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WALA/com.ibm.wala.shrike/src/com/ibm/wala/shrikeCT/ClassReader.java

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/*******************************************************************************
* Copyright (c) 2002,2006 IBM Corporation.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package com.ibm.wala.shrikeCT;
/**
* This is the core class for reading class file data.
*
* ClassReader performs lazy parsing, and thus most of the methods can throw an InvalidClassFileException.
*/
public final class ClassReader implements ClassConstants {
private final byte[] bytes;
private int[] methodOffsets;
private int[] fieldOffsets;
private ConstantPoolParser cpParser;
private int classInfoOffset;
private int attrInfoOffset;
private int interfaceCount;
/**
* Build a reader.
*
* If the class file data is corrupt an exception might not be thrown immediately. Instead an exception might be thrown later,
* during the execution of some access method. This is a consequence of the 'lazy parsing' performed by ClassReader.
*
* @param bytes the class file data
* @throws InvalidClassFileException the class file data is corrupt
*/
public ClassReader(byte[] bytes) throws InvalidClassFileException {
this.bytes = bytes;
parse();
}
private void checkLength(int offset, int required) throws InvalidClassFileException {
if (bytes.length < offset + required) {
throw new InvalidClassFileException(offset, "file truncated, expected " + required + " bytes, saw only "
+ (bytes.length - offset));
}
}
private void parse() throws InvalidClassFileException {
int offset = 0;
checkLength(offset, 10);
int magic = getInt(offset);
int minorVersion = getUShort(offset + 4);
int majorVersion = getUShort(offset + 6);
int constantPoolCount = getUShort(offset + 8);
offset += 10;
if (magic != MAGIC) {
throw new InvalidClassFileException(offset, "bad magic number: " + magic);
}
if (majorVersion < 45 || majorVersion > 52) {
throw new InvalidClassFileException(offset, "unknown class file version: " + majorVersion + "." + minorVersion);
}
cpParser = new ConstantPoolParser(bytes, offset, constantPoolCount);
offset += cpParser.getRawSize();
classInfoOffset = offset;
checkLength(offset, 8);
// int accessFlags = getUShort(offset);
// int thisClass = getUShort(offset + 2);
// int superClass = getUShort(offset + 4);
interfaceCount = getUShort(offset + 6);
if (interfaceCount < 0) {
throw new InvalidClassFileException(offset, "negative interface count: " + interfaceCount);
}
offset += 8;
checkLength(offset, interfaceCount * 2);
offset += interfaceCount * 2;
checkLength(offset, 2);
int fieldCount = getUShort(offset);
if (fieldCount < 0) {
throw new InvalidClassFileException(offset, "negative field count: " + interfaceCount);
}
offset = parseFields(offset + 2, fieldCount);
checkLength(offset, 2);
int methodCount = getUShort(offset);
if (methodCount < 0) {
throw new InvalidClassFileException(offset, "negative method count: " + interfaceCount);
}
offset = parseMethods(offset + 2, methodCount);
attrInfoOffset = offset;
checkLength(offset, 2);
int attrCount = getUShort(offset);
offset = skipAttributes(offset + 2, attrCount);
if (offset != bytes.length) {
throw new InvalidClassFileException(offset, "extra data in class file");
}
}
private int skipAttributes(int offset, int count) throws InvalidClassFileException {
if (count < 0) {
throw new InvalidClassFileException(offset, "negative attribute count: " + interfaceCount);
}
for (int i = 0; i < count; i++) {
checkLength(offset, 6);
int size = getInt(offset + 2);
if (size < 0) {
throw new InvalidClassFileException(offset, "negative attribute size: " + size);
}
offset += 6;
checkLength(offset, size);
offset += size;
}
return offset;
}
private int parseFields(int offset, int count) throws InvalidClassFileException {
fieldOffsets = new int[count + 1];
for (int i = 0; i < count; i++) {
fieldOffsets[i] = offset;
checkLength(offset, 8);
offset = skipAttributes(offset + 8, getUShort(offset + 6));
}
fieldOffsets[count] = offset;
return offset;
}
private int parseMethods(int offset, int count) throws InvalidClassFileException {
methodOffsets = new int[count + 1];
for (int i = 0; i < count; i++) {
methodOffsets[i] = offset;
checkLength(offset, 8);
offset = skipAttributes(offset + 8, getUShort(offset + 6));
}
methodOffsets[count] = offset;
return offset;
}
/**
* @return the raw class data bytes
*/
public byte[] getBytes() {
return bytes;
}
/**
* @return the magic number at the start of the class file.
*/
public int getMagic() {
return getInt(0);
}
/**
* @return the minor version of the class file
*/
public int getMinorVersion() {
return getUShort(4);
}
/**
* @return the major version of the class file
*/
public int getMajorVersion() {
return getUShort(6);
}
/**
* @return the access flags for the class
*/
public int getAccessFlags() {
return getUShort(classInfoOffset);
}
/**
* @return the index of the constant pool entry for the class name
*/
public int getNameIndex() {
return getUShort(classInfoOffset + 2);
}
String getClassFromAddress(int addr) throws InvalidClassFileException {
int c = getUShort(addr);
if (c == 0) {
return null;
} else {
try {
return cpParser.getCPClass(c);
} catch (IllegalArgumentException ex) {
throw new InvalidClassFileException(addr, "Invalid class constant pool index: " + c);
}
}
}
/**
* @return the name of the class in JVM format (e.g., java/lang/Object)
*/
public String getName() throws InvalidClassFileException {
String s = getClassFromAddress(classInfoOffset + 2);
if (s == null) {
throw new InvalidClassFileException(classInfoOffset + 2, "Null class name not allowed");
} else {
return s;
}
}
/**
* @return the constant pool index of the superclass name, or 0 if this is java.lang.Object
*/
public int getSuperNameIndex() {
return getUShort(classInfoOffset + 4);
}
/**
* @return the superclass name in JVM format (e.g., java/lang/Object), or null if this class is java.lang.Object
*/
public String getSuperName() throws InvalidClassFileException {
return getClassFromAddress(classInfoOffset + 4);
}
/**
* @return the number of interfaces this class implements
*/
public int getInterfaceCount() {
return interfaceCount;
}
private void verifyInterfaceIndex(int i) {
if (i < 0 || i >= interfaceCount) {
throw new IllegalArgumentException("Invalid interface index: " + i);
}
}
/**
* @return the constant pool index of the name of the i'th implemented interface
*/
public int getInterfaceNameIndex(int i) {
verifyInterfaceIndex(i);
return getUShort(classInfoOffset + 8 + 2 * i);
}
/**
* @return an array of the constant pool indices for the names of the implemented interfaces
*/
public int[] getInterfaceNameIndices() {
int[] indices = new int[interfaceCount];
for (int i = 0; i < interfaceCount; i++) {
indices[i] = getUShort(classInfoOffset + 8 + 2 * i);
}
return indices;
}
/**
* @return the name of the i'th implemented interface
*/
public String getInterfaceName(int i) throws InvalidClassFileException {
verifyInterfaceIndex(i);
String s = getClassFromAddress(classInfoOffset + 8 + 2 * i);
if (s == null) {
throw new InvalidClassFileException(classInfoOffset + 8 + 2 * i, "Null interface name not allowed");
} else {
return s;
}
}
/**
* @return an array of the names of the implemented interfaces
*/
public String[] getInterfaceNames() throws InvalidClassFileException {
String[] names = new String[interfaceCount];
for (int i = 0; i < interfaceCount; i++) {
String s = getClassFromAddress(classInfoOffset + 8 + 2 * i);
if (s == null) {
throw new InvalidClassFileException(classInfoOffset + 8 + 2 * i, "Null interface name not allowed");
}
names[i] = s;
}
return names;
}
/**
* This method allows direct read-only access to the constant pool for the class.
*
* @return the constant pool for the class
*/
public ConstantPoolParser getCP() {
return cpParser;
}
/**
* @return the signed 32-bit value at offset i in the class data
*/
public int getInt(int i) {
return (bytes[i] << 24) + ((bytes[i + 1] & 0xFF) << 16) + ((bytes[i + 2] & 0xFF) << 8) + (bytes[i + 3] & 0xFF);
}
/**
* @return the unsigned 16-bit value at offset i in the class data
*/
public int getUShort(int i) {
return ((bytes[i] & 0xFF) << 8) + (bytes[i + 1] & 0xFF);
}
/**
* @return the signed 16-bit value at offset i in the class data
*/
public int getShort(int i) {
return (bytes[i] << 8) + (bytes[i + 1] & 0xFF);
}
/**
* @return the signed 8-bit value at offset i in the class data
*/
public byte getByte(int i) {
return bytes[i];
}
/**
* @return the unsigned 8-bit value at offset i in the class data
*/
public int getUnsignedByte(int i) {
return bytes[i] & 0xff;
}
/**
* @return the number of fields in the class
*/
public int getFieldCount() {
return fieldOffsets.length - 1;
}
private void verifyFieldIndex(int f) {
if (f < 0 || f >= fieldOffsets.length - 1) {
throw new IllegalArgumentException("Invalid field index: " + f);
}
}
/**
* @return the access flags for the f'th field
*/
public int getFieldAccessFlags(int f) {
verifyFieldIndex(f);
return getUShort(fieldOffsets[f]);
}
String getUtf8FromAddress(int addr) throws InvalidClassFileException {
int s = getUShort(addr);
if (s == 0) {
return null;
} else {
try {
return cpParser.getCPUtf8(s);
} catch (IllegalArgumentException ex) {
throw new InvalidClassFileException(addr, "Invalid Utf8 constant pool index: " + s);
}
}
}
/**
* @return the name of the f'th field
*/
public String getFieldName(int f) throws InvalidClassFileException {
verifyFieldIndex(f);
return getUtf8FromAddress(fieldOffsets[f] + 2);
}
/**
* @return the type of the f'th field, in JVM format (e.g., I, Z, java/lang/Object)
*/
public String getFieldType(int f) throws InvalidClassFileException {
verifyFieldIndex(f);
return getUtf8FromAddress(fieldOffsets[f] + 4);
}
/**
* @return the index of the constant pool entry for the name of the f'th field, in JVM format (e.g., I, Z, Ljava/lang/Object;)
*/
public int getFieldNameIndex(int f) {
verifyFieldIndex(f);
return getUShort(fieldOffsets[f] + 2);
}
/**
* @return the index of the constant pool entry for the type of the f'th field, in JVM format (e.g., I, Z, Ljava/lang/Object;)
*/
public int getFieldTypeIndex(int f) {
verifyFieldIndex(f);
return getUShort(fieldOffsets[f] + 4);
}
/**
* AttrIterator provides access to attributes in the class file.
*
* AttrIterators can be reused for many different iterations, like this:
*
* <pre>
* AttrIterator iter = new AttrIterator();
* int fieldCount = reader.getFieldCount();
* for (int i = 0; i &lt; fieldCount; i++) {
* reader.initFieldAttributeIterator(i, iter);
* for (; iter.isValid(); iter.advance()) {
* if (iter.getName().equals(&quot;ConstantValue&quot;)) {
* ConstantValueReader cv = new ConstantValueReader(iter);
* ...
* }
* }
* }
* </pre>
*/
public static final class AttrIterator {
ClassReader cr;
int offset;
int size;
private int remaining;
/**
* Create a blank iterator. The iterator is not valid until it is initialized by some other class.
*/
public AttrIterator() {
}
private void setSize() {
if (remaining > 0) {
size = 6 + cr.getInt(offset + 2);
}
}
void init(ClassReader cr, int offset) {
this.cr = cr;
this.offset = offset + 2;
this.remaining = cr.getUShort(offset);
setSize();
}
void verifyValid() {
if (remaining <= 0) {
throw new IllegalArgumentException("Attempt to manipulate invalid AttrIterator");
}
}
public ClassReader getClassReader() {
verifyValid();
return cr;
}
/**
* The attribute iterator must be valid.
*
* @return the offset of the raw attribute data (including attribute header) in the class file data
*/
public int getRawOffset() {
verifyValid();
return offset;
}
/**
* The attribute iterator must be valid.
*
* @return the size of the raw attribute data (including attribute header) in the class file data
*/
public int getRawSize() {
verifyValid();
return size;
}
/**
* The attribute iterator must be valid.
*
* @return the offset of the attribute data (excluding attribute header) in the class file data
*/
public int getDataOffset() {
verifyValid();
return offset + 6;
}
/**
* The attribute iterator must be valid.
*
* @return the size of the attribute data (excluding attribute header) in the class file data
*/
public int getDataSize() {
verifyValid();
return size - 6;
}
/**
* @return the number of attributes left in the list, including this attribute (if valid)
*/
public int getRemainingAttributesCount() {
return remaining;
}
/**
* The attribute iterator must be valid.
*
* @return the constant pool index of the name of the attribute
*/
public int getNameIndex() {
verifyValid();
return cr.getUShort(offset);
}
/**
* The attribute iterator must be valid.
*
* @return the name of the attribute
*/
public String getName() throws InvalidClassFileException {
verifyValid();
String s = cr.getUtf8FromAddress(offset);
if (s == null) {
throw new InvalidClassFileException(offset, "Null attribute name");
} else {
return s;
}
}
/**
* @return whether this iterator is valid
*/
public boolean isValid() {
return remaining > 0;
}
/**
* The attribute iterator must be valid.
*
* The iterator is advanced to the next attribute (which might not exist, so the iterator might become invalid).
*/
public void advance() {
verifyValid();
offset += size;
remaining--;
setSize();
}
}
/**
* Point iter at the list of attributes for field f.
*
* @throws IllegalArgumentException if iter is null
*/
public void initFieldAttributeIterator(int f, AttrIterator iter) {
if (iter == null) {
throw new IllegalArgumentException("iter is null");
}
verifyFieldIndex(f);
iter.init(this, fieldOffsets[f] + 6);
}
/**
* @return the offset of the raw class data for field f
*/
public int getFieldRawOffset(int f) {
verifyFieldIndex(f);
return fieldOffsets[f];
}
/**
* @return the size of the raw class data for field f
*/
public int getFieldRawSize(int f) {
verifyFieldIndex(f);
return fieldOffsets[f + 1] - fieldOffsets[f];
}
/**
* @return the number of methods in the class
*/
public int getMethodCount() {
return methodOffsets.length - 1;
}
private void verifyMethodIndex(int m) {
if (m < 0 || m >= methodOffsets.length - 1) {
throw new IllegalArgumentException("Invalid method index: " + m);
}
}
/**
* @return the offset of the raw class data for method m
*/
public int getMethodRawOffset(int m) {
verifyMethodIndex(m);
return methodOffsets[m];
}
/**
* @return the size of the raw class data for method m
*/
public int getMethodRawSize(int m) {
verifyMethodIndex(m);
return methodOffsets[m + 1] - methodOffsets[m];
}
/**
* @return the access flags for method m
*/
public int getMethodAccessFlags(int m) {
verifyMethodIndex(m);
return getUShort(methodOffsets[m]);
}
/**
* @return the name of method m
*/
public String getMethodName(int m) throws InvalidClassFileException {
verifyMethodIndex(m);
return getUtf8FromAddress(methodOffsets[m] + 2);
}
/**
* @return the method descriptor of method m in JVM format (e.g., (ILjava/lang/Object;)V )
*/
public String getMethodType(int m) throws InvalidClassFileException {
verifyMethodIndex(m);
return getUtf8FromAddress(methodOffsets[m] + 4);
}
/**
* @return the constant pool index of the name of method m
*/
public int getMethodNameIndex(int m) {
verifyMethodIndex(m);
return getUShort(methodOffsets[m] + 2);
}
/**
* @return the constant pool index of the method descriptor of method m
*/
public int getMethodTypeIndex(int m) {
verifyMethodIndex(m);
return getUShort(methodOffsets[m] + 4);
}
/**
* Point iter at the list of attributes for method m.
*
* @throws IllegalArgumentException if iter is null
*/
public void initMethodAttributeIterator(int m, AttrIterator iter) {
if (iter == null) {
throw new IllegalArgumentException("iter is null");
}
verifyMethodIndex(m);
iter.init(this, methodOffsets[m] + 6);
}
/**
* Point iter at the list of attributes for the class.
*
* @throws IllegalArgumentException if iter is null
*/
public void initClassAttributeIterator(AttrIterator iter) {
if (iter == null) {
throw new IllegalArgumentException("iter is null");
}
iter.init(this, attrInfoOffset);
}
}
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