payload_generator/ext2_filesystem.cc - aosp/platform/system/update_engine - Git at Google

 //
 // Copyright (C) 2015 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.
 //

 #include "update_engine/payload_generator/ext2_filesystem.h"

 #include <et/com_err.h>
 #if defined(__clang__)
 // TODO(*): Remove these pragmas when b/35721782 is fixed.
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wmacro-redefined"
 #endif
 #include <ext2fs/ext2_io.h>
 #include <ext2fs/ext2fs.h>
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif

 #include <map>
 #include <set>

 #include <base/logging.h>
 #include <base/strings/stringprintf.h>

 #include "update_engine/common/utils.h"
 #include "update_engine/payload_generator/extent_ranges.h"
 #include "update_engine/payload_generator/extent_utils.h"
 #include "update_engine/update_metadata.pb.h"

 using std::set;
 using std::string;
 using std::unique_ptr;
 using std::vector;

 namespace chromeos_update_engine {

 namespace {
 // Processes all blocks belonging to an inode and adds them to the extent list.
 // This function should match the prototype expected by ext2fs_block_iterate2().
 int ProcessInodeAllBlocks(ext2_filsys fs,
                           blk_t* blocknr,
                           e2_blkcnt_t blockcnt,
                           blk_t ref_blk,
                           int ref_offset,
                           void* priv) {
   vector<Extent>* extents = static_cast<vector<Extent>*>(priv);
   AppendBlockToExtents(extents, *blocknr);
   return 0;
 }

 // Processes only indirect, double indirect or triple indirect metadata
 // blocks belonging to an inode. This function should match the prototype of
 // ext2fs_block_iterate2().
 int AddMetadataBlocks(ext2_filsys fs,
                       blk_t* blocknr,
                       e2_blkcnt_t blockcnt,
                       blk_t ref_blk,
                       int ref_offset,
                       void* priv) {
   set<uint64_t>* blocks = static_cast<set<uint64_t>*>(priv);
   // If |blockcnt| is non-negative, |blocknr| points to the physical block
   // number.
   // If |blockcnt| is negative, it is one of the values: BLOCK_COUNT_IND,
   // BLOCK_COUNT_DIND, BLOCK_COUNT_TIND or BLOCK_COUNT_TRANSLATOR and
   // |blocknr| points to a block in the first three cases. The last case is
   // only used by GNU Hurd, so we shouldn't see those cases here.
   if (blockcnt == BLOCK_COUNT_IND || blockcnt == BLOCK_COUNT_DIND ||
       blockcnt == BLOCK_COUNT_TIND) {
     blocks->insert(*blocknr);
   }
   return 0;
 }

 struct UpdateFileAndAppendState {
   std::map<ext2_ino_t, FilesystemInterface::File>* inodes = nullptr;
   set<ext2_ino_t>* used_inodes = nullptr;
   vector<FilesystemInterface::File>* files = nullptr;
   ext2_filsys filsys;
 };

 int UpdateFileAndAppend(ext2_ino_t dir,
                         int entry,
                         struct ext2_dir_entry* dirent,
                         int offset,
                         int blocksize,
                         char* buf,
                         void* priv_data) {
   UpdateFileAndAppendState* state =
       static_cast<UpdateFileAndAppendState*>(priv_data);
   uint32_t file_type = dirent->name_len >> 8;
   // Directories can't have hard links, and they are added from the outer loop.
   if (file_type == EXT2_FT_DIR)
     return 0;

   auto ino_file = state->inodes->find(dirent->inode);
   if (ino_file == state->inodes->end())
     return 0;
   auto dir_file = state->inodes->find(dir);
   if (dir_file == state->inodes->end())
     return 0;
   string basename(dirent->name, dirent->name_len & 0xff);
   ino_file->second.name = dir_file->second.name;
   if (dir_file->second.name != "/")
     ino_file->second.name += "/";
   ino_file->second.name += basename;

   // Append this file to the output. If the file has a hard link, it will be
   // added twice to the output, but with different names, which is ok. That will
   // help identify all the versions of the same file.
   state->files->push_back(ino_file->second);
   state->used_inodes->insert(dirent->inode);
   return 0;
 }

 }  // namespace

 unique_ptr<Ext2Filesystem> Ext2Filesystem::CreateFromFile(
     const string& filename) {
   if (filename.empty())
     return nullptr;
   unique_ptr<Ext2Filesystem> result(new Ext2Filesystem());
   result->filename_ = filename;

   errcode_t err = ext2fs_open(filename.c_str(),
                               0,  // flags (read only)
                               0,  // superblock block number
                               0,  // block_size (autodetect)
                               unix_io_manager,
                               &result->filsys_);
   if (err) {
     LOG(ERROR) << "Opening ext2fs " << filename;
     return nullptr;
   }
   return result;
 }

 Ext2Filesystem::~Ext2Filesystem() {
   ext2fs_free(filsys_);
 }

 size_t Ext2Filesystem::GetBlockSize() const {
   return filsys_->blocksize;
 }

 size_t Ext2Filesystem::GetBlockCount() const {
   return ext2fs_blocks_count(filsys_->super);
 }

 bool Ext2Filesystem::GetFiles(vector<File>* files) const {
   TEST_AND_RETURN_FALSE_ERRCODE(ext2fs_read_inode_bitmap(filsys_));

   ext2_inode_scan iscan;
   TEST_AND_RETURN_FALSE_ERRCODE(
       ext2fs_open_inode_scan(filsys_, 0 /* buffer_blocks */, &iscan));

   std::map<ext2_ino_t, File> inodes;

   // List of directories. We need to first parse all the files in a directory
   // to later fix the absolute paths.
   vector<ext2_ino_t> directories;

   set<uint64_t> inode_blocks;

   // Iterator
   ext2_ino_t it_ino;
   ext2_inode it_inode;

   bool ok = true;
   while (true) {
     errcode_t error = ext2fs_get_next_inode(iscan, &it_ino, &it_inode);
     if (error) {
       LOG(ERROR) << "Failed to retrieve next inode (" << error << ")";
       ok = false;
       break;
     }
     if (it_ino == 0)
       break;

     // Skip inodes that are not in use.
     if (!ext2fs_test_inode_bitmap(filsys_->inode_map, it_ino))
       continue;

     File& file = inodes[it_ino];
     if (it_ino == EXT2_RESIZE_INO) {
       file.name = "<group-descriptors>";
     } else {
       file.name = base::StringPrintf("<inode-%u>", it_ino);
     }

     memset(&file.file_stat, 0, sizeof(file.file_stat));
     file.file_stat.st_ino = it_ino;
     file.file_stat.st_mode = it_inode.i_mode;
     file.file_stat.st_nlink = it_inode.i_links_count;
     file.file_stat.st_uid = it_inode.i_uid;
     file.file_stat.st_gid = it_inode.i_gid;
     file.file_stat.st_size = it_inode.i_size;
     file.file_stat.st_blksize = filsys_->blocksize;
     file.file_stat.st_blocks = it_inode.i_blocks;
     file.file_stat.st_atime = it_inode.i_atime;
     file.file_stat.st_mtime = it_inode.i_mtime;
     file.file_stat.st_ctime = it_inode.i_ctime;

     bool is_dir = (ext2fs_check_directory(filsys_, it_ino) == 0);
     if (is_dir)
       directories.push_back(it_ino);

     if (!ext2fs_inode_has_valid_blocks(&it_inode))
       continue;

     // Process the inode data and metadata blocks.
     // For normal files, inode blocks are indirect, double indirect
     // and triple indirect blocks (no data blocks). For directories and
     // the journal, all blocks are considered metadata blocks.
     int flags = it_ino < EXT2_GOOD_OLD_FIRST_INO ? 0 : BLOCK_FLAG_DATA_ONLY;
     error = ext2fs_block_iterate2(filsys_,
                                   it_ino,
                                   flags,
                                   nullptr,  // block_buf
                                   ProcessInodeAllBlocks,
                                   &file.extents);

     if (error) {
       LOG(ERROR) << "Failed to enumerate inode " << it_ino << " blocks ("
                  << error << ")";
       continue;
     }
     if (it_ino >= EXT2_GOOD_OLD_FIRST_INO) {
       ext2fs_block_iterate2(
           filsys_, it_ino, 0, nullptr, AddMetadataBlocks, &inode_blocks);
     }
   }
   ext2fs_close_inode_scan(iscan);
   if (!ok)
     return false;

   // The set of inodes already added to the output. There can be less elements
   // here than in files since the later can contain repeated inodes due to
   // hardlink files.
   set<ext2_ino_t> used_inodes;

   UpdateFileAndAppendState priv_data;
   priv_data.inodes = &inodes;
   priv_data.used_inodes = &used_inodes;
   priv_data.files = files;
   priv_data.filsys = filsys_;

   files->clear();
   // Iterate over all the files of each directory to update the name and add it.
   for (ext2_ino_t dir_ino : directories) {
     char* dir_name = nullptr;
     errcode_t error = ext2fs_get_pathname(filsys_, dir_ino, 0, &dir_name);
     if (error) {
       // Not being able to read a directory name is not a fatal error, it is
       // just skiped.
       LOG(WARNING) << "Reading directory name on inode " << dir_ino
                    << " (error " << error << ")";
       inodes[dir_ino].name = base::StringPrintf("<dir-%u>", dir_ino);
     } else {
       inodes[dir_ino].name = dir_name;
       files->push_back(inodes[dir_ino]);
       used_inodes.insert(dir_ino);
     }
     ext2fs_free_mem(&dir_name);

     error = ext2fs_dir_iterate2(filsys_,
                                 dir_ino,
                                 0,
                                 nullptr /* block_buf */,
                                 UpdateFileAndAppend,
                                 &priv_data);
     if (error) {
       LOG(WARNING) << "Failed to enumerate files in directory "
                    << inodes[dir_ino].name << " (error " << error << ")";
     }
   }

   // Add <inode-blocks> file with the blocks that hold inodes.
   File inode_file;
   inode_file.name = "<inode-blocks>";
   for (uint64_t block : inode_blocks) {
     AppendBlockToExtents(&inode_file.extents, block);
   }
   files->push_back(inode_file);

   // Add <free-spacce> blocs.
   errcode_t error = ext2fs_read_block_bitmap(filsys_);
   if (error) {
     LOG(ERROR) << "Reading the blocks bitmap (error " << error << ")";
   } else {
     File free_space;
     free_space.name = "<free-space>";
     blk64_t blk_start = ext2fs_get_block_bitmap_start2(filsys_->block_map);
     blk64_t blk_end = ext2fs_get_block_bitmap_end2(filsys_->block_map);
     for (blk64_t block = blk_start; block < blk_end; block++) {
       if (!ext2fs_test_block_bitmap2(filsys_->block_map, block))
         AppendBlockToExtents(&free_space.extents, block);
     }
     files->push_back(free_space);
   }

   // Add all the unreachable files plus the pseudo-files with an inode. Since
   // these inodes aren't files in the filesystem, ignore the empty ones.
   for (const auto& ino_file : inodes) {
     if (used_inodes.find(ino_file.first) != used_inodes.end())
       continue;
     if (ino_file.second.extents.empty())
       continue;

     File file = ino_file.second;
     ExtentRanges ranges;
     ranges.AddExtents(file.extents);
     file.extents = ranges.GetExtentsForBlockCount(ranges.blocks());

     files->push_back(file);
   }

   return true;
 }

 bool Ext2Filesystem::LoadSettings(brillo::KeyValueStore* store) const {
   // First search for the settings inode following symlinks if we find some.
   ext2_ino_t ino_num = 0;
   errcode_t err = ext2fs_namei_follow(filsys_,
                                       EXT2_ROOT_INO /* root */,
                                       EXT2_ROOT_INO /* cwd */,
                                       "/etc/update_engine.conf",
                                       &ino_num);
   if (err != 0)
     return false;

   ext2_inode ino_data;
   if (ext2fs_read_inode(filsys_, ino_num, &ino_data) != 0)
     return false;

   // Load the list of blocks and then the contents of the inodes.
   vector<Extent> extents;
   err = ext2fs_block_iterate2(filsys_,
                               ino_num,
                               BLOCK_FLAG_DATA_ONLY,
                               nullptr,  // block_buf
                               ProcessInodeAllBlocks,
                               &extents);
   if (err != 0)
     return false;

   brillo::Blob blob;
   uint64_t physical_size = utils::BlocksInExtents(extents) * filsys_->blocksize;
   // Sparse holes in the settings file are not supported.
   if (EXT2_I_SIZE(&ino_data) > physical_size)
     return false;
   if (!utils::ReadExtents(
           filename_, extents, &blob, physical_size, filsys_->blocksize))
     return false;

   string text(blob.begin(), blob.begin() + EXT2_I_SIZE(&ino_data));
   return store->LoadFromString(text);
 }

 }  // namespace chromeos_update_engine
	//
	// Copyright (C) 2015 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.
	//

	#include "update_engine/payload_generator/ext2_filesystem.h"

	#include <et/com_err.h>
	#if defined(__clang__)
	// TODO(*): Remove these pragmas when b/35721782 is fixed.
	#pragma clang diagnostic push
	#pragma clang diagnostic ignored "-Wmacro-redefined"
	#endif
	#include <ext2fs/ext2_io.h>
	#include <ext2fs/ext2fs.h>
	#if defined(__clang__)
	#pragma clang diagnostic pop
	#endif

	#include <map>
	#include <set>

	#include <base/logging.h>
	#include <base/strings/stringprintf.h>

	#include "update_engine/common/utils.h"
	#include "update_engine/payload_generator/extent_ranges.h"
	#include "update_engine/payload_generator/extent_utils.h"
	#include "update_engine/update_metadata.pb.h"

	using std::set;
	using std::string;
	using std::unique_ptr;
	using std::vector;

	namespace chromeos_update_engine {

	namespace {
	// Processes all blocks belonging to an inode and adds them to the extent list.
	// This function should match the prototype expected by ext2fs_block_iterate2().
	int ProcessInodeAllBlocks(ext2_filsys fs,
	blk_t* blocknr,
	e2_blkcnt_t blockcnt,
	blk_t ref_blk,
	int ref_offset,
	void* priv) {
	vector<Extent>* extents = static_cast<vector<Extent>*>(priv);
	AppendBlockToExtents(extents, *blocknr);
	return 0;
	}

	// Processes only indirect, double indirect or triple indirect metadata
	// blocks belonging to an inode. This function should match the prototype of
	// ext2fs_block_iterate2().
	int AddMetadataBlocks(ext2_filsys fs,
	blk_t* blocknr,
	e2_blkcnt_t blockcnt,
	blk_t ref_blk,
	int ref_offset,
	void* priv) {
	set<uint64_t>* blocks = static_cast<set<uint64_t>*>(priv);
	// If \|blockcnt\| is non-negative, \|blocknr\| points to the physical block
	// number.
	// If \|blockcnt\| is negative, it is one of the values: BLOCK_COUNT_IND,
	// BLOCK_COUNT_DIND, BLOCK_COUNT_TIND or BLOCK_COUNT_TRANSLATOR and
	// \|blocknr\| points to a block in the first three cases. The last case is
	// only used by GNU Hurd, so we shouldn't see those cases here.
	if (blockcnt == BLOCK_COUNT_IND \|\| blockcnt == BLOCK_COUNT_DIND \|\|
	blockcnt == BLOCK_COUNT_TIND) {
	blocks->insert(*blocknr);
	}
	return 0;
	}

	struct UpdateFileAndAppendState {
	std::map<ext2_ino_t, FilesystemInterface::File>* inodes = nullptr;
	set<ext2_ino_t>* used_inodes = nullptr;
	vector<FilesystemInterface::File>* files = nullptr;
	ext2_filsys filsys;
	};

	int UpdateFileAndAppend(ext2_ino_t dir,
	int entry,
	struct ext2_dir_entry* dirent,
	int offset,
	int blocksize,
	char* buf,
	void* priv_data) {
	UpdateFileAndAppendState* state =
	static_cast<UpdateFileAndAppendState*>(priv_data);
	uint32_t file_type = dirent->name_len >> 8;
	// Directories can't have hard links, and they are added from the outer loop.
	if (file_type == EXT2_FT_DIR)
	return 0;

	auto ino_file = state->inodes->find(dirent->inode);
	if (ino_file == state->inodes->end())
	return 0;
	auto dir_file = state->inodes->find(dir);
	if (dir_file == state->inodes->end())
	return 0;
	string basename(dirent->name, dirent->name_len & 0xff);
	ino_file->second.name = dir_file->second.name;
	if (dir_file->second.name != "/")
	ino_file->second.name += "/";
	ino_file->second.name += basename;

	// Append this file to the output. If the file has a hard link, it will be
	// added twice to the output, but with different names, which is ok. That will
	// help identify all the versions of the same file.
	state->files->push_back(ino_file->second);
	state->used_inodes->insert(dirent->inode);
	return 0;
	}

	} // namespace

	unique_ptr<Ext2Filesystem> Ext2Filesystem::CreateFromFile(
	const string& filename) {
	if (filename.empty())
	return nullptr;
	unique_ptr<Ext2Filesystem> result(new Ext2Filesystem());
	result->filename_ = filename;

	errcode_t err = ext2fs_open(filename.c_str(),
	0, // flags (read only)
	0, // superblock block number
	0, // block_size (autodetect)
	unix_io_manager,
	&result->filsys_);
	if (err) {
	LOG(ERROR) << "Opening ext2fs " << filename;
	return nullptr;
	}
	return result;
	}

	Ext2Filesystem::~Ext2Filesystem() {
	ext2fs_free(filsys_);
	}

	size_t Ext2Filesystem::GetBlockSize() const {
	return filsys_->blocksize;
	}

	size_t Ext2Filesystem::GetBlockCount() const {
	return ext2fs_blocks_count(filsys_->super);
	}

	bool Ext2Filesystem::GetFiles(vector<File>* files) const {
	TEST_AND_RETURN_FALSE_ERRCODE(ext2fs_read_inode_bitmap(filsys_));

	ext2_inode_scan iscan;
	TEST_AND_RETURN_FALSE_ERRCODE(
	ext2fs_open_inode_scan(filsys_, 0 /* buffer_blocks */, &iscan));

	std::map<ext2_ino_t, File> inodes;

	// List of directories. We need to first parse all the files in a directory
	// to later fix the absolute paths.
	vector<ext2_ino_t> directories;

	set<uint64_t> inode_blocks;

	// Iterator
	ext2_ino_t it_ino;
	ext2_inode it_inode;

	bool ok = true;
	while (true) {
	errcode_t error = ext2fs_get_next_inode(iscan, &it_ino, &it_inode);
	if (error) {
	LOG(ERROR) << "Failed to retrieve next inode (" << error << ")";
	ok = false;
	break;
	}
	if (it_ino == 0)
	break;

	// Skip inodes that are not in use.
	if (!ext2fs_test_inode_bitmap(filsys_->inode_map, it_ino))
	continue;

	File& file = inodes[it_ino];
	if (it_ino == EXT2_RESIZE_INO) {
	file.name = "<group-descriptors>";
	} else {
	file.name = base::StringPrintf("<inode-%u>", it_ino);
	}

	memset(&file.file_stat, 0, sizeof(file.file_stat));
	file.file_stat.st_ino = it_ino;
	file.file_stat.st_mode = it_inode.i_mode;
	file.file_stat.st_nlink = it_inode.i_links_count;
	file.file_stat.st_uid = it_inode.i_uid;
	file.file_stat.st_gid = it_inode.i_gid;
	file.file_stat.st_size = it_inode.i_size;
	file.file_stat.st_blksize = filsys_->blocksize;
	file.file_stat.st_blocks = it_inode.i_blocks;
	file.file_stat.st_atime = it_inode.i_atime;
	file.file_stat.st_mtime = it_inode.i_mtime;
	file.file_stat.st_ctime = it_inode.i_ctime;

	bool is_dir = (ext2fs_check_directory(filsys_, it_ino) == 0);
	if (is_dir)
	directories.push_back(it_ino);

	if (!ext2fs_inode_has_valid_blocks(&it_inode))
	continue;

	// Process the inode data and metadata blocks.
	// For normal files, inode blocks are indirect, double indirect
	// and triple indirect blocks (no data blocks). For directories and
	// the journal, all blocks are considered metadata blocks.
	int flags = it_ino < EXT2_GOOD_OLD_FIRST_INO ? 0 : BLOCK_FLAG_DATA_ONLY;
	error = ext2fs_block_iterate2(filsys_,
	it_ino,
	flags,
	nullptr, // block_buf
	ProcessInodeAllBlocks,
	&file.extents);

	if (error) {
	LOG(ERROR) << "Failed to enumerate inode " << it_ino << " blocks ("
	<< error << ")";
	continue;
	}
	if (it_ino >= EXT2_GOOD_OLD_FIRST_INO) {
	ext2fs_block_iterate2(
	filsys_, it_ino, 0, nullptr, AddMetadataBlocks, &inode_blocks);
	}
	}
	ext2fs_close_inode_scan(iscan);
	if (!ok)
	return false;

	// The set of inodes already added to the output. There can be less elements
	// here than in files since the later can contain repeated inodes due to
	// hardlink files.
	set<ext2_ino_t> used_inodes;

	UpdateFileAndAppendState priv_data;
	priv_data.inodes = &inodes;
	priv_data.used_inodes = &used_inodes;
	priv_data.files = files;
	priv_data.filsys = filsys_;

	files->clear();
	// Iterate over all the files of each directory to update the name and add it.
	for (ext2_ino_t dir_ino : directories) {
	char* dir_name = nullptr;
	errcode_t error = ext2fs_get_pathname(filsys_, dir_ino, 0, &dir_name);
	if (error) {
	// Not being able to read a directory name is not a fatal error, it is
	// just skiped.
	LOG(WARNING) << "Reading directory name on inode " << dir_ino
	<< " (error " << error << ")";
	inodes[dir_ino].name = base::StringPrintf("<dir-%u>", dir_ino);
	} else {
	inodes[dir_ino].name = dir_name;
	files->push_back(inodes[dir_ino]);
	used_inodes.insert(dir_ino);
	}
	ext2fs_free_mem(&dir_name);

	error = ext2fs_dir_iterate2(filsys_,
	dir_ino,
	0,
	nullptr /* block_buf */,
	UpdateFileAndAppend,
	&priv_data);
	if (error) {
	LOG(WARNING) << "Failed to enumerate files in directory "
	<< inodes[dir_ino].name << " (error " << error << ")";
	}
	}

	// Add <inode-blocks> file with the blocks that hold inodes.
	File inode_file;
	inode_file.name = "<inode-blocks>";
	for (uint64_t block : inode_blocks) {
	AppendBlockToExtents(&inode_file.extents, block);
	}
	files->push_back(inode_file);

	// Add <free-spacce> blocs.
	errcode_t error = ext2fs_read_block_bitmap(filsys_);
	if (error) {
	LOG(ERROR) << "Reading the blocks bitmap (error " << error << ")";
	} else {
	File free_space;
	free_space.name = "<free-space>";
	blk64_t blk_start = ext2fs_get_block_bitmap_start2(filsys_->block_map);
	blk64_t blk_end = ext2fs_get_block_bitmap_end2(filsys_->block_map);
	for (blk64_t block = blk_start; block < blk_end; block++) {
	if (!ext2fs_test_block_bitmap2(filsys_->block_map, block))
	AppendBlockToExtents(&free_space.extents, block);
	}
	files->push_back(free_space);
	}

	// Add all the unreachable files plus the pseudo-files with an inode. Since
	// these inodes aren't files in the filesystem, ignore the empty ones.
	for (const auto& ino_file : inodes) {
	if (used_inodes.find(ino_file.first) != used_inodes.end())
	continue;
	if (ino_file.second.extents.empty())
	continue;

	File file = ino_file.second;
	ExtentRanges ranges;
	ranges.AddExtents(file.extents);
	file.extents = ranges.GetExtentsForBlockCount(ranges.blocks());

	files->push_back(file);
	}

	return true;
	}

	bool Ext2Filesystem::LoadSettings(brillo::KeyValueStore* store) const {
	// First search for the settings inode following symlinks if we find some.
	ext2_ino_t ino_num = 0;
	errcode_t err = ext2fs_namei_follow(filsys_,
	EXT2_ROOT_INO /* root */,
	EXT2_ROOT_INO /* cwd */,
	"/etc/update_engine.conf",
	&ino_num);
	if (err != 0)
	return false;

	ext2_inode ino_data;
	if (ext2fs_read_inode(filsys_, ino_num, &ino_data) != 0)
	return false;

	// Load the list of blocks and then the contents of the inodes.
	vector<Extent> extents;
	err = ext2fs_block_iterate2(filsys_,
	ino_num,
	BLOCK_FLAG_DATA_ONLY,
	nullptr, // block_buf
	ProcessInodeAllBlocks,
	&extents);
	if (err != 0)
	return false;

	brillo::Blob blob;
	uint64_t physical_size = utils::BlocksInExtents(extents) * filsys_->blocksize;
	// Sparse holes in the settings file are not supported.
	if (EXT2_I_SIZE(&ino_data) > physical_size)
	return false;
	if (!utils::ReadExtents(
	filename_, extents, &blob, physical_size, filsys_->blocksize))
	return false;

	string text(blob.begin(), blob.begin() + EXT2_I_SIZE(&ino_data));
	return store->LoadFromString(text);
	}

	} // namespace chromeos_update_engine