/**
* Returns true iff mgen is a constructor
*
* @return true iff mgen is a constructor
*/
private boolean is_constructor(MethodGen mgen) {
if (mgen.getName().equals("<init>") || mgen.getName().equals("")) {
// log ("method '%s' is a constructor%n", mgen.getName());
return (true);
} else return (false);
}
/** Instrument the specified method to replace mapped calls. */
public void instrument_method(Method m, MethodGen mg) {
// Loop through each instruction, making substitutions
InstructionList il = mg.getInstructionList();
for (InstructionHandle ih = il.getStart(); ih != null; ) {
if (debug_instrument_inst.enabled()) {
debug_instrument_inst.log("instrumenting instruction %s%n", ih);
// ih.getInstruction().toString(pool.getConstantPool()));
}
InstructionList new_il = null;
// Remember the next instruction to process
InstructionHandle next_ih = ih.getNext();
// Get the translation for this instruction (if any)
new_il = xform_inst(mg, ih.getInstruction());
if (debug_instrument_inst.enabled()) debug_instrument_inst.log(" new inst: %s%n", new_il);
// If this instruction was modified, replace it with the new
// instruction list. If this instruction was the target of any
// jumps or line numbers , replace them with the first
// instruction in the new list
replace_instructions(il, ih, new_il);
ih = next_ih;
}
}
/**
* Transforms invoke instructions that match the specified list for this class to call the
* specified static call instead.
*/
private InstructionList xform_inst(MethodGen mg, Instruction inst) {
switch (inst.getOpcode()) {
case Constants.INVOKESTATIC:
{
InstructionList il = new InstructionList();
INVOKESTATIC is = (INVOKESTATIC) inst;
String cname = is.getClassName(pgen);
String mname = is.getMethodName(pgen);
Type[] args = is.getArgumentTypes(pgen);
MethodDef orig = new MethodDef(cname + "." + mname, args);
MethodInfo call = method_map.get(orig);
if (call != null) {
call.cnt++;
String classname = call.method_class;
String methodname = mname;
debug_map.log(
"%s.%s: Replacing method %s.%s (%s) with %s.%s%n",
mg.getClassName(),
mg.getName(),
cname,
mname,
UtilMDE.join(args, ", "),
classname,
methodname);
il.append(
ifact.createInvoke(
classname, methodname, is.getReturnType(pgen), args, Constants.INVOKESTATIC));
}
return (il);
}
case Constants.INVOKEVIRTUAL:
{
InstructionList il = new InstructionList();
INVOKEVIRTUAL iv = (INVOKEVIRTUAL) inst;
String cname = iv.getClassName(pgen);
String mname = iv.getMethodName(pgen);
Type[] args = iv.getArgumentTypes(pgen);
Type instance_type = iv.getReferenceType(pgen);
Type[] new_args = BCELUtil.insert_type(instance_type, args);
MethodDef orig = new MethodDef(cname + "." + mname, args);
if (debug_class) System.out.printf("looking for %s in map %s%n", orig, method_map);
MethodInfo call = method_map.get(orig);
if (call != null) {
call.cnt++;
String classname = call.method_class;
String methodname = mname;
debug_map.log(
"Replacing method %s.%s (%s) with %s.%s%n",
cname, mname, ArraysMDE.toString(args), classname, methodname);
il.append(
ifact.createInvoke(
classname,
methodname,
iv.getReturnType(pgen),
new_args,
Constants.INVOKESTATIC));
}
return (il);
}
default:
return (null);
}
}
/**
* Processes each method in cg replacing any specified calls with static user calls.
*
* @param fullClassName must be packageName.className
*/
private boolean map_calls(ClassGen cg, String fullClassName, ClassLoader loader) {
boolean transformed = false;
try {
pgen = cg.getConstantPool();
// Loop through each method in the class
Method[] methods = cg.getMethods();
for (int i = 0; i < methods.length; i++) {
MethodGen mg = new MethodGen(methods[i], cg.getClassName(), pgen);
// Get the instruction list and skip methods with no instructions
InstructionList il = mg.getInstructionList();
if (il == null) continue;
if (debug) out.format("Original code: %s%n", mg.getMethod().getCode());
instrument_method(methods[i], mg);
// Remove the Local variable type table attribute (if any).
// Evidently, some changes we make require this to be updated, but
// without BCEL support, that would be hard to do. Just delete it
// for now (since it is optional, and we are unlikely to be used by
// a debugger)
for (Attribute a : mg.getCodeAttributes()) {
if (is_local_variable_type_table(a)) {
mg.removeCodeAttribute(a);
}
}
// Update the instruction list
mg.setInstructionList(il);
mg.update();
// Update the max stack and Max Locals
mg.setMaxLocals();
mg.setMaxStack();
mg.update();
// Update the method in the class
cg.replaceMethod(methods[i], mg.getMethod());
if (debug) out.format("Modified code: %s%n", mg.getMethod().getCode());
// verify the new method
// StackVer stackver = new StackVer();
// VerificationResult vr = stackver.do_stack_ver (mg);
// log ("vr for method %s = %s%n", mg.getName(), vr);
// if (vr.getStatus() != VerificationResult.VERIFIED_OK) {
// System.out.printf ("Warning BCEL Verify failed for method %s: %s",
// mg.getName(), vr);
// System.out.printf ("Code: %n%s%n", mg.getMethod().getCode());
// System.exit(1);
// }
}
cg.update();
} catch (Exception e) {
out.format("Unexpected exception encountered: " + e);
e.printStackTrace();
}
return transformed;
}
