440 lines
10 KiB
C++
440 lines
10 KiB
C++
/*
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* Copyright (C) 2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#define LOG_TAG "backup_data"
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#include <utils/BackupHelpers.h>
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#include <utils/ByteOrder.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <cutils/log.h>
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namespace android {
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/*
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* File Format (v1):
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*
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* All ints are stored little-endian.
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*
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* - An app_header_v1 struct.
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* - The name of the package, utf-8, null terminated, padded to 4-byte boundary.
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* - A sequence of zero or more key/value paires (entities), each with
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* - A entity_header_v1 struct
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* - The key, utf-8, null terminated, padded to 4-byte boundary.
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* - The value, padded to 4 byte boundary
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*/
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const static int ROUND_UP[4] = { 0, 3, 2, 1 };
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static inline size_t
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round_up(size_t n)
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{
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return n + ROUND_UP[n % 4];
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}
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static inline size_t
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padding_extra(size_t n)
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{
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return ROUND_UP[n % 4];
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}
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BackupDataWriter::BackupDataWriter(int fd)
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:m_fd(fd),
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m_status(NO_ERROR),
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m_pos(0),
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m_entityCount(0)
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{
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}
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BackupDataWriter::~BackupDataWriter()
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{
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}
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// Pad out anything they've previously written to the next 4 byte boundary.
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status_t
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BackupDataWriter::write_padding_for(int n)
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{
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ssize_t amt;
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ssize_t paddingSize;
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paddingSize = padding_extra(n);
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if (paddingSize > 0) {
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uint32_t padding = 0xbcbcbcbc;
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amt = write(m_fd, &padding, paddingSize);
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if (amt != paddingSize) {
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m_status = errno;
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return m_status;
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}
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m_pos += amt;
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}
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return NO_ERROR;
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}
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status_t
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BackupDataWriter::WriteAppHeader(const String8& packageName, int cookie)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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ssize_t amt;
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amt = write_padding_for(m_pos);
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if (amt != 0) {
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return amt;
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}
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app_header_v1 header;
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ssize_t nameLen;
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nameLen = packageName.length();
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header.type = tolel(BACKUP_HEADER_APP_V1);
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header.packageLen = tolel(nameLen);
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header.cookie = cookie;
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amt = write(m_fd, &header, sizeof(app_header_v1));
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if (amt != sizeof(app_header_v1)) {
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m_status = errno;
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return m_status;
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}
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m_pos += amt;
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amt = write(m_fd, packageName.string(), nameLen+1);
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if (amt != nameLen+1) {
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m_status = errno;
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return m_status;
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}
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m_pos += amt;
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return NO_ERROR;
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}
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status_t
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BackupDataWriter::WriteEntityHeader(const String8& key, size_t dataSize)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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ssize_t amt;
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amt = write_padding_for(m_pos);
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if (amt != 0) {
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return amt;
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}
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entity_header_v1 header;
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ssize_t keyLen;
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keyLen = key.length();
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header.type = tolel(BACKUP_HEADER_ENTITY_V1);
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header.keyLen = tolel(keyLen);
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header.dataSize = tolel(dataSize);
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amt = write(m_fd, &header, sizeof(entity_header_v1));
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if (amt != sizeof(entity_header_v1)) {
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m_status = errno;
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return m_status;
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}
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m_pos += amt;
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amt = write(m_fd, key.string(), keyLen+1);
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if (amt != keyLen+1) {
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m_status = errno;
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return m_status;
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}
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m_pos += amt;
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amt = write_padding_for(keyLen+1);
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m_entityCount++;
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return amt;
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}
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status_t
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BackupDataWriter::WriteEntityData(const void* data, size_t size)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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// We don't write padding here, because they're allowed to call this several
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// times with smaller buffers. We write it at the end of WriteEntityHeader
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// instead.
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ssize_t amt = write(m_fd, data, size);
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if (amt != (ssize_t)size) {
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m_status = errno;
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return m_status;
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}
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m_pos += amt;
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return NO_ERROR;
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}
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status_t
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BackupDataWriter::WriteAppFooter(int cookie)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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ssize_t amt;
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amt = write_padding_for(m_pos);
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if (amt != 0) {
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return amt;
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}
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app_footer_v1 footer;
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ssize_t nameLen;
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footer.type = tolel(BACKUP_FOOTER_APP_V1);
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footer.entityCount = tolel(m_entityCount);
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footer.cookie = cookie;
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amt = write(m_fd, &footer, sizeof(app_footer_v1));
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if (amt != sizeof(app_footer_v1)) {
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m_status = errno;
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return m_status;
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}
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m_pos += amt;
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return NO_ERROR;
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}
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BackupDataReader::BackupDataReader(int fd)
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:m_fd(fd),
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m_status(NO_ERROR),
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m_pos(0),
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m_entityCount(0)
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{
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memset(&m_header, 0, sizeof(m_header));
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}
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BackupDataReader::~BackupDataReader()
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{
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}
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status_t
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BackupDataReader::Status()
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{
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return m_status;
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}
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#define CHECK_SIZE(actual, expected) \
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do { \
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if ((actual) != (expected)) { \
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if ((actual) == 0) { \
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m_status = EIO; \
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} else { \
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m_status = errno; \
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} \
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return m_status; \
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} \
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} while(0)
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#define SKIP_PADDING() \
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do { \
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status_t err = skip_padding(); \
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if (err != NO_ERROR) { \
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m_status = err; \
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return err; \
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} \
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} while(0)
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status_t
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BackupDataReader::ReadNextHeader(int* type)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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int amt;
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SKIP_PADDING();
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amt = read(m_fd, &m_header, sizeof(m_header));
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CHECK_SIZE(amt, sizeof(m_header));
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// validate and fix up the fields.
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m_header.type = fromlel(m_header.type);
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switch (m_header.type)
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{
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case BACKUP_HEADER_APP_V1:
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m_header.app.packageLen = fromlel(m_header.app.packageLen);
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if (m_header.app.packageLen < 0) {
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LOGD("App header at %d has packageLen<0: 0x%08x\n", (int)m_pos,
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(int)m_header.app.packageLen);
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m_status = EINVAL;
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}
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m_header.app.cookie = m_header.app.cookie;
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break;
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case BACKUP_HEADER_ENTITY_V1:
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m_header.entity.keyLen = fromlel(m_header.entity.keyLen);
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if (m_header.entity.keyLen <= 0) {
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LOGD("Entity header at %d has keyLen<=0: 0x%08x\n", (int)m_pos,
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(int)m_header.entity.keyLen);
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m_status = EINVAL;
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}
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m_header.entity.dataSize = fromlel(m_header.entity.dataSize);
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m_entityCount++;
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break;
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case BACKUP_FOOTER_APP_V1:
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m_header.footer.entityCount = fromlel(m_header.footer.entityCount);
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if (m_header.footer.entityCount < 0) {
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LOGD("Entity header at %d has entityCount<0: 0x%08x\n", (int)m_pos,
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(int)m_header.footer.entityCount);
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m_status = EINVAL;
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}
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m_header.footer.cookie = m_header.footer.cookie;
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break;
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default:
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LOGD("Chunk header at %d has invalid type: 0x%08x", (int)m_pos, (int)m_header.type);
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m_status = EINVAL;
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}
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m_pos += sizeof(m_header);
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if (type) {
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*type = m_header.type;
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}
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return m_status;
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}
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status_t
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BackupDataReader::ReadAppHeader(String8* packageName, int* cookie)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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if (m_header.type != BACKUP_HEADER_APP_V1) {
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return EINVAL;
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}
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size_t size = m_header.app.packageLen;
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char* buf = packageName->lockBuffer(size);
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if (buf == NULL) {
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packageName->unlockBuffer();
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m_status = ENOMEM;
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return m_status;
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}
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int amt = read(m_fd, buf, size+1);
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CHECK_SIZE(amt, (int)size+1);
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packageName->unlockBuffer(size);
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m_pos += size+1;
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*cookie = m_header.app.cookie;
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return NO_ERROR;
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}
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bool
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BackupDataReader::HasEntities()
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{
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return m_status == NO_ERROR && m_header.type == BACKUP_HEADER_ENTITY_V1;
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}
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status_t
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BackupDataReader::ReadEntityHeader(String8* key, size_t* dataSize)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
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return EINVAL;
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}
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size_t size = m_header.entity.keyLen;
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char* buf = key->lockBuffer(size);
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if (key == NULL) {
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key->unlockBuffer();
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m_status = ENOMEM;
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return m_status;
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}
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int amt = read(m_fd, buf, size+1);
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CHECK_SIZE(amt, (int)size+1);
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key->unlockBuffer(size);
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m_pos += size+1;
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*dataSize = m_header.entity.dataSize;
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SKIP_PADDING();
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return NO_ERROR;
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}
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status_t
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BackupDataReader::SkipEntityData()
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
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return EINVAL;
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}
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if (m_header.entity.dataSize > 0) {
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int pos = lseek(m_fd, m_header.entity.dataSize, SEEK_CUR);
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return pos == -1 ? (int)errno : (int)NO_ERROR;
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} else {
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return NO_ERROR;
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}
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}
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status_t
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BackupDataReader::ReadEntityData(void* data, size_t size)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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int amt = read(m_fd, data, size);
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CHECK_SIZE(amt, (int)size);
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m_pos += size;
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return NO_ERROR;
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}
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status_t
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BackupDataReader::ReadAppFooter(int* cookie)
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{
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if (m_status != NO_ERROR) {
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return m_status;
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}
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if (m_header.type != BACKUP_FOOTER_APP_V1) {
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return EINVAL;
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}
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if (m_header.footer.entityCount != m_entityCount) {
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LOGD("entity count mismatch actual=%d expected=%d", m_entityCount,
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m_header.footer.entityCount);
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m_status = EINVAL;
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return m_status;
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}
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*cookie = m_header.footer.cookie;
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return NO_ERROR;
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}
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status_t
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BackupDataReader::skip_padding()
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{
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ssize_t amt;
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ssize_t paddingSize;
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paddingSize = padding_extra(m_pos);
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if (paddingSize > 0) {
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uint32_t padding;
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amt = read(m_fd, &padding, paddingSize);
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CHECK_SIZE(amt, paddingSize);
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m_pos += amt;
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}
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return NO_ERROR;
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}
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} // namespace android
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