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
40static jfieldID s_chunkSizeField = 0;
41static jfieldID s_keyPrefixField = 0;
42
43static int
44readHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj)
45{
46    chunk_header_v1 flattenedHeader;
47    ssize_t amt;
48    String8 keyPrefix;
49    char* buf;
50
51    int fd = jniGetFDFromFileDescriptor(env, fdObj);
52
53    amt = read(fd, &flattenedHeader.headerSize, sizeof(flattenedHeader.headerSize));
54    if (amt != sizeof(flattenedHeader.headerSize)) {
55        return -1;
56    }
57
58    int remainingHeader = flattenedHeader.headerSize - sizeof(flattenedHeader.headerSize);
59
60    if (flattenedHeader.headerSize < (int)sizeof(chunk_header_v1)) {
61        ALOGW("Skipping unknown header: %d bytes", flattenedHeader.headerSize);
62        if (remainingHeader > 0) {
63            lseek(fd, remainingHeader, SEEK_CUR);
64            // >0 means skip this chunk
65            return 1;
66        }
67    }
68
69    amt = read(fd, &flattenedHeader.version,
70            sizeof(chunk_header_v1)-sizeof(flattenedHeader.headerSize));
71    if (amt <= 0) {
72        ALOGW("Failed reading chunk header");
73        return -1;
74    }
75    remainingHeader -= sizeof(chunk_header_v1)-sizeof(flattenedHeader.headerSize);
76
77    if (flattenedHeader.version != VERSION_1_HEADER) {
78        ALOGW("Skipping unknown header version: 0x%08x, %d bytes", flattenedHeader.version,
79                flattenedHeader.headerSize);
80        if (remainingHeader > 0) {
81            lseek(fd, remainingHeader, SEEK_CUR);
82            // >0 means skip this chunk
83            return 1;
84        }
85    }
86
87#if 0
88    ALOGD("chunk header:");
89    ALOGD("  headerSize=%d", flattenedHeader.headerSize);
90    ALOGD("  version=0x%08x", flattenedHeader.version);
91    ALOGD("  dataSize=%d", flattenedHeader.dataSize);
92    ALOGD("  nameLength=%d", flattenedHeader.nameLength);
93#endif
94
95    if (flattenedHeader.dataSize < 0 || flattenedHeader.nameLength < 0 ||
96            remainingHeader < flattenedHeader.nameLength) {
97        ALOGW("Malformed V1 header remainingHeader=%d dataSize=%d nameLength=%d", remainingHeader,
98                flattenedHeader.dataSize, flattenedHeader.nameLength);
99        return -1;
100    }
101
102    buf = keyPrefix.lockBuffer(flattenedHeader.nameLength);
103    if (buf == NULL) {
104        ALOGW("unable to allocate %d bytes", flattenedHeader.nameLength);
105        return -1;
106    }
107
108    amt = read(fd, buf, flattenedHeader.nameLength);
109    buf[flattenedHeader.nameLength] = 0;
110
111    keyPrefix.unlockBuffer(flattenedHeader.nameLength);
112
113    remainingHeader -= flattenedHeader.nameLength;
114
115    if (remainingHeader > 0) {
116        lseek(fd, remainingHeader, SEEK_CUR);
117    }
118
119    env->SetIntField(headerObj, s_chunkSizeField, flattenedHeader.dataSize);
120    env->SetObjectField(headerObj, s_keyPrefixField, env->NewStringUTF(keyPrefix.string()));
121
122    return 0;
123}
124
125static int
126skipChunk_native(JNIEnv* env, jobject clazz, jobject fdObj, jint bytesToSkip)
127{
128    int fd = jniGetFDFromFileDescriptor(env, fdObj);
129
130    lseek(fd, bytesToSkip, SEEK_CUR);
131
132    return 0;
133}
134
135static int
136padding_len(int len)
137{
138    len = len % 4;
139    return len == 0 ? len : 4 - len;
140}
141
142static int
143allocateHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj)
144{
145    int pos;
146    jstring nameObj;
147    int nameLength;
148    int namePadding;
149    int headerSize;
150
151    int fd = jniGetFDFromFileDescriptor(env, fdObj);
152
153    nameObj = (jstring)env->GetObjectField(headerObj, s_keyPrefixField);
154
155    nameLength = env->GetStringUTFLength(nameObj);
156    namePadding = padding_len(nameLength);
157
158    headerSize = sizeof(chunk_header_v1) + nameLength + namePadding;
159
160    pos = lseek(fd, 0, SEEK_CUR);
161
162    lseek(fd, headerSize, SEEK_CUR);
163
164    return pos;
165}
166
167static int
168writeHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj, jint pos)
169{
170    int err;
171    chunk_header_v1 header;
172    int namePadding;
173    int prevPos;
174    jstring nameObj;
175    const char* buf;
176
177    int fd = jniGetFDFromFileDescriptor(env, fdObj);
178    prevPos = lseek(fd, 0, SEEK_CUR);
179
180    nameObj = (jstring)env->GetObjectField(headerObj, s_keyPrefixField);
181    header.nameLength = env->GetStringUTFLength(nameObj);
182    namePadding = padding_len(header.nameLength);
183
184    header.headerSize = sizeof(chunk_header_v1) + header.nameLength + namePadding;
185    header.version = VERSION_1_HEADER;
186    header.dataSize = prevPos - (pos + header.headerSize);
187
188    lseek(fd, pos, SEEK_SET);
189    err = write(fd, &header, sizeof(chunk_header_v1));
190    if (err != sizeof(chunk_header_v1)) {
191        return errno;
192    }
193
194    buf = env->GetStringUTFChars(nameObj, NULL);
195    err = write(fd, buf, header.nameLength);
196    env->ReleaseStringUTFChars(nameObj, buf);
197    if (err != header.nameLength) {
198        return errno;
199    }
200
201    if (namePadding != 0) {
202        int zero = 0;
203        err = write(fd, &zero, namePadding);
204        if (err != namePadding) {
205            return errno;
206        }
207    }
208
209    lseek(fd, prevPos, SEEK_SET);
210    return 0;
211}
212
213static const JNINativeMethod g_methods[] = {
214    { "readHeader_native",
215       "(Landroid/app/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;)I",
216       (void*)readHeader_native },
217    { "skipChunk_native",
218        "(Ljava/io/FileDescriptor;I)I",
219        (void*)skipChunk_native },
220    { "allocateHeader_native",
221        "(Landroid/app/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;)I",
222        (void*)allocateHeader_native },
223    { "writeHeader_native",
224       "(Landroid/app/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;I)I",
225       (void*)writeHeader_native },
226};
227
228int register_android_backup_BackupHelperDispatcher(JNIEnv* env)
229{
230    jclass clazz = env->FindClass("android/app/backup/BackupHelperDispatcher$Header");
231    LOG_FATAL_IF(clazz == NULL,
232            "Unable to find class android.app.backup.BackupHelperDispatcher.Header");
233    s_chunkSizeField = env->GetFieldID(clazz, "chunkSize", "I");
234    LOG_FATAL_IF(s_chunkSizeField == NULL,
235            "Unable to find chunkSize field in android.app.backup.BackupHelperDispatcher.Header");
236    s_keyPrefixField = env->GetFieldID(clazz, "keyPrefix", "Ljava/lang/String;");
237    LOG_FATAL_IF(s_keyPrefixField == NULL,
238            "Unable to find keyPrefix field in android.app.backup.BackupHelperDispatcher.Header");
239
240    return AndroidRuntime::registerNativeMethods(env, "android/app/backup/BackupHelperDispatcher",
241            g_methods, NELEM(g_methods));
242}
243
244}
245