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. */
dexGetFirstHandlerOffset(const DexCode * pCode)26 u4 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. */
dexGetHandlersSize(const DexCode * pCode)40 u4 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. */
dexFindCatchHandlerOffset0(u2 triesSize,const DexTry * pTries,u4 address)52 int 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. */
dexCatchIteratorGetEndOffset(DexCatchIterator * pIterator,const DexCode * pCode)85 u4 dexCatchIteratorGetEndOffset(DexCatchIterator* pIterator,
86 const DexCode* pCode) {
87 while (dexCatchIteratorNext(pIterator) != NULL) /* empty */ ;
88
89 return (u4) (pIterator->pEncodedData - dexGetCatchHandlerData(pCode));
90 }
91