intercept SIGSEGV and throw NullPointerExceptions

makefile

@@ -28,7 +28,7 @@ src = src
 classpath = classpath
 test = test
 
-input = $(test-build)/Misc.class
+input = List
 
 build-cxx = g++
 build-cc = gcc
@@ -215,7 +215,7 @@ else
 	flags = -cp $(test-build)
 endif
 
-args = $(flags) $(call class-name,$(test-build),$(input))
+args = $(flags) $(input)
 
 .PHONY: build
 build: $(interpreter) $(archive) $(classpath-dep) $(test-dep)

src/compiler.h

@@ -2,6 +2,7 @@
 #define COMPILER_H
 
 #include "system.h"
+#include "zone.h"
 
 namespace vm {
 
@@ -20,18 +21,15 @@ class Promise {
 
 class Compiler {
  public:
-  class NullHandler {
+  class TraceHandler {
    public:
-    virtual ~NullHandler() { }
+    virtual ~TraceHandler() { }
 
-    virtual void handleMaybeNull(Promise* address) = 0;
+    virtual void handleTrace(Promise* address) = 0;
   };
 
   virtual ~Compiler() { }
 
-  virtual void setNullHandler(NullHandler*) = 0;
-
-  virtual Promise* machineIp() = 0;
   virtual Promise* machineIp(unsigned logicalIp) = 0;
 
   virtual Promise* poolAppend(intptr_t) = 0;
@@ -44,7 +42,7 @@ class Compiler {
                           int displacement = 0,
                           Operand* index = 0,
                           unsigned scale = 1,
-                          bool maybeNull = false) = 0;
+                          TraceHandler* traceHandler = 0) = 0;
 
   virtual Operand* stack() = 0;
   virtual Operand* base() = 0;
@@ -58,15 +56,17 @@ class Compiler {
   virtual Operand* label() = 0;
   virtual void mark(Operand*) = 0;
 
-  virtual Promise* indirectCall
-  (Operand* address, unsigned argumentCount, ...) = 0;
+  virtual void indirectCall
+  (Operand* address, TraceHandler* traceHandler,
+   unsigned argumentCount, ...) = 0;
   virtual void indirectCallNoReturn
-  (Operand* address, unsigned argumentCount, ...) = 0;
-  virtual Promise* directCall
+  (Operand* address, TraceHandler* traceHandler,
+   unsigned argumentCount, ...) = 0;
+  virtual void directCall
   (Operand* address, unsigned argumentCount, ...) = 0;
 
-  virtual void call(Operand*) = 0;
-  virtual void alignedCall(Operand*) = 0;
+  virtual void call(Operand*, TraceHandler*) = 0;
+  virtual void alignedCall(Operand*, TraceHandler*) = 0;
   virtual void return4(Operand*) = 0;
   virtual void return8(Operand*) = 0;
   virtual void ret() = 0;
@@ -141,7 +141,7 @@ class Compiler {
 };
 
 Compiler*
-makeCompiler(System* system, void* indirectCaller);
+makeCompiler(System* system, Zone* zone, void* indirectCaller);
 
 } // namespace vm
 

src/posix.cpp

@@ -55,6 +55,12 @@ void
 handleSignal(int signal, siginfo_t* info, void* context)
 {
   if (signal == SIGSEGV) {
+    sigset_t set;
+
+    sigemptyset(&set);
+    sigaddset(&set, SIGSEGV);
+    sigprocmask(SIG_UNBLOCK, &set, 0);
+
     greg_t* registers
       = static_cast<ucontext_t*>(context)->uc_mcontext.gregs;
 
@@ -66,8 +72,10 @@ handleSignal(int signal, siginfo_t* info, void* context)
     if (not handled) {
       if (oldSegFaultHandler.sa_flags & SA_SIGINFO) {
         oldSegFaultHandler.sa_sigaction(signal, info, context);
-      } else {
+      } else if (oldSegFaultHandler.sa_handler) {
         oldSegFaultHandler.sa_handler(signal);
+      } else {
+        abort();
       }
     }
   }

test/NullPointer.java

@@ -0,0 +1,92 @@
+public class NullPointer {
+  private int x;
+  private Object y;
+
+  public static void main(String[] args) {
+    // invokeinterface
+    try {
+      ((Runnable) null).run();
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // invokevirtual
+    try {
+      ((Object) null).toString();
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // arraylength
+    try {
+      int a = ((byte[]) null).length;
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // iaload
+    try {
+      int a = ((byte[]) null)[42];
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // aaload
+    try {
+      Object a = ((Object[]) null)[42];
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // getfield (int)
+    try {
+      int a = ((NullPointer) null).x;
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // getfield (Object)
+    try {
+      Object a = ((NullPointer) null).y;
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // iastore
+    try {
+      ((byte[]) null)[42] = 42;
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // aastore
+    try {
+      ((Object[]) null)[42] = null;
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // putfield (int)
+    try {
+      ((NullPointer) null).x = 42;
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // putfield (Object)
+    try {
+      ((NullPointer) null).y = null;
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+
+    // monitorenter
+    try {
+      synchronized ((Object) null) {
+        int a = 42;
+      }
+    } catch (NullPointerException e) {
+      e.printStackTrace();
+    }
+  }
+}