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
27namespace android {
28
29static 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
44const static int ROUND_UP[4] = { 0, 3, 2, 1 };
45
46static inline size_t
47padding_extra(size_t n)
48{
49    return ROUND_UP[n % 4];
50}
51
52BackupDataWriter::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
61BackupDataWriter::~BackupDataWriter()
62{
63}
64
65// Pad out anything they've previously written to the next 4 byte boundary.
66status_t
67BackupDataWriter::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
86status_t
87BackupDataWriter::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
145status_t
146BackupDataWriter::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
170void
171BackupDataWriter::SetKeyPrefix(const String8& keyPrefix)
172{
173    m_keyPrefix = keyPrefix;
174}
175
176
177BackupDataReader::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
188BackupDataReader::~BackupDataReader()
189{
190}
191
192status_t
193BackupDataReader::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
222status_t
223BackupDataReader::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
291bool
292BackupDataReader::HasEntities()
293{
294    return m_status == NO_ERROR && m_header.type == BACKUP_HEADER_ENTITY_V1;
295}
296
297status_t
298BackupDataReader::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
311status_t
312BackupDataReader::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
331ssize_t
332BackupDataReader::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
364status_t
365BackupDataReader::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