android_backup_BackupHelperDispatcher.cpp revision 4528186e0d65fc68ef0dd1941aa2ac8aefcd55a3 
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 "BackupHelperDispatcher_native"
18#include <utils/Log.h>
19
20#include "JNIHelp.h"
21#include <android_runtime/AndroidRuntime.h>
22
23#include <sys/types.h>
24#include <sys/uio.h>
25#include <unistd.h>
26
27
28#define VERSION_1_HEADER 0x01706c48  // 'Hlp'1 little endian
29
30namespace android
31{
32
33struct chunk_header_v1 {
34    int headerSize;
35    int version;
36    int dataSize; // corresponds to Header.chunkSize
37    int nameLength; // not including the NULL terminator, which is not written to the file
38};
39
40// java.io.FileDescriptor
41static jfieldID s_descriptorField = 0;
42static jfieldID s_chunkSizeField = 0;
43static jfieldID s_keyPrefixField = 0;
44
45static int
46readHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj)
47{
48    chunk_header_v1 flattenedHeader;
49    int fd;
50    ssize_t amt;
51    String8 keyPrefix;
52    char* buf;
53
54    fd = env->GetIntField(fdObj, s_descriptorField);
55
56    amt = read(fd, &flattenedHeader.headerSize, sizeof(flattenedHeader.headerSize));
57    if (amt != sizeof(flattenedHeader.headerSize)) {
58        return -1;
59    }
60
61    int remainingHeader = flattenedHeader.headerSize - sizeof(flattenedHeader.headerSize);
62
63    if (flattenedHeader.headerSize < (int)sizeof(chunk_header_v1)) {
64        LOGW("Skipping unknown header: %d bytes", flattenedHeader.headerSize);
65        if (remainingHeader > 0) {
66            lseek(fd, remainingHeader, SEEK_CUR);
67            // >0 means skip this chunk
68            return 1;
69        }
70    }
71
72    amt = read(fd, &flattenedHeader.version,
73            sizeof(chunk_header_v1)-sizeof(flattenedHeader.headerSize));
74    if (amt <= 0) {
75        LOGW("Failed reading chunk header");
76        return -1;
77    }
78    remainingHeader -= sizeof(chunk_header_v1)-sizeof(flattenedHeader.headerSize);
79
80    if (flattenedHeader.version != VERSION_1_HEADER) {
81        LOGW("Skipping unknown header version: 0x%08x, %d bytes", flattenedHeader.version,
82                flattenedHeader.headerSize);
83        if (remainingHeader > 0) {
84            lseek(fd, remainingHeader, SEEK_CUR);
85            // >0 means skip this chunk
86            return 1;
87        }
88    }
89
90#if 0
91    LOGD("chunk header:");
92    LOGD("  headerSize=%d", flattenedHeader.headerSize);
93    LOGD("  version=0x%08x", flattenedHeader.version);
94    LOGD("  dataSize=%d", flattenedHeader.dataSize);
95    LOGD("  nameLength=%d", flattenedHeader.nameLength);
96#endif
97
98    if (flattenedHeader.dataSize < 0 || flattenedHeader.nameLength < 0 ||
99            remainingHeader < flattenedHeader.nameLength) {
100        LOGW("Malformed V1 header remainingHeader=%d dataSize=%d nameLength=%d", remainingHeader,
101                flattenedHeader.dataSize, flattenedHeader.nameLength);
102        return -1;
103    }
104
105    buf = keyPrefix.lockBuffer(flattenedHeader.nameLength);
106    if (buf == NULL) {
107        LOGW("unable to allocate %d bytes", flattenedHeader.nameLength);
108        return -1;
109    }
110
111    amt = read(fd, buf, flattenedHeader.nameLength);
112    buf[flattenedHeader.nameLength] = 0;
113
114    keyPrefix.unlockBuffer(flattenedHeader.nameLength);
115
116    remainingHeader -= flattenedHeader.nameLength;
117
118    if (remainingHeader > 0) {
119        lseek(fd, remainingHeader, SEEK_CUR);
120    }
121
122    env->SetIntField(headerObj, s_chunkSizeField, flattenedHeader.dataSize);
123    env->SetObjectField(headerObj, s_keyPrefixField, env->NewStringUTF(keyPrefix.string()));
124
125    return 0;
126}
127
128static int
129skipChunk_native(JNIEnv* env, jobject clazz, jobject fdObj, jint bytesToSkip)
130{
131    int fd;
132
133    fd = env->GetIntField(fdObj, s_descriptorField);
134
135    lseek(fd, bytesToSkip, SEEK_CUR);
136
137    return 0;
138}
139
140static int
141padding_len(int len)
142{
143    len = len % 4;
144    return len == 0 ? len : 4 - len;
145}
146
147static int
148allocateHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj)
149{
150    int pos;
151    jstring nameObj;
152    int nameLength;
153    int namePadding;
154    int headerSize;
155    int fd;
156
157    fd = env->GetIntField(fdObj, s_descriptorField);
158
159    nameObj = (jstring)env->GetObjectField(headerObj, s_keyPrefixField);
160
161    nameLength = env->GetStringUTFLength(nameObj);
162    namePadding = padding_len(nameLength);
163
164    headerSize = sizeof(chunk_header_v1) + nameLength + namePadding;
165
166    pos = lseek(fd, 0, SEEK_CUR);
167
168    lseek(fd, headerSize, SEEK_CUR);
169
170    return pos;
171}
172
173static int
174writeHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj, jint pos)
175{
176    int err;
177    chunk_header_v1 header;
178    int fd;
179    int namePadding;
180    int prevPos;
181    jstring nameObj;
182    const char* buf;
183
184    fd = env->GetIntField(fdObj, s_descriptorField);
185    prevPos = lseek(fd, 0, SEEK_CUR);
186
187    nameObj = (jstring)env->GetObjectField(headerObj, s_keyPrefixField);
188    header.nameLength = env->GetStringUTFLength(nameObj);
189    namePadding = padding_len(header.nameLength);
190
191    header.headerSize = sizeof(chunk_header_v1) + header.nameLength + namePadding;
192    header.version = VERSION_1_HEADER;
193    header.dataSize = prevPos - (pos + header.headerSize);
194
195    lseek(fd, pos, SEEK_SET);
196    err = write(fd, &header, sizeof(chunk_header_v1));
197    if (err != sizeof(chunk_header_v1)) {
198        return errno;
199    }
200
201    buf = env->GetStringUTFChars(nameObj, NULL);
202    err = write(fd, buf, header.nameLength);
203    env->ReleaseStringUTFChars(nameObj, buf);
204    if (err != header.nameLength) {
205        return errno;
206    }
207
208    if (namePadding != 0) {
209        int zero = 0;
210        err = write(fd, &zero, namePadding);
211        if (err != namePadding) {
212            return errno;
213        }
214    }
215
216    lseek(fd, prevPos, SEEK_SET);
217    return 0;
218}
219
220static const JNINativeMethod g_methods[] = {
221    { "readHeader_native",
222       "(Landroid/app/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;)I",
223       (void*)readHeader_native },
224    { "skipChunk_native",
225        "(Ljava/io/FileDescriptor;I)I",
226        (void*)skipChunk_native },
227    { "allocateHeader_native",
228        "(Landroid/app/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;)I",
229        (void*)allocateHeader_native },
230    { "writeHeader_native",
231       "(Landroid/app/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;I)I",
232       (void*)writeHeader_native },
233};
234
235int register_android_backup_BackupHelperDispatcher(JNIEnv* env)
236{
237    jclass clazz;
238
239    clazz = env->FindClass("java/io/FileDescriptor");
240    LOG_FATAL_IF(clazz == NULL, "Unable to find class java.io.FileDescriptor");
241    s_descriptorField = env->GetFieldID(clazz, "descriptor", "I");
242    LOG_FATAL_IF(s_descriptorField == NULL,
243            "Unable to find descriptor field in java.io.FileDescriptor");
244
245    clazz = env->FindClass("android/app/backup/BackupHelperDispatcher$Header");
246    LOG_FATAL_IF(clazz == NULL,
247            "Unable to find class android.app.backup.BackupHelperDispatcher.Header");
248    s_chunkSizeField = env->GetFieldID(clazz, "chunkSize", "I");
249    LOG_FATAL_IF(s_chunkSizeField == NULL,
250            "Unable to find chunkSize field in android.app.backup.BackupHelperDispatcher.Header");
251    s_keyPrefixField = env->GetFieldID(clazz, "keyPrefix", "Ljava/lang/String;");
252    LOG_FATAL_IF(s_keyPrefixField == NULL,
253            "Unable to find keyPrefix field in android.app.backup.BackupHelperDispatcher.Header");
254
255    return AndroidRuntime::registerNativeMethods(env, "android/app/backup/BackupHelperDispatcher",
256            g_methods, NELEM(g_methods));
257}
258
259}
260