android_app_backup_FullBackup.cpp revision 987f79f60bb1f0a4bcd3ef22e57301c743f0b94f 
1/*
2 * Copyright (C) 2011 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 "FullBackup_native"
18#include <utils/Log.h>
19#include <utils/String8.h>
20
21#include "JNIHelp.h"
22#include <android_runtime/AndroidRuntime.h>
23
24#include <androidfw/BackupHelpers.h>
25
26#include "core_jni_helpers.h"
27
28#include <string.h>
29
30namespace android
31{
32
33// android.app.backup.BackupDataOutput
34static struct {
35    // This is actually a native pointer to the underlying BackupDataWriter instance
36    jfieldID mBackupWriter;
37} sBackupDataOutput;
38
39/*
40 * Write files to the given output.  This implementation does *not* create
41 * a standalone archive suitable for restore on its own.  In particular, the identification of
42 * the application's name etc is not in-band here; it's assumed that the calling code has
43 * taken care of supplying that information previously in the output stream.
44 *
45 * The file format is 'tar's, with special semantics applied by use of a "fake" directory
46 * hierarchy within the tar stream:
47 *
48 * apps/packagename/a/Filename.apk - this is an actual application binary, which will be
49 *   installed on the target device at restore time.  These need to appear first in the tar
50 *   stream.
51 * apps/packagename/obb/[relpath] - OBB containers belonging the app
52 * apps/packagename/r/[relpath] - these are files at the root of the app's data tree
53 * apps/packagename/f/[relpath] - this is a file within the app's getFilesDir() tree, stored
54 *   at [relpath] relative to the top of that tree.
55 * apps/packagename/db/[relpath] - as with "files" but for the getDatabasePath() tree
56 * apps/packagename/sp/[relpath] - as with "files" but for the getSharedPrefsFile() tree
57 * apps/packagename/c/[relpath] - as with "files" but for the getCacheDir() tree
58 *
59 * and for the shared storage hierarchy:
60 *
61 * shared/[relpaths] - files belonging in the device's shared storage location.  This will
62 *    *not* include .obb files; those are saved with their owning apps.
63 *
64 * This method writes one file data block.  'domain' is the name of the appropriate pseudo-
65 * directory to be applied for this file; 'linkdomain' is the pseudo-dir for a relative
66 * symlink's antecedent.
67 *
68 * packagename: the package name to use as the top level directory tag
69 * domain:      which semantic name the file is to be stored under (a, r, f, db, etc)
70 * linkdomain:  where a symlink points for purposes of rewriting; current unused
71 * rootpath:    prefix to be snipped from full path when encoding in tar
72 * path:        absolute path to the file to be saved
73 * dataOutput:  the BackupDataOutput object that we're saving into
74 */
75static jint backupToTar(JNIEnv* env, jobject clazz, jstring packageNameObj,
76        jstring domainObj, jstring linkdomain,
77        jstring rootpathObj, jstring pathObj, jobject dataOutputObj) {
78    // Extract the various strings, allowing for null object pointers
79    const char* packagenamechars = (packageNameObj) ? env->GetStringUTFChars(packageNameObj, NULL) : NULL;
80    const char* rootchars = (rootpathObj) ? env->GetStringUTFChars(rootpathObj, NULL) : NULL;
81    const char* pathchars = (pathObj) ? env->GetStringUTFChars(pathObj, NULL) : NULL;
82    const char* domainchars = (domainObj) ? env->GetStringUTFChars(domainObj, NULL) : NULL;
83
84    String8 packageName(packagenamechars ? packagenamechars : "");
85    String8 rootpath(rootchars ? rootchars : "");
86    String8 path(pathchars ? pathchars : "");
87    String8 domain(domainchars ? domainchars : "");
88
89    if (domainchars) env->ReleaseStringUTFChars(domainObj, domainchars);
90    if (pathchars) env->ReleaseStringUTFChars(pathObj, pathchars);
91    if (rootchars) env->ReleaseStringUTFChars(rootpathObj, rootchars);
92    if (packagenamechars) env->ReleaseStringUTFChars(packageNameObj, packagenamechars);
93
94    // Extract the data output fd
95    BackupDataWriter* writer = (BackupDataWriter*) env->GetLongField(dataOutputObj,
96            sBackupDataOutput.mBackupWriter);
97
98    // Validate
99    if (!writer) {
100        ALOGE("No output stream provided [%s]", path.string());
101        return (jint) -1;
102    }
103
104    if (path.length() < rootpath.length()) {
105        ALOGE("file path [%s] shorter than root path [%s]",
106                path.string(), rootpath.string());
107        return (jint) -1;
108    }
109
110    return (jint) write_tarfile(packageName, domain, rootpath, path, writer);
111}
112
113static const JNINativeMethod g_methods[] = {
114    { "backupToTar",
115            "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Landroid/app/backup/BackupDataOutput;)I",
116            (void*)backupToTar },
117};
118
119int register_android_app_backup_FullBackup(JNIEnv* env)
120{
121    jclass clazz = FindClassOrDie(env, "android/app/backup/BackupDataOutput");
122
123    sBackupDataOutput.mBackupWriter = GetFieldIDOrDie(env, clazz, "mBackupWriter", "J");
124
125    return RegisterMethodsOrDie(env, "android/app/backup/FullBackup", g_methods, NELEM(g_methods));
126}
127
128}
129