package org.hibernate.bytecode.javassist;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Iterator;
import java.util.List;
import javassist.CannotCompileException;
import javassist.bytecode.AccessFlag;
import javassist.bytecode.BadBytecode;
import javassist.bytecode.Bytecode;
import javassist.bytecode.ClassFile;
import javassist.bytecode.CodeAttribute;
import javassist.bytecode.CodeIterator;
import javassist.bytecode.ConstPool;
import javassist.bytecode.Descriptor;
import javassist.bytecode.FieldInfo;
import javassist.bytecode.MethodInfo;
import javassist.bytecode.Opcode;
/**
* The thing that handles actual class enhancement in regards to
* intercepting field accesses.
*
* @author Muga Nishizawa
* @author Steve Ebersole
*/
public class FieldTransformer {
private static final String EACH_READ_METHOD_PREFIX = "$javassist_read_";
private static final String EACH_WRITE_METHOD_PREFIX = "$javassist_write_";
private static final String FIELD_HANDLED_TYPE_NAME = FieldHandled.class
.getName();
private static final String HANDLER_FIELD_NAME = "$JAVASSIST_READ_WRITE_HANDLER";
private static final String FIELD_HANDLER_TYPE_NAME = FieldHandler.class
.getName();
private static final String HANDLER_FIELD_DESCRIPTOR = 'L' + FIELD_HANDLER_TYPE_NAME
.replace('.', '/') + ';';
private static final String GETFIELDHANDLER_METHOD_NAME = "getFieldHandler";
private static final String SETFIELDHANDLER_METHOD_NAME = "setFieldHandler";
private static final String GETFIELDHANDLER_METHOD_DESCRIPTOR = "()"
+ HANDLER_FIELD_DESCRIPTOR;
private static final String SETFIELDHANDLER_METHOD_DESCRIPTOR = "("
+ HANDLER_FIELD_DESCRIPTOR + ")V";
private FieldFilter filter;
public FieldTransformer() {
this(null);
}
public FieldTransformer(FieldFilter f) {
filter = f;
}
public void setFieldFilter(FieldFilter f) {
filter = f;
}
public void transform(File file) throws Exception {
DataInputStream in = new DataInputStream(new FileInputStream(file));
ClassFile classfile = new ClassFile(in);
transform(classfile);
DataOutputStream out = new DataOutputStream(new FileOutputStream(file));
try {
classfile.write(out);
} finally {
out.close();
}
}
public void transform(ClassFile classfile) throws Exception {
if (classfile.isInterface()) {
return;
}
try {
addFieldHandlerField(classfile);
addGetFieldHandlerMethod(classfile);
addSetFieldHandlerMethod(classfile);
addFieldHandledInterface(classfile);
addReadWriteMethods(classfile);
transformInvokevirtualsIntoPutAndGetfields(classfile);
} catch (CannotCompileException e) {
throw new RuntimeException(e.getMessage(), e);
}
}
private void addFieldHandlerField(ClassFile classfile)
throws CannotCompileException {
ConstPool cp = classfile.getConstPool();
FieldInfo finfo = new FieldInfo(cp, HANDLER_FIELD_NAME,
HANDLER_FIELD_DESCRIPTOR);
finfo.setAccessFlags(AccessFlag.PRIVATE | AccessFlag.TRANSIENT);
classfile.addField(finfo);
}
private void addGetFieldHandlerMethod(ClassFile classfile)
throws CannotCompileException {
ConstPool cp = classfile.getConstPool();
int this_class_index = cp.getThisClassInfo();
MethodInfo minfo = new MethodInfo(cp, GETFIELDHANDLER_METHOD_NAME,
GETFIELDHANDLER_METHOD_DESCRIPTOR);
/* local variable | this | */
Bytecode code = new Bytecode(cp, 2, 1);
// aload_0 // load this
code.addAload(0);
// getfield // get field "$JAVASSIST_CALLBACK" defined already
code.addOpcode(Opcode.GETFIELD);
int field_index = cp.addFieldrefInfo(this_class_index,
HANDLER_FIELD_NAME, HANDLER_FIELD_DESCRIPTOR);
code.addIndex(field_index);
// areturn // return the value of the field
code.addOpcode(Opcode.ARETURN);
minfo.setCodeAttribute(code.toCodeAttribute());
minfo.setAccessFlags(AccessFlag.PUBLIC);
classfile.addMethod(minfo);
}
private void addSetFieldHandlerMethod(ClassFile classfile)
throws CannotCompileException {
ConstPool cp = classfile.getConstPool();
int this_class_index = cp.getThisClassInfo();
MethodInfo minfo = new MethodInfo(cp, SETFIELDHANDLER_METHOD_NAME,
SETFIELDHANDLER_METHOD_DESCRIPTOR);
/* local variables | this | callback | */
Bytecode code = new Bytecode(cp, 3, 3);
// aload_0 // load this
code.addAload(0);
// aload_1 // load callback
code.addAload(1);
// putfield // put field "$JAVASSIST_CALLBACK" defined already
code.addOpcode(Opcode.PUTFIELD);
int field_index = cp.addFieldrefInfo(this_class_index,
HANDLER_FIELD_NAME, HANDLER_FIELD_DESCRIPTOR);
code.addIndex(field_index);
// return
code.addOpcode(Opcode.RETURN);
minfo.setCodeAttribute(code.toCodeAttribute());
minfo.setAccessFlags(AccessFlag.PUBLIC);
classfile.addMethod(minfo);
}
private void addFieldHandledInterface(ClassFile classfile) {
String[] interfaceNames = classfile.getInterfaces();
String[] newInterfaceNames = new String[interfaceNames.length + 1];
System.arraycopy(interfaceNames, 0, newInterfaceNames, 0,
interfaceNames.length);
newInterfaceNames[newInterfaceNames.length - 1] = FIELD_HANDLED_TYPE_NAME;
classfile.setInterfaces(newInterfaceNames);
}
private void addReadWriteMethods(ClassFile classfile)
throws CannotCompileException {
List fields = classfile.getFields();
for (Iterator field_iter = fields.iterator(); field_iter.hasNext();) {
FieldInfo finfo = (FieldInfo) field_iter.next();
if ((finfo.getAccessFlags() & AccessFlag.STATIC) == 0
&& (!finfo.getName().equals(HANDLER_FIELD_NAME))) {
// case of non-static field
if (filter.handleRead(finfo.getDescriptor(), finfo
.getName())) {
addReadMethod(classfile, finfo);
}
if (filter.handleWrite(finfo.getDescriptor(), finfo
.getName())) {
addWriteMethod(classfile, finfo);
}
}
}
}
private void addReadMethod(ClassFile classfile, FieldInfo finfo)
throws CannotCompileException {
ConstPool cp = classfile.getConstPool();
int this_class_index = cp.getThisClassInfo();
String desc = "()" + finfo.getDescriptor();
MethodInfo minfo = new MethodInfo(cp, EACH_READ_METHOD_PREFIX
+ finfo.getName(), desc);
/* local variables | target obj | each oldvalue | */
Bytecode code = new Bytecode(cp, 5, 3);
// aload_0
code.addAload(0);
// getfield // get each field
code.addOpcode(Opcode.GETFIELD);
int base_field_index = cp.addFieldrefInfo(this_class_index, finfo
.getName(), finfo.getDescriptor());
code.addIndex(base_field_index);
// aload_0
code.addAload(0);
// invokeinterface // invoke Enabled.getInterceptFieldCallback()
int enabled_class_index = cp.addClassInfo(FIELD_HANDLED_TYPE_NAME);
code.addInvokeinterface(enabled_class_index,
GETFIELDHANDLER_METHOD_NAME, GETFIELDHANDLER_METHOD_DESCRIPTOR,
1);
// ifnonnull
code.addOpcode(Opcode.IFNONNULL);
code.addIndex(4);
// *return // each type
addTypeDependDataReturn(code, finfo.getDescriptor());
// *store_1 // each type
addTypeDependDataStore(code, finfo.getDescriptor(), 1);
// aload_0
code.addAload(0);
// invokeinterface // invoke Enabled.getInterceptFieldCallback()
code.addInvokeinterface(enabled_class_index,
GETFIELDHANDLER_METHOD_NAME, GETFIELDHANDLER_METHOD_DESCRIPTOR,
1);
// aload_0
code.addAload(0);
// ldc // name of the field
code.addLdc(finfo.getName());
// *load_1 // each type
addTypeDependDataLoad(code, finfo.getDescriptor(), 1);
// invokeinterface // invoke Callback.read*() // each type
addInvokeFieldHandlerMethod(classfile, code, finfo.getDescriptor(),
true);
// *return // each type
addTypeDependDataReturn(code, finfo.getDescriptor());
minfo.setCodeAttribute(code.toCodeAttribute());
minfo.setAccessFlags(AccessFlag.PUBLIC);
classfile.addMethod(minfo);
}
private void addWriteMethod(ClassFile classfile, FieldInfo finfo)
throws CannotCompileException {
ConstPool cp = classfile.getConstPool();
int this_class_index = cp.getThisClassInfo();
String desc = "(" + finfo.getDescriptor() + ")V";
MethodInfo minfo = new MethodInfo(cp, EACH_WRITE_METHOD_PREFIX
+ finfo.getName(), desc);
/* local variables | target obj | each oldvalue | */
Bytecode code = new Bytecode(cp, 6, 3);
// aload_0
code.addAload(0);
// invokeinterface // enabled.getInterceptFieldCallback()
int enabled_class_index = cp.addClassInfo(FIELD_HANDLED_TYPE_NAME);
code.addInvokeinterface(enabled_class_index,
GETFIELDHANDLER_METHOD_NAME, GETFIELDHANDLER_METHOD_DESCRIPTOR,
1);
// ifnonnull (label1)
code.addOpcode(Opcode.IFNONNULL);
code.addIndex(9);
// aload_0
code.addAload(0);
// *load_1
addTypeDependDataLoad(code, finfo.getDescriptor(), 1);
// putfield
code.addOpcode(Opcode.PUTFIELD);
int base_field_index = cp.addFieldrefInfo(this_class_index, finfo
.getName(), finfo.getDescriptor());
code.addIndex(base_field_index);
code.growStack(-Descriptor.dataSize(finfo.getDescriptor()));
// return ;
code.addOpcode(Opcode.RETURN);
// aload_0
code.addAload(0);
// dup
code.addOpcode(Opcode.DUP);
// invokeinterface // enabled.getInterceptFieldCallback()
code.addInvokeinterface(enabled_class_index,
GETFIELDHANDLER_METHOD_NAME, GETFIELDHANDLER_METHOD_DESCRIPTOR,
1);
// aload_0
code.addAload(0);
// ldc // field name
code.addLdc(finfo.getName());
// aload_0
code.addAload(0);
// getfield // old value of the field
code.addOpcode(Opcode.GETFIELD);
code.addIndex(base_field_index);
code.growStack(Descriptor.dataSize(finfo.getDescriptor()) - 1);
// *load_1
addTypeDependDataLoad(code, finfo.getDescriptor(), 1);
// invokeinterface // callback.write*(..)
addInvokeFieldHandlerMethod(classfile, code, finfo.getDescriptor(),
false);
// putfield // new value of the field
code.addOpcode(Opcode.PUTFIELD);
code.addIndex(base_field_index);
code.growStack(-Descriptor.dataSize(finfo.getDescriptor()));
// return
code.addOpcode(Opcode.RETURN);
minfo.setCodeAttribute(code.toCodeAttribute());
minfo.setAccessFlags(AccessFlag.PUBLIC);
classfile.addMethod(minfo);
}
private void transformInvokevirtualsIntoPutAndGetfields(ClassFile classfile)
throws CannotCompileException {
List methods = classfile.getMethods();
for (Iterator method_iter = methods.iterator(); method_iter.hasNext();) {
MethodInfo minfo = (MethodInfo) method_iter.next();
String methodName = minfo.getName();
if (methodName.startsWith(EACH_READ_METHOD_PREFIX)
|| methodName.startsWith(EACH_WRITE_METHOD_PREFIX)
|| methodName.equals(GETFIELDHANDLER_METHOD_NAME)
|| methodName.equals(SETFIELDHANDLER_METHOD_NAME)) {
continue;
}
CodeAttribute codeAttr = minfo.getCodeAttribute();
if (codeAttr == null) {
return;
}
CodeIterator iter = codeAttr.iterator();
while (iter.hasNext()) {
try {
int pos = iter.next();
pos = transformInvokevirtualsIntoGetfields(classfile, iter, pos);
pos = transformInvokevirtualsIntoPutfields(classfile, iter, pos);
} catch (BadBytecode e) {
throw new CannotCompileException(e);
}
}
}
}
private int transformInvokevirtualsIntoGetfields(ClassFile classfile, CodeIterator iter, int pos) {
ConstPool cp = classfile.getConstPool();
int c = iter.byteAt(pos);
if (c != Opcode.GETFIELD) {
return pos;
}
int index = iter.u16bitAt(pos + 1);
String fieldName = cp.getFieldrefName(index);
String className = cp.getFieldrefClassName(index);
if ( !filter.handleReadAccess( className, fieldName ) ) {
return pos;
}
String desc = "()" + cp.getFieldrefType( index );
int read_method_index = cp.addMethodrefInfo(
cp.getThisClassInfo(),
EACH_READ_METHOD_PREFIX + fieldName,
desc
);
iter.writeByte(Opcode.INVOKEVIRTUAL, pos);
iter.write16bit(read_method_index, pos + 1);
return pos;
}
private int transformInvokevirtualsIntoPutfields(
ClassFile classfile,
CodeIterator iter, int pos) {
ConstPool cp = classfile.getConstPool();
int c = iter.byteAt(pos);
if (c != Opcode.PUTFIELD) {
return pos;
}
int index = iter.u16bitAt(pos + 1);
String fieldName = cp.getFieldrefName(index);
String className = cp.getFieldrefClassName(index);
if ( !filter.handleWriteAccess( className, fieldName ) ) {
return pos;
}
String desc = "(" + cp.getFieldrefType( index ) + ")V";
int write_method_index = cp.addMethodrefInfo(
cp.getThisClassInfo(),
EACH_WRITE_METHOD_PREFIX + fieldName,
desc
);
iter.writeByte(Opcode.INVOKEVIRTUAL, pos);
iter.write16bit(write_method_index, pos + 1);
return pos;
}
private static void addInvokeFieldHandlerMethod(ClassFile classfile,
Bytecode code, String typeName, boolean isReadMethod) {
ConstPool cp = classfile.getConstPool();
// invokeinterface
int callback_type_index = cp.addClassInfo(FIELD_HANDLER_TYPE_NAME);
if ((typeName.charAt(0) == 'L')
&& (typeName.charAt(typeName.length() - 1) == ';')
|| (typeName.charAt(0) == '[')) {
// reference type
int indexOfL = typeName.indexOf('L');
String type;
if (indexOfL == 0) {
// not array
type = typeName.substring(1, typeName.length() - 1);
type = type.replace('/', '.');
} else if (indexOfL == -1) {
// array of primitive type
// do nothing
type = typeName;
} else {
// array of reference type
type = typeName.replace('/', '.');
}
if (isReadMethod) {
code
.addInvokeinterface(
callback_type_index,
"readObject",
"(Ljava/lang/Object;Ljava/lang/String;Ljava/lang/Object;)Ljava/lang/Object;",
4);
// checkcast
code.addCheckcast(type);
} else {
code
.addInvokeinterface(
callback_type_index,
"writeObject",
"(Ljava/lang/Object;Ljava/lang/String;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;",
5);
// checkcast
code.addCheckcast(type);
}
} else if (typeName.equals("Z")) {
// boolean
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readBoolean",
"(Ljava/lang/Object;Ljava/lang/String;Z)Z", 4);
} else {
code.addInvokeinterface(callback_type_index, "writeBoolean",
"(Ljava/lang/Object;Ljava/lang/String;ZZ)Z", 5);
}
} else if (typeName.equals("B")) {
// byte
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readByte",
"(Ljava/lang/Object;Ljava/lang/String;B)B", 4);
} else {
code.addInvokeinterface(callback_type_index, "writeByte",
"(Ljava/lang/Object;Ljava/lang/String;BB)B", 5);
}
} else if (typeName.equals("C")) {
// char
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readChar",
"(Ljava/lang/Object;Ljava/lang/String;C)C", 4);
} else {
code.addInvokeinterface(callback_type_index, "writeChar",
"(Ljava/lang/Object;Ljava/lang/String;CC)C", 5);
}
} else if (typeName.equals("I")) {
// int
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readInt",
"(Ljava/lang/Object;Ljava/lang/String;I)I", 4);
} else {
code.addInvokeinterface(callback_type_index, "writeInt",
"(Ljava/lang/Object;Ljava/lang/String;II)I", 5);
}
} else if (typeName.equals("S")) {
// short
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readShort",
"(Ljava/lang/Object;Ljava/lang/String;S)S", 4);
} else {
code.addInvokeinterface(callback_type_index, "writeShort",
"(Ljava/lang/Object;Ljava/lang/String;SS)S", 5);
}
} else if (typeName.equals("D")) {
// double
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readDouble",
"(Ljava/lang/Object;Ljava/lang/String;D)D", 5);
} else {
code.addInvokeinterface(callback_type_index, "writeDouble",
"(Ljava/lang/Object;Ljava/lang/String;DD)D", 7);
}
} else if (typeName.equals("F")) {
// float
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readFloat",
"(Ljava/lang/Object;Ljava/lang/String;F)F", 4);
} else {
code.addInvokeinterface(callback_type_index, "writeFloat",
"(Ljava/lang/Object;Ljava/lang/String;FF)F", 5);
}
} else if (typeName.equals("J")) {
// long
if (isReadMethod) {
code.addInvokeinterface(callback_type_index, "readLong",
"(Ljava/lang/Object;Ljava/lang/String;J)J", 5);
} else {
code.addInvokeinterface(callback_type_index, "writeLong",
"(Ljava/lang/Object;Ljava/lang/String;JJ)J", 7);
}
} else {
// bad type
throw new RuntimeException("bad type: " + typeName);
}
}
private static void addTypeDependDataLoad(Bytecode code, String typeName,
int i) {
if ((typeName.charAt(0) == 'L')
&& (typeName.charAt(typeName.length() - 1) == ';')
|| (typeName.charAt(0) == '[')) {
// reference type
code.addAload(i);
} else if (typeName.equals("Z") || typeName.equals("B")
|| typeName.equals("C") || typeName.equals("I")
|| typeName.equals("S")) {
// boolean, byte, char, int, short
code.addIload(i);
} else if (typeName.equals("D")) {
// double
code.addDload(i);
} else if (typeName.equals("F")) {
// float
code.addFload(i);
} else if (typeName.equals("J")) {
// long
code.addLload(i);
} else {
// bad type
throw new RuntimeException("bad type: " + typeName);
}
}
private static void addTypeDependDataStore(Bytecode code, String typeName,
int i) {
if ((typeName.charAt(0) == 'L')
&& (typeName.charAt(typeName.length() - 1) == ';')
|| (typeName.charAt(0) == '[')) {
// reference type
code.addAstore(i);
} else if (typeName.equals("Z") || typeName.equals("B")
|| typeName.equals("C") || typeName.equals("I")
|| typeName.equals("S")) {
// boolean, byte, char, int, short
code.addIstore(i);
} else if (typeName.equals("D")) {
// double
code.addDstore(i);
} else if (typeName.equals("F")) {
// float
code.addFstore(i);
} else if (typeName.equals("J")) {
// long
code.addLstore(i);
} else {
// bad type
throw new RuntimeException("bad type: " + typeName);
}
}
private static void addTypeDependDataReturn(Bytecode code, String typeName) {
if ((typeName.charAt(0) == 'L')
&& (typeName.charAt(typeName.length() - 1) == ';')
|| (typeName.charAt(0) == '[')) {
// reference type
code.addOpcode(Opcode.ARETURN);
} else if (typeName.equals("Z") || typeName.equals("B")
|| typeName.equals("C") || typeName.equals("I")
|| typeName.equals("S")) {
// boolean, byte, char, int, short
code.addOpcode(Opcode.IRETURN);
} else if (typeName.equals("D")) {
// double
code.addOpcode(Opcode.DRETURN);
} else if (typeName.equals("F")) {
// float
code.addOpcode(Opcode.FRETURN);
} else if (typeName.equals("J")) {
// long
code.addOpcode(Opcode.LRETURN);
} else {
// bad type
throw new RuntimeException("bad type: " + typeName);
}
}
}