/*
* 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/BackupHelpers.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
*/
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::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;
}
String8 k;
if (m_keyPrefix.length() > 0) {
k = m_keyPrefix;
k += ":";
k += key;
} else {
k = key;
}
if (false) {
LOGD("Writing entity: prefix='%s' key='%s' dataSize=%d", m_keyPrefix.string(), key.string(),
dataSize);
}
entity_header_v1 header;
ssize_t keyLen;
keyLen = k.length();
header.type = tolel(BACKUP_HEADER_ENTITY_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, k.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;
}
void
BackupDataWriter::SetKeyPrefix(const String8& keyPrefix)
{
m_keyPrefix = keyPrefix;
}
BackupDataReader::BackupDataReader(int fd)
:m_fd(fd),
m_done(false),
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; \
m_done = true; \
} else { \
m_status = errno; \
LOGD("CHECK_SIZE(a=%ld e=%ld) failed at line %d m_status='%s'", \
long(actual), long(expected), __LINE__, strerror(m_status)); \
} \
return m_status; \
} \
} while(0)
#define SKIP_PADDING() \
do { \
status_t err = skip_padding(); \
if (err != NO_ERROR) { \
LOGD("SKIP_PADDING FAILED at line %d", __LINE__); \
m_status = err; \
return err; \
} \
} while(0)
status_t
BackupDataReader::ReadNextHeader(bool* done, int* type)
{
*done = m_done;
if (m_status != NO_ERROR) {
return m_status;
}
int amt;
amt = skip_padding();
if (amt == EIO) {
*done = m_done = true;
return NO_ERROR;
}
else if (amt != NO_ERROR) {
return amt;
}
amt = read(m_fd, &m_header, sizeof(m_header));
*done = m_done = (amt == 0);
if (*done) {
return NO_ERROR;
}
CHECK_SIZE(amt, sizeof(m_header));
m_pos += sizeof(m_header);
if (type) {
*type = m_header.type;
}
// validate and fix up the fields.
m_header.type = fromlel(m_header.type);
switch (m_header.type)
{
case BACKUP_HEADER_ENTITY_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);
m_entityCount++;
// read the rest of the header (filename)
size_t size = m_header.entity.keyLen;
char* buf = m_key.lockBuffer(size);
if (buf == NULL) {
m_status = ENOMEM;
return m_status;
}
int amt = read(m_fd, buf, size+1);
CHECK_SIZE(amt, (int)size+1);
m_key.unlockBuffer(size);
m_pos += size+1;
SKIP_PADDING();
m_dataEndPos = m_pos + m_header.entity.dataSize;
break;
}
default:
LOGD("Chunk header at %d has invalid type: 0x%08x", (int)m_pos, (int)m_header.type);
m_status = EINVAL;
}
return m_status;
}
bool
BackupDataReader::HasEntities()
{
return m_status == NO_ERROR && m_header.type == BACKUP_HEADER_ENTITY_V1;
}
status_t
BackupDataReader::ReadEntityHeader(String8* key, size_t* dataSize)
{
if (m_status != NO_ERROR) {
return m_status;
}
if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
return EINVAL;
}
*key = m_key;
*dataSize = m_header.entity.dataSize;
return NO_ERROR;
}
status_t
BackupDataReader::SkipEntityData()
{
if (m_status != NO_ERROR) {
return m_status;
}
if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
return EINVAL;
}
if (m_header.entity.dataSize > 0) {
int pos = lseek(m_fd, m_dataEndPos, SEEK_SET);
if (pos == -1) {
return errno;
}
}
SKIP_PADDING();
return NO_ERROR;
}
ssize_t
BackupDataReader::ReadEntityData(void* data, size_t size)
{
if (m_status != NO_ERROR) {
return -1;
}
int remaining = m_dataEndPos - m_pos;
//LOGD("ReadEntityData size=%d m_pos=0x%x m_dataEndPos=0x%x remaining=%d\n",
// size, m_pos, m_dataEndPos, remaining);
if (remaining <= 0) {
return 0;
}
if (((int)size) > remaining) {
size = remaining;
}
//LOGD(" reading %d bytes", size);
int amt = read(m_fd, data, size);
if (amt < 0) {
m_status = errno;
return -1;
}
if (amt == 0) {
m_status = EIO;
m_done = true;
}
m_pos += amt;
return amt;
}
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