1 /*
2 * Copyright (C) 2009 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 // See imgdiff.c in this directory for a description of the patch file
18 // format.
19
20 #include <stdio.h>
21 #include <sys/stat.h>
22 #include <errno.h>
23 #include <unistd.h>
24 #include <string.h>
25
26 #include "zlib.h"
27 #include "mincrypt/sha.h"
28 #include "applypatch.h"
29 #include "imgdiff.h"
30 #include "utils.h"
31
32 /*
33 * Apply the patch given in 'patch_filename' to the source data given
34 * by (old_data, old_size). Write the patched output to the 'output'
35 * file, and update the SHA context with the output data as well.
36 * Return 0 on success.
37 */
ApplyImagePatch(const unsigned char * old_data,ssize_t old_size,const Value * patch,SinkFn sink,void * token,SHA_CTX * ctx,const Value * bonus_data)38 int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
39 const Value* patch,
40 SinkFn sink, void* token, SHA_CTX* ctx,
41 const Value* bonus_data) {
42 ssize_t pos = 12;
43 char* header = patch->data;
44 if (patch->size < 12) {
45 printf("patch too short to contain header\n");
46 return -1;
47 }
48
49 // IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
50 // (IMGDIFF1, which is no longer supported, used CHUNK_NORMAL and
51 // CHUNK_GZIP.)
52 if (memcmp(header, "IMGDIFF2", 8) != 0) {
53 printf("corrupt patch file header (magic number)\n");
54 return -1;
55 }
56
57 int num_chunks = Read4(header+8);
58
59 int i;
60 for (i = 0; i < num_chunks; ++i) {
61 // each chunk's header record starts with 4 bytes.
62 if (pos + 4 > patch->size) {
63 printf("failed to read chunk %d record\n", i);
64 return -1;
65 }
66 int type = Read4(patch->data + pos);
67 pos += 4;
68
69 if (type == CHUNK_NORMAL) {
70 char* normal_header = patch->data + pos;
71 pos += 24;
72 if (pos > patch->size) {
73 printf("failed to read chunk %d normal header data\n", i);
74 return -1;
75 }
76
77 size_t src_start = Read8(normal_header);
78 size_t src_len = Read8(normal_header+8);
79 size_t patch_offset = Read8(normal_header+16);
80
81 ApplyBSDiffPatch(old_data + src_start, src_len,
82 patch, patch_offset, sink, token, ctx);
83 } else if (type == CHUNK_RAW) {
84 char* raw_header = patch->data + pos;
85 pos += 4;
86 if (pos > patch->size) {
87 printf("failed to read chunk %d raw header data\n", i);
88 return -1;
89 }
90
91 ssize_t data_len = Read4(raw_header);
92
93 if (pos + data_len > patch->size) {
94 printf("failed to read chunk %d raw data\n", i);
95 return -1;
96 }
97 SHA_update(ctx, patch->data + pos, data_len);
98 if (sink((unsigned char*)patch->data + pos,
99 data_len, token) != data_len) {
100 printf("failed to write chunk %d raw data\n", i);
101 return -1;
102 }
103 pos += data_len;
104 } else if (type == CHUNK_DEFLATE) {
105 // deflate chunks have an additional 60 bytes in their chunk header.
106 char* deflate_header = patch->data + pos;
107 pos += 60;
108 if (pos > patch->size) {
109 printf("failed to read chunk %d deflate header data\n", i);
110 return -1;
111 }
112
113 size_t src_start = Read8(deflate_header);
114 size_t src_len = Read8(deflate_header+8);
115 size_t patch_offset = Read8(deflate_header+16);
116 size_t expanded_len = Read8(deflate_header+24);
117 size_t target_len = Read8(deflate_header+32);
118 int level = Read4(deflate_header+40);
119 int method = Read4(deflate_header+44);
120 int windowBits = Read4(deflate_header+48);
121 int memLevel = Read4(deflate_header+52);
122 int strategy = Read4(deflate_header+56);
123
124 // Decompress the source data; the chunk header tells us exactly
125 // how big we expect it to be when decompressed.
126
127 // Note: expanded_len will include the bonus data size if
128 // the patch was constructed with bonus data. The
129 // deflation will come up 'bonus_size' bytes short; these
130 // must be appended from the bonus_data value.
131 size_t bonus_size = (i == 1 && bonus_data != NULL) ? bonus_data->size : 0;
132
133 unsigned char* expanded_source = malloc(expanded_len);
134 if (expanded_source == NULL) {
135 printf("failed to allocate %d bytes for expanded_source\n",
136 expanded_len);
137 return -1;
138 }
139
140 z_stream strm;
141 strm.zalloc = Z_NULL;
142 strm.zfree = Z_NULL;
143 strm.opaque = Z_NULL;
144 strm.avail_in = src_len;
145 strm.next_in = (unsigned char*)(old_data + src_start);
146 strm.avail_out = expanded_len;
147 strm.next_out = expanded_source;
148
149 int ret;
150 ret = inflateInit2(&strm, -15);
151 if (ret != Z_OK) {
152 printf("failed to init source inflation: %d\n", ret);
153 return -1;
154 }
155
156 // Because we've provided enough room to accommodate the output
157 // data, we expect one call to inflate() to suffice.
158 ret = inflate(&strm, Z_SYNC_FLUSH);
159 if (ret != Z_STREAM_END) {
160 printf("source inflation returned %d\n", ret);
161 return -1;
162 }
163 // We should have filled the output buffer exactly, except
164 // for the bonus_size.
165 if (strm.avail_out != bonus_size) {
166 printf("source inflation short by %d bytes\n", strm.avail_out-bonus_size);
167 return -1;
168 }
169 inflateEnd(&strm);
170
171 if (bonus_size) {
172 memcpy(expanded_source + (expanded_len - bonus_size),
173 bonus_data->data, bonus_size);
174 }
175
176 // Next, apply the bsdiff patch (in memory) to the uncompressed
177 // data.
178 unsigned char* uncompressed_target_data;
179 ssize_t uncompressed_target_size;
180 if (ApplyBSDiffPatchMem(expanded_source, expanded_len,
181 patch, patch_offset,
182 &uncompressed_target_data,
183 &uncompressed_target_size) != 0) {
184 return -1;
185 }
186
187 // Now compress the target data and append it to the output.
188
189 // we're done with the expanded_source data buffer, so we'll
190 // reuse that memory to receive the output of deflate.
191 unsigned char* temp_data = expanded_source;
192 ssize_t temp_size = expanded_len;
193 if (temp_size < 32768) {
194 // ... unless the buffer is too small, in which case we'll
195 // allocate a fresh one.
196 free(temp_data);
197 temp_data = malloc(32768);
198 temp_size = 32768;
199 }
200
201 // now the deflate stream
202 strm.zalloc = Z_NULL;
203 strm.zfree = Z_NULL;
204 strm.opaque = Z_NULL;
205 strm.avail_in = uncompressed_target_size;
206 strm.next_in = uncompressed_target_data;
207 ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
208 do {
209 strm.avail_out = temp_size;
210 strm.next_out = temp_data;
211 ret = deflate(&strm, Z_FINISH);
212 ssize_t have = temp_size - strm.avail_out;
213
214 if (sink(temp_data, have, token) != have) {
215 printf("failed to write %ld compressed bytes to output\n",
216 (long)have);
217 return -1;
218 }
219 SHA_update(ctx, temp_data, have);
220 } while (ret != Z_STREAM_END);
221 deflateEnd(&strm);
222
223 free(temp_data);
224 free(uncompressed_target_data);
225 } else {
226 printf("patch chunk %d is unknown type %d\n", i, type);
227 return -1;
228 }
229 }
230
231 return 0;
232 }
233