/**
* ASM: a very small and fast Java bytecode manipulation framework
* Copyright (c) 2000-2005 INRIA, France Telecom
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.objectweb.asm.attrs;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.objectweb.asm.Attribute;
import org.objectweb.asm.ByteVector;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
/**
* StackMapAttribute is used by CDLC preverifier. Definition is given in
* appendix "CLDC Byte Code Typechecker Specification" from CDLC 1.1
* specification. <p> <i>Note that this implementation does not calculate
* StackMapFrame structures from the method bytecode. If method code is changed
* or generated from scratch, then developer is responsible to prepare a correct
* StackMapFrame structures.</i> <p> The format of the stack map in the class
* file is given below. In the following, <ul> <li>if the length of the
* method's byte code1 is 65535 or less, then <tt>uoffset</tt> represents the
* type u2; otherwise <tt>uoffset</tt> represents the type u4.</li> <li>If
* the maximum number of local variables for the method is 65535 or less, then
* <tt>ulocalvar</tt> represents the type u2; otherwise <tt>ulocalvar</tt>
* represents the type u4.</li> <li>If the maximum size of the operand stack
* is 65535 or less, then <tt>ustack</tt> represents the type u2; otherwise
* ustack represents the type u4.</li> </ul>
*
* <pre>
* stack_map { // attribute StackMap
* u2 attribute_name_index;
* u4 attribute_length
* uoffset number_of_entries;
* stack_map_frame entries[number_of_entries];
* }
* </pre>
*
* Each stack map frame has the following format:
*
* <pre>
* stack_map_frame {
* uoffset offset;
* ulocalvar number_of_locals;
* verification_type_info locals[number_of_locals];
* ustack number_of_stack_items;
* verification_type_info stack[number_of_stack_items];
* }
* </pre>
*
* The <tt>verification_type_info</tt> structure consists of a one-byte tag
* followed by zero or more bytes, giving more information about the tag. Each
* <tt>verification_type_info</tt> structure specifies the verification type
* of one or two locations.
*
* <pre>
* union verification_type_info {
* Top_variable_info;
* Integer_variable_info;
* Float_variable_info;
* Long_variable_info;
* Double_variable_info;
* Null_variable_info;
* UninitializedThis_variable_info;
* Object_variable_info;
* Uninitialized_variable_info;
* }
*
* Top_variable_info {
* u1 tag = ITEM_Top; // 0
* }
*
* Integer_variable_info {
* u1 tag = ITEM_Integer; // 1
* }
*
* Float_variable_info {
* u1 tag = ITEM_Float; // 2
* }
*
* Long_variable_info {
* u1 tag = ITEM_Long; // 4
* }
*
* Double_variable_info {
* u1 tag = ITEM_Double; // 3
* }
*
* Null_variable_info {
* u1 tag = ITEM_Null; // 5
* }
*
* UninitializedThis_variable_info {
* u1 tag = ITEM_UninitializedThis; // 6
* }
*
* Object_variable_info {
* u1 tag = ITEM_Object; // 7
* u2 cpool_index;
* }
*
* Uninitialized_variable_info {
* u1 tag = ITEM_Uninitialized // 8
* uoffset offset;
* }
* </pre>
*
* @see <a href="http://www.jcp.org/en/jsr/detail?id=139">JSR 139 : Connected
* Limited Device Configuration 1.1</a>
*
* @author Eugene Kuleshov
*/
public class StackMapAttribute extends Attribute {
static final int MAX_SIZE = 65535;
/**
* A List of <code>StackMapFrame</code> instances.
*/
public List frames = new ArrayList();
public StackMapAttribute() {
super("StackMap");
}
public StackMapAttribute(List frames) {
this();
this.frames = frames;
}
public List getFrames() {
return frames;
}
public StackMapFrame getFrame(Label label) {
for (int i = 0; i < frames.size(); i++) {
StackMapFrame frame = (StackMapFrame) frames.get(i);
if (frame.label == label) {
return frame;
}
}
return null;
}
public boolean isUnknown() {
return false;
}
public boolean isCodeAttribute() {
return true;
}
protected Attribute read(
ClassReader cr,
int off,
int len,
char[] buf,
int codeOff,
Label[] labels)
{
StackMapAttribute attr = new StackMapAttribute();
// note that this is not the size of Code attribute
boolean isExtCodeSize = cr.readInt(codeOff + 4) > MAX_SIZE;
boolean isExtLocals = cr.readUnsignedShort(codeOff + 2) > MAX_SIZE;
boolean isExtStack = cr.readUnsignedShort(codeOff) > MAX_SIZE;
int size = 0;
if (isExtCodeSize) {
size = cr.readInt(off);
off += 4;
} else {
size = cr.readUnsignedShort(off);
off += 2;
}
for (int i = 0; i < size; i++) {
int offset;
if (isExtCodeSize) {
offset = cr.readInt(off);
off += 4;
} else {
offset = cr.readUnsignedShort(off);
off += 2;
}
Label label = getLabel(offset, labels);
List locals = new ArrayList();
List stack = new ArrayList();
off = readTypeInfo(cr,
off,
locals,
labels,
buf,
isExtLocals,
isExtCodeSize);
off = readTypeInfo(cr,
off,
stack,
labels,
buf,
isExtStack,
isExtCodeSize);
attr.frames.add(new StackMapFrame(label, locals, stack));
}
return attr;
}
private int readTypeInfo(
ClassReader cr,
int off,
List info,
Label[] labels,
char[] buf,
boolean isExt,
boolean isExtCode)
{
int n = 0;
if (isExt) {
n = cr.readInt(off);
off += 4;
} else {
n = cr.readUnsignedShort(off);
off += 2;
}
for (int j = 0; j < n; j++) {
int itemType = cr.readByte(off++);
StackMapType typeInfo = StackMapType.getTypeInfo(itemType);
info.add(typeInfo);
switch (itemType) {
case StackMapType.ITEM_Object: //
typeInfo.setObject(cr.readClass(off, buf));
off += 2;
break;
case StackMapType.ITEM_Uninitialized: //
int offset;
if (isExtCode) {
offset = cr.readInt(off);
off += 4;
} else {
offset = cr.readUnsignedShort(off);
off += 2;
}
typeInfo.setLabel(getLabel(offset, labels));
break;
}
}
return off;
}
private void writeTypeInfo(ByteVector bv, ClassWriter cw, List info, int max)
{
if (max > StackMapAttribute.MAX_SIZE) {
bv.putInt(info.size());
} else {
bv.putShort(info.size());
}
for (int j = 0; j < info.size(); j++) {
StackMapType typeInfo = (StackMapType) info.get(j);
bv.putByte(typeInfo.getType());
switch (typeInfo.getType()) {
case StackMapType.ITEM_Object: //
bv.putShort(cw.newClass(typeInfo.getObject()));
break;
case StackMapType.ITEM_Uninitialized: //
bv.putShort(typeInfo.getLabel().getOffset());
break;
}
}
}
private Label getLabel(int offset, Label[] labels) {
Label l = labels[offset];
if (l != null) {
return l;
}
return labels[offset] = new Label();
}
protected ByteVector write(
ClassWriter cw,
byte[] code,
int len,
int maxStack,
int maxLocals)
{
ByteVector bv = new ByteVector();
if (code != null && code.length > MAX_SIZE) { // TODO verify value
bv.putInt(frames.size());
} else {
bv.putShort(frames.size());
}
for (int i = 0; i < frames.size(); i++) {
writeFrame((StackMapFrame) frames.get(i),
cw,
maxStack,
maxLocals,
bv);
}
return bv;
}
protected Label[] getLabels() {
HashSet labels = new HashSet();
for (int i = 0; i < frames.size(); i++) {
getFrameLabels((StackMapFrame) frames.get(i), labels);
}
return (Label[]) labels.toArray(new Label[labels.size()]);
}
private void writeFrame(
StackMapFrame frame,
ClassWriter cw,
int maxStack,
int maxLocals,
ByteVector bv)
{
bv.putShort(frame.label.getOffset());
writeTypeInfo(bv, cw, frame.locals, maxLocals);
writeTypeInfo(bv, cw, frame.stack, maxStack);
}
private void getFrameLabels(StackMapFrame frame, Set labels) {
labels.add(frame.label);
getTypeInfoLabels(labels, frame.locals);
getTypeInfoLabels(labels, frame.stack);
}
private void getTypeInfoLabels(Set labels, List info) {
for (Iterator it = info.iterator(); it.hasNext();) {
StackMapType typeInfo = (StackMapType) it.next();
if (typeInfo.getType() == StackMapType.ITEM_Uninitialized) {
labels.add(typeInfo.getLabel());
}
}
}
public String toString() {
StringBuffer sb = new StringBuffer("StackMap[");
for (int i = 0; i < frames.size(); i++) {
sb.append('\n').append('[').append(frames.get(i)).append(']');
}
sb.append("\n]");
return sb.toString();
}
}