CheckClassAdapter can be also used to verify bytecode
* transformations in order to make sure transformed bytecode is sane. For
* example:
*
*
* InputStream is = ...; // get bytes for the source class * ClassReader cr = new ClassReader(is); * ClassWriter cw = new ClassWriter(cr, ClassWriter.COMPUTE_MAXS); * ClassVisitor cv = new MyClassAdapter(new CheckClassAdapter(cw)); * cr.accept(cv, 0); * * StringWriter sw = new StringWriter(); * PrintWriter pw = new PrintWriter(sw); * CheckClassAdapter.verify(new ClassReader(cw.toByteArray()), false, pw); * assertTrue(sw.toString(), sw.toString().length()==0); ** * Above code runs transformed bytecode trough the *
CheckClassAdapter. It won't be exactly the same verification
* as JVM does, but it run data flow analysis for the code of each method and
* checks that expectations are met for each method instruction.
*
* If method bytecode has errors, assertion text will show the erroneous * instruction number and dump of the failed method with information about * locals and stack slot for each instruction. For example (format is - * insnNumber locals : stack): * *
* org.mockito.asm.tree.analysis.AnalyzerException: Error at instruction 71: Expected I, but found . * at org.mockito.asm.tree.analysis.Analyzer.analyze(Analyzer.java:289) * at org.mockito.asm.util.CheckClassAdapter.verify(CheckClassAdapter.java:135) * ... * remove()V * 00000 LinkedBlockingQueue$Itr . . . . . . . . : * ICONST_0 * 00001 LinkedBlockingQueue$Itr . . . . . . . . : I * ISTORE 2 * 00001 LinkedBlockingQueue$Itr . I . . . . . . : * ... * * 00071 LinkedBlockingQueue$Itr . I . . . . . . : * ILOAD 1 * 00072 ? * INVOKESPECIAL java/lang/Integer.* * In the above output you can see that variable 1 loaded by *(I)V * ... *
ILOAD 1 instruction at position 00071 is not
* initialized. You can also see that at the beginning of the method (code
* inserted by the transformation) variable 2 is initialized.
*
* Note that when used like that, CheckClassAdapter.verify()
* can trigger additional class loading, because it is using
* SimpleVerifier.
*
* @author Eric Bruneton
*/
public class CheckClassAdapter extends ClassAdapter {
/**
* true if the visit method has been called.
*/
private boolean start;
/**
* true if the visitSource method has been called.
*/
private boolean source;
/**
* true if the visitOuterClass method has been called.
*/
private boolean outer;
/**
* true if the visitEnd method has been called.
*/
private boolean end;
/**
* Checks a given class.
Usage: CheckClassAdapter <fully qualified
* class name or class file name>
*
* @param args the command line arguments.
*
* @throws Exception if the class cannot be found, or if an IO exception
* occurs.
*/
public static void main(final String[] args) throws Exception {
if (args.length != 1) {
System.err.println("Verifies the given class.");
System.err.println("Usage: CheckClassAdapter "
+ "ClassReader that contains bytecode for the
* analysis.
* @param dump true if bytecode should be printed out not only when errors
* are found.
* @param pw write where results going to be printed
*/
public static void verify(
final ClassReader cr,
final boolean dump,
final PrintWriter pw)
{
ClassNode cn = new ClassNode();
cr.accept(new CheckClassAdapter(cn), ClassReader.SKIP_DEBUG);
Type syperType = cn.superName == null
? null
: Type.getObjectType(cn.superName);
List methods = cn.methods;
for (int i = 0; i < methods.size(); ++i) {
MethodNode method = (MethodNode) methods.get(i);
Analyzer a = new Analyzer(new SimpleVerifier(Type.getObjectType(cn.name),
syperType,
false));
try {
a.analyze(cn.name, method);
if (!dump) {
continue;
}
} catch (Exception e) {
e.printStackTrace(pw);
}
Frame[] frames = a.getFrames();
TraceMethodVisitor mv = new TraceMethodVisitor();
pw.println(method.name + method.desc);
for (int j = 0; j < method.instructions.size(); ++j) {
method.instructions.get(j).accept(mv);
StringBuffer s = new StringBuffer();
Frame f = frames[j];
if (f == null) {
s.append('?');
} else {
for (int k = 0; k < f.getLocals(); ++k) {
s.append(getShortName(f.getLocal(k).toString()))
.append(' ');
}
s.append(" : ");
for (int k = 0; k < f.getStackSize(); ++k) {
s.append(getShortName(f.getStack(k).toString()))
.append(' ');
}
}
while (s.length() < method.maxStack + method.maxLocals + 1) {
s.append(' ');
}
pw.print(Integer.toString(j + 100000).substring(1));
pw.print(" " + s + " : " + mv.buf); // mv.text.get(j));
}
for (int j = 0; j < method.tryCatchBlocks.size(); ++j) {
((TryCatchBlockNode) method.tryCatchBlocks.get(j)).accept(mv);
pw.print(" " + mv.buf);
}
pw.println();
}
pw.flush();
}
private static String getShortName(final String name) {
int n = name.lastIndexOf('/');
int k = name.length();
if (name.charAt(k - 1) == ';') {
k--;
}
return n == -1 ? name : name.substring(n + 1, k);
}
/**
* Constructs a new {@link CheckClassAdapter}.
*
* @param cv the class visitor to which this adapter must delegate calls.
*/
public CheckClassAdapter(final ClassVisitor cv) {
super(cv);
}
// ------------------------------------------------------------------------
// Implementation of the ClassVisitor interface
// ------------------------------------------------------------------------
public void visit(
final int version,
final int access,
final String name,
final String signature,
final String superName,
final String[] interfaces)
{
if (start) {
throw new IllegalStateException("visit must be called only once");
}
start = true;
checkState();
checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_FINAL
+ Opcodes.ACC_SUPER + Opcodes.ACC_INTERFACE
+ Opcodes.ACC_ABSTRACT + Opcodes.ACC_SYNTHETIC
+ Opcodes.ACC_ANNOTATION + Opcodes.ACC_ENUM
+ Opcodes.ACC_DEPRECATED);
if (name == null || !name.endsWith("package-info")) {
CheckMethodAdapter.checkInternalName(name, "class name");
}
if ("java/lang/Object".equals(name)) {
if (superName != null) {
throw new IllegalArgumentException("The super class name of the Object class must be 'null'");
}
} else {
CheckMethodAdapter.checkInternalName(superName, "super class name");
}
if (signature != null) {
CheckMethodAdapter.checkClassSignature(signature);
}
if ((access & Opcodes.ACC_INTERFACE) != 0) {
if (!"java/lang/Object".equals(superName)) {
throw new IllegalArgumentException("The super class name of interfaces must be 'java/lang/Object'");
}
}
if (interfaces != null) {
for (int i = 0; i < interfaces.length; ++i) {
CheckMethodAdapter.checkInternalName(interfaces[i],
"interface name at index " + i);
}
}
cv.visit(version, access, name, signature, superName, interfaces);
}
public void visitSource(final String file, final String debug) {
checkState();
if (source) {
throw new IllegalStateException("visitSource can be called only once.");
}
source = true;
cv.visitSource(file, debug);
}
public void visitOuterClass(
final String owner,
final String name,
final String desc)
{
checkState();
if (outer) {
throw new IllegalStateException("visitOuterClass can be called only once.");
}
outer = true;
if (owner == null) {
throw new IllegalArgumentException("Illegal outer class owner");
}
if (desc != null) {
CheckMethodAdapter.checkMethodDesc(desc);
}
cv.visitOuterClass(owner, name, desc);
}
public void visitInnerClass(
final String name,
final String outerName,
final String innerName,
final int access)
{
checkState();
CheckMethodAdapter.checkInternalName(name, "class name");
if (outerName != null) {
CheckMethodAdapter.checkInternalName(outerName, "outer class name");
}
if (innerName != null) {
CheckMethodAdapter.checkIdentifier(innerName, "inner class name");
}
checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_PRIVATE
+ Opcodes.ACC_PROTECTED + Opcodes.ACC_STATIC
+ Opcodes.ACC_FINAL + Opcodes.ACC_INTERFACE
+ Opcodes.ACC_ABSTRACT + Opcodes.ACC_SYNTHETIC
+ Opcodes.ACC_ANNOTATION + Opcodes.ACC_ENUM);
cv.visitInnerClass(name, outerName, innerName, access);
}
public FieldVisitor visitField(
final int access,
final String name,
final String desc,
final String signature,
final Object value)
{
checkState();
checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_PRIVATE
+ Opcodes.ACC_PROTECTED + Opcodes.ACC_STATIC
+ Opcodes.ACC_FINAL + Opcodes.ACC_VOLATILE
+ Opcodes.ACC_TRANSIENT + Opcodes.ACC_SYNTHETIC
+ Opcodes.ACC_ENUM + Opcodes.ACC_DEPRECATED);
CheckMethodAdapter.checkIdentifier(name, "field name");
CheckMethodAdapter.checkDesc(desc, false);
if (signature != null) {
CheckMethodAdapter.checkFieldSignature(signature);
}
if (value != null) {
CheckMethodAdapter.checkConstant(value);
}
FieldVisitor av = cv.visitField(access, name, desc, signature, value);
return new CheckFieldAdapter(av);
}
public MethodVisitor visitMethod(
final int access,
final String name,
final String desc,
final String signature,
final String[] exceptions)
{
checkState();
checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_PRIVATE
+ Opcodes.ACC_PROTECTED + Opcodes.ACC_STATIC
+ Opcodes.ACC_FINAL + Opcodes.ACC_SYNCHRONIZED
+ Opcodes.ACC_BRIDGE + Opcodes.ACC_VARARGS + Opcodes.ACC_NATIVE
+ Opcodes.ACC_ABSTRACT + Opcodes.ACC_STRICT
+ Opcodes.ACC_SYNTHETIC + Opcodes.ACC_DEPRECATED);
CheckMethodAdapter.checkMethodIdentifier(name, "method name");
CheckMethodAdapter.checkMethodDesc(desc);
if (signature != null) {
CheckMethodAdapter.checkMethodSignature(signature);
}
if (exceptions != null) {
for (int i = 0; i < exceptions.length; ++i) {
CheckMethodAdapter.checkInternalName(exceptions[i],
"exception name at index " + i);
}
}
return new CheckMethodAdapter(cv.visitMethod(access,
name,
desc,
signature,
exceptions));
}
public AnnotationVisitor visitAnnotation(
final String desc,
final boolean visible)
{
checkState();
CheckMethodAdapter.checkDesc(desc, false);
return new CheckAnnotationAdapter(cv.visitAnnotation(desc, visible));
}
public void visitAttribute(final Attribute attr) {
checkState();
if (attr == null) {
throw new IllegalArgumentException("Invalid attribute (must not be null)");
}
cv.visitAttribute(attr);
}
public void visitEnd() {
checkState();
end = true;
cv.visitEnd();
}
// ------------------------------------------------------------------------
// Utility methods
// ------------------------------------------------------------------------
/**
* Checks that the visit method has been called and that visitEnd has not
* been called.
*/
private void checkState() {
if (!start) {
throw new IllegalStateException("Cannot visit member before visit has been called.");
}
if (end) {
throw new IllegalStateException("Cannot visit member after visitEnd has been called.");
}
}
/**
* Checks that the given access flags do not contain invalid flags. This
* method also checks that mutually incompatible flags are not set
* simultaneously.
*
* @param access the access flags to be checked
* @param possibleAccess the valid access flags.
*/
static void checkAccess(final int access, final int possibleAccess) {
if ((access & ~possibleAccess) != 0) {
throw new IllegalArgumentException("Invalid access flags: "
+ access);
}
int pub = (access & Opcodes.ACC_PUBLIC) == 0 ? 0 : 1;
int pri = (access & Opcodes.ACC_PRIVATE) == 0 ? 0 : 1;
int pro = (access & Opcodes.ACC_PROTECTED) == 0 ? 0 : 1;
if (pub + pri + pro > 1) {
throw new IllegalArgumentException("public private and protected are mutually exclusive: "
+ access);
}
int fin = (access & Opcodes.ACC_FINAL) == 0 ? 0 : 1;
int abs = (access & Opcodes.ACC_ABSTRACT) == 0 ? 0 : 1;
if (fin + abs > 1) {
throw new IllegalArgumentException("final and abstract are mutually exclusive: "
+ access);
}
}
}