ext2_filesystem.cc revision dcb18612576aeb59fbd8ba066b1b7a3a7bca8490 
1//
2// Copyright (C) 2015 The Android Open Source Project
3//
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at
7//
8//      http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15//
16
17#include "update_engine/payload_generator/ext2_filesystem.h"
18
19#include <et/com_err.h>
20// TODO: Remove these pragmas when b/35721782 is fixed.
21#pragma clang diagnostic push
22#pragma clang diagnostic ignored "-Wmacro-redefined"
23#include <ext2fs/ext2_io.h>
24#include <ext2fs/ext2fs.h>
25#pragma clang diagnostic pop
26
27#include <map>
28#include <set>
29
30#include <base/logging.h>
31#include <base/strings/stringprintf.h>
32
33#include "update_engine/common/utils.h"
34#include "update_engine/payload_generator/extent_ranges.h"
35#include "update_engine/payload_generator/extent_utils.h"
36#include "update_engine/update_metadata.pb.h"
37
38using std::set;
39using std::string;
40using std::unique_ptr;
41using std::vector;
42
43namespace chromeos_update_engine {
44
45namespace {
46// Processes all blocks belonging to an inode and adds them to the extent list.
47// This function should match the prototype expected by ext2fs_block_iterate2().
48int ProcessInodeAllBlocks(ext2_filsys fs,
49                          blk_t* blocknr,
50                          e2_blkcnt_t blockcnt,
51                          blk_t ref_blk,
52                          int ref_offset,
53                          void* priv) {
54  vector<Extent>* extents = static_cast<vector<Extent>*>(priv);
55  AppendBlockToExtents(extents, *blocknr);
56  return 0;
57}
58
59// Processes only indirect, double indirect or triple indirect metadata
60// blocks belonging to an inode. This function should match the prototype of
61// ext2fs_block_iterate2().
62int AddMetadataBlocks(ext2_filsys fs,
63                      blk_t* blocknr,
64                      e2_blkcnt_t blockcnt,
65                      blk_t ref_blk,
66                      int ref_offset,
67                      void* priv) {
68  set<uint64_t>* blocks = static_cast<set<uint64_t>*>(priv);
69  // If |blockcnt| is non-negative, |blocknr| points to the physical block
70  // number.
71  // If |blockcnt| is negative, it is one of the values: BLOCK_COUNT_IND,
72  // BLOCK_COUNT_DIND, BLOCK_COUNT_TIND or BLOCK_COUNT_TRANSLATOR and
73  // |blocknr| points to a block in the first three cases. The last case is
74  // only used by GNU Hurd, so we shouldn't see those cases here.
75  if (blockcnt == BLOCK_COUNT_IND || blockcnt == BLOCK_COUNT_DIND ||
76      blockcnt == BLOCK_COUNT_TIND) {
77    blocks->insert(*blocknr);
78  }
79  return 0;
80}
81
82struct UpdateFileAndAppendState {
83  std::map<ext2_ino_t, FilesystemInterface::File>* inodes = nullptr;
84  set<ext2_ino_t>* used_inodes = nullptr;
85  vector<FilesystemInterface::File>* files = nullptr;
86  ext2_filsys filsys;
87};
88
89int UpdateFileAndAppend(ext2_ino_t dir,
90                        int entry,
91                        struct ext2_dir_entry *dirent,
92                        int offset,
93                        int blocksize,
94                        char *buf,
95                        void *priv_data) {
96  UpdateFileAndAppendState* state =
97      static_cast<UpdateFileAndAppendState*>(priv_data);
98  uint32_t file_type = dirent->name_len >> 8;
99  // Directories can't have hard links, and they are added from the outer loop.
100  if (file_type == EXT2_FT_DIR)
101    return 0;
102
103  auto ino_file = state->inodes->find(dirent->inode);
104  if (ino_file == state->inodes->end())
105    return 0;
106  auto dir_file = state->inodes->find(dir);
107  if (dir_file == state->inodes->end())
108    return 0;
109  string basename(dirent->name, dirent->name_len & 0xff);
110  ino_file->second.name = dir_file->second.name;
111  if (dir_file->second.name != "/")
112    ino_file->second.name += "/";
113  ino_file->second.name += basename;
114
115  // Append this file to the output. If the file has a hard link, it will be
116  // added twice to the output, but with different names, which is ok. That will
117  // help identify all the versions of the same file.
118  state->files->push_back(ino_file->second);
119  state->used_inodes->insert(dirent->inode);
120  return 0;
121}
122
123}  // namespace
124
125unique_ptr<Ext2Filesystem> Ext2Filesystem::CreateFromFile(
126    const string& filename) {
127  if (filename.empty())
128    return nullptr;
129  unique_ptr<Ext2Filesystem> result(new Ext2Filesystem());
130  result->filename_ = filename;
131
132  errcode_t err = ext2fs_open(filename.c_str(),
133                              0,  // flags (read only)
134                              0,  // superblock block number
135                              0,  // block_size (autodetect)
136                              unix_io_manager,
137                              &result->filsys_);
138  if (err) {
139    LOG(ERROR) << "Opening ext2fs " << filename;
140    return nullptr;
141  }
142  return result;
143}
144
145Ext2Filesystem::~Ext2Filesystem() {
146  ext2fs_free(filsys_);
147}
148
149size_t Ext2Filesystem::GetBlockSize() const {
150  return filsys_->blocksize;
151}
152
153size_t Ext2Filesystem::GetBlockCount() const {
154  return ext2fs_blocks_count(filsys_->super);
155}
156
157bool Ext2Filesystem::GetFiles(vector<File>* files) const {
158  TEST_AND_RETURN_FALSE_ERRCODE(ext2fs_read_inode_bitmap(filsys_));
159
160  ext2_inode_scan iscan;
161  TEST_AND_RETURN_FALSE_ERRCODE(
162      ext2fs_open_inode_scan(filsys_, 0 /* buffer_blocks */, &iscan));
163
164  std::map<ext2_ino_t, File> inodes;
165
166  // List of directories. We need to first parse all the files in a directory
167  // to later fix the absolute paths.
168  vector<ext2_ino_t> directories;
169
170  set<uint64_t> inode_blocks;
171
172  // Iterator
173  ext2_ino_t it_ino;
174  ext2_inode it_inode;
175
176  bool ok = true;
177  while (true) {
178    errcode_t error = ext2fs_get_next_inode(iscan, &it_ino, &it_inode);
179    if (error) {
180      LOG(ERROR) << "Failed to retrieve next inode (" << error << ")";
181      ok = false;
182      break;
183    }
184    if (it_ino == 0)
185      break;
186
187    // Skip inodes that are not in use.
188    if (!ext2fs_test_inode_bitmap(filsys_->inode_map, it_ino))
189      continue;
190
191    File& file = inodes[it_ino];
192    if (it_ino == EXT2_RESIZE_INO) {
193      file.name = "<group-descriptors>";
194    } else {
195      file.name = base::StringPrintf("<inode-%u>", it_ino);
196    }
197
198    memset(&file.file_stat, 0, sizeof(file.file_stat));
199    file.file_stat.st_ino = it_ino;
200    file.file_stat.st_mode = it_inode.i_mode;
201    file.file_stat.st_nlink = it_inode.i_links_count;
202    file.file_stat.st_uid = it_inode.i_uid;
203    file.file_stat.st_gid = it_inode.i_gid;
204    file.file_stat.st_size = it_inode.i_size;
205    file.file_stat.st_blksize = filsys_->blocksize;
206    file.file_stat.st_blocks = it_inode.i_blocks;
207    file.file_stat.st_atime = it_inode.i_atime;
208    file.file_stat.st_mtime = it_inode.i_mtime;
209    file.file_stat.st_ctime = it_inode.i_ctime;
210
211    bool is_dir = (ext2fs_check_directory(filsys_, it_ino) == 0);
212    if (is_dir)
213      directories.push_back(it_ino);
214
215    if (!ext2fs_inode_has_valid_blocks(&it_inode))
216      continue;
217
218    // Process the inode data and metadata blocks.
219    // For normal files, inode blocks are indirect, double indirect
220    // and triple indirect blocks (no data blocks). For directories and
221    // the journal, all blocks are considered metadata blocks.
222    int flags = it_ino < EXT2_GOOD_OLD_FIRST_INO ? 0 : BLOCK_FLAG_DATA_ONLY;
223    error = ext2fs_block_iterate2(filsys_, it_ino, flags,
224                                  nullptr,  // block_buf
225                                  ProcessInodeAllBlocks,
226                                  &file.extents);
227
228    if (error) {
229      LOG(ERROR) << "Failed to enumerate inode " << it_ino
230                << " blocks (" << error << ")";
231      continue;
232    }
233    if (it_ino >= EXT2_GOOD_OLD_FIRST_INO) {
234      ext2fs_block_iterate2(filsys_, it_ino, 0, nullptr,
235                            AddMetadataBlocks,
236                            &inode_blocks);
237    }
238  }
239  ext2fs_close_inode_scan(iscan);
240  if (!ok)
241    return false;
242
243  // The set of inodes already added to the output. There can be less elements
244  // here than in files since the later can contain repeated inodes due to
245  // hardlink files.
246  set<ext2_ino_t> used_inodes;
247
248  UpdateFileAndAppendState priv_data;
249  priv_data.inodes = &inodes;
250  priv_data.used_inodes = &used_inodes;
251  priv_data.files = files;
252  priv_data.filsys = filsys_;
253
254  files->clear();
255  // Iterate over all the files of each directory to update the name and add it.
256  for (ext2_ino_t dir_ino : directories) {
257    char* dir_name = nullptr;
258    errcode_t error = ext2fs_get_pathname(filsys_, dir_ino, 0, &dir_name);
259    if (error) {
260      // Not being able to read a directory name is not a fatal error, it is
261      // just skiped.
262      LOG(WARNING) << "Reading directory name on inode " << dir_ino
263                   << " (error " << error << ")";
264      inodes[dir_ino].name = base::StringPrintf("<dir-%u>", dir_ino);
265    } else {
266      inodes[dir_ino].name = dir_name;
267      files->push_back(inodes[dir_ino]);
268      used_inodes.insert(dir_ino);
269    }
270    ext2fs_free_mem(&dir_name);
271
272    error = ext2fs_dir_iterate2(
273        filsys_, dir_ino, 0, nullptr /* block_buf */,
274        UpdateFileAndAppend, &priv_data);
275    if (error) {
276      LOG(WARNING) << "Failed to enumerate files in directory "
277                   << inodes[dir_ino].name << " (error " << error << ")";
278    }
279  }
280
281  // Add <inode-blocks> file with the blocks that hold inodes.
282  File inode_file;
283  inode_file.name = "<inode-blocks>";
284  for (uint64_t block : inode_blocks) {
285    AppendBlockToExtents(&inode_file.extents, block);
286  }
287  files->push_back(inode_file);
288
289  // Add <free-spacce> blocs.
290  errcode_t error = ext2fs_read_block_bitmap(filsys_);
291  if (error) {
292    LOG(ERROR) << "Reading the blocks bitmap (error " << error << ")";
293  } else {
294    File free_space;
295    free_space.name = "<free-space>";
296    blk64_t blk_start = ext2fs_get_block_bitmap_start2(filsys_->block_map);
297    blk64_t blk_end = ext2fs_get_block_bitmap_end2(filsys_->block_map);
298    for (blk64_t block = blk_start; block < blk_end; block++) {
299      if (!ext2fs_test_block_bitmap2(filsys_->block_map, block))
300        AppendBlockToExtents(&free_space.extents, block);
301    }
302    files->push_back(free_space);
303  }
304
305  // Add all the unreachable files plus the pseudo-files with an inode. Since
306  // these inodes aren't files in the filesystem, ignore the empty ones.
307  for (const auto& ino_file : inodes) {
308    if (used_inodes.find(ino_file.first) != used_inodes.end())
309      continue;
310    if (ino_file.second.extents.empty())
311      continue;
312
313    File file = ino_file.second;
314    ExtentRanges ranges;
315    ranges.AddExtents(file.extents);
316    file.extents = ranges.GetExtentsForBlockCount(ranges.blocks());
317
318    files->push_back(file);
319  }
320
321  return true;
322}
323
324bool Ext2Filesystem::LoadSettings(brillo::KeyValueStore* store) const {
325  // First search for the settings inode following symlinks if we find some.
326  ext2_ino_t ino_num = 0;
327  errcode_t err = ext2fs_namei_follow(
328      filsys_, EXT2_ROOT_INO /* root */, EXT2_ROOT_INO /* cwd */,
329      "/etc/update_engine.conf", &ino_num);
330  if (err != 0)
331    return false;
332
333  ext2_inode ino_data;
334  if (ext2fs_read_inode(filsys_, ino_num, &ino_data) != 0)
335    return false;
336
337  // Load the list of blocks and then the contents of the inodes.
338  vector<Extent> extents;
339  err = ext2fs_block_iterate2(filsys_, ino_num, BLOCK_FLAG_DATA_ONLY,
340                              nullptr,  // block_buf
341                              ProcessInodeAllBlocks,
342                              &extents);
343  if (err != 0)
344    return false;
345
346  brillo::Blob blob;
347  uint64_t physical_size = BlocksInExtents(extents) * filsys_->blocksize;
348  // Sparse holes in the settings file are not supported.
349  if (EXT2_I_SIZE(&ino_data) > physical_size)
350    return false;
351  if (!utils::ReadExtents(filename_, extents, &blob, physical_size,
352                          filsys_->blocksize))
353    return false;
354
355  string text(blob.begin(), blob.begin() + EXT2_I_SIZE(&ino_data));
356  return store->LoadFromString(text);
357}
358
359}  // namespace chromeos_update_engine
360