1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/*
18 * Functions for dealing with try-catch info.
19 */
20
21#include "DexCatch.h"
22
23/* Get the first handler offset for the given DexCode.
24 * It's not 0 because the handlers list is prefixed with its size
25 * (in entries) as a uleb128. */
26u4 dexGetFirstHandlerOffset(const DexCode* pCode) {
27    if (pCode->triesSize == 0) {
28        return 0;
29    }
30
31    const u1* baseData = dexGetCatchHandlerData(pCode);
32    const u1* data = baseData;
33
34    readUnsignedLeb128(&data);
35
36    return data - baseData;
37}
38
39/* Get count of handler lists for the given DexCode. */
40u4 dexGetHandlersSize(const DexCode* pCode) {
41    if (pCode->triesSize == 0) {
42        return 0;
43    }
44
45    const u1* data = dexGetCatchHandlerData(pCode);
46
47    return readUnsignedLeb128(&data);
48}
49
50/* Helper for dexFindCatchHandlerOffset(), which does an actual search
51 * in the tries table. Returns -1 if there is no applicable handler. */
52int dexFindCatchHandlerOffset0(u2 triesSize, const DexTry* pTries,
53        u4 address) {
54    // Note: Signed type is important for max and min.
55    int min = 0;
56    int max = triesSize - 1;
57
58    while (max >= min) {
59        int guess = (min + max) >> 1;
60        const DexTry* pTry = &pTries[guess];
61        u4 start = pTry->startAddr;
62
63        if (address < start) {
64            max = guess - 1;
65            continue;
66        }
67
68        u4 end = start + pTry->insnCount;
69
70        if (address >= end) {
71            min = guess + 1;
72            continue;
73        }
74
75        // We have a winner!
76        return (int) pTry->handlerOff;
77    }
78
79    // No match.
80    return -1;
81}
82
83/* Get the handler offset just past the end of the one just iterated over.
84 * This ends the iteration if it wasn't already. */
85u4 dexCatchIteratorGetEndOffset(DexCatchIterator* pIterator,
86        const DexCode* pCode) {
87    while (dexCatchIteratorNext(pIterator) != NULL) /* empty */ ;
88
89    return (u4) (pIterator->pEncodedData - dexGetCatchHandlerData(pCode));
90}
91