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diff --git a/include/utils/BackupHelpers.h b/include/utils/BackupHelpers.h
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+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _UTILS_BACKUP_HELPERS_H
+#define _UTILS_BACKUP_HELPERS_H
+
+#include <utils/Errors.h>
+#include <utils/String8.h>
+
+namespace android {
+
+enum {
+    BACKUP_HEADER_APP_V1 = 0x31707041, // App1 (little endian)
+    BACKUP_HEADER_ENTITY_V1 = 0x61746144, // Data (little endian)
+    BACKUP_FOOTER_APP_V1 = 0x746f6f46, // Foot (little endian)
+};
+
+// the sizes of all of these match.
+typedef struct {
+    int type; // == BACKUP_HEADER_APP_V1
+    int packageLen; // length of the name of the package that follows, not including the null.
+    int cookie;
+} app_header_v1;
+
+typedef struct {
+    int type; // BACKUP_HEADER_ENTITY_V1
+    int keyLen; // length of the key name, not including the null terminator
+    int dataSize; // size of the data, not including the padding, -1 means delete
+} entity_header_v1;
+
+typedef struct {
+    int type; // BACKUP_FOOTER_APP_V1
+    int entityCount; // the number of entities that were written
+    int cookie;
+} app_footer_v1;
+
+
+/**
+ * Writes the data.
+ *
+ * If an error occurs, it poisons this object and all write calls will fail
+ * with the error that occurred.
+ */
+class BackupDataWriter
+{
+public:
+    BackupDataWriter(int fd);
+    // does not close fd
+    ~BackupDataWriter();
+
+    status_t WriteAppHeader(const String8& packageName, int cookie);
+
+    status_t WriteEntityHeader(const String8& key, size_t dataSize);
+    status_t WriteEntityData(const void* data, size_t size);
+
+    status_t WriteAppFooter(int cookie);
+
+private:
+    explicit BackupDataWriter();
+    status_t write_padding_for(int n);
+    
+    int m_fd;
+    status_t m_status;
+    ssize_t m_pos;
+    int m_entityCount;
+};
+
+/**
+ * Reads the data.
+ *
+ * If an error occurs, it poisons this object and all write calls will fail
+ * with the error that occurred.
+ */
+class BackupDataReader
+{
+public:
+    BackupDataReader(int fd);
+    // does not close fd
+    ~BackupDataReader();
+
+    status_t Status();
+    status_t ReadNextHeader(int* type = NULL);
+
+    status_t ReadAppHeader(String8* packageName, int* cookie);
+    bool HasEntities();
+    status_t ReadEntityHeader(String8* key, size_t* dataSize);
+    status_t SkipEntityData(); // must be called with the pointer at the begining of the data.
+    status_t ReadEntityData(void* data, size_t size);
+    status_t ReadAppFooter(int* cookie);
+
+private:
+    explicit BackupDataReader();
+    status_t skip_padding();
+    
+    int m_fd;
+    status_t m_status;
+    ssize_t m_pos;
+    int m_entityCount;
+    union {
+        int type;
+        app_header_v1 app;
+        entity_header_v1 entity;
+        app_footer_v1 footer;
+    } m_header;
+};
+
+int back_up_files(int oldSnapshotFD, BackupDataWriter* dataStream, int newSnapshotFD,
+        char const* fileBase, char const* const* files, int fileCount);
+
+
+#define TEST_BACKUP_HELPERS 1
+
+#if TEST_BACKUP_HELPERS
+int backup_helper_test_empty();
+int backup_helper_test_four();
+int backup_helper_test_files();
+int backup_helper_test_data_writer();
+int backup_helper_test_data_reader();
+#endif
+
+} // namespace android
+
+#endif // _UTILS_BACKUP_HELPERS_H