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