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