ZipEntry.cpp revision 48a621c2779c74cba3555c96e3fbc7b1989ac90b 
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
27using namespace android;
28
29#define LOG(...) fprintf(stderr, __VA_ARGS__)
30
31/* Jan 01 2008 */
32#define STATIC_DATE (28 << 9 | 1 << 5 | 1)
33#define STATIC_TIME 0
34
35/*
36 * Initialize a new ZipEntry structure from a FILE* positioned at a
37 * CentralDirectoryEntry. Rewrites the headers to remove the dynamic
38 * timestamps.
39 *
40 * On exit, the file pointer will be at the start of the next CDE or
41 * at the EOCD.
42 */
43status_t ZipEntry::initAndRewriteFromCDE(FILE* fp)
44{
45    status_t result;
46    long posn;
47
48    /* read the CDE */
49    result = mCDE.rewrite(fp);
50    if (result != 0) {
51        LOG("mCDE.rewrite failed\n");
52        return result;
53    }
54
55    /* using the info in the CDE, go load up the LFH */
56    posn = ftell(fp);
57    if (fseek(fp, mCDE.mLocalHeaderRelOffset, SEEK_SET) != 0) {
58        LOG("local header seek failed (%ld)\n",
59            mCDE.mLocalHeaderRelOffset);
60        return -1;
61    }
62
63    result = mLFH.rewrite(fp);
64    if (result != 0) {
65        LOG("mLFH.rewrite failed\n");
66        return result;
67    }
68
69    if (fseek(fp, posn, SEEK_SET) != 0)
70        return -1;
71
72    return 0;
73}
74
75/*
76 * ===========================================================================
77 *      ZipEntry::LocalFileHeader
78 * ===========================================================================
79 */
80
81/*
82 * Rewrite a local file header.
83 *
84 * On entry, "fp" points to the signature at the start of the header.
85 */
86status_t ZipEntry::LocalFileHeader::rewrite(FILE* fp)
87{
88    status_t result = 0;
89    unsigned char buf[kLFHLen];
90
91    if (fread(buf, 1, kLFHLen, fp) != kLFHLen)
92        return -1;
93
94    if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
95        LOG("whoops: didn't find expected signature\n");
96        return -1;
97    }
98
99    ZipEntry::putShortLE(&buf[0x0a], STATIC_TIME);
100    ZipEntry::putShortLE(&buf[0x0c], STATIC_DATE);
101
102    if (fseek(fp, -kLFHLen, SEEK_CUR) != 0)
103        return -1;
104
105    if (fwrite(buf, 1, kLFHLen, fp) != kLFHLen)
106        return -1;
107
108    return 0;
109}
110
111/*
112 * ===========================================================================
113 *      ZipEntry::CentralDirEntry
114 * ===========================================================================
115 */
116
117/*
118 * Read and rewrite the central dir entry that appears next in the file.
119 *
120 * On entry, "fp" should be positioned on the signature bytes for the
121 * entry.  On exit, "fp" will point at the signature word for the next
122 * entry or for the EOCD.
123 */
124status_t ZipEntry::CentralDirEntry::rewrite(FILE* fp)
125{
126    status_t result = 0;
127    unsigned char buf[kCDELen];
128    unsigned short fileNameLength, extraFieldLength, fileCommentLength;
129
130    if (fread(buf, 1, kCDELen, fp) != kCDELen)
131        return -1;
132
133    if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
134        LOG("Whoops: didn't find expected signature\n");
135        return -1;
136    }
137
138    ZipEntry::putShortLE(&buf[0x0c], STATIC_TIME);
139    ZipEntry::putShortLE(&buf[0x0e], STATIC_DATE);
140
141    fileNameLength = ZipEntry::getShortLE(&buf[0x1c]);
142    extraFieldLength = ZipEntry::getShortLE(&buf[0x1e]);
143    fileCommentLength = ZipEntry::getShortLE(&buf[0x20]);
144    mLocalHeaderRelOffset = ZipEntry::getLongLE(&buf[0x2a]);
145
146    if (fseek(fp, -kCDELen, SEEK_CUR) != 0)
147        return -1;
148
149    if (fwrite(buf, 1, kCDELen, fp) != kCDELen)
150        return -1;
151
152    if (fseek(fp, fileNameLength + extraFieldLength + fileCommentLength, SEEK_CUR) != 0)
153        return -1;
154
155    return 0;
156}
157