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package org.jf.dexlib2.dexbacked;
import com.google.common.collect.ImmutableList;
import org.jf.dexlib2.dexbacked.instruction.DexBackedInstruction;
import org.jf.dexlib2.dexbacked.raw.CodeItem;
import org.jf.dexlib2.dexbacked.util.DebugInfo;
import org.jf.dexlib2.dexbacked.util.FixedSizeList;
import org.jf.dexlib2.dexbacked.util.VariableSizeListIterator;
import org.jf.dexlib2.dexbacked.util.VariableSizeLookaheadIterator;
import org.jf.dexlib2.iface.MethodImplementation;
import org.jf.dexlib2.iface.debug.DebugItem;
import org.jf.dexlib2.iface.instruction.Instruction;
import org.jf.util.AlignmentUtils;
import org.jf.util.ExceptionWithContext;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Iterator;
import java.util.List;
public class DexBackedMethodImplementation implements MethodImplementation {
@Nonnull public final DexBackedDexFile dexFile;
@Nonnull public final DexBackedMethod method;
private final int codeOffset;
public DexBackedMethodImplementation(@Nonnull DexBackedDexFile dexFile,
@Nonnull DexBackedMethod method,
int codeOffset) {
this.dexFile = dexFile;
this.method = method;
this.codeOffset = codeOffset;
}
@Override public int getRegisterCount() { return dexFile.readUshort(codeOffset); }
@Nonnull @Override public Iterable<? extends Instruction> getInstructions() {
// instructionsSize is the number of 16-bit code units in the instruction list, not the number of instructions
int instructionsSize = dexFile.readSmallUint(codeOffset + CodeItem.INSTRUCTION_COUNT_OFFSET);
final int instructionsStartOffset = codeOffset + CodeItem.INSTRUCTION_START_OFFSET;
final int endOffset = instructionsStartOffset + (instructionsSize*2);
return new Iterable<Instruction>() {
@Override
public Iterator<Instruction> iterator() {
return new VariableSizeLookaheadIterator<Instruction>(dexFile, instructionsStartOffset) {
@Override
protected Instruction readNextItem(@Nonnull DexReader reader) {
if (reader.getOffset() >= endOffset) {
return endOfData();
}
Instruction instruction = DexBackedInstruction.readFrom(reader);
// Does the instruction extend past the end of the method?
int offset = reader.getOffset();
if (offset > endOffset || offset < 0) {
throw new ExceptionWithContext("The last instruction in method %s is truncated", method);
}
return instruction;
}
};
}
};
}
@Nonnull
@Override
public List<? extends DexBackedTryBlock> getTryBlocks() {
final int triesSize = dexFile.readUshort(codeOffset + CodeItem.TRIES_SIZE_OFFSET);
if (triesSize > 0) {
int instructionsSize = dexFile.readSmallUint(codeOffset + CodeItem.INSTRUCTION_COUNT_OFFSET);
final int triesStartOffset = AlignmentUtils.alignOffset(
codeOffset + CodeItem.INSTRUCTION_START_OFFSET + (instructionsSize*2), 4);
final int handlersStartOffset = triesStartOffset + triesSize*CodeItem.TryItem.ITEM_SIZE;
return new FixedSizeList<DexBackedTryBlock>() {
@Nonnull
@Override
public DexBackedTryBlock readItem(int index) {
return new DexBackedTryBlock(dexFile,
triesStartOffset + index*CodeItem.TryItem.ITEM_SIZE,
handlersStartOffset);
}
@Override
public int size() {
return triesSize;
}
};
}
return ImmutableList.of();
}
@Nonnull
private DebugInfo getDebugInfo() {
int debugOffset = dexFile.readInt(codeOffset + CodeItem.DEBUG_INFO_OFFSET);
if (debugOffset == -1 || debugOffset == 0) {
return DebugInfo.newOrEmpty(dexFile, 0, this);
}
if (debugOffset < 0) {
System.err.println(String.format("%s: Invalid debug offset", method));
return DebugInfo.newOrEmpty(dexFile, 0, this);
}
if (debugOffset >= dexFile.buf.length) {
System.err.println(String.format("%s: Invalid debug offset", method));
return DebugInfo.newOrEmpty(dexFile, 0, this);
}
return DebugInfo.newOrEmpty(dexFile, debugOffset, this);
}
@Nonnull @Override
public Iterable<? extends DebugItem> getDebugItems() {
return getDebugInfo();
}
@Nonnull
public Iterator<String> getParameterNames(@Nullable DexReader dexReader) {
return getDebugInfo().getParameterNames(dexReader);
}
/**
* Calculate and return the private size of a method implementation.
*
* Calculated as: debug info size + instructions size + try-catch size
*
* @return size in bytes
*/
public int getSize() {
int debugSize = getDebugInfo().getSize();
//set last offset just before bytecode instructions (after insns_size)
int lastOffset = codeOffset + CodeItem.INSTRUCTION_START_OFFSET;
//set code_item ending offset to the end of instructions list (insns_size * ushort)
lastOffset += dexFile.readSmallUint(codeOffset + CodeItem.INSTRUCTION_COUNT_OFFSET) * 2;
//read any exception handlers and move code_item offset to the end
for (DexBackedTryBlock tryBlock: getTryBlocks()) {
Iterator<? extends DexBackedExceptionHandler> tryHandlerIter =
tryBlock.getExceptionHandlers().iterator();
while (tryHandlerIter.hasNext()) {
tryHandlerIter.next();
}
lastOffset = ((VariableSizeListIterator)tryHandlerIter).getReaderOffset();
}
//method impl size = debug block size + code_item size
return debugSize + (lastOffset - codeOffset);
}
}