_INFINITY;
+    public static final double NaN = java.lang.Double.NaN;
+    public static final double MAX_VALUE = java.lang.Double.MAX_VALUE;
+    public static final double MIN_NORMAL = java.lang.Double.MIN_NORMAL;
+    public static final double MIN_VALUE = java.lang.Double.MIN_VALUE;
+    public static final int MAX_EXPONENT = java.lang.Double.MAX_EXPONENT;
+    public static final int MIN_EXPONENT = java.lang.Double.MIN_EXPONENT;
+    public static final int BYTES = java.lang.Double.BYTES;
+    public static final int SIZE = java.lang.Double.SIZE;
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Double> TYPE = (Class) java.lang.Double.TYPE;
+
+    private final double value;
+
+    public Double(double value) {
+        this.value = value;
+    }
+
+    public Double(String s) throws NumberFormatException {
+        this.value = parseDouble(s);
+    }
+
+    @Override
+    public double doubleValue() {
+        return value;
+    }
+
+    @Override
+    public float floatValue() {
+        return (float)value;
+    }
+
+    @Override
+    public long longValue() {
+        return (long)value;
+    }
+
+    @Override
+    public int intValue() {
+        return (int)value;
+    }
+
+    @Override
+    public short shortValue() {
+        return (short)value;
+    }
+
+    @Override
+    public byte byteValue() {
+        return (byte)value;
+    }
+
+    public boolean isNaN() {
+        return java.lang.Double.isNaN(value);
+    }
+
+    public boolean isInfinite() {
+        return isInfinite(this.value);
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof Double) && doubleToLongBits(((Double)other).value) == doubleToLongBits(value);
+    }
+
+    @Override
+    public int hashCode() {
+        return hashCode(value);
+    }
+
+    public static int hashCode(double d) {
+        return java.lang.Double.hashCode(d);
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Double.toString(value);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Double fromDJVM() {
+        return value;
+    }
+
+    @Override
+    public int compareTo(@NotNull Double other) {
+        return compare(this.value, other.value);
+    }
+
+    public static String toString(double d) {
+        return String.toDJVM(java.lang.Double.toString(d));
+    }
+
+    public static String toHexString(double d) {
+        return String.toDJVM(java.lang.Double.toHexString(d));
+    }
+
+    public static Double valueOf(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Double.valueOf(String.fromDJVM(s)));
+    }
+
+    public static Double valueOf(double d) {
+        return new Double(d);
+    }
+
+    public static double parseDouble(String s) throws NumberFormatException {
+        return java.lang.Double.parseDouble(String.fromDJVM(s));
+    }
+
+    public static boolean isNaN(double d) {
+        return java.lang.Double.isNaN(d);
+    }
+
+    public static boolean isInfinite(double d) {
+        return java.lang.Double.isInfinite(d);
+    }
+
+    public static boolean isFinite(double d) {
+        return java.lang.Double.isFinite(d);
+    }
+
+    public static long doubleToLongBits(double d) {
+        return java.lang.Double.doubleToLongBits(d);
+    }
+
+    public static long doubleToRawLongBits(double d) {
+        return java.lang.Double.doubleToRawLongBits(d);
+    }
+
+    public static double longBitsToDouble(long bits) {
+        return java.lang.Double.longBitsToDouble(bits);
+    }
+
+    public static int compare(double d1, double d2) {
+        return java.lang.Double.compare(d1, d2);
+    }
+
+    public static double sum(double a, double b) {
+        return java.lang.Double.sum(a, b);
+    }
+
+    public static double max(double a, double b) {
+        return java.lang.Double.max(a, b);
+    }
+
+    public static double min(double a, double b) {
+        return java.lang.Double.min(a, b);
+    }
+
+    public static Double toDJVM(java.lang.Double d) {
+        return (d == null) ? null : valueOf(d);
+    }
+}

djvm/src/main/java/sandbox/java/lang/Enum.java

@@ -0,0 +1,27 @@
+package sandbox.java.lang;
+
+import java.io.Serializable;
+
+/**
+ * This is a dummy class. We will load the actual Enum class at run-time.
+ */
+@SuppressWarnings("unused")
+public abstract class Enum<E extends Enum<E>> extends Object implements Comparable<E>, Serializable {
+
+    private final String name;
+    private final int ordinal;
+
+    protected Enum(String name, int ordinal) {
+        this.name = name;
+        this.ordinal = ordinal;
+    }
+
+    public String name() {
+        return name;
+    }
+
+    public int ordinal() {
+        return ordinal;
+    }
+
+}

djvm/src/main/java/sandbox/java/lang/Float.java

@@ -0,0 +1,163 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Float extends Number implements Comparable<Float> {
+    public static final float POSITIVE_INFINITY = java.lang.Float.POSITIVE_INFINITY;
+    public static final float NEGATIVE_INFINITY = java.lang.Float.NEGATIVE_INFINITY;
+    public static final float NaN = java.lang.Float.NaN;
+    public static final float MAX_VALUE = java.lang.Float.MAX_VALUE;
+    public static final float MIN_NORMAL = java.lang.Float.MIN_NORMAL;
+    public static final float MIN_VALUE = java.lang.Float.MIN_VALUE;
+    public static final int MAX_EXPONENT = java.lang.Float.MAX_EXPONENT;
+    public static final int MIN_EXPONENT = java.lang.Float.MIN_EXPONENT;
+    public static final int BYTES = java.lang.Float.BYTES;
+    public static final int SIZE = java.lang.Float.SIZE;
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Float> TYPE = (Class) java.lang.Float.TYPE;
+
+    private final float value;
+
+    public Float(float value) {
+        this.value = value;
+    }
+
+    public Float(String s) throws NumberFormatException {
+        this.value = parseFloat(s);
+    }
+
+    @Override
+    public int hashCode() {
+        return hashCode(value);
+    }
+
+    public static int hashCode(float f) {
+        return java.lang.Float.hashCode(f);
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return other instanceof Float && floatToIntBits(((Float)other).value) == floatToIntBits(this.value);
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Float.toString(value);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Float fromDJVM() {
+        return value;
+    }
+
+    @Override
+    public double doubleValue() {
+        return (double)value;
+    }
+
+    @Override
+    public float floatValue() {
+        return value;
+    }
+
+    @Override
+    public long longValue() {
+        return (long)value;
+    }
+
+    @Override
+    public int intValue() {
+        return (int)value;
+    }
+
+    @Override
+    public short shortValue() {
+        return (short)value;
+    }
+
+    @Override
+    public byte byteValue() {
+        return (byte)value;
+    }
+
+    @Override
+    public int compareTo(@NotNull Float other) {
+        return compare(this.value, other.value);
+    }
+
+    public boolean isNaN() {
+        return isNaN(value);
+    }
+
+    public boolean isInfinite() {
+        return isInfinite(value);
+    }
+
+    public static String toString(float f) {
+        return String.valueOf(f);
+    }
+
+    public static String toHexString(float f) {
+        return String.toDJVM(java.lang.Float.toHexString(f));
+    }
+
+    public static Float valueOf(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Float.valueOf(String.fromDJVM(s)));
+    }
+
+    public static Float valueOf(float f) {
+        return new Float(f);
+    }
+
+    public static float parseFloat(String s) throws NumberFormatException {
+        return java.lang.Float.parseFloat(String.fromDJVM(s));
+    }
+
+    public static boolean isNaN(float f) {
+        return java.lang.Float.isNaN(f);
+    }
+
+    public static boolean isInfinite(float f) {
+        return java.lang.Float.isInfinite(f);
+    }
+
+    public static boolean isFinite(float f) {
+        return java.lang.Float.isFinite(f);
+    }
+
+    public static int floatToIntBits(float f) {
+        return java.lang.Float.floatToIntBits(f);
+    }
+
+    public static int floatToRawIntBits(float f) {
+        return java.lang.Float.floatToIntBits(f);
+    }
+
+    public static float intBitsToFloat(int bits) {
+        return java.lang.Float.intBitsToFloat(bits);
+    }
+
+    public static int compare(float f1, float f2) {
+        return java.lang.Float.compare(f1, f2);
+    }
+
+    public static float sum(float a, float b) {
+        return java.lang.Float.sum(a, b);
+    }
+
+    public static float max(float a, float b) {
+        return java.lang.Float.max(a, b);
+    }
+
+    public static float min(float a, float b) {
+        return java.lang.Float.min(a, b);
+    }
+
+    public static Float toDJVM(java.lang.Float f) {
+        return (f == null) ? null : valueOf(f);
+    }
+}

djvm/src/main/java/sandbox/java/lang/Integer.java

@@ -0,0 +1,241 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Integer extends Number implements Comparable<Integer> {
+
+    public static final int MIN_VALUE = java.lang.Integer.MIN_VALUE;
+    public static final int MAX_VALUE = java.lang.Integer.MAX_VALUE;
+    public static final int BYTES = java.lang.Integer.BYTES;
+    public static final int SIZE = java.lang.Integer.SIZE;
+
+    static final int[] SIZE_TABLE = new int[] { 9, 99, 999, 9999, 99999, 999999, 9999999, 99999999, 999999999, MAX_VALUE };
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Integer> TYPE = (Class) java.lang.Integer.TYPE;
+
+    private final int value;
+
+    public Integer(int value) {
+        this.value = value;
+    }
+
+    public Integer(String s) throws NumberFormatException {
+        this.value = parseInt(s, 10);
+    }
+
+    @Override
+    public int hashCode() {
+        return Integer.hashCode(value);
+    }
+
+    public static int hashCode(int i) {
+        return java.lang.Integer.hashCode(i);
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof Integer) && (value == ((Integer) other).value);
+    }
+
+    @Override
+    public int intValue() {
+        return value;
+    }
+
+    @Override
+    public long longValue() {
+        return value;
+    }
+
+    @Override
+    public short shortValue() {
+        return (short) value;
+    }
+
+    @Override
+    public byte byteValue() {
+        return (byte) value;
+    }
+
+    @Override
+    public float floatValue() {
+        return (float) value;
+    }
+
+    @Override
+    public double doubleValue() {
+        return (double) value;
+    }
+
+    @Override
+    public int compareTo(@NotNull Integer other) {
+        return compare(this.value, other.value);
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Integer.toString(value);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Integer fromDJVM() {
+        return value;
+    }
+
+    public static String toString(int i, int radix) {
+        return String.toDJVM(java.lang.Integer.toString(i, radix));
+    }
+
+    public static String toUnsignedString(int i, int radix) {
+        return String.toDJVM(java.lang.Integer.toUnsignedString(i, radix));
+    }
+
+    public static String toHexString(int i) {
+        return String.toDJVM(java.lang.Integer.toHexString(i));
+    }
+
+    public static String toOctalString(int i) {
+        return String.toDJVM(java.lang.Integer.toOctalString(i));
+    }
+
+    public static String toBinaryString(int i) {
+        return String.toDJVM(java.lang.Integer.toBinaryString(i));
+    }
+
+    public static String toString(int i) {
+        return String.toDJVM(java.lang.Integer.toString(i));
+    }
+
+    public static String toUnsignedString(int i) {
+        return String.toDJVM(java.lang.Integer.toUnsignedString(i));
+    }
+
+    public static int parseInt(String s, int radix) throws NumberFormatException {
+        return java.lang.Integer.parseInt(String.fromDJVM(s), radix);
+    }
+
+    public static int parseInt(String s) throws NumberFormatException {
+        return java.lang.Integer.parseInt(String.fromDJVM(s));
+    }
+
+    public static int parseUnsignedInt(String s, int radix) throws NumberFormatException {
+        return java.lang.Integer.parseUnsignedInt(String.fromDJVM(s), radix);
+    }
+
+    public static int parseUnsignedInt(String s) throws NumberFormatException {
+        return java.lang.Integer.parseUnsignedInt(String.fromDJVM(s));
+    }
+
+    public static Integer valueOf(String s, int radix) throws NumberFormatException {
+        return toDJVM(java.lang.Integer.valueOf(String.fromDJVM(s), radix));
+    }
+
+    public static Integer valueOf(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Integer.valueOf(String.fromDJVM(s)));
+    }
+
+    public static Integer valueOf(int i) {
+        return new Integer(i);
+    }
+
+    public static Integer decode(String nm) throws NumberFormatException {
+        return new Integer(java.lang.Integer.decode(String.fromDJVM(nm)));
+    }
+
+    public static int compare(int x, int y) {
+        return java.lang.Integer.compare(x, y);
+    }
+
+    public static int compareUnsigned(int x, int y) {
+        return java.lang.Integer.compareUnsigned(x, y);
+    }
+
+    public static long toUnsignedLong(int x) {
+        return java.lang.Integer.toUnsignedLong(x);
+    }
+
+    public static int divideUnsigned(int dividend, int divisor) {
+        return java.lang.Integer.divideUnsigned(dividend, divisor);
+    }
+
+    public static int remainderUnsigned(int dividend, int divisor) {
+        return java.lang.Integer.remainderUnsigned(dividend, divisor);
+    }
+
+    public static int highestOneBit(int i) {
+        return java.lang.Integer.highestOneBit(i);
+    }
+
+    public static int lowestOneBit(int i) {
+        return java.lang.Integer.lowestOneBit(i);
+    }
+
+    public static int numberOfLeadingZeros(int i) {
+        return java.lang.Integer.numberOfLeadingZeros(i);
+    }
+
+    public static int numberOfTrailingZeros(int i) {
+        return java.lang.Integer.numberOfTrailingZeros(i);
+    }
+
+    public static int bitCount(int i) {
+        return java.lang.Integer.bitCount(i);
+    }
+
+    public static int rotateLeft(int i, int distance) {
+        return java.lang.Integer.rotateLeft(i, distance);
+    }
+
+    public static int rotateRight(int i, int distance) {
+        return java.lang.Integer.rotateRight(i, distance);
+    }
+
+    public static int reverse(int i) {
+        return java.lang.Integer.reverse(i);
+    }
+
+    public static int signum(int i) {
+        return java.lang.Integer.signum(i);
+    }
+
+    public static int reverseBytes(int i) {
+        return java.lang.Integer.reverseBytes(i);
+    }
+
+    public static int sum(int a, int b) {
+        return java.lang.Integer.sum(a, b);
+    }
+
+    public static int max(int a, int b) {
+        return java.lang.Integer.max(a, b);
+    }
+
+    public static int min(int a, int b) {
+        return java.lang.Integer.min(a, b);
+    }
+
+    public static Integer toDJVM(java.lang.Integer i) {
+        return (i == null) ? null : valueOf(i);
+    }
+
+    static int stringSize(final int number) {
+        int i = 0;
+        while (number > SIZE_TABLE[i]) {
+            ++i;
+        }
+        return i + 1;
+    }
+
+    static void getChars(final int number, int index, char[] buffer) {
+        java.lang.String s = java.lang.Integer.toString(number);
+        int length = s.length();
+
+        while (length > 0) {
+            buffer[--index] = s.charAt(--length);
+        }
+    }
+}

djvm/src/main/java/sandbox/java/lang/Iterable.java

@@ -0,0 +1,15 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Iterator;
+
+/**
+ * This is a dummy class that implements just enough of [java.lang.Iterable]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+public interface Iterable<T> extends java.lang.Iterable<T> {
+    @Override
+    @NotNull
+    Iterator<T> iterator();
+}

djvm/src/main/java/sandbox/java/lang/Long.java

@@ -0,0 +1,239 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Long extends Number implements Comparable<Long> {
+
+    public static final long MIN_VALUE = java.lang.Long.MIN_VALUE;
+    public static final long MAX_VALUE = java.lang.Long.MAX_VALUE;
+    public static final int BYTES = java.lang.Long.BYTES;
+    public static final int SIZE = java.lang.Long.SIZE;
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Long> TYPE = (Class) java.lang.Long.TYPE;
+
+    private final long value;
+
+    public Long(long value) {
+        this.value = value;
+    }
+
+    public Long(String s) throws NumberFormatException {
+        this.value = parseLong(s, 10);
+    }
+
+    @Override
+    public int hashCode() {
+        return hashCode(value);
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof Long) && ((Long) other).longValue() == value;
+    }
+
+    public static int hashCode(long l) {
+        return java.lang.Long.hashCode(l);
+    }
+
+    @Override
+    public int intValue() {
+        return (int) value;
+    }
+
+    @Override
+    public long longValue() {
+        return value;
+    }
+
+    @Override
+    public short shortValue() {
+        return (short) value;
+    }
+
+    @Override
+    public byte byteValue() {
+        return (byte) value;
+    }
+
+    @Override
+    public float floatValue() {
+        return (float) value;
+    }
+
+    @Override
+    public double doubleValue() {
+        return (double) value;
+    }
+
+    @Override
+    public int compareTo(@NotNull Long other) {
+        return compare(value, other.value);
+    }
+
+    public static int compare(long x, long y) {
+        return java.lang.Long.compare(x, y);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Long fromDJVM() {
+        return value;
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Long.toString(value);
+    }
+
+    public static String toString(long l) {
+        return String.toDJVM(java.lang.Long.toString(l));
+    }
+
+    public static String toString(long l, int radix) {
+        return String.toDJVM(java.lang.Long.toString(l, radix));
+    }
+
+    public static String toUnsignedString(long l, int radix) {
+        return String.toDJVM(java.lang.Long.toUnsignedString(l, radix));
+    }
+
+    public static String toUnsignedString(long l) {
+        return String.toDJVM(java.lang.Long.toUnsignedString(l));
+    }
+
+    public static String toHexString(long l) {
+        return String.toDJVM(java.lang.Long.toHexString(l));
+    }
+
+    public static String toOctalString(long l) {
+        return String.toDJVM(java.lang.Long.toOctalString(l));
+    }
+
+    public static String toBinaryString(long l) {
+        return String.toDJVM(java.lang.Long.toBinaryString(l));
+    }
+
+    public static long parseLong(String s, int radix) throws NumberFormatException {
+        return java.lang.Long.parseLong(String.fromDJVM(s), radix);
+    }
+
+    public static long parseLong(String s) throws NumberFormatException {
+        return java.lang.Long.parseLong(String.fromDJVM(s));
+    }
+
+    public static long parseUnsignedLong(String s, int radix) throws NumberFormatException {
+        return java.lang.Long.parseUnsignedLong(String.fromDJVM(s), radix);
+    }
+
+    public static long parseUnsignedLong(String s) throws NumberFormatException {
+        return java.lang.Long.parseUnsignedLong(String.fromDJVM(s));
+    }
+
+    public static Long valueOf(String s, int radix) throws NumberFormatException {
+        return toDJVM(java.lang.Long.valueOf(String.fromDJVM(s), radix));
+    }
+
+    public static Long valueOf(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Long.valueOf(String.fromDJVM(s)));
+    }
+
+    public static Long valueOf(long l) {
+        return new Long(l);
+    }
+
+    public static Long decode(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Long.decode(String.fromDJVM(s)));
+    }
+
+    public static int compareUnsigned(long x, long y) {
+        return java.lang.Long.compareUnsigned(x, y);
+    }
+
+    public static long divideUnsigned(long dividend, long divisor) {
+        return java.lang.Long.divideUnsigned(dividend, divisor);
+    }
+
+    public static long remainderUnsigned(long dividend, long divisor) {
+        return java.lang.Long.remainderUnsigned(dividend, divisor);
+    }
+
+    public static long highestOneBit(long l) {
+        return java.lang.Long.highestOneBit(l);
+    }
+
+    public static long lowestOneBit(long l) {
+        return java.lang.Long.lowestOneBit(l);
+    }
+
+    public static int numberOfLeadingZeros(long l) {
+        return java.lang.Long.numberOfLeadingZeros(l);
+    }
+
+    public static int numberOfTrailingZeros(long l) {
+        return java.lang.Long.numberOfTrailingZeros(l);
+    }
+
+    public static int bitCount(long l) {
+        return java.lang.Long.bitCount(l);
+    }
+
+    public static long rotateLeft(long i, int distance) {
+        return java.lang.Long.rotateLeft(i, distance);
+    }
+
+    public static long rotateRight(long i, int distance) {
+        return java.lang.Long.rotateRight(i, distance);
+    }
+
+    public static long reverse(long l) {
+        return java.lang.Long.reverse(l);
+    }
+
+    public static int signum(long l) {
+        return java.lang.Long.signum(l);
+    }
+
+    public static long reverseBytes(long l) {
+        return java.lang.Long.reverseBytes(l);
+    }
+
+    public static long sum(long a, long b) {
+        return java.lang.Long.sum(a, b);
+    }
+
+    public static long max(long a, long b) {
+        return java.lang.Long.max(a, b);
+    }
+
+    public static long min(long a, long b) {
+        return java.lang.Long.min(a, b);
+    }
+
+    public static Long toDJVM(java.lang.Long l) {
+        return (l == null) ? null : valueOf(l);
+    }
+
+    static int stringSize(final long number) {
+        long l = 10;
+        int i = 1;
+
+        while ((i < 19) && (number >= l)) {
+            l *= 10;
+            ++i;
+        }
+
+        return i;
+    }
+
+    static void getChars(final long number, int index, char[] buffer) {
+        java.lang.String s = java.lang.Long.toString(number);
+        int length = s.length();
+
+        while (length > 0) {
+            buffer[--index] = s.charAt(--length);
+        }
+    }
+}

djvm/src/main/java/sandbox/java/lang/Number.java

@@ -0,0 +1,21 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+import java.io.Serializable;
+
+@SuppressWarnings("unused")
+public abstract class Number extends Object implements Serializable {
+
+    public abstract double doubleValue();
+    public abstract float floatValue();
+    public abstract long longValue();
+    public abstract int intValue();
+    public abstract short shortValue();
+    public abstract byte byteValue();
+
+    @Override
+    @NotNull
+    public String toDJVMString() {
+        return String.toDJVM(toString());
+    }
+}

djvm/src/main/java/sandbox/java/lang/Object.java

@@ -0,0 +1,71 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+import sandbox.net.corda.djvm.rules.RuleViolationError;
+
+public class Object {
+
+    @Override
+    public int hashCode() {
+        return sandbox.java.lang.System.identityHashCode(this);
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return toDJVMString().toString();
+    }
+
+    @NotNull
+    public String toDJVMString() {
+        return String.toDJVM("sandbox.java.lang.Object@" + java.lang.Integer.toString(hashCode(), 16));
+    }
+
+    @NotNull
+    java.lang.Object fromDJVM() {
+        return this;
+    }
+
+    public static java.lang.Object[] fromDJVM(java.lang.Object[] args) {
+        if (args == null) {
+            return null;
+        }
+
+        java.lang.Object[] unwrapped = (java.lang.Object[]) java.lang.reflect.Array.newInstance(
+            fromDJVM(args.getClass().getComponentType()), args.length
+        );
+        int i = 0;
+        for (java.lang.Object arg : args) {
+            unwrapped[i] = unwrap(arg);
+            ++i;
+        }
+        return unwrapped;
+    }
+
+    private static java.lang.Object unwrap(java.lang.Object arg) {
+        if (arg instanceof Object) {
+            return ((Object) arg).fromDJVM();
+        } else if (Object[].class.isAssignableFrom(arg.getClass())) {
+            return fromDJVM((Object[]) arg);
+        } else {
+            return arg;
+        }
+    }
+
+    private static Class<?> fromDJVM(Class<?> type) {
+        try {
+            java.lang.String name = type.getName();
+            return Class.forName(name.startsWith("sandbox.") ? name.substring(8) : name);
+        } catch (ClassNotFoundException e) {
+            throw new RuleViolationError(e.getMessage());
+        }
+    }
+
+    static java.util.Locale fromDJVM(sandbox.java.util.Locale locale) {
+        return java.util.Locale.forLanguageTag(locale.toLanguageTag().fromDJVM());
+    }
+
+    static java.nio.charset.Charset fromDJVM(sandbox.java.nio.charset.Charset charset) {
+        return java.nio.charset.Charset.forName(charset.name().fromDJVM());
+    }
+}

djvm/src/main/java/sandbox/java/lang/Runtime.java

@@ -0,0 +1,27 @@
+package sandbox.java.lang;
+
+@SuppressWarnings("unused")
+public final class Runtime extends Object {
+    private static final Runtime RUNTIME = new Runtime();
+
+    private Runtime() {}
+
+    public static Runtime getRuntime() {
+        return RUNTIME;
+    }
+
+    /**
+     * Everything inside the sandbox is single-threaded.
+     * @return 1
+     */
+    public int availableProcessors() {
+        return 1;
+    }
+
+    public void loadLibrary(String libraryName) {}
+
+    public void load(String fileName) {}
+
+    public void runFinalization() {}
+    public void gc() {}
+}

djvm/src/main/java/sandbox/java/lang/Short.java

@@ -0,0 +1,128 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+
+@SuppressWarnings({"unused", "WeakerAccess"})
+public final class Short extends Number implements Comparable<Short> {
+    public static final short MIN_VALUE = java.lang.Short.MIN_VALUE;
+    public static final short MAX_VALUE = java.lang.Short.MAX_VALUE;
+    public static final int BYTES = java.lang.Short.BYTES;
+    public static final int SIZE = java.lang.Short.SIZE;
+
+    @SuppressWarnings("unchecked")
+    public static final Class<Short> TYPE = (Class) java.lang.Short.TYPE;
+
+    private final short value;
+
+    public Short(short value) {
+        this.value = value;
+    }
+
+    public Short(String s) throws NumberFormatException {
+        this.value = parseShort(s);
+    }
+
+    @Override
+    public byte byteValue() {
+        return (byte)value;
+    }
+
+    @Override
+    public short shortValue() {
+        return value;
+    }
+
+    @Override
+    public int intValue() {
+        return value;
+    }
+
+    @Override
+    public long longValue() {
+        return (long)value;
+    }
+
+    @Override
+    public float floatValue() {
+        return (float)value;
+    }
+
+    @Override
+    public double doubleValue() {
+        return (double)value;
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return java.lang.Integer.toString(value);
+    }
+
+    @Override
+    @NotNull
+    java.lang.Short fromDJVM() {
+        return value;
+    }
+
+    @Override
+    public int hashCode() {
+        return hashCode(value);
+    }
+
+    public static int hashCode(short value) {
+        return java.lang.Short.hashCode(value);
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof Short) && ((Short) other).value == value;
+    }
+
+    public int compareTo(@NotNull Short other) {
+        return compare(this.value, other.value);
+    }
+
+    public static int compare(short x, short y) {
+        return java.lang.Short.compare(x, y);
+    }
+
+    public static short reverseBytes(short value) {
+        return java.lang.Short.reverseBytes(value);
+    }
+
+    public static int toUnsignedInt(short x) {
+        return java.lang.Short.toUnsignedInt(x);
+    }
+
+    public static long toUnsignedLong(short x) {
+        return java.lang.Short.toUnsignedLong(x);
+    }
+
+    public static short parseShort(String s, int radix) throws NumberFormatException {
+        return java.lang.Short.parseShort(String.fromDJVM(s), radix);
+    }
+
+    public static short parseShort(String s) throws NumberFormatException {
+        return java.lang.Short.parseShort(String.fromDJVM(s));
+    }
+
+    public static Short valueOf(String s, int radix) throws NumberFormatException {
+        return toDJVM(java.lang.Short.valueOf(String.fromDJVM(s), radix));
+    }
+
+    public static Short valueOf(String s) throws NumberFormatException {
+        return toDJVM(java.lang.Short.valueOf(String.fromDJVM(s)));
+    }
+
+    public static Short valueOf(short s) {
+        return new Short(s);
+    }
+
+    public static Short decode(String nm) throws NumberFormatException {
+        return toDJVM(java.lang.Short.decode(String.fromDJVM(nm)));
+    }
+
+    public static Short toDJVM(java.lang.Short i) {
+        return (i == null) ? null : valueOf(i);
+    }
+}

djvm/src/main/java/sandbox/java/lang/String.java

@@ -0,0 +1,398 @@
+package sandbox.java.lang;
+
+import org.jetbrains.annotations.NotNull;
+import sandbox.java.nio.charset.Charset;
+import sandbox.java.util.Comparator;
+import sandbox.java.util.Locale;
+
+import java.io.Serializable;
+import java.io.UnsupportedEncodingException;
+
+@SuppressWarnings("unused")
+public final class String extends Object implements Comparable<String>, CharSequence, Serializable {
+    public static final Comparator<String> CASE_INSENSITIVE_ORDER = new CaseInsensitiveComparator();
+
+    private static class CaseInsensitiveComparator extends Object implements Comparator<String>, Serializable {
+        @Override
+        public int compare(String s1, String s2) {
+            return java.lang.String.CASE_INSENSITIVE_ORDER.compare(String.fromDJVM(s1), String.fromDJVM(s2));
+        }
+    }
+
+    private static final String TRUE = new String("true");
+    private static final String FALSE = new String("false");
+
+    private final java.lang.String value;
+
+    public String() {
+        this.value = "";
+    }
+
+    public String(java.lang.String value) {
+        this.value = value;
+    }
+
+    public String(char value[]) {
+        this.value = new java.lang.String(value);
+    }
+
+    public String(char value[], int offset, int count) {
+        this.value = new java.lang.String(value, offset, count);
+    }
+
+    public String(int[] codePoints, int offset, int count) {
+        this.value = new java.lang.String(codePoints, offset, count);
+    }
+
+    @Deprecated
+    public String(byte ascii[], int hibyte, int offset, int count) {
+        this.value = new java.lang.String(ascii, hibyte, offset, count);
+    }
+
+    @Deprecated
+    public String(byte ascii[], int hibyte) {
+        this.value = new java.lang.String(ascii, hibyte);
+    }
+
+    public String(byte bytes[], int offset, int length, String charsetName)
+            throws UnsupportedEncodingException {
+        this.value = new java.lang.String(bytes, offset, length, fromDJVM(charsetName));
+    }
+
+    public String(byte bytes[], int offset, int length, Charset charset) {
+        this.value = new java.lang.String(bytes, offset, length, fromDJVM(charset));
+    }
+
+    public String(byte bytes[], String charsetName)
+            throws UnsupportedEncodingException {
+        this.value = new java.lang.String(bytes, fromDJVM(charsetName));
+    }
+
+    public String(byte bytes[], Charset charset) {
+        this.value = new java.lang.String(bytes, fromDJVM(charset));
+    }
+
+    public String(byte bytes[], int offset, int length) {
+        this.value = new java.lang.String(bytes, offset, length);
+    }
+
+    public String(byte bytes[]) {
+        this.value = new java.lang.String(bytes);
+    }
+
+    public String(StringBuffer buffer) {
+        this.value = buffer.toString();
+    }
+
+    public String(StringBuilder builder) {
+        this.value = builder.toString();
+    }
+
+    @Override
+    public char charAt(int index) {
+        return value.charAt(index);
+    }
+
+    @Override
+    public int length() {
+        return value.length();
+    }
+
+    public boolean isEmpty() {
+        return value.isEmpty();
+    }
+
+    public int codePointAt(int index) {
+        return value.codePointAt(index);
+    }
+
+    public int codePointBefore(int index) {
+        return value.codePointBefore(index);
+    }
+
+    public int codePointCount(int beginIndex, int endIndex) {
+        return value.codePointCount(beginIndex, endIndex);
+    }
+
+    public int offsetByCodePoints(int index, int codePointOffset) {
+        return value.offsetByCodePoints(index, codePointOffset);
+    }
+
+    public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) {
+        value.getChars(srcBegin, srcEnd, dst, dstBegin);
+    }
+
+    @Deprecated
+    public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
+        value.getBytes(srcBegin, srcEnd, dst, dstBegin);
+    }
+
+    public byte[] getBytes(String charsetName) throws UnsupportedEncodingException {
+        return value.getBytes(fromDJVM(charsetName));
+    }
+
+    public byte[] getBytes(Charset charset) {
+        return value.getBytes(fromDJVM(charset));
+    }
+
+    public byte[] getBytes() {
+        return value.getBytes();
+    }
+
+    @Override
+    public boolean equals(java.lang.Object other) {
+        return (other instanceof String) && ((String) other).value.equals(value);
+    }
+
+    @Override
+    public int hashCode() {
+        return value.hashCode();
+    }
+
+    @Override
+    @NotNull
+    public java.lang.String toString() {
+        return value;
+    }
+
+    @Override
+    @NotNull
+    public String toDJVMString() {
+        return this;
+    }
+
+    @Override
+    @NotNull
+    java.lang.String fromDJVM() {
+        return value;
+    }
+
+    public boolean contentEquals(StringBuffer sb) {
+        return value.contentEquals((CharSequence) sb);
+    }
+
+    public boolean contentEquals(CharSequence cs) {
+        return value.contentEquals(cs);
+    }
+
+    public boolean equalsIgnoreCase(String anotherString) {
+        return value.equalsIgnoreCase(fromDJVM(anotherString));
+    }
+
+    @Override
+    public CharSequence subSequence(int start, int end) {
+        return toDJVM((java.lang.String) value.subSequence(start, end));
+    }
+
+    @Override
+    public int compareTo(@NotNull String other) {
+        return value.compareTo(other.toString());
+    }
+
+    public int compareToIgnoreCase(String str) {
+        return value.compareToIgnoreCase(fromDJVM(str));
+    }
+
+    public boolean regionMatches(int toffset, String other, int ooffset, int len) {
+        return value.regionMatches(toffset, fromDJVM(other), ooffset, len);
+    }
+
+    public boolean regionMatches(boolean ignoreCase, int toffset,
+                                 String other, int ooffset, int len) {
+        return value.regionMatches(ignoreCase, toffset, fromDJVM(other), ooffset, len);
+    }
+
+    public boolean startsWith(String prefix, int toffset) {
+        return value.startsWith(fromDJVM(prefix), toffset);
+    }
+
+    public boolean startsWith(String prefix) {
+        return value.startsWith(fromDJVM(prefix));
+    }
+
+    public boolean endsWith(String suffix) {
+        return value.endsWith(fromDJVM(suffix));
+    }
+
+    public int indexOf(int ch) {
+        return value.indexOf(ch);
+    }
+
+    public int indexOf(int ch, int fromIndex) {
+        return value.indexOf(ch, fromIndex);
+    }
+
+    public int lastIndexOf(int ch) {
+        return value.lastIndexOf(ch);
+    }
+
+    public int lastIndexOf(int ch, int fromIndex) {
+        return value.lastIndexOf(ch, fromIndex);
+    }
+
+    public int indexOf(String str) {
+        return value.indexOf(fromDJVM(str));
+    }
+
+    public int indexOf(String str, int fromIndex) {
+        return value.indexOf(fromDJVM(str), fromIndex);
+    }
+
+    public int lastIndexOf(String str) {
+        return value.lastIndexOf(fromDJVM(str));
+    }
+
+    public int lastIndexOf(String str, int fromIndex) {
+        return value.lastIndexOf(fromDJVM(str), fromIndex);
+    }
+
+    public String substring(int beginIndex) {
+        return toDJVM(value.substring(beginIndex));
+    }
+
+    public String substring(int beginIndex, int endIndex) {
+        return toDJVM(value.substring(beginIndex, endIndex));
+    }
+
+    public String concat(String str) {
+        return toDJVM(value.concat(fromDJVM(str)));
+    }
+
+    public String replace(char oldChar, char newChar) {
+        return toDJVM(value.replace(oldChar, newChar));
+    }
+
+    public boolean matches(String regex) {
+        return value.matches(fromDJVM(regex));
+    }
+
+    public boolean contains(CharSequence s) {
+        return value.contains(s);
+    }
+
+    public String replaceFirst(String regex, String replacement) {
+        return toDJVM(value.replaceFirst(fromDJVM(regex), fromDJVM(replacement)));
+    }
+
+    public String replaceAll(String regex, String replacement) {
+        return toDJVM(value.replaceAll(fromDJVM(regex), fromDJVM(replacement)));
+    }
+
+    public String replace(CharSequence target, CharSequence replacement) {
+        return toDJVM(value.replace(target, replacement));
+    }
+
+    public String[] split(String regex, int limit) {
+        return toDJVM(value.split(fromDJVM(regex), limit));
+    }
+
+    public String[] split(String regex) {
+        return toDJVM(value.split(fromDJVM(regex)));
+    }
+
+    public String toLowerCase(Locale locale) {
+        return toDJVM(value.toLowerCase(fromDJVM(locale)));
+    }
+
+    public String toLowerCase() {
+        return toDJVM(value.toLowerCase());
+    }
+
+    public String toUpperCase(Locale locale) {
+        return toDJVM(value.toUpperCase(fromDJVM(locale)));
+    }
+
+    public String toUpperCase() {
+        return toDJVM(value.toUpperCase());
+    }
+
+    public String trim() {
+        return toDJVM(value.trim());
+    }
+
+    public char[] toCharArray() {
+        return value.toCharArray();
+    }
+
+    public static String format(String format, java.lang.Object... args) {
+        return toDJVM(java.lang.String.format(fromDJVM(format), fromDJVM(args)));
+    }
+
+    public static String format(Locale locale, String format, java.lang.Object... args) {
+        return toDJVM(java.lang.String.format(fromDJVM(locale), fromDJVM(format), fromDJVM(args)));
+    }
+
+    public static String join(CharSequence delimiter, CharSequence... elements) {
+        return toDJVM(java.lang.String.join(delimiter, elements));
+    }
+
+    public static String join(CharSequence delimiter,
+                              Iterable<? extends CharSequence> elements) {
+        return toDJVM(java.lang.String.join(delimiter, elements));
+    }
+
+    public static String valueOf(java.lang.Object obj) {
+        return (obj instanceof Object) ? ((Object) obj).toDJVMString() : toDJVM(java.lang.String.valueOf(obj));
+    }
+
+    public static String valueOf(char data[]) {
+        return toDJVM(java.lang.String.valueOf(data));
+    }
+
+    public static String valueOf(char data[], int offset, int count) {
+        return toDJVM(java.lang.String.valueOf(data, offset, count));
+    }
+
+    public static String copyValueOf(char data[], int offset, int count) {
+        return toDJVM(java.lang.String.copyValueOf(data, offset, count));
+    }
+
+    public static String copyValueOf(char data[]) {
+        return toDJVM(java.lang.String.copyValueOf(data));
+    }
+
+    public static String valueOf(boolean b) {
+        return b ? TRUE : FALSE;
+    }
+
+    public static String valueOf(char c) {
+        return toDJVM(java.lang.String.valueOf(c));
+    }
+
+    public static String valueOf(int i) {
+        return toDJVM(java.lang.String.valueOf(i));
+    }
+
+    public static String valueOf(long l) {
+        return toDJVM(java.lang.String.valueOf(l));
+    }
+
+    public static String valueOf(float f) {
+        return toDJVM(java.lang.String.valueOf(f));
+    }
+
+    public static String valueOf(double d) {
+        return toDJVM(java.lang.String.valueOf(d));
+    }
+
+    static String[] toDJVM(java.lang.String[] value) {
+        if (value == null) {
+            return null;
+        }
+        String[] result = new String[value.length];
+        int i = 0;
+        for (java.lang.String v : value) {
+            result[i] = toDJVM(v);
+            ++i;
+        }
+        return result;
+    }
+
+    public static String toDJVM(java.lang.String value) {
+        return (value == null) ? null : new String(value);
+    }
+
+    public static java.lang.String fromDJVM(String value) {
+        return (value == null) ? null : value.fromDJVM();
+    }
+}

djvm/src/main/java/sandbox/java/lang/StringBuffer.java

@@ -0,0 +1,20 @@
+package sandbox.java.lang;
+
+import java.io.Serializable;
+
+/**
+ * This is a dummy class that implements just enough of [java.lang.StringBuffer]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+public abstract class StringBuffer extends Object implements CharSequence, Appendable, Serializable {
+
+    @Override
+    public abstract StringBuffer append(CharSequence seq);
+
+    @Override
+    public abstract StringBuffer append(CharSequence seq, int start, int end);
+
+    @Override
+    public abstract StringBuffer append(char c);
+
+}

djvm/src/main/java/sandbox/java/lang/StringBuilder.java

@@ -0,0 +1,20 @@
+package sandbox.java.lang;
+
+import java.io.Serializable;
+
+/**
+ * This is a dummy class that implements just enough of [java.lang.StringBuilder]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+public abstract class StringBuilder extends Object implements Appendable, CharSequence, Serializable {
+
+    @Override
+    public abstract StringBuilder append(CharSequence seq);
+
+    @Override
+    public abstract StringBuilder append(CharSequence seq, int start, int end);
+
+    @Override
+    public abstract StringBuilder append(char c);
+
+}

djvm/src/main/java/sandbox/java/lang/System.java

@@ -0,0 +1,28 @@
+package sandbox.java.lang;
+
+@SuppressWarnings({"WeakerAccess", "unused"})
+public final class System extends Object {
+
+    private System() {}
+
+    /*
+     * This class is duplicated into every sandbox, where everything is single-threaded.
+     */
+    private static final java.util.Map<java.lang.Integer, java.lang.Integer> objectHashCodes = new java.util.LinkedHashMap<>();
+    private static int objectCounter = 0;
+
+    public static int identityHashCode(java.lang.Object obj) {
+        int nativeHashCode = java.lang.System.identityHashCode(obj);
+        // TODO Instead of using a magic offset below, one could take in a per-context seed
+        return objectHashCodes.computeIfAbsent(nativeHashCode, i -> ++objectCounter + 0xfed_c0de);
+    }
+
+    public static final String lineSeparator = String.toDJVM("\n");
+
+    public static void arraycopy(java.lang.Object src, int srcPos, java.lang.Object dest, int destPos, int length) {
+        java.lang.System.arraycopy(src, srcPos, dest, destPos, length);
+    }
+
+    public static void runFinalization() {}
+    public static void gc() {}
+}

djvm/src/main/java/sandbox/java/lang/ThreadLocal.java

@@ -0,0 +1,59 @@
+package sandbox.java.lang;
+
+import sandbox.java.util.function.Supplier;
+
+/**
+ * Everything inside the sandbox is single-threaded, so this
+ * implementation of ThreadLocal<T> is sufficient.
+ * @param <T>
+ */
+@SuppressWarnings({"unused", "WeakerAccess"})
+public class ThreadLocal<T> extends Object {
+
+    private T value;
+    private boolean isSet;
+
+    public ThreadLocal() {
+    }
+
+    protected T initialValue() {
+        return null;
+    }
+
+    public T get() {
+        if (!isSet) {
+            set(initialValue());
+        }
+        return value;
+    }
+
+    public void set(T value) {
+        this.value = value;
+        this.isSet = true;
+    }
+
+    public void remove() {
+        value = null;
+        isSet = false;
+    }
+
+    public static <V> ThreadLocal<V> withInitial(Supplier<? extends V> supplier) {
+        return new SuppliedThreadLocal<>(supplier);
+    }
+
+    // Stub class for compiling ThreadLocal. The sandbox will import the
+    // actual SuppliedThreadLocal class at run-time. Having said that, we
+    // still need a working implementation here for the sake of our tests.
+    static final class SuppliedThreadLocal<T> extends ThreadLocal<T> {
+        private final Supplier<? extends T> supplier;
+
+        SuppliedThreadLocal(Supplier<? extends T> supplier) {
+            this.supplier = supplier;
+        }
+
+        @Override
+        protected T initialValue() {
+            return supplier.get();
+        }
+    }
+}

djvm/src/main/java/sandbox/java/nio/charset/Charset.java

@@ -0,0 +1,18 @@
+package sandbox.java.nio.charset;
+
+/**
+ * This is a dummy class that implements just enough of [java.nio.charset.Charset]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+@SuppressWarnings("unused")
+public abstract class Charset extends sandbox.java.lang.Object {
+    private final sandbox.java.lang.String canonicalName;
+
+    protected Charset(sandbox.java.lang.String canonicalName, sandbox.java.lang.String[] aliases) {
+        this.canonicalName = canonicalName;
+    }
+
+    public final sandbox.java.lang.String name() {
+        return canonicalName;
+    }
+}

djvm/src/main/java/sandbox/java/util/Comparator.java

@@ -0,0 +1,9 @@
+package sandbox.java.util;
+
+/**
+ * This is a dummy class that implements just enough of [java.util.Comparator]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+@FunctionalInterface
+public interface Comparator<T> extends java.util.Comparator<T> {
+}

djvm/src/main/java/sandbox/java/util/LinkedHashMap.java

@@ -0,0 +1,13 @@
+package sandbox.java.util;
+
+/**
+ * This is a dummy class to bootstrap us into the sandbox.
+ */
+public class LinkedHashMap<K, V> extends java.util.LinkedHashMap<K, V> implements Map<K, V> {
+    public LinkedHashMap(int initialSize) {
+        super(initialSize);
+    }
+
+    public LinkedHashMap() {
+    }
+}

djvm/src/main/java/sandbox/java/util/Locale.java

@@ -0,0 +1,9 @@
+package sandbox.java.util;
+
+/**
+ * This is a dummy class that implements just enough of [java.util.Locale]
+ * to allow us to compile [sandbox.java.lang.String].
+ */
+public abstract class Locale extends sandbox.java.lang.Object {
+    public abstract sandbox.java.lang.String toLanguageTag();
+}

djvm/src/main/java/sandbox/java/util/Map.java

@@ -0,0 +1,7 @@
+package sandbox.java.util;
+
+/**
+ * This is a dummy class to bootstrap us into the sandbox.
+ */
+public interface Map<K, V> extends java.util.Map<K, V> {
+}

djvm/src/main/java/sandbox/java/util/function/Function.java

@@ -0,0 +1,10 @@
+package sandbox.java.util.function;
+
+/**
+ * This is a dummy class that implements just enough of [java.util.function.Function]
+ * to allow us to compile [sandbox.Task].
+ */
+@FunctionalInterface
+public interface Function<T, R> {
+    R apply(T item);
+}

djvm/src/main/java/sandbox/java/util/function/Supplier.java

@@ -0,0 +1,10 @@
+package sandbox.java.util.function;
+
+/**
+ * This is a dummy class that implements just enough of [java.util.function.Supplier]
+ * to allow us to compile [sandbox.java.lang.ThreadLocal].
+ */
+@FunctionalInterface
+public interface Supplier<T> {
+    T get();
+}

djvm/src/main/java/sandbox/sun/misc/JavaLangAccess.java

@@ -0,0 +1,10 @@
+package sandbox.sun.misc;
+
+import sandbox.java.lang.Enum;
+
+@SuppressWarnings("unused")
+public interface JavaLangAccess {
+
+    <E extends Enum<E>> E[] getEnumConstantsShared(Class<E> enumClass);
+
+}

djvm/src/main/java/sandbox/sun/misc/SharedSecrets.java

@@ -0,0 +1,20 @@
+package sandbox.sun.misc;
+
+import sandbox.java.lang.Enum;
+
+@SuppressWarnings("unused")
+public class SharedSecrets extends sandbox.java.lang.Object {
+    private static final JavaLangAccess javaLangAccess = new JavaLangAccessImpl();
+
+    private static class JavaLangAccessImpl implements JavaLangAccess {
+        @SuppressWarnings("unchecked")
+        @Override
+        public <E extends Enum<E>> E[] getEnumConstantsShared(Class<E> enumClass) {
+            return (E[]) sandbox.java.lang.DJVM.getEnumConstantsShared(enumClass);
+        }
+    }
+
+    public static JavaLangAccess getJavaLangAccess() {
+        return javaLangAccess;
+    }
+}

djvm/src/main/kotlin/net/corda/djvm/analysis/AnalysisConfiguration.kt

@@ -1,12 +1,17 @@
 package net.corda.djvm.analysis
 
+import net.corda.djvm.code.EmitterModule
 import net.corda.djvm.code.ruleViolationError
 import net.corda.djvm.code.thresholdViolationError
 import net.corda.djvm.messages.Severity
 import net.corda.djvm.references.ClassModule
+import net.corda.djvm.references.Member
 import net.corda.djvm.references.MemberModule
+import net.corda.djvm.references.MethodBody
 import net.corda.djvm.source.BootstrapClassLoader
 import net.corda.djvm.source.SourceClassLoader
+import org.objectweb.asm.Opcodes.*
+import org.objectweb.asm.Type
 import sandbox.net.corda.djvm.costing.RuntimeCostAccounter
 import java.io.Closeable
 import java.io.IOException
@@ -41,19 +46,22 @@ class AnalysisConfiguration(
 
     /**
      * Classes that have already been declared in the sandbox namespace and that should be made
-     * available inside the sandboxed environment.
+     * available inside the sandboxed environment. These classes belong to the application
+     * classloader and so are shared across all sandboxes.
      */
-    val pinnedClasses: Set<String> = setOf(
-        SANDBOXED_OBJECT,
-        RuntimeCostAccounter.TYPE_NAME,
-        ruleViolationError,
-        thresholdViolationError
-    ) + additionalPinnedClasses
+    val pinnedClasses: Set<String> = MANDATORY_PINNED_CLASSES + additionalPinnedClasses
+
+    /**
+     * These interfaces are modified as they are mapped into the sandbox by
+     * having their unsandboxed version "stitched in" as a super-interface.
+     * And in some cases, we need to add some synthetic bridge methods as well.
+     */
+    val stitchedInterfaces: Map<String, List<Member>> get() = STITCHED_INTERFACES
 
     /**
      * Functionality used to resolve the qualified name and relevant information about a class.
      */
-    val classResolver: ClassResolver = ClassResolver(pinnedClasses, whitelist, SANDBOX_PREFIX)
+    val classResolver: ClassResolver = ClassResolver(pinnedClasses, TEMPLATE_CLASSES, whitelist, SANDBOX_PREFIX)
 
     private val bootstrapClassLoader = bootstrapJar?.let { BootstrapClassLoader(it, classResolver) }
     val supportingClassLoader = SourceClassLoader(classPath, classResolver, bootstrapClassLoader)
@@ -65,13 +73,114 @@ class AnalysisConfiguration(
         }
     }
 
+    fun isTemplateClass(className: String): Boolean = className in TEMPLATE_CLASSES
+    fun isPinnedClass(className: String): Boolean = className in pinnedClasses
+
     companion object {
         /**
          * The package name prefix to use for classes loaded into a sandbox.
          */
         private const val SANDBOX_PREFIX: String = "sandbox/"
 
-        private const val SANDBOXED_OBJECT = SANDBOX_PREFIX + "java/lang/Object"
+        /**
+         * These class must belong to the application class loader.
+         * They should already exist within the sandbox namespace.
+         */
+        private val MANDATORY_PINNED_CLASSES: Set<String> = setOf(
+            RuntimeCostAccounter.TYPE_NAME,
+            ruleViolationError,
+            thresholdViolationError
+        )
+
+        /**
+         * These classes will be duplicated into every sandbox's
+         * classloader.
+         */
+        private val TEMPLATE_CLASSES: Set<String> = setOf(
+            java.lang.Boolean::class.java,
+            java.lang.Byte::class.java,
+            java.lang.Character::class.java,
+            java.lang.Double::class.java,
+            java.lang.Float::class.java,
+            java.lang.Integer::class.java,
+            java.lang.Long::class.java,
+            java.lang.Number::class.java,
+            java.lang.Runtime::class.java,
+            java.lang.Short::class.java,
+            java.lang.String::class.java,
+            java.lang.String.CASE_INSENSITIVE_ORDER::class.java,
+            java.lang.System::class.java,
+            java.lang.ThreadLocal::class.java,
+            kotlin.Any::class.java,
+            sun.misc.JavaLangAccess::class.java,
+            sun.misc.SharedSecrets::class.java
+        ).sandboxed() + setOf(
+            "sandbox/Task",
+            "sandbox/java/lang/DJVM",
+            "sandbox/sun/misc/SharedSecrets\$1",
+            "sandbox/sun/misc/SharedSecrets\$JavaLangAccessImpl"
+        )
+
+        /**
+         * These interfaces will be modified as follows when
+         * added to the sandbox:
+         *
+         * <code>interface sandbox.A extends A</code>
+         */
+        private val STITCHED_INTERFACES: Map<String, List<Member>> = mapOf(
+            sandboxed(CharSequence::class.java) to listOf(
+                object : MethodBuilder(
+                    access = ACC_PUBLIC or ACC_SYNTHETIC or ACC_BRIDGE,
+                    className = "sandbox/java/lang/CharSequence",
+                    memberName = "subSequence",
+                    descriptor = "(II)Ljava/lang/CharSequence;"
+                ) {
+                    override fun writeBody(emitter: EmitterModule) = with(emitter) {
+                        pushObject(0)
+                        pushInteger(1)
+                        pushInteger(2)
+                        invokeInterface(className, memberName, "(II)L$className;")
+                        returnObject()
+                    }
+                }.withBody()
+                 .build(),
+                MethodBuilder(
+                    access = ACC_PUBLIC or ACC_ABSTRACT,
+                    className = "sandbox/java/lang/CharSequence",
+                    memberName = "toString",
+                    descriptor = "()Ljava/lang/String;"
+                ).build()
+            ),
+            sandboxed(Comparable::class.java) to emptyList(),
+            sandboxed(Comparator::class.java) to emptyList(),
+            sandboxed(Iterable::class.java) to emptyList()
+        )
+
+        private fun sandboxed(clazz: Class<*>) = SANDBOX_PREFIX + Type.getInternalName(clazz)
+        private fun Set<Class<*>>.sandboxed(): Set<String> = map(Companion::sandboxed).toSet()
     }
 
+    private open class MethodBuilder(
+            protected val access: Int,
+            protected val className: String,
+            protected val memberName: String,
+            protected val descriptor: String) {
+        private val bodies = mutableListOf<MethodBody>()
+
+        protected open fun writeBody(emitter: EmitterModule) {}
+
+        fun withBody(): MethodBuilder {
+            bodies.add(::writeBody)
+            return this
+        }
+
+        fun build() = Member(
+            access = access,
+            className = className,
+            memberName = memberName,
+            signature = descriptor,
+            genericsDetails = "",
+            body = bodies
+        )
+    }
 }

djvm/src/main/kotlin/net/corda/djvm/analysis/ClassAndMemberVisitor.kt

@@ -85,8 +85,12 @@ open class ClassAndMemberVisitor(
 
     /**
      * Process class after it has been fully traversed and analyzed.
+     * The [classVisitor] has finished visiting all of the class's
+     * existing elements (i.e. methods, fields, inner classes etc)
+     * and is about to complete. However, it can still add new
+     * elements to the class, if required.
      */
-    open fun visitClassEnd(clazz: ClassRepresentation) {}
+    open fun visitClassEnd(classVisitor: ClassVisitor, clazz: ClassRepresentation) {}
 
     /**
      * Extract the meta-data indicating the source file of the traversed class (i.e., where it is compiled from).
@@ -136,7 +140,7 @@ open class ClassAndMemberVisitor(
      */
     protected fun shouldBeProcessed(className: String): Boolean {
         return !configuration.whitelist.inNamespace(className) &&
-                className !in configuration.pinnedClasses
+                !configuration.isPinnedClass(className)
     }
 
     /**
@@ -241,7 +245,7 @@ open class ClassAndMemberVisitor(
                     .getClassReferencesFromClass(currentClass!!, configuration.analyzeAnnotations)
                     .forEach(::recordTypeReference)
             captureExceptions {
-                visitClassEnd(currentClass!!)
+                visitClassEnd(this, currentClass!!)
             }
             super.visitEnd()
         }
@@ -385,7 +389,9 @@ open class ClassAndMemberVisitor(
          */
         override fun visitCode() {
             tryReplaceMethodBody()
-            super.visitCode()
+            visit(MethodEntry(method)) {
+                super.visitCode()
+            }
         }
 
         /**
@@ -494,6 +500,15 @@ open class ClassAndMemberVisitor(
             }
         }
 
+        /**
+         * Transform values loaded from the constants pool.
+         */
+        override fun visitLdcInsn(value: Any) {
+            visit(ConstantInstruction(value), defaultFirst = true) {
+                super.visitLdcInsn(value)
+            }
+        }
+
         /**
          * Finish visiting this method, writing any new method body byte-code
          * if we haven't written it already. This would (presumably) only happen

djvm/src/main/kotlin/net/corda/djvm/analysis/ClassResolver.kt

@@ -26,6 +26,7 @@ import net.corda.djvm.code.asResourcePath
  */
 class ClassResolver(
         private val pinnedClasses: Set<String>,
+        private val templateClasses: Set<String>,
         private val whitelist: Whitelist,
         private val sandboxPrefix: String
 ) {
@@ -83,7 +84,7 @@ class ClassResolver(
      * Reverse the resolution of a class name.
      */
     fun reverse(resolvedClassName: String): String {
-        if (resolvedClassName in pinnedClasses) {
+        if (resolvedClassName in pinnedClasses || resolvedClassName in templateClasses) {
             return resolvedClassName
         }
         if (resolvedClassName.startsWith(sandboxPrefix)) {
@@ -103,10 +104,10 @@ class ClassResolver(
     }
 
     /**
-     * Resolve class name from a fully qualified name.
+     * Resolve sandboxed class name from a fully qualified name.
      */
     private fun resolveName(name: String): String {
-        return if (isPinnedOrWhitelistedClass(name)) {
+        return if (isPinnedOrWhitelistedClass(name) || name in templateClasses) {
             name
         } else {
             "$sandboxPrefix$name"
@@ -122,10 +123,10 @@ class ClassResolver(
                 sandboxRegex.matches(name)
     }
 
-    private val sandboxRegex = "^$sandboxPrefix.*$".toRegex()
+    private val sandboxRegex = "^$sandboxPrefix.*\$".toRegex()
 
     companion object {
-        private val complexArrayTypeRegex = "^(\\[+)L(.*);$".toRegex()
+        private val complexArrayTypeRegex = "^(\\[+)L(.*);\$".toRegex()
     }
 
 }

djvm/src/main/kotlin/net/corda/djvm/analysis/Whitelist.kt

@@ -89,36 +89,25 @@ open class Whitelist private constructor(
      * Enumerate all the entries of the whitelist.
      */
     val items: Set<String>
-        get() = textEntries + entries.map { it.pattern }
+        get() = textEntries + entries.map(Regex::pattern)
 
     companion object {
         private val everythingRegex = setOf(".*".toRegex())
 
         private val minimumSet = setOf(
-                "^java/lang/Boolean(\\..*)?$".toRegex(),
-                "^java/lang/Byte(\\..*)?$".toRegex(),
-                "^java/lang/Character(\\..*)?$".toRegex(),
-                "^java/lang/Class(\\..*)?$".toRegex(),
-                "^java/lang/ClassLoader(\\..*)?$".toRegex(),
-                "^java/lang/Cloneable(\\..*)?$".toRegex(),
-                "^java/lang/Comparable(\\..*)?$".toRegex(),
-                "^java/lang/Double(\\..*)?$".toRegex(),
-                "^java/lang/Enum(\\..*)?$".toRegex(),
-                "^java/lang/Float(\\..*)?$".toRegex(),
-                "^java/lang/Integer(\\..*)?$".toRegex(),
-                "^java/lang/Iterable(\\..*)?$".toRegex(),
-                "^java/lang/Long(\\..*)?$".toRegex(),
-                "^java/lang/Number(\\..*)?$".toRegex(),
-                "^java/lang/Object(\\..*)?$".toRegex(),
-                "^java/lang/Override(\\..*)?$".toRegex(),
-                "^java/lang/Short(\\..*)?$".toRegex(),
-                "^java/lang/String(\\..*)?$".toRegex(),
-                "^java/lang/ThreadDeath(\\..*)?$".toRegex(),
-                "^java/lang/Throwable(\\..*)?$".toRegex(),
-                "^java/lang/Void(\\..*)?$".toRegex(),
-                "^java/lang/.*Error(\\..*)?$".toRegex(),
-                "^java/lang/.*Exception(\\..*)?$".toRegex(),
-                "^java/lang/reflect/Array(\\..*)?$".toRegex()
+            "^java/lang/Class(\\..*)?\$".toRegex(),
+            "^java/lang/ClassLoader(\\..*)?\$".toRegex(),
+            "^java/lang/Cloneable(\\..*)?\$".toRegex(),
+            "^java/lang/Object(\\..*)?\$".toRegex(),
+            "^java/lang/Override(\\..*)?\$".toRegex(),
+                // TODO: sandbox exception handling!
+                "^java/lang/StackTraceElement\$".toRegex(),
+                "^java/lang/Throwable\$".toRegex(),
+            "^java/lang/Void\$".toRegex(),
+            "^java/lang/invoke/LambdaMetafactory\$".toRegex(),
+            "^java/lang/invoke/MethodHandles(\\\$.*)?\$".toRegex(),
+            "^java/lang/reflect/Array(\\..*)?\$".toRegex(),
+            "^java/io/Serializable\$".toRegex()
         )
 
         /**

djvm/src/main/kotlin/net/corda/djvm/code/ClassMutator.kt

@@ -2,26 +2,48 @@ package net.corda.djvm.code
 
 import net.corda.djvm.analysis.AnalysisConfiguration
 import net.corda.djvm.analysis.ClassAndMemberVisitor
+import net.corda.djvm.code.instructions.MethodEntry
 import net.corda.djvm.references.ClassRepresentation
 import net.corda.djvm.references.Member
+import net.corda.djvm.references.MethodBody
 import net.corda.djvm.utilities.Processor
 import net.corda.djvm.utilities.loggerFor
 import org.objectweb.asm.ClassVisitor
+import org.objectweb.asm.Opcodes.*
 
 /**
  * Helper class for applying a set of definition providers and emitters to a class or set of classes.
  *
  * @param classVisitor Class visitor to use when traversing the structure of classes.
+ * @property configuration The configuration to use for class analysis.
  * @property definitionProviders A set of providers used to update the name or meta-data of classes and members.
- * @property emitters A set of code emitters used to modify and instrument method bodies.
+ * @param emitters A set of code emitters used to modify and instrument method bodies.
  */
 class ClassMutator(
         classVisitor: ClassVisitor,
         private val configuration: AnalysisConfiguration,
         private val definitionProviders: List<DefinitionProvider> = emptyList(),
-        private val emitters: List<Emitter> = emptyList()
+        emitters: List<Emitter> = emptyList()
 ) : ClassAndMemberVisitor(configuration, classVisitor) {
 
+    /**
+     * Internal [Emitter] to add static field initializers to
+     * any class constructor method.
+     */
+    private inner class PrependClassInitializer : Emitter {
+        override fun emit(context: EmitterContext, instruction: Instruction) = context.emit {
+            if (instruction is MethodEntry
+                    && instruction.method.memberName == "<clinit>" && instruction.method.signature == "()V"
+                    && initializers.isNotEmpty()) {
+                writeByteCode(initializers)
+                initializers.clear()
+            }
+        }
+    }
+
+    private val emitters: List<Emitter> = emitters + PrependClassInitializer()
+    private val initializers = mutableListOf<MethodBody>()
+
     /**
      * Tracks whether any modifications have been applied to any of the processed class(es) and pertinent members.
      */
@@ -44,6 +66,29 @@ class ClassMutator(
         return super.visitClass(resultingClass)
     }
 
+    /**
+     * If we have some static fields to initialise, and haven't already added them
+     * to an existing class initialiser block then we need to create one.
+     */
+    override fun visitClassEnd(classVisitor: ClassVisitor, clazz: ClassRepresentation) {
+        tryWriteClassInitializer(classVisitor)
+        super.visitClassEnd(classVisitor, clazz)
+    }
+
+    private fun tryWriteClassInitializer(classVisitor: ClassVisitor) {
+        if (initializers.isNotEmpty()) {
+            classVisitor.visitMethod(ACC_STATIC, "<clinit>", "()V", null, null)?.also { mv ->
+                mv.visitCode()
+                EmitterModule(mv).writeByteCode(initializers)
+                mv.visitInsn(RETURN)
+                mv.visitMaxs(-1, -1)
+                mv.visitEnd()
+            }
+            initializers.clear()
+            hasBeenModified = true
+        }
+    }
+
     /**
      * Apply definition providers to a method. This can be used to update the name or definition (pertinent meta-data)
      * of a class member.
@@ -71,6 +116,7 @@ class ClassMutator(
         }
         if (field != resultingField) {
             logger.trace("Field has been mutated {}", field)
+            initializers += resultingField.body
             hasBeenModified = true
         }
         return super.visitField(clazz, resultingField)

djvm/src/main/kotlin/net/corda/djvm/code/EmitterModule.kt

@@ -1,5 +1,6 @@
 package net.corda.djvm.code
 
+import net.corda.djvm.references.MethodBody
 import org.objectweb.asm.Label
 import org.objectweb.asm.MethodVisitor
 import org.objectweb.asm.Opcodes.*
@@ -44,17 +45,9 @@ class EmitterModule(
     }
 
     /**
-     * Emit instruction for loading an integer constant onto the stack.
+     * Emit instruction for loading a constant onto the stack.
      */
-    fun loadConstant(constant: Int) {
-        hasEmittedCustomCode = true
-        methodVisitor.visitLdcInsn(constant)
-    }
-
-    /**
-     * Emit instruction for loading a string constant onto the stack.
-     */
-    fun loadConstant(constant: String) {
+    fun loadConstant(constant: Any) {
         hasEmittedCustomCode = true
         methodVisitor.visitLdcInsn(constant)
     }
@@ -67,6 +60,14 @@ class EmitterModule(
         methodVisitor.visitMethodInsn(INVOKESTATIC, owner, name, descriptor, isInterface)
     }
 
+    /**
+     * Emit instruction for invoking a virtual method.
+     */
+    fun invokeVirtual(owner: String, name: String, descriptor: String, isInterface: Boolean = false) {
+        hasEmittedCustomCode = true
+        methodVisitor.visitMethodInsn(INVOKEVIRTUAL, owner, name, descriptor, isInterface)
+    }
+
     /**
      * Emit instruction for invoking a special method, e.g. a constructor or a method on a super-type.
      */
@@ -82,6 +83,19 @@ class EmitterModule(
         invokeSpecial(Type.getInternalName(T::class.java), name, descriptor, isInterface)
     }
 
+    fun invokeInterface(owner: String, name: String, descriptor: String) {
+        methodVisitor.visitMethodInsn(INVOKEINTERFACE, owner, name, descriptor, true)
+        hasEmittedCustomCode = true
+    }
+
+    /**
+     * Emit instruction for storing a value into a static field.
+     */
+    fun putStatic(owner: String, name: String, descriptor: String) {
+        methodVisitor.visitFieldInsn(PUTSTATIC, owner, name, descriptor)
+        hasEmittedCustomCode = true
+    }
+
     /**
      * Emit instruction for popping one element off the stack.
      */
@@ -98,11 +112,52 @@ class EmitterModule(
         methodVisitor.visitInsn(DUP)
     }
 
+    /**
+     * Emit instruction for pushing an object reference
+     * from a register onto the stack.
+     */
+    fun pushObject(regNum: Int) {
+        methodVisitor.visitVarInsn(ALOAD, regNum)
+        hasEmittedCustomCode = true
+    }
+
+    /**
+     * Emit instruction for pushing an integer value
+     * from a register onto the stack.
+     */
+    fun pushInteger(regNum: Int) {
+        methodVisitor.visitVarInsn(ILOAD, regNum)
+        hasEmittedCustomCode = true
+    }
+
+    /**
+     * Emit instructions to rearrange the stack as follows:
+     *     [W1]    [W3]
+     *     [W2] -> [W1]
+     *     [w3]    [W2]
+     */
+    fun raiseThirdWordToTop() {
+        methodVisitor.visitInsn(DUP2_X1)
+        methodVisitor.visitInsn(POP2)
+        hasEmittedCustomCode = true
+    }
+
+    /**
+     * Emit instructions to rearrange the stack as follows:
+     *     [W1]    [W2]
+     *     [W2] -> [W3]
+     *     [W3]    [W1]
+     */
+    fun sinkTopToThirdWord() {
+        methodVisitor.visitInsn(DUP_X2)
+        methodVisitor.visitInsn(POP)
+        hasEmittedCustomCode = true
+    }
+
     /**
      * Emit a sequence of instructions for instantiating and throwing an exception based on the provided message.
      */
     fun <T : Throwable> throwException(exceptionType: Class<T>, message: String) {
-        hasEmittedCustomCode = true
         val exceptionName = Type.getInternalName(exceptionType)
         new(exceptionName)
         methodVisitor.visitInsn(DUP)
@@ -121,6 +176,14 @@ class EmitterModule(
         hasEmittedCustomCode = true
     }
 
+    /**
+     * Emit instruction for a function that returns an object reference.
+     */
+    fun returnObject() {
+        methodVisitor.visitInsn(ARETURN)
+        hasEmittedCustomCode = true
+    }
+
     /**
      * Emit instructions for a new line number.
      */
@@ -131,6 +194,15 @@ class EmitterModule(
         hasEmittedCustomCode = true
     }
 
+    /**
+     * Write the bytecode from these [MethodBody] objects as provided.
+     */
+    fun writeByteCode(bodies: Iterable<MethodBody>) {
+        for (body in bodies) {
+            body(this)
+        }
+    }
+
     /**
      * Tell the code writer not to emit the default instruction.
      */

djvm/src/main/kotlin/net/corda/djvm/code/Types.kt

@@ -12,4 +12,6 @@ val thresholdViolationError: String = Type.getInternalName(ThresholdViolationErr
  * Local extension method for normalizing a class name.
  */
 val String.asPackagePath: String get() = this.replace('/', '.')
-val String.asResourcePath: String get() = this.replace('.', '/')
+val String.asResourcePath: String get() = this.replace('.', '/')
+
+val String.emptyAsNull: String? get() = if (isEmpty()) null else this

djvm/src/main/kotlin/net/corda/djvm/code/instructions/ConstantInstruction.kt

@@ -0,0 +1,6 @@
+package net.corda.djvm.code.instructions
+
+import net.corda.djvm.code.Instruction
+import org.objectweb.asm.Opcodes
+
+class ConstantInstruction(val value: Any) : Instruction(Opcodes.LDC)

djvm/src/main/kotlin/net/corda/djvm/code/instructions/MethodEntry.kt

@@ -0,0 +1,9 @@
+package net.corda.djvm.code.instructions
+
+import net.corda.djvm.references.Member
+
+/**
+ * Pseudo-instruction marking the beginning of a method.
+ * @property method [Member] describing this method.
+ */
+class MethodEntry(val method: Member): NoOperationInstruction()

djvm/src/main/kotlin/net/corda/djvm/execution/SandboxExecutor.kt

@@ -5,6 +5,7 @@ import net.corda.djvm.analysis.AnalysisContext
 import net.corda.djvm.messages.Message
 import net.corda.djvm.references.ClassReference
 import net.corda.djvm.references.MemberReference
+import net.corda.djvm.references.ReferenceWithLocation
 import net.corda.djvm.rewiring.LoadedClass
 import net.corda.djvm.rewiring.SandboxClassLoader
 import net.corda.djvm.rewiring.SandboxClassLoadingException
@@ -67,12 +68,24 @@ open class SandboxExecutor<in TInput, out TOutput>(
         val context = AnalysisContext.fromConfiguration(configuration.analysisConfiguration)
         val result = IsolatedTask(runnableClass.qualifiedClassName, configuration).run {
             validate(context, classLoader, classSources)
-            val loadedClass = classLoader.loadClassAndBytes(runnableClass, context)
-            val instance = loadedClass.type.newInstance()
-            val method = loadedClass.type.getMethod("apply", Any::class.java)
+
+            // Load the "entry-point" task class into the sandbox. This task will marshall
+            // the input and outputs between Java types and sandbox wrapper types.
+            val taskClass = Class.forName("sandbox.Task", false, classLoader)
+
+            // Create the user's task object inside the sandbox.
+            val runnable = classLoader.loadForSandbox(runnableClass, context).type.newInstance()
+
+            // Fetch this sandbox's instance of Class<Function> so we can retrieve Task(Function)
+            // and then instantiate the Task.
+            val functionClass = Class.forName("sandbox.java.util.function.Function", false, classLoader)
+            val task = taskClass.getDeclaredConstructor(functionClass).newInstance(runnable)
+
+            // Execute the task...
+            val method = taskClass.getMethod("apply", Any::class.java)
             try {
                 @Suppress("UNCHECKED_CAST")
-                method.invoke(instance, input) as? TOutput
+                method.invoke(task, input) as? TOutput
             } catch (ex: InvocationTargetException) {
                 throw ex.targetException
             }
@@ -101,7 +114,7 @@ open class SandboxExecutor<in TInput, out TOutput>(
     fun load(classSource: ClassSource): LoadedClass {
         val context = AnalysisContext.fromConfiguration(configuration.analysisConfiguration)
         val result = IsolatedTask("LoadClass", configuration).run {
-            classLoader.loadClassAndBytes(classSource, context)
+            classLoader.loadForSandbox(classSource, context)
         }
         return result.output ?: throw ClassNotFoundException(classSource.qualifiedClassName)
     }
@@ -146,7 +159,7 @@ open class SandboxExecutor<in TInput, out TOutput>(
     ): ReferenceValidationSummary {
         processClassQueue(*classSources.toTypedArray()) { classSource, className ->
             val didLoad = try {
-                classLoader.loadClassAndBytes(classSource, context)
+                classLoader.loadForSandbox(classSource, context)
                 true
             } catch (exception: SandboxClassLoadingException) {
                 // Continue; all warnings and errors are captured in [context.messages]
@@ -155,7 +168,7 @@ open class SandboxExecutor<in TInput, out TOutput>(
             if (didLoad) {
                 context.classes[className]?.apply {
                     context.references.referencesFromLocation(className)
-                            .map { it.reference }
+                            .map(ReferenceWithLocation::reference)
                             .filterIsInstance<ClassReference>()
                             .filter { it.className != className }
                             .distinct()
@@ -201,6 +214,7 @@ open class SandboxExecutor<in TInput, out TOutput>(
         }
     }
 
-    private val logger = loggerFor<SandboxExecutor<TInput, TOutput>>()
-
+    private companion object {
+        private val logger = loggerFor<SandboxExecutor<*, *>>()
+    }
 }

djvm/src/main/kotlin/net/corda/djvm/rewiring/ClassRewriter.kt

@@ -1,23 +1,26 @@
 package net.corda.djvm.rewiring
 
 import net.corda.djvm.SandboxConfiguration
+import net.corda.djvm.analysis.AnalysisConfiguration
 import net.corda.djvm.analysis.AnalysisContext
+import net.corda.djvm.analysis.ClassAndMemberVisitor.Companion.API_VERSION
 import net.corda.djvm.code.ClassMutator
+import net.corda.djvm.code.EmitterModule
+import net.corda.djvm.code.emptyAsNull
+import net.corda.djvm.references.Member
 import net.corda.djvm.utilities.loggerFor
 import org.objectweb.asm.ClassReader
-import org.objectweb.asm.commons.ClassRemapper
+import org.objectweb.asm.ClassVisitor
 
 /**
- * Functionality for rewrite parts of a class as it is being loaded.
+ * Functionality for rewriting parts of a class as it is being loaded.
  *
  * @property configuration The configuration of the sandbox.
  * @property classLoader The class loader used to load the classes that are to be rewritten.
- * @property remapper A sandbox-aware remapper for inspecting and correcting type names and descriptors.
  */
 open class ClassRewriter(
         private val configuration: SandboxConfiguration,
-        private val classLoader: ClassLoader,
-        private val remapper: SandboxRemapper = SandboxRemapper(configuration.analysisConfiguration.classResolver)
+        private val classLoader: ClassLoader
 ) {
 
     /**
@@ -29,20 +32,53 @@ open class ClassRewriter(
     fun rewrite(reader: ClassReader, context: AnalysisContext): ByteCode {
         logger.debug("Rewriting class {}...", reader.className)
         val writer = SandboxClassWriter(reader, classLoader)
-        val classRemapper = ClassRemapper(writer, remapper)
+        val analysisConfiguration = configuration.analysisConfiguration
+        val classRemapper = SandboxClassRemapper(InterfaceStitcher(writer, analysisConfiguration), analysisConfiguration)
         val visitor = ClassMutator(
                 classRemapper,
-                configuration.analysisConfiguration,
+                analysisConfiguration,
                 configuration.definitionProviders,
                 configuration.emitters
         )
         visitor.analyze(reader, context, options = ClassReader.EXPAND_FRAMES)
-        val hasBeenModified = visitor.hasBeenModified
-        return ByteCode(writer.toByteArray(), hasBeenModified)
+        return ByteCode(writer.toByteArray(), visitor.hasBeenModified)
     }
 
     private companion object {
         private val logger = loggerFor<ClassRewriter>()
     }
 
+    /**
+     * Extra visitor that is applied after [SandboxRemapper]. This "stitches" the original
+     * unmapped interface as a super-interface of the mapped version.
+     */
+    private class InterfaceStitcher(parent: ClassVisitor, private val configuration: AnalysisConfiguration)
+        : ClassVisitor(API_VERSION, parent)
+    {
+        private val extraMethods = mutableListOf<Member>()
+
+        override fun visit(version: Int, access: Int, className: String, signature: String?, superName: String?, interfaces: Array<String>?) {
+            val stitchedInterfaces = configuration.stitchedInterfaces[className]?.let { methods ->
+                extraMethods += methods
+                arrayOf(*(interfaces ?: emptyArray()), configuration.classResolver.reverse(className))
+            } ?: interfaces
+
+            super.visit(version, access, className, signature, superName, stitchedInterfaces)
+        }
+
+        override fun visitEnd() {
+            for (method in extraMethods) {
+                method.apply {
+                    visitMethod(access, memberName, signature, genericsDetails.emptyAsNull, exceptions.toTypedArray())?.also { mv ->
+                        mv.visitCode()
+                        EmitterModule(mv).writeByteCode(body)
+                        mv.visitMaxs(-1, -1)
+                        mv.visitEnd()
+                    }
+                }
+            }
+            extraMethods.clear()
+            super.visitEnd()
+        }
+    }
 }

djvm/src/main/kotlin/net/corda/djvm/rewiring/SandboxClassLoader.kt

@@ -18,7 +18,7 @@ import net.corda.djvm.validation.RuleValidator
 class SandboxClassLoader(
         configuration: SandboxConfiguration,
         private val context: AnalysisContext
-) : ClassLoader(null) {
+) : ClassLoader() {
 
     private val analysisConfiguration = configuration.analysisConfiguration
 
@@ -36,11 +36,6 @@ class SandboxClassLoader(
     val analyzer: ClassAndMemberVisitor
         get() = ruleValidator
 
-    /**
-     * Set of classes that should be left untouched due to pinning.
-     */
-    private val pinnedClasses = analysisConfiguration.pinnedClasses
-
     /**
      * Set of classes that should be left untouched due to whitelisting.
      */
@@ -61,6 +56,17 @@ class SandboxClassLoader(
      */
     private val rewriter: ClassRewriter = ClassRewriter(configuration, supportingClassLoader)
 
+    /**
+     * Given a class name, provide its corresponding [LoadedClass] for the sandbox.
+     */
+    fun loadForSandbox(name: String, context: AnalysisContext): LoadedClass {
+        return loadClassAndBytes(ClassSource.fromClassName(analysisConfiguration.classResolver.resolveNormalized(name)), context)
+    }
+
+    fun loadForSandbox(source: ClassSource, context: AnalysisContext): LoadedClass {
+        return loadForSandbox(source.qualifiedClassName, context)
+    }
+
     /**
      * Load the class with the specified binary name.
      *
@@ -69,69 +75,68 @@ class SandboxClassLoader(
      *
      * @return The resulting <tt>Class</tt> object.
      */
+    @Throws(ClassNotFoundException::class)
     override fun loadClass(name: String, resolve: Boolean): Class<*> {
-        return loadClassAndBytes(ClassSource.fromClassName(name), context).type
+        val source = ClassSource.fromClassName(name)
+        return if (name.startsWith("sandbox.") && !analysisConfiguration.isPinnedClass(source.internalClassName)) {
+            loadClassAndBytes(source, context).type
+        } else {
+            super.loadClass(name, resolve)
+        }
     }
 
     /**
      * Load the class with the specified binary name.
      *
-     * @param source The class source, including the binary name of the class.
+     * @param request The class request, including the binary name of the class.
      * @param context The context in which the analysis is conducted.
      *
      * @return The resulting <tt>Class</tt> object and its byte code representation.
      */
-    fun loadClassAndBytes(source: ClassSource, context: AnalysisContext): LoadedClass {
-        logger.debug("Loading class {}, origin={}...", source.qualifiedClassName, source.origin)
-        val name = analysisConfiguration.classResolver.reverseNormalized(source.qualifiedClassName)
-        val resolvedName = analysisConfiguration.classResolver.resolveNormalized(name)
+    private fun loadClassAndBytes(request: ClassSource, context: AnalysisContext): LoadedClass {
+        logger.debug("Loading class {}, origin={}...", request.qualifiedClassName, request.origin)
+        val requestedPath = request.internalClassName
+        val sourceName = analysisConfiguration.classResolver.reverseNormalized(request.qualifiedClassName)
+        val resolvedName = analysisConfiguration.classResolver.resolveNormalized(sourceName)
 
         // Check if the class has already been loaded.
-        val loadedClass = loadedClasses[name]
+        val loadedClass = loadedClasses[requestedPath]
         if (loadedClass != null) {
-            logger.trace("Class {} already loaded", source.qualifiedClassName)
+            logger.trace("Class {} already loaded", request.qualifiedClassName)
             return loadedClass
+        } else if (analysisConfiguration.isPinnedClass(requestedPath)) {
+            logger.debug("Class {} is loaded unmodified", request.qualifiedClassName)
+            return loadUnmodifiedClass(requestedPath)
         }
 
-        // Load the byte code for the specified class.
-        val reader = supportingClassLoader.classReader(name, context, source.origin)
+        val byteCode = if (analysisConfiguration.isTemplateClass(requestedPath)) {
+            loadUnmodifiedByteCode(requestedPath)
+        } else {
+            // Load the byte code for the specified class.
+            val reader = supportingClassLoader.classReader(sourceName, context, request.origin)
 
-        // Analyse the class if not matching the whitelist.
-        val readClassName = reader.className
-        if (!analysisConfiguration.whitelist.matches(readClassName)) {
-            logger.trace("Class {} does not match with the whitelist", source.qualifiedClassName)
-            logger.trace("Analyzing class {}...", source.qualifiedClassName)
-            analyzer.analyze(reader, context)
-        }
-
-        // Check if the class should be left untouched.
-        val qualifiedName = name.asResourcePath
-        if (qualifiedName in pinnedClasses) {
-            logger.trace("Class {} is marked as pinned", source.qualifiedClassName)
-            val pinnedClasses = LoadedClass(
-                    supportingClassLoader.loadClass(name),
-                    ByteCode(ByteArray(0), false)
-            )
-            loadedClasses[name] = pinnedClasses
-            if (source.origin != null) {
-                context.recordClassOrigin(name, ClassReference(source.origin))
+            // Analyse the class if not matching the whitelist.
+            val readClassName = reader.className
+            if (!analysisConfiguration.whitelist.matches(readClassName)) {
+                logger.trace("Class {} does not match with the whitelist", request.qualifiedClassName)
+                logger.trace("Analyzing class {}...", request.qualifiedClassName)
+                analyzer.analyze(reader, context)
             }
-            return pinnedClasses
-        }
 
-        // Check if any errors were found during analysis.
-        if (context.messages.errorCount > 0) {
-            logger.trace("Errors detected after analyzing class {}", source.qualifiedClassName)
-            throw SandboxClassLoadingException(context)
-        }
+            // Check if any errors were found during analysis.
+            if (context.messages.errorCount > 0) {
+                logger.debug("Errors detected after analyzing class {}", request.qualifiedClassName)
+                throw SandboxClassLoadingException(context)
+            }
 
-        // Transform the class definition and byte code in accordance with provided rules.
-        val byteCode = rewriter.rewrite(reader, context)
+            // Transform the class definition and byte code in accordance with provided rules.
+            rewriter.rewrite(reader, context)
+        }
 
         // Try to define the transformed class.
         val clazz = try {
             when {
-                whitelistedClasses.matches(qualifiedName) -> supportingClassLoader.loadClass(name)
+                whitelistedClasses.matches(sourceName.asResourcePath) -> supportingClassLoader.loadClass(sourceName)
                 else -> defineClass(resolvedName, byteCode.bytes, 0, byteCode.bytes.size)
             }
         } catch (exception: SecurityException) {
@@ -140,19 +145,31 @@ class SandboxClassLoader(
 
         // Cache transformed class.
         val classWithByteCode = LoadedClass(clazz, byteCode)
-        loadedClasses[name] = classWithByteCode
-        if (source.origin != null) {
-            context.recordClassOrigin(name, ClassReference(source.origin))
+        loadedClasses[requestedPath] = classWithByteCode
+        if (request.origin != null) {
+            context.recordClassOrigin(sourceName, ClassReference(request.origin))
         }
 
         logger.debug("Loaded class {}, bytes={}, isModified={}",
-                source.qualifiedClassName, byteCode.bytes.size, byteCode.isModified)
+                request.qualifiedClassName, byteCode.bytes.size, byteCode.isModified)
 
         return classWithByteCode
     }
 
+    private fun loadUnmodifiedByteCode(internalClassName: String): ByteCode {
+        return ByteCode((getSystemClassLoader().getResourceAsStream("$internalClassName.class")
+                ?: throw ClassNotFoundException(internalClassName)).readBytes(), false)
+    }
+
+    private fun loadUnmodifiedClass(className: String): LoadedClass {
+        return LoadedClass(supportingClassLoader.loadClass(className), UNMODIFIED).apply {
+            loadedClasses[className] = this
+        }
+    }
+
     private companion object {
         private val logger = loggerFor<SandboxClassLoader>()
+        private val UNMODIFIED = ByteCode(ByteArray(0), false)
     }
 
 }

djvm/src/main/kotlin/net/corda/djvm/rewiring/SandboxClassRemapper.kt

@@ -0,0 +1,52 @@
+package net.corda.djvm.rewiring
+
+import net.corda.djvm.analysis.AnalysisConfiguration
+import net.corda.djvm.analysis.ClassAndMemberVisitor.Companion.API_VERSION
+import org.objectweb.asm.ClassVisitor
+import org.objectweb.asm.Label
+import org.objectweb.asm.MethodVisitor
+import org.objectweb.asm.commons.ClassRemapper
+
+class SandboxClassRemapper(cv: ClassVisitor, private val configuration: AnalysisConfiguration)
+    : ClassRemapper(cv, SandboxRemapper(configuration.classResolver, configuration.whitelist)
+) {
+    override fun createMethodRemapper(mv: MethodVisitor): MethodVisitor {
+        return MethodRemapperWithPinning(mv, super.createMethodRemapper(mv))
+    }
+
+    /**
+     * Do not attempt to remap references to methods and fields on pinned classes.
+     * For example, the methods on [RuntimeCostAccounter] really DO use [java.lang.String]
+     * rather than [sandbox.java.lang.String].
+     */
+    private inner class MethodRemapperWithPinning(private val nonmapper: MethodVisitor, remapper: MethodVisitor)
+        : MethodVisitor(API_VERSION, remapper) {
+
+        private fun mapperFor(element: Element): MethodVisitor {
+            return if (configuration.isPinnedClass(element.owner) || configuration.isTemplateClass(element.owner) || isUnmapped(element)) {
+                nonmapper
+            } else {
+                mv
+            }
+        }
+
+        override fun visitMethodInsn(opcode: Int, owner: String, name: String, descriptor: String, isInterface: Boolean) {
+            val method = Element(owner, name, descriptor)
+            return mapperFor(method).visitMethodInsn(opcode, owner, name, descriptor, isInterface)
+        }
+
+        override fun visitTryCatchBlock(start: Label, end: Label, handler: Label, type: String?) {
+            // Don't map caught exception names - these could be thrown by the JVM itself.
+            nonmapper.visitTryCatchBlock(start, end, handler, type)
+        }
+
+        override fun visitFieldInsn(opcode: Int, owner: String, name: String, descriptor: String) {
+            val field = Element(owner, name, descriptor)
+            return mapperFor(field).visitFieldInsn(opcode, owner, name, descriptor)
+        }
+    }
+
+    private fun isUnmapped(element: Element): Boolean = configuration.whitelist.matches(element.owner)
+
+    private data class Element(val owner: String, val name: String, val descriptor: String)
+}

djvm/src/main/kotlin/net/corda/djvm/rewiring/SandboxClassWriter.kt

@@ -8,13 +8,13 @@ import org.objectweb.asm.ClassWriter.COMPUTE_MAXS
 import org.objectweb.asm.Type
 
 /**
- * Class writer for sandbox execution, with configurable a [classLoader] to ensure correct deduction of the used class
+ * Class writer for sandbox execution, with a configurable classloader to ensure correct deduction of the used class
  * hierarchy.
  *
  * @param classReader The [ClassReader] used to read the original class. It will be used to copy the entire constant
  * pool and bootstrap methods from the original class and also to copy other fragments of original byte code where
  * applicable.
- * @property classLoader The class loader used to load the classes that are to be rewritten.
+ * @property cloader The class loader used to load the classes that are to be rewritten.
  * @param flags Option flags that can be used to modify the default behaviour of this class. Must be zero or a
  * combination of [COMPUTE_MAXS] and [COMPUTE_FRAMES]. These option flags do not affect methods that are copied as is
  * in the new class. This means that neither the maximum stack size nor the stack frames will be computed for these
@@ -61,7 +61,7 @@ open class SandboxClassWriter(
         }
     }
 
-    companion object {
+    private companion object {
 
         private const val OBJECT_NAME = "java/lang/Object"
 

djvm/src/main/kotlin/net/corda/djvm/rewiring/SandboxRemapper.kt

@@ -1,15 +1,19 @@
 package net.corda.djvm.rewiring
 
 import net.corda.djvm.analysis.ClassResolver
+import net.corda.djvm.analysis.Whitelist
+import org.objectweb.asm.*
 import org.objectweb.asm.commons.Remapper
 
 /**
  * Class name and descriptor re-mapper for use in a sandbox.
  *
  * @property classResolver Functionality for resolving the class name of a sandboxed or sandboxable class.
+ * @property whitelist Identifies the Java APIs which are not mapped into the sandbox namespace.
  */
 open class SandboxRemapper(
-        private val classResolver: ClassResolver
+        private val classResolver: ClassResolver,
+        private val whitelist: Whitelist
 ) : Remapper() {
 
     /**
@@ -26,6 +30,32 @@ open class SandboxRemapper(
         return rewriteTypeName(super.map(typename))
     }
 
+    /**
+     * Mapper for [Type] and [Handle] objects.
+     */
+    override fun mapValue(obj: Any?): Any? {
+        return if (obj is Handle && whitelist.matches(obj.owner)) {
+            obj
+        } else {
+            super.mapValue(obj)
+        }
+    }
+
+    /**
+     * All [Object.toString] methods must be transformed to [sandbox.java.lang.Object.toDJVMString],
+     * to allow the return type to change to [sandbox.java.lang.String].
+     *
+     * The [sandbox.java.lang.Object] class is pinned and not mapped.
+     */
+    override fun mapMethodName(owner: String, name: String, descriptor: String): String {
+        val newName = if (name == "toString" && descriptor == "()Ljava/lang/String;") {
+            "toDJVMString"
+        } else {
+            name
+        }
+        return super.mapMethodName(owner, newName, descriptor)
+    }
+
     /**
      * Function for rewriting a descriptor.
      */

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/ArgumentUnwrapper.kt

@@ -0,0 +1,35 @@
+package net.corda.djvm.rules.implementation
+
+import net.corda.djvm.code.Emitter
+import net.corda.djvm.code.EmitterContext
+import net.corda.djvm.code.Instruction
+import net.corda.djvm.code.instructions.MemberAccessInstruction
+
+/**
+ * Some whitelisted functions have [java.lang.String] arguments, so we
+ * need to unwrap the [sandbox.java.lang.String] object before invoking.
+ *
+ * There are lots of rabbits in this hole because method arguments are
+ * theoretically arbitrary. However, in practice WE control the whitelist.
+ */
+class ArgumentUnwrapper : Emitter {
+    override fun emit(context: EmitterContext, instruction: Instruction) = context.emit {
+        if (instruction is MemberAccessInstruction && context.whitelist.matches(instruction.owner)) {
+            fun unwrapString() = invokeStatic("sandbox/java/lang/String", "fromDJVM", "(Lsandbox/java/lang/String;)Ljava/lang/String;")
+
+            if (hasStringArgument(instruction)) {
+                unwrapString()
+            } else if (instruction.owner == "java/lang/Class" && instruction.signature.startsWith("(Ljava/lang/String;ZLjava/lang/ClassLoader;)")) {
+                /**
+                 * [kotlin.jvm.internal.Intrinsics.checkHasClass] invokes [Class.forName], so I'm
+                 * adding support for both of this function's variants. For now.
+                 */
+                raiseThirdWordToTop()
+                unwrapString()
+                sinkTopToThirdWord()
+            }
+        }
+    }
+
+    private fun hasStringArgument(method: MemberAccessInstruction) = method.signature.contains("Ljava/lang/String;)")
+}

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/DisallowNonDeterministicMethods.kt

@@ -17,7 +17,7 @@ class DisallowNonDeterministicMethods : Emitter {
     override fun emit(context: EmitterContext, instruction: Instruction) = context.emit {
         if (instruction is MemberAccessInstruction && isForbidden(instruction)) {
             when (instruction.operation) {
-                INVOKEVIRTUAL -> {
+                INVOKEVIRTUAL, INVOKESPECIAL -> {
                     throwException<RuleViolationError>("Disallowed reference to API; ${memberFormatter.format(instruction.member)}")
                     preventDefault()
                 }
@@ -31,12 +31,20 @@ class DisallowNonDeterministicMethods : Emitter {
                             || instruction.signature.contains("Ljava/lang/reflect/"))
                     )
 
+    private fun isClassLoading(instruction: MemberAccessInstruction): Boolean =
+            (instruction.owner == "java/lang/ClassLoader") && instruction.memberName in CLASSLOADING_METHODS
+
     private fun isObjectMonitor(instruction: MemberAccessInstruction): Boolean =
-            (instruction.signature == "()V" && (instruction.memberName == "notify" || instruction.memberName == "notifyAll" || instruction.memberName == "wait"))
+            (instruction.signature == "()V" && instruction.memberName in MONITOR_METHODS)
                     || (instruction.memberName == "wait" && (instruction.signature == "(J)V" || instruction.signature == "(JI)V"))
 
     private fun isForbidden(instruction: MemberAccessInstruction): Boolean
-            = instruction.isMethod && (isClassReflection(instruction) || isObjectMonitor(instruction))
+            = instruction.isMethod && (isClassReflection(instruction) || isObjectMonitor(instruction) || isClassLoading(instruction))
 
     private val memberFormatter = MemberFormatter()
+
+    private companion object {
+        private val MONITOR_METHODS = setOf("notify", "notifyAll", "wait")
+        private val CLASSLOADING_METHODS = setOf("defineClass", "loadClass", "findClass")
+    }
 }

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/ReturnTypeWrapper.kt

@@ -0,0 +1,27 @@
+package net.corda.djvm.rules.implementation
+
+import net.corda.djvm.code.Emitter
+import net.corda.djvm.code.EmitterContext
+import net.corda.djvm.code.Instruction
+import net.corda.djvm.code.instructions.MemberAccessInstruction
+
+/**
+ * Whitelisted classes may still return [java.lang.String] from some
+ * functions, e.g. [java.lang.Object.toString]. So always explicitly
+ * invoke [sandbox.java.lang.String.toDJVM] after these.
+ */
+class ReturnTypeWrapper : Emitter {
+    override fun emit(context: EmitterContext, instruction: Instruction) = context.emit {
+        if (instruction is MemberAccessInstruction && context.whitelist.matches(instruction.owner)) {
+            fun invokeMethod() = invokeVirtual(instruction.owner, instruction.memberName, instruction.signature)
+
+            if (hasStringReturnType(instruction)) {
+                preventDefault()
+                invokeMethod()
+                invokeStatic("sandbox/java/lang/String", "toDJVM", "(Ljava/lang/String;)Lsandbox/java/lang/String;")
+            }
+        }
+    }
+
+    private fun hasStringReturnType(method: MemberAccessInstruction) = method.signature.endsWith(")Ljava/lang/String;")
+}

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/RewriteClassMethods.kt

@@ -0,0 +1,56 @@
+package net.corda.djvm.rules.implementation
+
+import net.corda.djvm.code.Emitter
+import net.corda.djvm.code.EmitterContext
+import net.corda.djvm.code.Instruction
+import net.corda.djvm.code.instructions.MemberAccessInstruction
+import org.objectweb.asm.Opcodes.*
+
+/**
+ * The enum-related methods on [Class] all require that enums use [java.lang.Enum]
+ * as their super class. So replace their all invocations with ones to equivalent
+ * methods on the DJVM class that require [sandbox.java.lang.Enum] instead.
+ */
+class RewriteClassMethods : Emitter {
+    override fun emit(context: EmitterContext, instruction: Instruction) = context.emit {
+        if (instruction is MemberAccessInstruction && instruction.owner == "java/lang/Class") {
+            when (instruction.operation) {
+                INVOKEVIRTUAL -> if (instruction.memberName == "enumConstantDirectory" && instruction.signature == "()Ljava/util/Map;") {
+                    invokeStatic(
+                        owner = "sandbox/java/lang/DJVM",
+                        name = "enumConstantDirectory",
+                        descriptor = "(Ljava/lang/Class;)Lsandbox/java/util/Map;"
+                    )
+                    preventDefault()
+                } else if (instruction.memberName == "isEnum" && instruction.signature == "()Z") {
+                    invokeStatic(
+                        owner = "sandbox/java/lang/DJVM",
+                        name = "isEnum",
+                        descriptor = "(Ljava/lang/Class;)Z"
+                    )
+                    preventDefault()
+                } else if (instruction.memberName == "getEnumConstants" && instruction.signature == "()[Ljava/lang/Object;") {
+                    invokeStatic(
+                        owner = "sandbox/java/lang/DJVM",
+                        name = "getEnumConstants",
+                        descriptor = "(Ljava/lang/Class;)[Ljava/lang/Object;")
+                    preventDefault()
+                }
+
+                INVOKESTATIC -> if (isClassForName(instruction)) {
+                    invokeStatic(
+                        owner = "sandbox/java/lang/DJVM",
+                        name = "classForName",
+                        descriptor = instruction.signature
+                    )
+                    preventDefault()
+                }
+            }
+        }
+    }
+
+    private fun isClassForName(instruction: MemberAccessInstruction): Boolean
+        = instruction.memberName == "forName" &&
+            (instruction.signature == "(Ljava/lang/String;)Ljava/lang/Class;" ||
+                    instruction.signature == "(Ljava/lang/String;ZLjava/lang/ClassLoader;)Ljava/lang/Class;")
+}

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/StaticConstantRemover.kt

@@ -0,0 +1,30 @@
+package net.corda.djvm.rules.implementation
+
+import net.corda.djvm.analysis.AnalysisRuntimeContext
+import net.corda.djvm.code.EmitterModule
+import net.corda.djvm.code.MemberDefinitionProvider
+import net.corda.djvm.references.Member
+
+/**
+ * Removes static constant objects that are initialised directly in the byte-code.
+ * Currently, the only use-case is for re-initialising [String] fields.
+ */
+class StaticConstantRemover : MemberDefinitionProvider {
+
+    override fun define(context: AnalysisRuntimeContext, member: Member): Member = when {
+        isConstantField(member) -> member.copy(body = listOf(StringFieldInitializer(member)::writeInitializer), value = null)
+        else -> member
+    }
+
+    private fun isConstantField(member: Member): Boolean = member.value != null && member.signature == "Ljava/lang/String;"
+
+    class StringFieldInitializer(private val member: Member) {
+        fun writeInitializer(emitter: EmitterModule): Unit = with(emitter) {
+            member.value?.apply {
+                loadConstant(this)
+                invokeStatic("sandbox/java/lang/String", "toDJVM", "(Ljava/lang/String;)Lsandbox/java/lang/String;", false)
+                putStatic(member.className, member.memberName, "Lsandbox/java/lang/String;")
+            }
+        }
+    }
+}

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/StringConstantWrapper.kt

@@ -0,0 +1,22 @@
+package net.corda.djvm.rules.implementation
+
+import net.corda.djvm.code.Emitter
+import net.corda.djvm.code.EmitterContext
+import net.corda.djvm.code.Instruction
+import net.corda.djvm.code.instructions.ConstantInstruction
+
+/**
+ * Ensure that [String] constants loaded from the Constants
+ * Pool are wrapped into [sandbox.java.lang.String].
+ */
+class StringConstantWrapper : Emitter {
+    override fun emit(context: EmitterContext, instruction: Instruction) = context.emit {
+        if (instruction is ConstantInstruction) {
+            when (instruction.value) {
+                is String -> {
+                    invokeStatic("sandbox/java/lang/String", "toDJVM", "(Ljava/lang/String;)Lsandbox/java/lang/String;", false)
+                }
+            }
+        }
+    }
+}

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/StubOutNativeMethods.kt

@@ -23,7 +23,7 @@ class StubOutNativeMethods : MemberDefinitionProvider {
 
     private fun writeExceptionMethodBody(emitter: EmitterModule): Unit = with(emitter) {
         lineNumber(0)
-        throwException(RuleViolationError::class.java, "Native method has been deleted")
+        throwException<RuleViolationError>("Native method has been deleted")
     }
 
     private fun writeStubMethodBody(emitter: EmitterModule): Unit = with(emitter) {

djvm/src/main/kotlin/net/corda/djvm/rules/implementation/StubOutReflectionMethods.kt

@@ -19,7 +19,7 @@ class StubOutReflectionMethods : MemberDefinitionProvider {
 
     private fun writeMethodBody(emitter: EmitterModule): Unit = with(emitter) {
         lineNumber(0)
-        throwException(RuleViolationError::class.java, "Disallowed reference to reflection API")
+        throwException<RuleViolationError>("Disallowed reference to reflection API")
     }
 
     // The method must be public and with a Java implementation.

djvm/src/main/kotlin/net/corda/djvm/source/ClassSource.kt

@@ -1,17 +1,20 @@
 package net.corda.djvm.source
 
+import net.corda.djvm.code.asResourcePath
 import java.nio.file.Path
 
 /**
  * The source of one or more compiled Java classes.
  *
  * @property qualifiedClassName The fully qualified class name.
+ * @property internalClassName The fully qualified internal class name, i.e. with '/' instead of '.'.
  * @property origin The origin of the class source, if any.
  */
 class ClassSource private constructor(
         val qualifiedClassName: String = "",
         val origin: String? = null
 ) {
+    val internalClassName: String = qualifiedClassName.asResourcePath
 
     companion object {
 

djvm/src/main/kotlin/net/corda/djvm/utilities/Discovery.kt

@@ -7,7 +7,7 @@ import java.lang.reflect.Modifier
  * Find and instantiate types that implement a certain interface.
  */
 object Discovery {
-    const val FORBIDDEN_CLASS_MASK = (Modifier.STATIC or Modifier.ABSTRACT)
+    const val FORBIDDEN_CLASS_MASK = (Modifier.STATIC or Modifier.ABSTRACT or Modifier.PRIVATE or Modifier.PROTECTED)
 
     /**
      * Get an instance of each concrete class that implements interface or class [T].

djvm/src/main/kotlin/net/corda/djvm/validation/RuleValidator.kt

@@ -17,6 +17,7 @@ import org.objectweb.asm.ClassVisitor
  * Helper class for validating a set of rules for a class or set of classes.
  *
  * @property rules A set of rules to validate for provided classes.
+ * @param configuration The configuration to use for class analysis.
  * @param classVisitor Class visitor to use when traversing the structure of classes.
  */
 class RuleValidator(

djvm/src/main/kotlin/sandbox/Task.kt

@@ -0,0 +1,24 @@
+@file:JvmName("TaskTypes")
+package sandbox
+
+import sandbox.java.lang.sandbox
+import sandbox.java.lang.unsandbox
+
+typealias SandboxFunction<TInput, TOutput> = sandbox.java.util.function.Function<TInput, TOutput>
+
+@Suppress("unused")
+class Task(private val function: SandboxFunction<in Any?, out Any?>?) : SandboxFunction<Any?, Any?> {
+
+    /**
+     * This function runs inside the sandbox. It marshalls the input
+     * object to its sandboxed equivalent, executes the user's code
+     * and then marshalls the result out again.
+     *
+     * The marshalling should be effective for Java primitives,
+     * Strings and Enums, as well as for arrays of these types.
+     */
+    override fun apply(input: Any?): Any? {
+        return function?.apply(input?.sandbox())?.unsandbox()
+    }
+
+}

djvm/src/main/kotlin/sandbox/java/lang/DJVM.kt

@@ -0,0 +1,158 @@
+@file:JvmName("DJVM")
+@file:Suppress("unused")
+package sandbox.java.lang
+
+import org.objectweb.asm.Opcodes.ACC_ENUM
+
+private const val SANDBOX_PREFIX = "sandbox."
+
+fun Any.unsandbox(): Any {
+    return when (this) {
+        is Enum<*> -> fromDJVMEnum()
+        is Object -> fromDJVM()
+        is Array<*> -> fromDJVMArray()
+        else -> this
+    }
+}
+
+fun Any.sandbox(): Any {
+    return when (this) {
+        is kotlin.String -> String.toDJVM(this)
+        is kotlin.Char -> Character.toDJVM(this)
+        is kotlin.Long -> Long.toDJVM(this)
+        is kotlin.Int -> Integer.toDJVM(this)
+        is kotlin.Short -> Short.toDJVM(this)
+        is kotlin.Byte -> Byte.toDJVM(this)
+        is kotlin.Float -> Float.toDJVM(this)
+        is kotlin.Double -> Double.toDJVM(this)
+        is kotlin.Boolean -> Boolean.toDJVM(this)
+        is kotlin.Enum<*> -> toDJVMEnum()
+        is Array<*> -> toDJVMArray<Object>()
+        else -> this
+    }
+}
+
+private fun Array<*>.fromDJVMArray(): Array<*> = Object.fromDJVM(this)
+
+/**
+ * These functions use the "current" classloader, i.e. classloader
+ * that owns this DJVM class.
+ */
+private fun Class<*>.toDJVMType(): Class<*> = Class.forName(name.toSandboxPackage())
+private fun Class<*>.fromDJVMType(): Class<*> = Class.forName(name.fromSandboxPackage())
+
+private fun kotlin.String.toSandboxPackage(): kotlin.String {
+    return if (startsWith(SANDBOX_PREFIX)) {
+        this
+    } else {
+        SANDBOX_PREFIX + this
+    }
+}
+
+private fun kotlin.String.fromSandboxPackage(): kotlin.String {
+    return if (startsWith(SANDBOX_PREFIX)) {
+        drop(SANDBOX_PREFIX.length)
+    } else {
+        this
+    }
+}
+
+private inline fun <reified T : Object> Array<*>.toDJVMArray(): Array<out T?> {
+    @Suppress("unchecked_cast")
+    return (java.lang.reflect.Array.newInstance(javaClass.componentType.toDJVMType(), size) as Array<T?>).also {
+        for ((i, item) in withIndex()) {
+            it[i] = item?.sandbox() as T
+        }
+    }
+}
+
+private fun Enum<*>.fromDJVMEnum(): kotlin.Enum<*> {
+    return javaClass.fromDJVMType().enumConstants[ordinal()] as kotlin.Enum<*>
+}
+
+private fun kotlin.Enum<*>.toDJVMEnum(): Enum<*> {
+    @Suppress("unchecked_cast")
+    return (getEnumConstants(javaClass.toDJVMType() as Class<Enum<*>>) as Array<Enum<*>>)[ordinal]
+}
+
+/**
+ * Replacement functions for the members of Class<*> that support Enums.
+ */
+fun isEnum(clazz: Class<*>): kotlin.Boolean
+        = (clazz.modifiers and ACC_ENUM != 0) && (clazz.superclass == sandbox.java.lang.Enum::class.java)
+
+fun getEnumConstants(clazz: Class<out Enum<*>>): Array<*>? {
+    return getEnumConstantsShared(clazz)?.clone()
+}
+
+internal fun enumConstantDirectory(clazz: Class<out Enum<*>>): sandbox.java.util.Map<String, out Enum<*>>? {
+    // DO NOT replace get with Kotlin's [] because Kotlin would use java.util.Map.
+    return allEnumDirectories.get(clazz) ?: createEnumDirectory(clazz)
+}
+
+@Suppress("unchecked_cast")
+internal fun getEnumConstantsShared(clazz: Class<out Enum<*>>): Array<out Enum<*>>? {
+    return if (isEnum(clazz)) {
+        // DO NOT replace get with Kotlin's [] because Kotlin would use java.util.Map.
+        allEnums.get(clazz) ?: createEnum(clazz)
+    } else {
+        null
+    }
+}
+
+@Suppress("unchecked_cast")
+private fun createEnum(clazz: Class<out Enum<*>>): Array<out Enum<*>>? {
+    return clazz.getMethod("values").let { method ->
+        method.isAccessible = true
+        method.invoke(null) as? Array<out Enum<*>>
+    // DO NOT replace put with Kotlin's [] because Kotlin would use java.util.Map.
+    }?.apply { allEnums.put(clazz, this) }
+}
+
+private fun createEnumDirectory(clazz: Class<out Enum<*>>): sandbox.java.util.Map<String, out Enum<*>> {
+    val universe = getEnumConstantsShared(clazz) ?: throw IllegalArgumentException("${clazz.name} is not an enum type")
+    val directory = sandbox.java.util.LinkedHashMap<String, Enum<*>>(2 * universe.size)
+    for (entry in universe) {
+        // DO NOT replace put with Kotlin's [] because Kotlin would use java.util.Map.
+        directory.put(entry.name(), entry)
+    }
+    // DO NOT replace put with Kotlin's [] because Kotlin would use java.util.Map.
+    allEnumDirectories.put(clazz, directory)
+    return directory
+}
+
+private val allEnums: sandbox.java.util.Map<Class<out Enum<*>>, Array<out Enum<*>>> = sandbox.java.util.LinkedHashMap()
+private val allEnumDirectories: sandbox.java.util.Map<Class<out Enum<*>>, sandbox.java.util.Map<String, out Enum<*>>> = sandbox.java.util.LinkedHashMap()
+
+/**
+ * Replacement functions for Class<*>.forName(...) which protect
+ * against users loading classes from outside the sandbox.
+ */
+@Throws(ClassNotFoundException::class)
+fun classForName(className: kotlin.String): Class<*> {
+    return Class.forName(toSandbox(className))
+}
+
+@Throws(ClassNotFoundException::class)
+fun classForName(className: kotlin.String, initialize: kotlin.Boolean, classLoader: ClassLoader): Class<*> {
+    return Class.forName(toSandbox(className), initialize, classLoader)
+}
+
+/**
+ * Force the qualified class name into the sandbox.* namespace.
+ * Throw [ClassNotFoundException] anyway if we wouldn't want to
+ * return the resulting sandbox class. E.g. for any of our own
+ * internal classes.
+ */
+private fun toSandbox(className: kotlin.String): kotlin.String {
+    if (bannedClasses.any { it.matches(className) }) {
+        throw ClassNotFoundException(className)
+    }
+    return SANDBOX_PREFIX + className
+}
+
+private val bannedClasses = setOf(
+    "^java\\.lang\\.DJVM(.*)?\$".toRegex(),
+    "^net\\.corda\\.djvm\\..*\$".toRegex(),
+    "^Task\$".toRegex()
+)

djvm/src/main/kotlin/sandbox/java/lang/Object.kt

@@ -1,19 +0,0 @@
-package sandbox.java.lang
-
-/**
- * Sandboxed implementation of `java/lang/Object`.
- */
-@Suppress("EqualsOrHashCode")
-open class Object {
-
-    /**
-     * Deterministic hash code for objects.
-     */
-    override fun hashCode(): Int = sandbox.java.lang.System.identityHashCode(this)
-
-    /**
-     * Deterministic string representation of [Object].
-     */
-    override fun toString(): String = "sandbox.java.lang.Object@${hashCode().toString(16)}"
-
-}

djvm/src/main/kotlin/sandbox/java/lang/System.kt

@@ -1,99 +0,0 @@
-@file:Suppress("UNUSED_PARAMETER")
-
-package sandbox.java.lang
-
-import java.io.IOException
-import java.util.*
-
-object System {
-
-    private var objectCounter = object : ThreadLocal<Int>() {
-        override fun initialValue() = 0
-    }
-
-    private var objectHashCodes = object : ThreadLocal<MutableMap<Int, Int>>() {
-        override fun initialValue() = mutableMapOf<Int, Int>()
-    }
-
-    @JvmField
-    val `in`: java.io.InputStream? = null
-
-    @JvmField
-    val out: java.io.PrintStream? = null
-
-    @JvmField
-    val err: java.io.PrintStream? = null
-
-    fun setIn(stream: java.io.InputStream) {}
-
-    fun setOut(stream: java.io.PrintStream) {}
-
-    fun setErr(stream: java.io.PrintStream) {}
-
-    fun console(): java.io.Console? {
-        throw NotImplementedError()
-    }
-
-    @Throws(java.io.IOException::class)
-    fun inheritedChannel(): java.nio.channels.Channel? {
-        throw IOException()
-    }
-
-    fun setSecurityManager(manager: java.lang.SecurityManager) {}
-
-    fun getSecurityManager(): java.lang.SecurityManager? = null
-
-    fun currentTimeMillis(): Long = 0L
-
-    fun nanoTime(): Long = 0L
-
-    fun arraycopy(src: Object, srcPos: Int, dest: Object, destPos: Int, length: Int) {
-        java.lang.System.arraycopy(src, srcPos, dest, destPos, length)
-    }
-
-    fun identityHashCode(obj: Object): Int {
-        val nativeHashCode = java.lang.System.identityHashCode(obj)
-        // TODO Instead of using a magic offset below, one could take in a per-context seed
-        return objectHashCodes.get().getOrPut(nativeHashCode) {
-            val newCounter = objectCounter.get() + 1
-            objectCounter.set(newCounter)
-            0xfed_c0de + newCounter
-        }
-    }
-
-    fun getProperties(): java.util.Properties {
-        return Properties()
-    }
-
-    fun lineSeparator() = "\n"
-
-    fun setProperties(properties: java.util.Properties) {}
-
-    fun getProperty(property: String): String? = null
-
-    fun getProperty(property: String, defaultValue: String): String? = defaultValue
-
-    fun setProperty(property: String, value: String): String? = null
-
-    fun clearProperty(property: String): String? = null
-
-    fun getenv(variable: String): String? = null
-
-    @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
-    fun getenv(): java.util.Map<String, String>? = null
-
-    fun exit(exitCode: Int) {}
-
-    fun gc() {}
-
-    fun runFinalization() {}
-
-    fun runFinalizersOnExit(flag: Boolean) {}
-
-    fun load(path: String) {}
-
-    fun loadLibrary(path: String) {}
-
-    fun mapLibraryName(path: String): String? = null
-
-}

djvm/src/test/kotlin/foo/bar/sandbox/KotlinClass.kt

@@ -1,12 +1,9 @@
 package foo.bar.sandbox
 
-import java.util.*
-
-fun testRandom(): Int {
-    val random = Random()
-    return random.nextInt()
+fun testClock(): Long {
+    return System.nanoTime()
 }
 
-fun String.toNumber(): Int {
-    return this.toInt()
+fun String.toNumber(): Long {
+    return this.toLong()
 }

djvm/src/test/kotlin/net/corda/djvm/DJVMTest.kt

@@ -0,0 +1,126 @@
+package net.corda.djvm
+
+import org.assertj.core.api.Assertions.*
+import org.junit.Assert.*
+import org.junit.Test
+import sandbox.java.lang.sandbox
+import sandbox.java.lang.unsandbox
+
+class DJVMTest {
+
+    @Test
+    fun testDJVMString() {
+        val djvmString = sandbox.java.lang.String("New Value")
+        assertNotEquals(djvmString, "New Value")
+        assertEquals(djvmString, "New Value".sandbox())
+    }
+
+    @Test
+    fun testSimpleIntegerFormats() {
+        val result = sandbox.java.lang.String.format("%d-%d-%d-%d".toDJVM(),
+                          10.toDJVM(), 999999L.toDJVM(), 1234.toShort().toDJVM(), 108.toByte().toDJVM()).toString()
+        assertEquals("10-999999-1234-108", result)
+    }
+
+    @Test
+    fun testHexFormat() {
+        val result = sandbox.java.lang.String.format("%0#6x".toDJVM(), 768.toDJVM()).toString()
+        assertEquals("0x0300", result)
+    }
+
+    @Test
+    fun testDoubleFormat() {
+        val result = sandbox.java.lang.String.format("%9.4f".toDJVM(), 1234.5678.toDJVM()).toString()
+        assertEquals("1234.5678", result)
+    }
+
+    @Test
+    fun testFloatFormat() {
+        val result = sandbox.java.lang.String.format("%7.2f".toDJVM(), 1234.5678f.toDJVM()).toString()
+        assertEquals("1234.57", result)
+    }
+
+    @Test
+    fun testCharFormat() {
+        val result = sandbox.java.lang.String.format("[%c]".toDJVM(), 'A'.toDJVM()).toString()
+        assertEquals("[A]", result)
+    }
+
+    @Test
+    fun testObjectFormat() {
+        val result = sandbox.java.lang.String.format("%s".toDJVM(), object : sandbox.java.lang.Object() {}).toString()
+        assertThat(result).startsWith("sandbox.java.lang.Object@")
+    }
+
+    @Test
+    fun testStringEquality() {
+        val number = sandbox.java.lang.String.valueOf((Double.MIN_VALUE / 2.0) * 2.0)
+        require(number == "0.0".sandbox())
+    }
+
+    @Test
+    fun testSandboxingArrays() {
+        val result = arrayOf(1, 10L, "Hello World", '?', false, 1234.56).sandbox()
+        assertThat(result)
+            .isEqualTo(arrayOf(1.toDJVM(), 10L.toDJVM(), "Hello World".toDJVM(), '?'.toDJVM(), false.toDJVM(), 1234.56.toDJVM()))
+    }
+
+    @Test
+    fun testUnsandboxingObjectArray() {
+        val result = arrayOf<sandbox.java.lang.Object>(1.toDJVM(), 10L.toDJVM(), "Hello World".toDJVM(), '?'.toDJVM(), false.toDJVM(), 1234.56.toDJVM()).unsandbox()
+        assertThat(result)
+                .isEqualTo(arrayOf(1, 10L, "Hello World", '?', false, 1234.56))
+    }
+
+    @Test
+    fun testSandboxingPrimitiveArray() {
+        val result = intArrayOf(1, 2, 3, 10).sandbox()
+        assertThat(result).isEqualTo(intArrayOf(1, 2, 3, 10))
+    }
+
+    @Test
+    fun testSandboxingIntegersAsObjectArray() {
+        val result = arrayOf(1, 2, 3, 10).sandbox()
+        assertThat(result).isEqualTo(arrayOf(1.toDJVM(), 2.toDJVM(), 3.toDJVM(), 10.toDJVM()))
+    }
+
+    @Test
+    fun testUnsandboxingArrays() {
+        val arr = arrayOf(
+            Array(1) { "Hello".toDJVM() },
+            Array(1) { 1234000L.toDJVM() },
+            Array(1) { 1234.toDJVM() },
+            Array(1) { 923.toShort().toDJVM() },
+            Array(1) { 27.toByte().toDJVM() },
+            Array(1) { 'X'.toDJVM() },
+            Array(1) { 987.65f.toDJVM() },
+            Array(1) { 343.282.toDJVM() },
+            Array(1) { true.toDJVM() },
+            ByteArray(1) { 127.toByte() },
+            CharArray(1) { '?'}
+        )
+        val result = arr.unsandbox() as Array<*>
+        assertEquals(arr.size, result.size)
+        assertArrayEquals(Array(1) { "Hello" }, result[0] as Array<*>)
+        assertArrayEquals(Array(1) { 1234000L }, result[1] as Array<*>)
+        assertArrayEquals(Array(1) { 1234 }, result[2] as Array<*>)
+        assertArrayEquals(Array(1) { 923.toShort() }, result[3] as Array<*>)
+        assertArrayEquals(Array(1) { 27.toByte() }, result[4] as Array<*>)
+        assertArrayEquals(Array(1) { 'X' }, result[5] as Array<*>)
+        assertArrayEquals(Array(1) { 987.65f }, result[6] as Array<*>)
+        assertArrayEquals(Array(1) { 343.282 }, result[7] as Array<*>)
+        assertArrayEquals(Array(1) { true }, result[8] as Array<*>)
+        assertArrayEquals(ByteArray(1) { 127.toByte() }, result[9] as ByteArray)
+        assertArrayEquals(CharArray(1) { '?' }, result[10] as CharArray)
+    }
+
+    private fun String.toDJVM(): sandbox.java.lang.String = sandbox.java.lang.String.toDJVM(this)
+    private fun Long.toDJVM(): sandbox.java.lang.Long = sandbox.java.lang.Long.toDJVM(this)
+    private fun Int.toDJVM(): sandbox.java.lang.Integer = sandbox.java.lang.Integer.toDJVM(this)
+    private fun Short.toDJVM(): sandbox.java.lang.Short = sandbox.java.lang.Short.toDJVM(this)
+    private fun Byte.toDJVM(): sandbox.java.lang.Byte = sandbox.java.lang.Byte.toDJVM(this)
+    private fun Float.toDJVM(): sandbox.java.lang.Float = sandbox.java.lang.Float.toDJVM(this)
+    private fun Double.toDJVM(): sandbox.java.lang.Double = sandbox.java.lang.Double.toDJVM(this)
+    private fun Char.toDJVM(): sandbox.java.lang.Character = sandbox.java.lang.Character.toDJVM(this)
+    private fun Boolean.toDJVM(): sandbox.java.lang.Boolean = sandbox.java.lang.Boolean.toDJVM(this)
+}

djvm/src/test/kotlin/net/corda/djvm/TestBase.kt

@@ -13,6 +13,7 @@ import net.corda.djvm.messages.Severity
 import net.corda.djvm.references.ClassHierarchy
 import net.corda.djvm.rewiring.LoadedClass
 import net.corda.djvm.rules.Rule
+import net.corda.djvm.rules.implementation.*
 import net.corda.djvm.source.ClassSource
 import net.corda.djvm.utilities.Discovery
 import net.corda.djvm.validation.RuleValidator
@@ -35,8 +36,19 @@ abstract class TestBase {
 
         val ALL_EMITTERS = Discovery.find<Emitter>()
 
+        // We need at least these emitters to handle the Java API classes.
+        val BASIC_EMITTERS: List<Emitter> = listOf(
+            ArgumentUnwrapper(),
+            ReturnTypeWrapper(),
+            RewriteClassMethods(),
+            StringConstantWrapper()
+        )
+
         val ALL_DEFINITION_PROVIDERS = Discovery.find<DefinitionProvider>()
 
+        // We need at least these providers to handle the Java API classes.
+        val BASIC_DEFINITION_PROVIDERS: List<DefinitionProvider> = listOf(StaticConstantRemover())
+
         val BLANK = emptySet<Any>()
 
         val DEFAULT = (ALL_RULES + ALL_EMITTERS + ALL_DEFINITION_PROVIDERS).distinctBy(Any::javaClass)
@@ -86,14 +98,6 @@ abstract class TestBase {
         }
     }
 
-    /**
-     * Short-hand for analysing a class.
-     */
-    inline fun analyze(block: (ClassAndMemberVisitor.(AnalysisContext) -> Unit)) {
-        val validator = RuleValidator(emptyList(), configuration)
-        block(validator, context)
-    }
-
     /**
      * Run action on a separate thread to ensure that the code is run off a clean slate. The sandbox context is local to
      * the current thread, so this allows inspection of the cost summary object, etc. from within the provided delegate.
@@ -106,8 +110,8 @@ abstract class TestBase {
             action: SandboxRuntimeContext.() -> Unit
     ) {
         val rules = mutableListOf<Rule>()
-        val emitters = mutableListOf<Emitter>()
-        val definitionProviders = mutableListOf<DefinitionProvider>()
+        val emitters = mutableListOf<Emitter>().apply { addAll(BASIC_EMITTERS) }
+        val definitionProviders = mutableListOf<DefinitionProvider>().apply { addAll(BASIC_DEFINITION_PROVIDERS) }
         val classSources = mutableListOf<ClassSource>()
         var executionProfile = ExecutionProfile.UNLIMITED
         var whitelist = Whitelist.MINIMAL
@@ -137,7 +141,12 @@ abstract class TestBase {
                     minimumSeverityLevel = minimumSeverityLevel
                 ).use { analysisConfiguration ->
                     SandboxRuntimeContext(SandboxConfiguration.of(
-                            executionProfile, rules, emitters, definitionProviders, enableTracing, analysisConfiguration
+                        executionProfile,
+                        rules.distinctBy(Any::javaClass),
+                        emitters.distinctBy(Any::javaClass),
+                        definitionProviders.distinctBy(Any::javaClass),
+                        enableTracing,
+                        analysisConfiguration
                     )).use {
                         assertThat(runtimeCosts).areZero()
                         action(this)
@@ -163,7 +172,7 @@ abstract class TestBase {
     inline fun <reified T : Any> SandboxRuntimeContext.loadClass(): LoadedClass = loadClass(T::class.jvmName)
 
     fun SandboxRuntimeContext.loadClass(className: String): LoadedClass =
-            classLoader.loadClassAndBytes(ClassSource.fromClassName(className), context)
+            classLoader.loadForSandbox(className, context)
 
     /**
      * Run the entry-point of the loaded [Callable] class.

djvm/src/test/kotlin/net/corda/djvm/Utilities.kt

@@ -0,0 +1,22 @@
+package net.corda.djvm
+
+import sandbox.net.corda.djvm.costing.ThresholdViolationError
+import sandbox.net.corda.djvm.rules.RuleViolationError
+
+object Utilities {
+    fun throwRuleViolationError(): Nothing = throw RuleViolationError("Can't catch this!")
+
+    fun throwThresholdViolationError(): Nothing = throw ThresholdViolationError("Can't catch this!")
+
+    fun throwContractConstraintViolation(): Nothing = throw IllegalArgumentException("Contract constraint violated")
+
+    fun throwError(): Nothing = throw Error()
+
+    fun throwThrowable(): Nothing = throw Throwable()
+
+    fun throwThreadDeath(): Nothing = throw ThreadDeath()
+
+    fun throwStackOverflowError(): Nothing = throw StackOverflowError("FAKE OVERFLOW!")
+
+    fun throwOutOfMemoryError(): Nothing = throw OutOfMemoryError("FAKE OOM!")
+}

djvm/src/test/kotlin/net/corda/djvm/analysis/ClassResolverTest.kt

@@ -5,25 +5,25 @@ import org.junit.Test
 
 class ClassResolverTest {
 
-    private val resolver = ClassResolver(emptySet(), Whitelist.MINIMAL, "sandbox/")
+    private val resolver = ClassResolver(emptySet(), emptySet(), Whitelist.MINIMAL, "sandbox/")
 
     @Test
     fun `can resolve class name`() {
         assertThat(resolver.resolve("java/lang/Object")).isEqualTo("java/lang/Object")
-        assertThat(resolver.resolve("java/lang/String")).isEqualTo("java/lang/String")
+        assertThat(resolver.resolve("java/lang/String")).isEqualTo("sandbox/java/lang/String")
         assertThat(resolver.resolve("foo/bar/Test")).isEqualTo("sandbox/foo/bar/Test")
     }
 
     @Test
     fun `can resolve class name for arrays`() {
         assertThat(resolver.resolve("[Ljava/lang/Object;")).isEqualTo("[Ljava/lang/Object;")
-        assertThat(resolver.resolve("[Ljava/lang/String;")).isEqualTo("[Ljava/lang/String;")
+        assertThat(resolver.resolve("[Ljava/lang/String;")).isEqualTo("[Lsandbox/java/lang/String;")
         assertThat(resolver.resolve("[Lfoo/bar/Test;")).isEqualTo("[Lsandbox/foo/bar/Test;")
         assertThat(resolver.resolve("[[Ljava/lang/Object;")).isEqualTo("[[Ljava/lang/Object;")
-        assertThat(resolver.resolve("[[Ljava/lang/String;")).isEqualTo("[[Ljava/lang/String;")
+        assertThat(resolver.resolve("[[Ljava/lang/String;")).isEqualTo("[[Lsandbox/java/lang/String;")
         assertThat(resolver.resolve("[[Lfoo/bar/Test;")).isEqualTo("[[Lsandbox/foo/bar/Test;")
         assertThat(resolver.resolve("[[[Ljava/lang/Object;")).isEqualTo("[[[Ljava/lang/Object;")
-        assertThat(resolver.resolve("[[[Ljava/lang/String;")).isEqualTo("[[[Ljava/lang/String;")
+        assertThat(resolver.resolve("[[[Ljava/lang/String;")).isEqualTo("[[[Lsandbox/java/lang/String;")
         assertThat(resolver.resolve("[[[Lfoo/bar/Test;")).isEqualTo("[[[Lsandbox/foo/bar/Test;")
     }
 

djvm/src/test/kotlin/net/corda/djvm/analysis/WhitelistTest.kt

@@ -11,8 +11,8 @@ class WhitelistTest : TestBase() {
         val whitelist = Whitelist.MINIMAL
         assertThat(whitelist.matches("java/lang/Object")).isTrue()
         assertThat(whitelist.matches("java/lang/Object.<init>:()V")).isTrue()
-        assertThat(whitelist.matches("java/lang/Integer")).isTrue()
-        assertThat(whitelist.matches("java/lang/Integer.<init>:(I)V")).isTrue()
+        assertThat(whitelist.matches("java/lang/reflect/Array")).isTrue()
+        assertThat(whitelist.matches("java/lang/reflect/Array.setInt(Ljava/lang/Object;II)V")).isTrue()
     }
 
     @Test

djvm/src/test/kotlin/net/corda/djvm/assertions/AssertiveClassWithByteCode.kt

@@ -28,4 +28,9 @@ class AssertiveClassWithByteCode(private val loadedClass: LoadedClass) {
         assertThat(loadedClass.type.name).isEqualTo(className)
         return this
     }
+
+    fun hasInterface(className: String): AssertiveClassWithByteCode {
+        assertThat(loadedClass.type.interfaces.map(Class<*>::getName)).contains(className)
+        return this
+    }
 }

djvm/src/test/kotlin/net/corda/djvm/costing/RuntimeCostTest.kt

@@ -4,6 +4,7 @@ import org.assertj.core.api.Assertions.assertThat
 import org.assertj.core.api.Assertions.assertThatExceptionOfType
 import org.junit.Test
 import sandbox.net.corda.djvm.costing.ThresholdViolationError
+import kotlin.concurrent.thread
 
 class RuntimeCostTest {
 
@@ -16,17 +17,13 @@ class RuntimeCostTest {
 
     @Test
     fun `cannot increment cost beyond threshold`() {
-        Thread {
+        thread(name = "Foo") {
             val cost = RuntimeCost(10) { "failed in ${it.name}" }
             assertThatExceptionOfType(ThresholdViolationError::class.java)
                     .isThrownBy { cost.increment(11) }
                     .withMessage("failed in Foo")
             assertThat(cost.value).isEqualTo(11)
-        }.apply {
-            name = "Foo"
-            start()
-            join()
-        }
+        }.join()
     }
 
 }

djvm/src/test/kotlin/net/corda/djvm/execution/SandboxEnumTest.kt

@@ -0,0 +1,86 @@
+package net.corda.djvm.execution
+
+import net.corda.djvm.TestBase
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Test
+import java.util.*
+import java.util.function.Function
+
+class SandboxEnumTest : TestBase() {
+    @Test
+    fun `test enum inside sandbox`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<Int, Array<String>>(configuration)
+        contractExecutor.run<TransformEnum>(0).apply {
+            assertThat(result).isEqualTo(arrayOf("ONE", "TWO", "THREE"))
+        }
+    }
+
+    @Test
+    fun `return enum from sandbox`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, ExampleEnum>(configuration)
+        contractExecutor.run<FetchEnum>("THREE").apply {
+            assertThat(result).isEqualTo(ExampleEnum.THREE)
+        }
+    }
+
+    @Test
+    fun `test we can identify class as Enum`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<ExampleEnum, Boolean>(configuration)
+        contractExecutor.run<AssertEnum>(ExampleEnum.THREE).apply {
+            assertThat(result).isTrue()
+        }
+    }
+
+    @Test
+    fun `test we can create EnumMap`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<ExampleEnum, Int>(configuration)
+        contractExecutor.run<UseEnumMap>(ExampleEnum.TWO).apply {
+            assertThat(result).isEqualTo(1)
+        }
+    }
+
+    @Test
+    fun `test we can create EnumSet`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<ExampleEnum, Boolean>(configuration)
+        contractExecutor.run<UseEnumSet>(ExampleEnum.ONE).apply {
+            assertThat(result).isTrue()
+        }
+    }
+}
+
+
+class AssertEnum : Function<ExampleEnum, Boolean> {
+    override fun apply(input: ExampleEnum): Boolean {
+        return input::class.java.isEnum
+    }
+}
+
+class TransformEnum : Function<Int, Array<String>> {
+    override fun apply(input: Int): Array<String> {
+        return ExampleEnum.values().map(ExampleEnum::name).toTypedArray()
+    }
+}
+
+class FetchEnum : Function<String, ExampleEnum> {
+    override fun apply(input: String): ExampleEnum {
+        return ExampleEnum.valueOf(input)
+    }
+}
+
+class UseEnumMap : Function<ExampleEnum, Int> {
+    override fun apply(input: ExampleEnum): Int {
+        val map = EnumMap<ExampleEnum, String>(ExampleEnum::class.java)
+        map[input] = input.name
+        return map.size
+    }
+}
+
+class UseEnumSet : Function<ExampleEnum, Boolean> {
+    override fun apply(input: ExampleEnum): Boolean {
+        return EnumSet.allOf(ExampleEnum::class.java).contains(input)
+    }
+}
+
+enum class ExampleEnum {
+    ONE, TWO, THREE
+}

djvm/src/test/kotlin/net/corda/djvm/execution/SandboxExecutorTest.kt

@@ -1,10 +1,19 @@
 package net.corda.djvm.execution
 
 import foo.bar.sandbox.MyObject
-import foo.bar.sandbox.testRandom
+import foo.bar.sandbox.testClock
 import foo.bar.sandbox.toNumber
 import net.corda.djvm.TestBase
 import net.corda.djvm.analysis.Whitelist
+import net.corda.djvm.Utilities
+import net.corda.djvm.Utilities.throwContractConstraintViolation
+import net.corda.djvm.Utilities.throwError
+import net.corda.djvm.Utilities.throwOutOfMemoryError
+import net.corda.djvm.Utilities.throwRuleViolationError
+import net.corda.djvm.Utilities.throwStackOverflowError
+import net.corda.djvm.Utilities.throwThreadDeath
+import net.corda.djvm.Utilities.throwThresholdViolationError
+import net.corda.djvm.Utilities.throwThrowable
 import net.corda.djvm.assertions.AssertionExtensions.withProblem
 import net.corda.djvm.rewiring.SandboxClassLoadingException
 import org.assertj.core.api.Assertions.assertThat
@@ -13,8 +22,8 @@ import org.junit.Test
 import sandbox.net.corda.djvm.costing.ThresholdViolationError
 import sandbox.net.corda.djvm.rules.RuleViolationError
 import java.nio.file.Files
-import java.util.*
 import java.util.function.Function
+import java.util.stream.Collectors.*
 
 class SandboxExecutorTest : TestBase() {
 
@@ -34,7 +43,7 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `can load and execute contract`() = sandbox(
-            pinnedClasses = setOf(Transaction::class.java)
+            pinnedClasses = setOf(Transaction::class.java, Utilities::class.java)
     ) {
         val contractExecutor = DeterministicSandboxExecutor<Transaction, Unit>(configuration)
         val tx = Transaction(1)
@@ -44,13 +53,13 @@ class SandboxExecutorTest : TestBase() {
                 .withMessageContaining("Contract constraint violated")
     }
 
-    class Contract : Function<Transaction?, Unit> {
-        override fun apply(input: Transaction?) {
-            throw IllegalArgumentException("Contract constraint violated")
+    class Contract : Function<Transaction, Unit> {
+        override fun apply(input: Transaction) {
+            throwContractConstraintViolation()
         }
     }
 
-    data class Transaction(val id: Int?)
+    data class Transaction(val id: Int)
 
     @Test
     fun `can load and execute code that overrides object hash code`() = sandbox(DEFAULT) {
@@ -65,7 +74,11 @@ class SandboxExecutorTest : TestBase() {
             val obj = Object()
             val hash1 = obj.hashCode()
             val hash2 = obj.hashCode()
-            require(hash1 == hash2)
+            //require(hash1 == hash2)
+            // TODO: Replace require() once we have working exception support.
+            if (hash1 != hash2) {
+                throwError()
+            }
             return Object().hashCode()
         }
     }
@@ -123,37 +136,37 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `can detect illegal references in Kotlin meta-classes`() = sandbox(DEFAULT, ExecutionProfile.DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, Int>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, Long>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestKotlinMetaClasses>(0) }
-                .withCauseInstanceOf(RuleViolationError::class.java)
-                .withMessageContaining("Disallowed reference to reflection API")
+                .withCauseInstanceOf(NoSuchMethodError::class.java)
+                .withProblem("sandbox.java.lang.System.nanoTime()J")
     }
 
-    class TestKotlinMetaClasses : Function<Int, Int> {
-        override fun apply(input: Int): Int {
-            val someNumber = testRandom()
+    class TestKotlinMetaClasses : Function<Int, Long> {
+        override fun apply(input: Int): Long {
+            val someNumber = testClock()
             return "12345".toNumber() * someNumber
         }
     }
 
     @Test
     fun `cannot execute runnable that references non-deterministic code`() = sandbox(DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, Int>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, Long>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestNonDeterministicCode>(0) }
-                .withCauseInstanceOf(RuleViolationError::class.java)
-                .withProblem("Disallowed reference to reflection API")
+                .withCauseInstanceOf(NoSuchMethodError::class.java)
+                .withProblem("sandbox.java.lang.System.currentTimeMillis()J")
     }
 
-    class TestNonDeterministicCode : Function<Int, Int> {
-        override fun apply(input: Int): Int {
-            return Random().nextInt()
+    class TestNonDeterministicCode : Function<Int, Long> {
+        override fun apply(input: Int): Long {
+            return System.currentTimeMillis()
         }
     }
 
     @Test
-    fun `cannot execute runnable that catches ThreadDeath`() = sandbox(DEFAULT) {
+    fun `cannot execute runnable that catches ThreadDeath`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         TestCatchThreadDeath().apply {
             assertThat(apply(0)).isEqualTo(1)
         }
@@ -167,7 +180,7 @@ class SandboxExecutorTest : TestBase() {
     class TestCatchThreadDeath : Function<Int, Int> {
         override fun apply(input: Int): Int {
             return try {
-                throw ThreadDeath()
+                throwThreadDeath()
             } catch (exception: ThreadDeath) {
                 1
             }
@@ -175,7 +188,7 @@ class SandboxExecutorTest : TestBase() {
     }
 
     @Test
-    fun `cannot execute runnable that catches ThresholdViolationError`() = sandbox(DEFAULT) {
+    fun `cannot execute runnable that catches ThresholdViolationError`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         TestCatchThresholdViolationError().apply {
             assertThat(apply(0)).isEqualTo(1)
         }
@@ -190,7 +203,7 @@ class SandboxExecutorTest : TestBase() {
     class TestCatchThresholdViolationError : Function<Int, Int> {
         override fun apply(input: Int): Int {
             return try {
-                throw ThresholdViolationError("Can't catch this!")
+                throwThresholdViolationError()
             } catch (exception: ThresholdViolationError) {
                 1
             }
@@ -198,7 +211,7 @@ class SandboxExecutorTest : TestBase() {
     }
 
     @Test
-    fun `cannot execute runnable that catches RuleViolationError`() = sandbox(DEFAULT) {
+    fun `cannot execute runnable that catches RuleViolationError`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         TestCatchRuleViolationError().apply {
             assertThat(apply(0)).isEqualTo(1)
         }
@@ -213,7 +226,7 @@ class SandboxExecutorTest : TestBase() {
     class TestCatchRuleViolationError : Function<Int, Int> {
         override fun apply(input: Int): Int {
             return try {
-                throw RuleViolationError("Can't catch this!")
+                throwRuleViolationError()
             } catch (exception: RuleViolationError) {
                 1
             }
@@ -221,7 +234,7 @@ class SandboxExecutorTest : TestBase() {
     }
 
     @Test
-    fun `can catch Throwable`() = sandbox(DEFAULT) {
+    fun `can catch Throwable`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         val contractExecutor = DeterministicSandboxExecutor<Int, Int>(configuration)
         contractExecutor.run<TestCatchThrowableAndError>(1).apply {
             assertThat(result).isEqualTo(1)
@@ -229,7 +242,7 @@ class SandboxExecutorTest : TestBase() {
     }
 
     @Test
-    fun `can catch Error`() = sandbox(DEFAULT) {
+    fun `can catch Error`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         val contractExecutor = DeterministicSandboxExecutor<Int, Int>(configuration)
         contractExecutor.run<TestCatchThrowableAndError>(2).apply {
             assertThat(result).isEqualTo(2)
@@ -237,7 +250,7 @@ class SandboxExecutorTest : TestBase() {
     }
 
     @Test
-    fun `cannot catch ThreadDeath`() = sandbox(DEFAULT) {
+    fun `cannot catch ThreadDeath`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         val contractExecutor = DeterministicSandboxExecutor<Int, Int>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestCatchThrowableErrorsAndThreadDeath>(3) }
@@ -248,8 +261,8 @@ class SandboxExecutorTest : TestBase() {
         override fun apply(input: Int): Int {
             return try {
                 when (input) {
-                    1 -> throw Throwable()
-                    2 -> throw Error()
+                    1 -> throwThrowable()
+                    2 -> throwError()
                     else -> 0
                 }
             } catch (exception: Error) {
@@ -264,20 +277,20 @@ class SandboxExecutorTest : TestBase() {
         override fun apply(input: Int): Int {
             return try {
                 when (input) {
-                    1 -> throw Throwable()
-                    2 -> throw Error()
+                    1 -> throwThrowable()
+                    2 -> throwError()
                     3 -> try {
-                        throw ThreadDeath()
+                        throwThreadDeath()
                     } catch (ex: ThreadDeath) {
                         3
                     }
                     4 -> try {
-                        throw StackOverflowError("FAKE OVERFLOW!")
+                        throwStackOverflowError()
                     } catch (ex: StackOverflowError) {
                         4
                     }
                     5 -> try {
-                        throw OutOfMemoryError("FAKE OOM!")
+                        throwOutOfMemoryError()
                     } catch (ex: OutOfMemoryError) {
                         5
                     }
@@ -292,7 +305,7 @@ class SandboxExecutorTest : TestBase() {
     }
 
     @Test
-    fun `cannot catch stack-overflow error`() = sandbox(DEFAULT) {
+    fun `cannot catch stack-overflow error`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         val contractExecutor = DeterministicSandboxExecutor<Int, Int>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestCatchThrowableErrorsAndThreadDeath>(4) }
@@ -301,7 +314,7 @@ class SandboxExecutorTest : TestBase() {
     }
 
     @Test
-    fun `cannot catch out-of-memory error`() = sandbox(DEFAULT) {
+    fun `cannot catch out-of-memory error`() = sandbox(DEFAULT, pinnedClasses = setOf(Utilities::class.java)) {
         val contractExecutor = DeterministicSandboxExecutor<Int, Int>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestCatchThrowableErrorsAndThreadDeath>(5) }
@@ -371,7 +384,7 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `can load and execute code that uses notify()`() = sandbox(DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, String>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, String?>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestMonitors>(1) }
                 .withCauseInstanceOf(RuleViolationError::class.java)
@@ -381,7 +394,7 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `can load and execute code that uses notifyAll()`() = sandbox(DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, String>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, String?>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestMonitors>(2) }
                 .withCauseInstanceOf(RuleViolationError::class.java)
@@ -391,7 +404,7 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `can load and execute code that uses wait()`() = sandbox(DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, String>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, String?>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestMonitors>(3) }
                 .withCauseInstanceOf(RuleViolationError::class.java)
@@ -401,7 +414,7 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `can load and execute code that uses wait(long)`() = sandbox(DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, String>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, String?>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestMonitors>(4) }
                 .withCauseInstanceOf(RuleViolationError::class.java)
@@ -411,7 +424,7 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `can load and execute code that uses wait(long,int)`() = sandbox(DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, String>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, String?>(configuration)
         assertThatExceptionOfType(SandboxException::class.java)
                 .isThrownBy { contractExecutor.run<TestMonitors>(5) }
                 .withCauseInstanceOf(RuleViolationError::class.java)
@@ -421,13 +434,13 @@ class SandboxExecutorTest : TestBase() {
 
     @Test
     fun `code after forbidden APIs is intact`() = sandbox(DEFAULT) {
-        val contractExecutor = DeterministicSandboxExecutor<Int, String>(configuration)
+        val contractExecutor = DeterministicSandboxExecutor<Int, String?>(configuration)
         assertThat(contractExecutor.run<TestMonitors>(0).result)
                 .isEqualTo("unknown")
     }
 
-    class TestMonitors : Function<Int, String> {
-        override fun apply(input: Int): String {
+    class TestMonitors : Function<Int, String?> {
+        override fun apply(input: Int): String? {
             return synchronized(this) {
                 @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
                 val javaObject = this as java.lang.Object
@@ -493,6 +506,73 @@ class SandboxExecutorTest : TestBase() {
         }
     }
 
+    @Test
+    fun `check building a string`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String?, String?>(configuration)
+        contractExecutor.run<TestStringBuilding>("Hello Sandbox!").apply {
+            assertThat(result)
+                .isEqualTo("SANDBOX: Boolean=true, Char='X', Integer=1234, Long=99999, Short=3200, Byte=101, String='Hello Sandbox!', Float=123.456, Double=987.6543")
+        }
+    }
+
+    class TestStringBuilding : Function<String?, String?> {
+        override fun apply(input: String?): String? {
+             return StringBuilder("SANDBOX")
+                    .append(": Boolean=").append(true)
+                    .append(", Char='").append('X')
+                    .append("', Integer=").append(1234)
+                    .append(", Long=").append(99999L)
+                    .append(", Short=").append(3200.toShort())
+                    .append(", Byte=").append(101.toByte())
+                    .append(", String='").append(input)
+                    .append("', Float=").append(123.456f)
+                    .append(", Double=").append(987.6543)
+                    .toString()
+        }
+    }
+
+    @Test
+    fun `check System-arraycopy still works with Objects`() = sandbox(DEFAULT) {
+        val source = arrayOf("one", "two", "three")
+        assertThat(TestArrayCopy().apply(source))
+            .isEqualTo(source)
+            .isNotSameAs(source)
+
+        val contractExecutor = DeterministicSandboxExecutor<Array<String>, Array<String>>(configuration)
+        contractExecutor.run<TestArrayCopy>(source).apply {
+            assertThat(result)
+                .isEqualTo(source)
+                .isNotSameAs(source)
+        }
+    }
+
+    class TestArrayCopy : Function<Array<String>, Array<String>> {
+        override fun apply(input: Array<String>): Array<String> {
+            val newArray = Array(input.size) { "" }
+            System.arraycopy(input, 0, newArray, 0, newArray.size)
+            return newArray
+        }
+    }
+
+    @Test
+    fun `test System-arraycopy still works with CharArray`() = sandbox(DEFAULT) {
+        val source = CharArray(10) { '?' }
+        val contractExecutor = DeterministicSandboxExecutor<CharArray, CharArray>(configuration)
+        contractExecutor.run<TestCharArrayCopy>(source).apply {
+            assertThat(result)
+                .isEqualTo(source)
+                .isNotSameAs(source)
+        }
+    }
+
+    class TestCharArrayCopy : Function<CharArray, CharArray> {
+        override fun apply(input: CharArray): CharArray {
+            val newArray = CharArray(input.size) { 'X' }
+            System.arraycopy(input, 0, newArray, 0, newArray.size)
+            return newArray
+        }
+    }
+
     @Test
     fun `can load and execute class that has finalize`() = sandbox(DEFAULT) {
         assertThatExceptionOfType(UnsupportedOperationException::class.java)
@@ -515,4 +595,152 @@ class SandboxExecutorTest : TestBase() {
             throw UnsupportedOperationException("Very Bad Thing")
         }
     }
+
+    @Test
+    fun `can execute parallel stream`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, String>(configuration)
+        contractExecutor.run<TestParallelStream>("Pebble").apply {
+            assertThat(result).isEqualTo("Five,Four,One,Pebble,Three,Two")
+        }
+    }
+
+    class TestParallelStream : Function<String, String> {
+        override fun apply(input: String): String {
+            return listOf(input, "One", input, "Two", input, "Three", input, "Four", input, "Five")
+                    .stream()
+                    .distinct()
+                    .sorted()
+                    .collect(joining(","))
+        }
+    }
+
+    @Test
+    fun `users cannot load our sandboxed classes`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, Class<*>>(configuration)
+        assertThatExceptionOfType(SandboxException::class.java)
+                .isThrownBy { contractExecutor.run<TestClassForName>("java.lang.DJVM") }
+                .withCauseInstanceOf(ClassNotFoundException::class.java)
+                .withMessageContaining("java.lang.DJVM")
+    }
+
+    @Test
+    fun `users can load sandboxed classes`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, Class<*>>(configuration)
+        contractExecutor.run<TestClassForName>("java.util.List").apply {
+            assertThat(result?.name).isEqualTo("sandbox.java.util.List")
+        }
+    }
+
+    class TestClassForName : Function<String, Class<*>> {
+        override fun apply(input: String): Class<*> {
+            return Class.forName(input)
+        }
+    }
+
+    @Test
+    fun `test case-insensitive string sorting`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<Array<String>, Array<String>>(configuration)
+        contractExecutor.run<CaseInsensitiveSort>(arrayOf("Zelda", "angela", "BOB", "betsy", "ALBERT")).apply {
+            assertThat(result).isEqualTo(arrayOf("ALBERT", "angela", "betsy", "BOB", "Zelda"))
+        }
+    }
+
+    class CaseInsensitiveSort : Function<Array<String>, Array<String>> {
+        override fun apply(input: Array<String>): Array<String> {
+            return listOf(*input).sortedWith(String.CASE_INSENSITIVE_ORDER).toTypedArray()
+        }
+    }
+
+    @Test
+    fun `test unicode characters`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<Int, String>(configuration)
+        contractExecutor.run<ExamineUnicodeBlock>(0x01f600).apply {
+            assertThat(result).isEqualTo("EMOTICONS")
+        }
+    }
+
+    class ExamineUnicodeBlock : Function<Int, String> {
+        override fun apply(codePoint: Int): String {
+            return Character.UnicodeBlock.of(codePoint).toString()
+        }
+    }
+
+    @Test
+    fun `test unicode scripts`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, Character.UnicodeScript?>(configuration)
+        contractExecutor.run<ExamineUnicodeScript>("COMMON").apply {
+            assertThat(result).isEqualTo(Character.UnicodeScript.COMMON)
+        }
+    }
+
+    class ExamineUnicodeScript : Function<String, Character.UnicodeScript?> {
+        override fun apply(scriptName: String): Character.UnicodeScript? {
+            val script = Character.UnicodeScript.valueOf(scriptName)
+            return if (script::class.java.isEnum) script else null
+        }
+    }
+
+    @Test
+    fun `test users cannot define new classes`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, Class<*>>(configuration)
+        assertThatExceptionOfType(SandboxException::class.java)
+                .isThrownBy { contractExecutor.run<DefineNewClass>("sandbox.java.lang.DJVM") }
+                .withCauseInstanceOf(RuleViolationError::class.java)
+                .withMessageContaining("Disallowed reference to API;")
+                .withMessageContaining("java.lang.ClassLoader.defineClass")
+    }
+
+    class DefineNewClass : Function<String, Class<*>> {
+        override fun apply(input: String): Class<*> {
+            val data = ByteArray(0)
+            val cl = object : ClassLoader(this::class.java.classLoader) {
+                fun define(): Class<*> {
+                    return super.defineClass(input, data, 0, data.size)
+                }
+            }
+            return cl.define()
+        }
+    }
+
+    @Test
+    fun `test users cannot load new classes`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, Class<*>>(configuration)
+        assertThatExceptionOfType(SandboxException::class.java)
+                .isThrownBy { contractExecutor.run<LoadNewClass>("sandbox.java.lang.DJVM") }
+                .withCauseInstanceOf(RuleViolationError::class.java)
+                .withMessageContaining("Disallowed reference to API;")
+                .withMessageContaining("java.lang.ClassLoader.loadClass")
+    }
+
+    class LoadNewClass : Function<String, Class<*>> {
+        override fun apply(input: String): Class<*> {
+            val cl = object : ClassLoader(this::class.java.classLoader) {
+                fun load(): Class<*> {
+                    return super.loadClass(input)
+                }
+            }
+            return cl.load()
+        }
+    }
+
+    @Test
+    fun `test users cannot lookup classes`() = sandbox(DEFAULT) {
+        val contractExecutor = DeterministicSandboxExecutor<String, Class<*>>(configuration)
+        assertThatExceptionOfType(SandboxException::class.java)
+                .isThrownBy { contractExecutor.run<FindClass>("sandbox.java.lang.DJVM") }
+                .withCauseInstanceOf(RuleViolationError::class.java)
+                .withMessageContaining("Disallowed reference to API;")
+                .withMessageContaining("java.lang.ClassLoader.findClass")
+    }
+
+    class FindClass : Function<String, Class<*>> {
+        override fun apply(input: String): Class<*> {
+            val cl = object : ClassLoader(this::class.java.classLoader) {
+                fun find(): Class<*> {
+                    return super.findClass(input)
+                }
+            }
+            return cl.find()
+        }
+    }
 }

djvm/src/test/kotlin/net/corda/djvm/rewiring/ClassRewriterTest.kt

@@ -1,16 +1,14 @@
 package net.corda.djvm.rewiring
 
-import foo.bar.sandbox.A
-import foo.bar.sandbox.B
-import foo.bar.sandbox.Empty
-import foo.bar.sandbox.StrictFloat
+import foo.bar.sandbox.*
 import net.corda.djvm.TestBase
 import net.corda.djvm.assertions.AssertionExtensions.assertThat
 import net.corda.djvm.execution.ExecutionProfile
-import org.assertj.core.api.Assertions.assertThatExceptionOfType
+import org.assertj.core.api.Assertions.*
 import org.junit.Test
 import sandbox.net.corda.djvm.costing.ThresholdViolationError
 import java.nio.file.Paths
+import java.util.*
 
 class ClassRewriterTest : TestBase() {
 
@@ -102,4 +100,44 @@ class ClassRewriterTest : TestBase() {
             return input
         }
     }
+
+    @Test
+    fun `can load class with constant fields`() = sandbox(DEFAULT) {
+        assertThat(loadClass<ObjectWithConstants>())
+                .hasClassName("sandbox.net.corda.djvm.rewiring.ObjectWithConstants")
+                .hasBeenModified()
+    }
+
+    @Test
+    fun `test rewrite static method`() = sandbox(DEFAULT) {
+        assertThat(loadClass<Arrays>())
+                .hasClassName("sandbox.java.util.Arrays")
+                .hasBeenModified()
+    }
+
+    @Test
+    fun `test stitch new super-interface`() = sandbox(DEFAULT) {
+        assertThat(loadClass<CharSequence>())
+                .hasClassName("sandbox.java.lang.CharSequence")
+                .hasInterface("java.lang.CharSequence")
+                .hasBeenModified()
+    }
+
+    @Test
+    fun `test class with stitched interface`() = sandbox(DEFAULT) {
+        assertThat(loadClass<StringBuilder>())
+                .hasClassName("sandbox.java.lang.StringBuilder")
+                .hasInterface("sandbox.java.lang.CharSequence")
+                .hasBeenModified()
+    }
 }
+
+@Suppress("unused")
+private object ObjectWithConstants {
+    const val MESSAGE = "Hello Sandbox!"
+    const val BIG_NUMBER = 99999L
+    const val NUMBER = 100
+    const val CHAR = '?'
+    const val BYTE = 7f.toByte()
+    val DATA = Array(0) { "" }
+}

djvm/src/test/kotlin/net/corda/djvm/source/SourceClassLoaderTest.kt

@@ -10,7 +10,7 @@ import java.nio.file.Path
 
 class SourceClassLoaderTest {
 
-    private val classResolver = ClassResolver(emptySet(), Whitelist.MINIMAL, "")
+    private val classResolver = ClassResolver(emptySet(), emptySet(), Whitelist.MINIMAL, "")
 
     @Test
     fun `can load class from Java's lang package when no files are provided to the class loader`() {