ZipEntry.cpp revision 41bc424c323f86806f04acd22304d4d149bc5dbe 
1/*
2 * Copyright (C) 2006 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// Access to entries in a Zip archive.
19//
20
21#include "ZipEntry.h"
22
23#include <stdio.h>
24#include <string.h>
25#include <assert.h>
26#include <inttypes.h>
27
28using namespace android;
29
30#define LOG(...) fprintf(stderr, __VA_ARGS__)
31
32/* Jan 01 2008 */
33#define STATIC_DATE (28 << 9 | 1 << 5 | 1)
34#define STATIC_TIME 0
35
36/*
37 * Initialize a new ZipEntry structure from a FILE* positioned at a
38 * CentralDirectoryEntry. Rewrites the headers to remove the dynamic
39 * timestamps.
40 *
41 * On exit, the file pointer will be at the start of the next CDE or
42 * at the EOCD.
43 */
44status_t ZipEntry::initAndRewriteFromCDE(FILE* fp)
45{
46    status_t result;
47    long posn;
48
49    /* read the CDE */
50    result = mCDE.rewrite(fp);
51    if (result != 0) {
52        LOG("mCDE.rewrite failed\n");
53        return result;
54    }
55
56    /* using the info in the CDE, go load up the LFH */
57    posn = ftell(fp);
58    if (fseek(fp, mCDE.mLocalHeaderRelOffset, SEEK_SET) != 0) {
59        LOG("local header seek failed (%" PRIu32 ")\n",
60            mCDE.mLocalHeaderRelOffset);
61        return -1;
62    }
63
64    result = mLFH.rewrite(fp);
65    if (result != 0) {
66        LOG("mLFH.rewrite failed\n");
67        return result;
68    }
69
70    if (fseek(fp, posn, SEEK_SET) != 0)
71        return -1;
72
73    return 0;
74}
75
76/*
77 * ===========================================================================
78 *      ZipEntry::LocalFileHeader
79 * ===========================================================================
80 */
81
82/*
83 * Rewrite a local file header.
84 *
85 * On entry, "fp" points to the signature at the start of the header.
86 */
87status_t ZipEntry::LocalFileHeader::rewrite(FILE* fp)
88{
89    status_t result = 0;
90    uint8_t buf[kLFHLen];
91
92    if (fread(buf, 1, kLFHLen, fp) != kLFHLen)
93        return -1;
94
95    if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
96        LOG("whoops: didn't find expected signature\n");
97        return -1;
98    }
99
100    ZipEntry::putShortLE(&buf[0x0a], STATIC_TIME);
101    ZipEntry::putShortLE(&buf[0x0c], STATIC_DATE);
102
103    if (fseek(fp, -kLFHLen, SEEK_CUR) != 0)
104        return -1;
105
106    if (fwrite(buf, 1, kLFHLen, fp) != kLFHLen)
107        return -1;
108
109    return 0;
110}
111
112/*
113 * ===========================================================================
114 *      ZipEntry::CentralDirEntry
115 * ===========================================================================
116 */
117
118/*
119 * Read and rewrite the central dir entry that appears next in the file.
120 *
121 * On entry, "fp" should be positioned on the signature bytes for the
122 * entry.  On exit, "fp" will point at the signature word for the next
123 * entry or for the EOCD.
124 */
125status_t ZipEntry::CentralDirEntry::rewrite(FILE* fp)
126{
127    status_t result = 0;
128    uint8_t buf[kCDELen];
129    uint16_t fileNameLength, extraFieldLength, fileCommentLength;
130
131    if (fread(buf, 1, kCDELen, fp) != kCDELen)
132        return -1;
133
134    if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
135        LOG("Whoops: didn't find expected signature\n");
136        return -1;
137    }
138
139    ZipEntry::putShortLE(&buf[0x0c], STATIC_TIME);
140    ZipEntry::putShortLE(&buf[0x0e], STATIC_DATE);
141
142    fileNameLength = ZipEntry::getShortLE(&buf[0x1c]);
143    extraFieldLength = ZipEntry::getShortLE(&buf[0x1e]);
144    fileCommentLength = ZipEntry::getShortLE(&buf[0x20]);
145    mLocalHeaderRelOffset = ZipEntry::getLongLE(&buf[0x2a]);
146
147    if (fseek(fp, -kCDELen, SEEK_CUR) != 0)
148        return -1;
149
150    if (fwrite(buf, 1, kCDELen, fp) != kCDELen)
151        return -1;
152
153    if (fseek(fp, fileNameLength + extraFieldLength + fileCommentLength, SEEK_CUR) != 0)
154        return -1;
155
156    return 0;
157}
158