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
28 using 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 */
initAndRewriteFromCDE(FILE * fp)44 status_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 */
rewrite(FILE * fp)87 status_t ZipEntry::LocalFileHeader::rewrite(FILE* fp)
88 {
89 uint8_t 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 */
rewrite(FILE * fp)124 status_t ZipEntry::CentralDirEntry::rewrite(FILE* fp)
125 {
126 uint8_t buf[kCDELen];
127 uint16_t fileNameLength, extraFieldLength, fileCommentLength;
128
129 if (fread(buf, 1, kCDELen, fp) != kCDELen)
130 return -1;
131
132 if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
133 LOG("Whoops: didn't find expected signature\n");
134 return -1;
135 }
136
137 ZipEntry::putShortLE(&buf[0x0c], STATIC_TIME);
138 ZipEntry::putShortLE(&buf[0x0e], STATIC_DATE);
139
140 fileNameLength = ZipEntry::getShortLE(&buf[0x1c]);
141 extraFieldLength = ZipEntry::getShortLE(&buf[0x1e]);
142 fileCommentLength = ZipEntry::getShortLE(&buf[0x20]);
143 mLocalHeaderRelOffset = ZipEntry::getLongLE(&buf[0x2a]);
144
145 if (fseek(fp, -kCDELen, SEEK_CUR) != 0)
146 return -1;
147
148 if (fwrite(buf, 1, kCDELen, fp) != kCDELen)
149 return -1;
150
151 if (fseek(fp, fileNameLength + extraFieldLength + fileCommentLength, SEEK_CUR) != 0)
152 return -1;
153
154 return 0;
155 }
156