162 lines
4.8 KiB
C
162 lines
4.8 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* Functions for dealing with try-catch info.
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*/
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#ifndef LIBDEX_DEXCATCH_H_
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#define LIBDEX_DEXCATCH_H_
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#include "DexFile.h"
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#include "Leb128.h"
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/*
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* Catch handler entry, used while iterating over catch_handler_items.
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*/
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struct DexCatchHandler {
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u4 typeIdx; /* type index of the caught exception type */
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u4 address; /* handler address */
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};
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/* Get the first handler offset for the given DexCode.
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* It's not 0 because the handlers list is prefixed with its size
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* (in entries) as a uleb128. */
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u4 dexGetFirstHandlerOffset(const DexCode* pCode);
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/* Get count of handler lists for the given DexCode. */
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u4 dexGetHandlersSize(const DexCode* pCode);
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/*
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* Iterator over catch handler data. This structure should be treated as
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* opaque.
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*/
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struct DexCatchIterator {
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const u1* pEncodedData;
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bool catchesAll;
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u4 countRemaining;
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DexCatchHandler handler;
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};
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/* Initialize a DexCatchIterator to emptiness. This mostly exists to
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* squelch innocuous warnings. */
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DEX_INLINE void dexCatchIteratorClear(DexCatchIterator* pIterator) {
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pIterator->pEncodedData = NULL;
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pIterator->catchesAll = false;
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pIterator->countRemaining = 0;
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pIterator->handler.typeIdx = 0;
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pIterator->handler.address = 0;
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}
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/* Initialize a DexCatchIterator with a direct pointer to encoded handlers. */
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DEX_INLINE void dexCatchIteratorInitToPointer(DexCatchIterator* pIterator,
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const u1* pEncodedData)
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{
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s4 count = readSignedLeb128(&pEncodedData);
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if (count <= 0) {
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pIterator->catchesAll = true;
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count = -count;
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} else {
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pIterator->catchesAll = false;
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}
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pIterator->pEncodedData = pEncodedData;
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pIterator->countRemaining = count;
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}
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/* Initialize a DexCatchIterator to a particular handler offset. */
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DEX_INLINE void dexCatchIteratorInit(DexCatchIterator* pIterator,
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const DexCode* pCode, u4 offset)
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{
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dexCatchIteratorInitToPointer(pIterator,
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dexGetCatchHandlerData(pCode) + offset);
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}
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/* Get the next item from a DexCatchIterator. Returns NULL if at end. */
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DEX_INLINE DexCatchHandler* dexCatchIteratorNext(DexCatchIterator* pIterator) {
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if (pIterator->countRemaining == 0) {
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if (! pIterator->catchesAll) {
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return NULL;
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}
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pIterator->catchesAll = false;
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pIterator->handler.typeIdx = kDexNoIndex;
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} else {
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u4 typeIdx = readUnsignedLeb128(&pIterator->pEncodedData);
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pIterator->handler.typeIdx = typeIdx;
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pIterator->countRemaining--;
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}
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pIterator->handler.address = readUnsignedLeb128(&pIterator->pEncodedData);
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return &pIterator->handler;
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}
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/* Get the handler offset just past the end of the one just iterated over.
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* This ends the iteration if it wasn't already. */
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u4 dexCatchIteratorGetEndOffset(DexCatchIterator* pIterator,
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const DexCode* pCode);
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/* Helper for dexFindCatchHandler(). Do not call directly. */
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int dexFindCatchHandlerOffset0(u2 triesSize, const DexTry* pTries,
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u4 address);
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/* Find the handler associated with a given address, if any.
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* Initializes the given iterator and returns true if a match is
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* found. Returns false if there is no applicable handler. */
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DEX_INLINE bool dexFindCatchHandler(DexCatchIterator *pIterator,
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const DexCode* pCode, u4 address) {
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u2 triesSize = pCode->triesSize;
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int offset = -1;
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// Short-circuit the overwhelmingly common cases.
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switch (triesSize) {
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case 0: {
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break;
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}
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case 1: {
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const DexTry* tries = dexGetTries(pCode);
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u4 start = tries[0].startAddr;
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if (address < start) {
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break;
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}
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u4 end = start + tries[0].insnCount;
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if (address >= end) {
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break;
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}
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offset = tries[0].handlerOff;
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break;
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}
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default: {
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offset = dexFindCatchHandlerOffset0(triesSize, dexGetTries(pCode),
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address);
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}
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}
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if (offset < 0) {
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dexCatchIteratorClear(pIterator); // This squelches warnings.
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return false;
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} else {
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dexCatchIteratorInit(pIterator, pCode, offset);
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return true;
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}
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}
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#endif // LIBDEX_DEXCATCH_H_
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