replicant-frameworks_native/libs/utils/backup_data.cpp
2009-05-15 18:20:19 -04:00

429 lines
10 KiB
C++

/*
* 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.
*/
#define LOG_TAG "backup_data"
#include <utils/backup_helpers.h>
#include <utils/ByteOrder.h>
#include <stdio.h>
#include <unistd.h>
#include <cutils/log.h>
namespace android {
/*
* File Format (v1):
*
* All ints are stored little-endian.
*
* - An app_header_v1 struct.
* - The name of the package, utf-8, null terminated, padded to 4-byte boundary.
* - A sequence of zero or more key/value paires (entities), each with
* - A entity_header_v1 struct
* - The key, utf-8, null terminated, padded to 4-byte boundary.
* - The value, padded to 4 byte boundary
*/
#define APP_MAGIC_V1 0x31707041 // App1 (little endian)
#define ENTITY_MAGIC_V1 0x61746144 // Data (little endian)
#define FOOTER_MAGIC_V1 0x746f6f46 // Foot (little endian)
const static int ROUND_UP[4] = { 0, 3, 2, 1 };
static inline size_t
round_up(size_t n)
{
return n + ROUND_UP[n % 4];
}
static inline size_t
padding_extra(size_t n)
{
return ROUND_UP[n % 4];
}
BackupDataWriter::BackupDataWriter(int fd)
:m_fd(fd),
m_status(NO_ERROR),
m_pos(0),
m_entityCount(0)
{
}
BackupDataWriter::~BackupDataWriter()
{
}
// Pad out anything they've previously written to the next 4 byte boundary.
status_t
BackupDataWriter::write_padding_for(int n)
{
ssize_t amt;
ssize_t paddingSize;
paddingSize = padding_extra(n);
if (paddingSize > 0) {
uint32_t padding = 0xbcbcbcbc;
amt = write(m_fd, &padding, paddingSize);
if (amt != paddingSize) {
m_status = errno;
return m_status;
}
m_pos += amt;
}
return NO_ERROR;
}
status_t
BackupDataWriter::WriteAppHeader(const String8& packageName, int cookie)
{
if (m_status != NO_ERROR) {
return m_status;
}
ssize_t amt;
amt = write_padding_for(m_pos);
if (amt != 0) {
return amt;
}
app_header_v1 header;
ssize_t nameLen;
nameLen = packageName.length();
header.type = tolel(APP_MAGIC_V1);
header.packageLen = tolel(nameLen);
header.cookie = cookie;
amt = write(m_fd, &header, sizeof(app_header_v1));
if (amt != sizeof(app_header_v1)) {
m_status = errno;
return m_status;
}
m_pos += amt;
amt = write(m_fd, packageName.string(), nameLen+1);
if (amt != nameLen+1) {
m_status = errno;
return m_status;
}
m_pos += amt;
return NO_ERROR;
}
status_t
BackupDataWriter::WriteEntityHeader(const String8& key, size_t dataSize)
{
if (m_status != NO_ERROR) {
return m_status;
}
ssize_t amt;
amt = write_padding_for(m_pos);
if (amt != 0) {
return amt;
}
entity_header_v1 header;
ssize_t keyLen;
keyLen = key.length();
header.type = tolel(ENTITY_MAGIC_V1);
header.keyLen = tolel(keyLen);
header.dataSize = tolel(dataSize);
amt = write(m_fd, &header, sizeof(entity_header_v1));
if (amt != sizeof(entity_header_v1)) {
m_status = errno;
return m_status;
}
m_pos += amt;
amt = write(m_fd, key.string(), keyLen+1);
if (amt != keyLen+1) {
m_status = errno;
return m_status;
}
m_pos += amt;
amt = write_padding_for(keyLen+1);
m_entityCount++;
return amt;
}
status_t
BackupDataWriter::WriteEntityData(const void* data, size_t size)
{
if (m_status != NO_ERROR) {
return m_status;
}
// We don't write padding here, because they're allowed to call this several
// times with smaller buffers. We write it at the end of WriteEntityHeader
// instead.
ssize_t amt = write(m_fd, data, size);
if (amt != (ssize_t)size) {
m_status = errno;
return m_status;
}
m_pos += amt;
return NO_ERROR;
}
status_t
BackupDataWriter::WriteAppFooter(int cookie)
{
if (m_status != NO_ERROR) {
return m_status;
}
ssize_t amt;
amt = write_padding_for(m_pos);
if (amt != 0) {
return amt;
}
app_footer_v1 footer;
ssize_t nameLen;
footer.type = tolel(FOOTER_MAGIC_V1);
footer.entityCount = tolel(m_entityCount);
footer.cookie = cookie;
amt = write(m_fd, &footer, sizeof(app_footer_v1));
if (amt != sizeof(app_footer_v1)) {
m_status = errno;
return m_status;
}
m_pos += amt;
return NO_ERROR;
}
BackupDataReader::BackupDataReader(int fd)
:m_fd(fd),
m_status(NO_ERROR),
m_pos(0),
m_entityCount(0)
{
memset(&m_header, 0, sizeof(m_header));
}
BackupDataReader::~BackupDataReader()
{
}
status_t
BackupDataReader::Status()
{
return m_status;
}
#define CHECK_SIZE(actual, expected) \
do { \
if ((actual) != (expected)) { \
if ((actual) == 0) { \
m_status = EIO; \
} else { \
m_status = errno; \
} \
return m_status; \
} \
} while(0)
#define SKIP_PADDING() \
do { \
status_t err = skip_padding(); \
if (err != NO_ERROR) { \
m_status = err; \
return err; \
} \
} while(0)
status_t
BackupDataReader::ReadNextHeader()
{
if (m_status != NO_ERROR) {
return m_status;
}
int amt;
SKIP_PADDING();
amt = read(m_fd, &m_header, sizeof(m_header));
CHECK_SIZE(amt, sizeof(m_header));
// validate and fix up the fields.
m_header.type = fromlel(m_header.type);
switch (m_header.type)
{
case APP_MAGIC_V1:
m_header.app.packageLen = fromlel(m_header.app.packageLen);
if (m_header.app.packageLen < 0) {
LOGD("App header at %d has packageLen<0: 0x%08x\n", (int)m_pos,
(int)m_header.app.packageLen);
m_status = EINVAL;
}
m_header.app.cookie = m_header.app.cookie;
break;
case ENTITY_MAGIC_V1:
m_header.entity.keyLen = fromlel(m_header.entity.keyLen);
if (m_header.entity.keyLen <= 0) {
LOGD("Entity header at %d has keyLen<=0: 0x%08x\n", (int)m_pos,
(int)m_header.entity.keyLen);
m_status = EINVAL;
}
m_header.entity.dataSize = fromlel(m_header.entity.dataSize);
if (m_header.entity.dataSize < 0) {
LOGD("Entity header at %d has dataSize<0: 0x%08x\n", (int)m_pos,
(int)m_header.entity.dataSize);
m_status = EINVAL;
}
m_entityCount++;
break;
case FOOTER_MAGIC_V1:
m_header.footer.entityCount = fromlel(m_header.footer.entityCount);
if (m_header.footer.entityCount < 0) {
LOGD("Entity header at %d has entityCount<0: 0x%08x\n", (int)m_pos,
(int)m_header.footer.entityCount);
m_status = EINVAL;
}
m_header.footer.cookie = m_header.footer.cookie;
break;
default:
LOGD("Chunk header at %d has invalid type: 0x%08x", (int)m_pos, (int)m_header.type);
m_status = EINVAL;
}
m_pos += sizeof(m_header);
return m_status;
}
status_t
BackupDataReader::ReadAppHeader(String8* packageName, int* cookie)
{
if (m_status != NO_ERROR) {
return m_status;
}
if (m_header.type != APP_MAGIC_V1) {
return EINVAL;
}
size_t size = m_header.app.packageLen;
char* buf = packageName->lockBuffer(size);
if (packageName == NULL) {
packageName->unlockBuffer();
m_status = ENOMEM;
return m_status;
}
int amt = read(m_fd, buf, size+1);
CHECK_SIZE(amt, (int)size+1);
packageName->unlockBuffer(size);
m_pos += size+1;
*cookie = m_header.app.cookie;
return NO_ERROR;
}
bool
BackupDataReader::HasEntities()
{
return m_status == NO_ERROR && m_header.type == ENTITY_MAGIC_V1;
}
status_t
BackupDataReader::ReadEntityHeader(String8* key, size_t* dataSize)
{
if (m_status != NO_ERROR) {
return m_status;
}
if (m_header.type != ENTITY_MAGIC_V1) {
return EINVAL;
}
size_t size = m_header.app.packageLen;
char* buf = key->lockBuffer(size);
if (key == NULL) {
key->unlockBuffer();
m_status = ENOMEM;
return m_status;
}
int amt = read(m_fd, buf, size+1);
CHECK_SIZE(amt, (int)size+1);
key->unlockBuffer(size);
m_pos += size+1;
*dataSize = m_header.entity.dataSize;
SKIP_PADDING();
return NO_ERROR;
}
status_t
BackupDataReader::ReadEntityData(void* data, size_t size)
{
if (m_status != NO_ERROR) {
return m_status;
}
int amt = read(m_fd, data, size);
CHECK_SIZE(amt, (int)size);
m_pos += size;
return NO_ERROR;
}
status_t
BackupDataReader::ReadAppFooter(int* cookie)
{
if (m_status != NO_ERROR) {
return m_status;
}
if (m_header.type != FOOTER_MAGIC_V1) {
return EINVAL;
}
if (m_header.footer.entityCount != m_entityCount) {
LOGD("entity count mismatch actual=%d expected=%d", m_entityCount,
m_header.footer.entityCount);
m_status = EINVAL;
return m_status;
}
*cookie = m_header.footer.cookie;
return NO_ERROR;
}
status_t
BackupDataReader::skip_padding()
{
ssize_t amt;
ssize_t paddingSize;
paddingSize = padding_extra(m_pos);
if (paddingSize > 0) {
uint32_t padding;
amt = read(m_fd, &padding, paddingSize);
CHECK_SIZE(amt, paddingSize);
m_pos += amt;
}
return NO_ERROR;
}
} // namespace android