libs/utils/BackupData.cpp - platform/frameworks/base - Gitiles

 /*
  * 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 (true) {
         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 failed with at line %d m_status='%s'", __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
	/*
	* 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 (true) {
	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 failed with at line %d m_status='%s'", __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