Refactor JNI command-line interface

Does not depend on ServalDResult class - appends output fields to a supplied
list instead, and returns the integer status

Does not depend on ServalDReentranceError class - uses
java.lang.IllegalStateException instead

commandline.c

@@ -95,19 +95,13 @@ int cli_usage() {
 
 #ifdef HAVE_JNI_H
 
-struct outv_field {
-  jstring jstr;
-};
-
-#define OUTV_BUFFER_ATOM	(8192)
-#define OUTC_INCREMENT		(256)
+#define OUTV_BUFFER_ALLOCSIZE	(8192)
 
 JNIEnv *jni_env = NULL;
 int jni_exception = 0;
 
-struct outv_field *outv = NULL;
-size_t outc = 0;
-size_t outc_limit = 0;
+jobject outv_list = NULL;
+jmethodID listAddMethodId = NULL;
 
 char *outv_buffer = NULL;
 char *outv_current = NULL;
@@ -117,8 +111,8 @@ static int outv_growbuf(size_t needed)
 {
   size_t newsize = (outv_limit - outv_current < needed) ? (outv_limit - outv_buffer) + needed : 0;
   if (newsize) {
-    // Round up to nearest multiple of OUTV_BUFFER_ATOM.
-    newsize = newsize + OUTV_BUFFER_ATOM - ((newsize - 1) % OUTV_BUFFER_ATOM + 1);
+    // Round up to nearest multiple of OUTV_BUFFER_ALLOCSIZE.
+    newsize = newsize + OUTV_BUFFER_ALLOCSIZE - ((newsize - 1) % OUTV_BUFFER_ALLOCSIZE + 1);
     size_t length = outv_current - outv_buffer;
     outv_buffer = realloc(outv_buffer, newsize);
     if (outv_buffer == NULL)
@@ -133,57 +127,52 @@ static int outv_end_field()
 {
   outv_growbuf(1);
   *outv_current++ = '\0';
-  if (outc == outc_limit) {
-    outc_limit += OUTC_INCREMENT;
-    size_t newsize = outc_limit * sizeof(struct outv_field);
-    outv = realloc(outv, newsize);
-  }
-  struct outv_field *f = &outv[outc];
-  f->jstr = (jstring)(*jni_env)->NewStringUTF(jni_env, outv_buffer);
+  jstring str = (jstring)(*jni_env)->NewStringUTF(jni_env, outv_buffer);
   outv_current = outv_buffer;
-  if (f->jstr == NULL) {
+  if (str == NULL) {
     jni_exception = 1;
     return WHY("Exception thrown from NewStringUTF()");
   }
-  ++outc;
+  (*jni_env)->CallBooleanMethod(jni_env, outv_list, listAddMethodId, str);
+  if ((*jni_env)->ExceptionOccurred(jni_env)) {
+    jni_exception = 1;
+    return WHY("Exception thrown from CallBooleanMethod()");
+  }
   return 0;
 }
 
 /* JNI entry point to command line.  See org.servalproject.servald.ServalD class for the Java side.
-   JNI method descriptor: "([Ljava/lang/String;)Lorg/servalproject/servald/ServalDResult;"
+   JNI method descriptor: "(Ljava/util/List;[Ljava/lang/String;)I"
 */
-JNIEXPORT jobject JNICALL Java_org_servalproject_servald_ServalD_command(JNIEnv *env, jobject this, jobjectArray args)
+JNIEXPORT jint JNICALL Java_org_servalproject_servald_ServalD_rawCommand(JNIEnv *env, jobject this, jobject outv, jobjectArray args)
 {
-  jclass resultClass = NULL;
   jclass stringClass = NULL;
-  jmethodID resultConstructorId = NULL;
-  jobjectArray outArray = NULL;
+  jclass listClass = NULL;
   jint status = 0;
   // Enforce non re-entrancy.
   if (jni_env) {
     jclass exceptionClass = NULL;
-    if ((exceptionClass = (*env)->FindClass(env, "org/servalproject/servald/ServalDReentranceError")) == NULL)
-      return NULL; // exception
+    if ((exceptionClass = (*env)->FindClass(env, "java/lang/IllegalStateException")) == NULL)
+      return -1; // exception
     (*env)->ThrowNew(env, exceptionClass, "re-entrancy not supported");
-    return NULL;
+    return -1;
   }
-
   // Get some handles to some classes and methods that we use later on.
-  if ((resultClass = (*env)->FindClass(env, "org/servalproject/servald/ServalDResult")) == NULL)
-    return NULL; // exception
-  if ((resultConstructorId = (*env)->GetMethodID(env, resultClass, "<init>", "(I[Ljava/lang/String;)V")) == NULL)
-    return NULL; // exception
   if ((stringClass = (*env)->FindClass(env, "java/lang/String")) == NULL)
-    return NULL; // exception
+    return -1; // exception
+  if ((listClass = (*env)->FindClass(env, "java/util/List")) == NULL)
+    return -1; // exception
+  if ((listAddMethodId = (*env)->GetMethodID(env, listClass, "add", "(Ljava/lang/Object;)Z")) == NULL)
+    return -1; // exception
   // Construct argv, argc from this method's arguments.
   jsize len = (*env)->GetArrayLength(env, args);
   const char **argv = malloc(sizeof(char*) * (len + 1));
   if (argv == NULL) {
     jclass exceptionClass = NULL;
     if ((exceptionClass = (*env)->FindClass(env, "java/lang/OutOfMemoryError")) == NULL)
-      return NULL; // exception
+      return -1; // exception
     (*env)->ThrowNew(env, exceptionClass, "malloc returned NULL");
-    return NULL;
+    return -1;
   }
   jsize i;
   for (i = 0; i <= len; ++i)
@@ -206,7 +195,7 @@ JNIEXPORT jobject JNICALL Java_org_servalproject_servald_ServalD_command(JNIEnv
   }
   if (!jni_exception) {
     // Set up the output buffer.
-    outc = 0;
+    outv_list = outv;
     outv_current = outv_buffer;
     // Execute the command.
     jni_env = env;
@@ -223,15 +212,8 @@ JNIEXPORT jobject JNICALL Java_org_servalproject_servald_ServalD_command(JNIEnv
   free(argv);
   // Deal with Java exceptions: NewStringUTF out of memory in outv_end_field().
   if (jni_exception || (outv_current != outv_buffer && outv_end_field() == -1))
-    return NULL;
-  // Pack the output fields into a Java array of strings.
-  if ((outArray = (*env)->NewObjectArray(env, outc, stringClass, NULL)) == NULL)
-    return NULL; // out of memory exception
-  for (i = 0; i != outc; ++i)
-    (*env)->SetObjectArrayElement(env, outArray, i, outv[i].jstr);
-  // Return the ResultD object constructed with the status integer and the array of output field
-  // strings.
-  return (*env)->NewObject(env, resultClass, resultConstructorId, status, outArray);
+    return -1;
+  return status;
 }
 
 #endif /* HAVE_JNI_H */
@@ -422,7 +404,7 @@ int cli_delim(const char *opt)
 {
 #ifdef HAVE_JNI_H
   if (jni_env) {
-    outv_end_field();
+    return outv_end_field();
   } else
 #endif
   {

java/org/servalproject/servald/ServalD.java

@@ -1,23 +1,33 @@
 package org.servalproject.servald;
 
-import org.servalproject.servald.ServalDResult;
+import java.util.List;
+import java.util.LinkedList;
 
 class ServalD
 {
+	int status;
+	List<String> outv;
+
 	public ServalD()
 	{
 		System.loadLibrary("servald");
 	}
 
-	public native ServalDResult command(String... args);
+	public native int rawCommand(List<String> outv, String... args);
+
+	public void command(String... args)
+	{
+		this.outv = new LinkedList<String>();
+		this.status = this.rawCommand(this.outv, args);
+	}
 
 	public static void main(String[] args)
 	{
-		ServalD sdi = new ServalD();
-		ServalDResult res = sdi.command(args);
-		for (String s: res.outv) {
+		ServalD servald = new ServalD();
+		servald.command(args);
+		for (String s: servald.outv) {
 			System.out.println(s);
 		}
-		System.exit(res.status);
+		System.exit(servald.status);
 	}
 }

java/org/servalproject/servald/ServalDReentranceError.java

@@ -1,5 +0,0 @@
-package org.servalproject.servald;
-
-class ServalDReentranceError extends RuntimeException
-{
-}

java/org/servalproject/servald/ServalDResult.java

@@ -1,14 +0,0 @@
-package org.servalproject.servald;
-
-class ServalDResult
-{
-	public int status;
-	public String[] outv;
-
-	public ServalDResult(int status, String[] outv)
-	{
-		this.status = status;
-		this.outv = outv;
-	}
-
-}

java/org/servalproject/servald/ServalDTests.java

@@ -2,8 +2,9 @@ package org.servalproject.servald;
 
 import java.lang.reflect.*;
 import java.util.Arrays;
+import java.util.List;
+import java.util.LinkedList;
 import org.servalproject.servald.ServalD;
-import org.servalproject.servald.ServalDResult;
 
 class ServalDTests
 {
@@ -24,11 +25,11 @@ class ServalDTests
 	public static void repeat(String[] args)
 	{
 		int repeat = Integer.decode(args[0]);
-		ServalD sdi = new ServalD();
+		ServalD servald = new ServalD();
 		for (int i = 0; i != repeat; ++i) {
-			ServalDResult res = sdi.command(Arrays.copyOfRange(args, 1, args.length));
-			System.out.print(res.status);
-			for (String s: res.outv) {
+			servald.command(Arrays.copyOfRange(args, 1, args.length));
+			System.out.print(servald.status);
+			for (String s: servald.outv) {
 				System.out.print(":");
 				System.out.print(s);
 			}

tests/dna_jni

@@ -34,8 +34,6 @@ compile_java_classes() {
    mkdir classes
    assert $JAVAC -d classes "$dna_source_root"/java/org/servalproject/servald/*.java
    assert [ -r classes/org/servalproject/servald/ServalD.class ]
-   assert [ -r classes/org/servalproject/servald/ServalDResult.class ]
-   assert [ -r classes/org/servalproject/servald/ServalDReentranceError.class ]
    assert [ -r classes/org/servalproject/servald/ServalDTests.class ]
 }