DexOptData.cpp revision b210a9f9c7ae17e2028a86d9a4e9a3b35472862a 
1/*
2 * Copyright (C) 2010 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 to parse and manipulate the additional data tables added
19 * to optimized .dex files.
20 */
21
22#include <zlib.h>
23
24#include "DexOptData.h"
25
26/*
27 * Check to see if a given data pointer is a valid double-word-aligned
28 * pointer into the given memory range (from start inclusive to end
29 * exclusive). Returns true if valid.
30 */
31static bool isValidPointer(const void* ptr, const void* start, const void* end)
32{
33    return (ptr >= start) && (ptr < end) && (((uintptr_t) ptr & 7) == 0);
34}
35
36/* (documented in header file) */
37u4 dexComputeOptChecksum(const DexOptHeader* pOptHeader)
38{
39    const u1* start = (const u1*) pOptHeader + pOptHeader->depsOffset;
40    const u1* end = (const u1*) pOptHeader +
41        pOptHeader->optOffset + pOptHeader->optLength;
42
43    uLong adler = adler32(0L, Z_NULL, 0);
44
45    return (u4) adler32(adler, start, end - start);
46}
47
48/* (documented in header file) */
49bool dexParseOptData(const u1* data, size_t length, DexFile* pDexFile)
50{
51    const void* pOptStart = data + pDexFile->pOptHeader->optOffset;
52    const void* pOptEnd = data + length;
53    const u4* pOpt = (const u4*) pOptStart;
54    u4 optLength = (const u1*) pOptEnd - (const u1*) pOptStart;
55
56    /*
57     * Make sure the opt data start is in range and aligned. This may
58     * seem like a superfluous check, but (a) if the file got
59     * truncated, it might turn out that pOpt >= pOptEnd; and (b)
60     * if the opt data header got corrupted, pOpt might not be
61     * properly aligned. This test will catch both of these cases.
62     */
63    if (!isValidPointer(pOpt, pOptStart, pOptEnd)) {
64        ALOGE("Bogus opt data start pointer");
65        return false;
66    }
67
68    /* Make sure that the opt data length is a whole number of words. */
69    if ((optLength & 3) != 0) {
70        ALOGE("Unaligned opt data area end");
71        return false;
72    }
73
74    /*
75     * Make sure that the opt data area is large enough to have at least
76     * one chunk header.
77     */
78    if (optLength < 8) {
79        ALOGE("Undersized opt data area (%u)", optLength);
80        return false;
81    }
82
83    /* Process chunks until we see the end marker. */
84    while (*pOpt != kDexChunkEnd) {
85        if (!isValidPointer(pOpt + 2, pOptStart, pOptEnd)) {
86            ALOGE("Bogus opt data content pointer at offset %u",
87                    ((const u1*) pOpt) - data);
88            return false;
89        }
90
91        u4 size = *(pOpt + 1);
92        const u1* pOptData = (const u1*) (pOpt + 2);
93
94        /*
95         * The rounded size is 64-bit aligned and includes +8 for the
96         * type/size header (which was extracted immediately above).
97         */
98        u4 roundedSize = (size + 8 + 7) & ~7;
99        const u4* pNextOpt = pOpt + (roundedSize / sizeof(u4));
100
101        if (!isValidPointer(pNextOpt, pOptStart, pOptEnd)) {
102            ALOGE("Opt data area problem for chunk of size %u at offset %u",
103                    size, ((const u1*) pOpt) - data);
104            return false;
105        }
106
107        switch (*pOpt) {
108        case kDexChunkClassLookup:
109            pDexFile->pClassLookup = (const DexClassLookup*) pOptData;
110            break;
111        case kDexChunkRegisterMaps:
112            ALOGV("+++ found register maps, size=%u", size);
113            pDexFile->pRegisterMapPool = pOptData;
114            break;
115        default:
116            ALOGI("Unknown chunk 0x%08x (%c%c%c%c), size=%d in opt data area",
117                *pOpt,
118                (char) ((*pOpt) >> 24), (char) ((*pOpt) >> 16),
119                (char) ((*pOpt) >> 8),  (char)  (*pOpt),
120                size);
121            break;
122        }
123
124        pOpt = pNextOpt;
125    }
126
127    return true;
128}
129