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 #define LOG_TAG "backup_data"
18
19 #include <androidfw/BackupHelpers.h>
20 #include <utils/ByteOrder.h>
21
22 #include <stdio.h>
23 #include <string.h>
24 #include <unistd.h>
25
26 #include <cutils/log.h>
27
28 namespace android {
29
30 static const bool DEBUG = false;
31
32 /*
33 * File Format (v1):
34 *
35 * All ints are stored little-endian.
36 *
37 * - An app_header_v1 struct.
38 * - The name of the package, utf-8, null terminated, padded to 4-byte boundary.
39 * - A sequence of zero or more key/value paires (entities), each with
40 * - A entity_header_v1 struct
41 * - The key, utf-8, null terminated, padded to 4-byte boundary.
42 * - The value, padded to 4 byte boundary
43 */
44
45 const static int ROUND_UP[4] = { 0, 3, 2, 1 };
46
47 static inline size_t
round_up(size_t n)48 round_up(size_t n)
49 {
50 return n + ROUND_UP[n % 4];
51 }
52
53 static inline size_t
padding_extra(size_t n)54 padding_extra(size_t n)
55 {
56 return ROUND_UP[n % 4];
57 }
58
BackupDataWriter(int fd)59 BackupDataWriter::BackupDataWriter(int fd)
60 :m_fd(fd),
61 m_status(NO_ERROR),
62 m_entityCount(0)
63 {
64 m_pos = (ssize_t) lseek(fd, 0, SEEK_CUR);
65 if (DEBUG) ALOGI("BackupDataWriter(%d) @ %ld", fd, (long)m_pos);
66 }
67
~BackupDataWriter()68 BackupDataWriter::~BackupDataWriter()
69 {
70 }
71
72 // Pad out anything they've previously written to the next 4 byte boundary.
73 status_t
write_padding_for(int n)74 BackupDataWriter::write_padding_for(int n)
75 {
76 ssize_t amt;
77 ssize_t paddingSize;
78
79 paddingSize = padding_extra(n);
80 if (paddingSize > 0) {
81 uint32_t padding = 0xbcbcbcbc;
82 if (DEBUG) ALOGI("writing %zd padding bytes for %d", paddingSize, n);
83 amt = write(m_fd, &padding, paddingSize);
84 if (amt != paddingSize) {
85 m_status = errno;
86 return m_status;
87 }
88 m_pos += amt;
89 }
90 return NO_ERROR;
91 }
92
93 status_t
WriteEntityHeader(const String8 & key,size_t dataSize)94 BackupDataWriter::WriteEntityHeader(const String8& key, size_t dataSize)
95 {
96 if (m_status != NO_ERROR) {
97 return m_status;
98 }
99
100 ssize_t amt;
101
102 amt = write_padding_for(m_pos);
103 if (amt != 0) {
104 return amt;
105 }
106
107 String8 k;
108 if (m_keyPrefix.length() > 0) {
109 k = m_keyPrefix;
110 k += ":";
111 k += key;
112 } else {
113 k = key;
114 }
115 if (DEBUG) {
116 ALOGD("Writing header: prefix='%s' key='%s' dataSize=%zu", m_keyPrefix.string(),
117 key.string(), dataSize);
118 }
119
120 entity_header_v1 header;
121 ssize_t keyLen;
122
123 keyLen = k.length();
124
125 header.type = tolel(BACKUP_HEADER_ENTITY_V1);
126 header.keyLen = tolel(keyLen);
127 header.dataSize = tolel(dataSize);
128
129 if (DEBUG) ALOGI("writing entity header, %zu bytes", sizeof(entity_header_v1));
130 amt = write(m_fd, &header, sizeof(entity_header_v1));
131 if (amt != sizeof(entity_header_v1)) {
132 m_status = errno;
133 return m_status;
134 }
135 m_pos += amt;
136
137 if (DEBUG) ALOGI("writing entity header key, %zd bytes", keyLen+1);
138 amt = write(m_fd, k.string(), keyLen+1);
139 if (amt != keyLen+1) {
140 m_status = errno;
141 return m_status;
142 }
143 m_pos += amt;
144
145 amt = write_padding_for(keyLen+1);
146
147 m_entityCount++;
148
149 return amt;
150 }
151
152 status_t
WriteEntityData(const void * data,size_t size)153 BackupDataWriter::WriteEntityData(const void* data, size_t size)
154 {
155 if (DEBUG) ALOGD("Writing data: size=%lu", (unsigned long) size);
156
157 if (m_status != NO_ERROR) {
158 if (DEBUG) {
159 ALOGD("Not writing data - stream in error state %d (%s)", m_status, strerror(m_status));
160 }
161 return m_status;
162 }
163
164 // We don't write padding here, because they're allowed to call this several
165 // times with smaller buffers. We write it at the end of WriteEntityHeader
166 // instead.
167 ssize_t amt = write(m_fd, data, size);
168 if (amt != (ssize_t)size) {
169 m_status = errno;
170 if (DEBUG) ALOGD("write returned error %d (%s)", m_status, strerror(m_status));
171 return m_status;
172 }
173 m_pos += amt;
174 return NO_ERROR;
175 }
176
177 void
SetKeyPrefix(const String8 & keyPrefix)178 BackupDataWriter::SetKeyPrefix(const String8& keyPrefix)
179 {
180 m_keyPrefix = keyPrefix;
181 }
182
183
BackupDataReader(int fd)184 BackupDataReader::BackupDataReader(int fd)
185 :m_fd(fd),
186 m_done(false),
187 m_status(NO_ERROR),
188 m_entityCount(0)
189 {
190 memset(&m_header, 0, sizeof(m_header));
191 m_pos = (ssize_t) lseek(fd, 0, SEEK_CUR);
192 if (DEBUG) ALOGI("BackupDataReader(%d) @ %ld", fd, (long)m_pos);
193 }
194
~BackupDataReader()195 BackupDataReader::~BackupDataReader()
196 {
197 }
198
199 status_t
Status()200 BackupDataReader::Status()
201 {
202 return m_status;
203 }
204
205 #define CHECK_SIZE(actual, expected) \
206 do { \
207 if ((actual) != (expected)) { \
208 if ((actual) == 0) { \
209 m_status = EIO; \
210 m_done = true; \
211 } else { \
212 m_status = errno; \
213 ALOGD("CHECK_SIZE(a=%ld e=%ld) failed at line %d m_status='%s'", \
214 long(actual), long(expected), __LINE__, strerror(m_status)); \
215 } \
216 return m_status; \
217 } \
218 } while(0)
219 #define SKIP_PADDING() \
220 do { \
221 status_t err = skip_padding(); \
222 if (err != NO_ERROR) { \
223 ALOGD("SKIP_PADDING FAILED at line %d", __LINE__); \
224 m_status = err; \
225 return err; \
226 } \
227 } while(0)
228
229 status_t
ReadNextHeader(bool * done,int * type)230 BackupDataReader::ReadNextHeader(bool* done, int* type)
231 {
232 *done = m_done;
233 if (m_status != NO_ERROR) {
234 return m_status;
235 }
236
237 int amt;
238
239 amt = skip_padding();
240 if (amt == EIO) {
241 *done = m_done = true;
242 return NO_ERROR;
243 }
244 else if (amt != NO_ERROR) {
245 return amt;
246 }
247 amt = read(m_fd, &m_header, sizeof(m_header));
248 *done = m_done = (amt == 0);
249 if (*done) {
250 return NO_ERROR;
251 }
252 CHECK_SIZE(amt, sizeof(m_header));
253 m_pos += sizeof(m_header);
254 if (type) {
255 *type = m_header.type;
256 }
257
258 // validate and fix up the fields.
259 m_header.type = fromlel(m_header.type);
260 switch (m_header.type)
261 {
262 case BACKUP_HEADER_ENTITY_V1:
263 {
264 m_header.entity.keyLen = fromlel(m_header.entity.keyLen);
265 if (m_header.entity.keyLen <= 0) {
266 ALOGD("Entity header at %d has keyLen<=0: 0x%08x\n", (int)m_pos,
267 (int)m_header.entity.keyLen);
268 m_status = EINVAL;
269 }
270 m_header.entity.dataSize = fromlel(m_header.entity.dataSize);
271 m_entityCount++;
272
273 // read the rest of the header (filename)
274 size_t size = m_header.entity.keyLen;
275 char* buf = m_key.lockBuffer(size);
276 if (buf == NULL) {
277 m_status = ENOMEM;
278 return m_status;
279 }
280 int amt = read(m_fd, buf, size+1);
281 CHECK_SIZE(amt, (int)size+1);
282 m_key.unlockBuffer(size);
283 m_pos += size+1;
284 SKIP_PADDING();
285 m_dataEndPos = m_pos + m_header.entity.dataSize;
286
287 break;
288 }
289 default:
290 ALOGD("Chunk header at %d has invalid type: 0x%08x",
291 (int)(m_pos - sizeof(m_header)), (int)m_header.type);
292 m_status = EINVAL;
293 }
294
295 return m_status;
296 }
297
298 bool
HasEntities()299 BackupDataReader::HasEntities()
300 {
301 return m_status == NO_ERROR && m_header.type == BACKUP_HEADER_ENTITY_V1;
302 }
303
304 status_t
ReadEntityHeader(String8 * key,size_t * dataSize)305 BackupDataReader::ReadEntityHeader(String8* key, size_t* dataSize)
306 {
307 if (m_status != NO_ERROR) {
308 return m_status;
309 }
310 if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
311 return EINVAL;
312 }
313 *key = m_key;
314 *dataSize = m_header.entity.dataSize;
315 return NO_ERROR;
316 }
317
318 status_t
SkipEntityData()319 BackupDataReader::SkipEntityData()
320 {
321 if (m_status != NO_ERROR) {
322 return m_status;
323 }
324 if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
325 return EINVAL;
326 }
327 if (m_header.entity.dataSize > 0) {
328 int pos = lseek(m_fd, m_dataEndPos, SEEK_SET);
329 if (pos == -1) {
330 return errno;
331 }
332 m_pos = pos;
333 }
334 SKIP_PADDING();
335 return NO_ERROR;
336 }
337
338 ssize_t
ReadEntityData(void * data,size_t size)339 BackupDataReader::ReadEntityData(void* data, size_t size)
340 {
341 if (m_status != NO_ERROR) {
342 return -1;
343 }
344 int remaining = m_dataEndPos - m_pos;
345 //ALOGD("ReadEntityData size=%d m_pos=0x%x m_dataEndPos=0x%x remaining=%d\n",
346 // size, m_pos, m_dataEndPos, remaining);
347 if (remaining <= 0) {
348 return 0;
349 }
350 if (((int)size) > remaining) {
351 size = remaining;
352 }
353 //ALOGD(" reading %d bytes", size);
354 int amt = read(m_fd, data, size);
355 if (amt < 0) {
356 m_status = errno;
357 return -1;
358 }
359 if (amt == 0) {
360 m_status = EIO;
361 m_done = true;
362 }
363 m_pos += amt;
364 return amt;
365 }
366
367 status_t
skip_padding()368 BackupDataReader::skip_padding()
369 {
370 ssize_t amt;
371 ssize_t paddingSize;
372
373 paddingSize = padding_extra(m_pos);
374 if (paddingSize > 0) {
375 uint32_t padding;
376 amt = read(m_fd, &padding, paddingSize);
377 CHECK_SIZE(amt, paddingSize);
378 m_pos += amt;
379 }
380 return NO_ERROR;
381 }
382
383
384 } // namespace android
385