AU: tolerate files that are symlinks in src image, yet not in new image.

delta_diff_generator.cc

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "update_engine/delta_diff_generator.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <sys/stat.h>
@@ skipping 123 matching lines @@
 // For each regular file within new_root, creates a node in the graph,
 // determines the best way to compress it (REPLACE, REPLACE_BZ, COPY, BSDIFF),
 // and writes any necessary data to the end of data_fd.
 bool DeltaReadFiles(Graph* graph,
                     vector<Block>* blocks,
                     const string& old_root,
                     const string& new_root,
                     int data_fd,
                     off_t* data_file_size) {
   set<ino_t> visited_inodes;
+  set<ino_t> visited_src_inodes;
   for (FilesystemIterator fs_iter(new_root,
                                   utils::SetWithValue<string>("/lost+found"));
        !fs_iter.IsEnd(); fs_iter.Increment()) {
     if (!S_ISREG(fs_iter.GetStat().st_mode))
       continue;
 
     // Make sure we visit each inode only once.
     if (utils::SetContainsKey(visited_inodes, fs_iter.GetStat().st_ino))
       continue;
     visited_inodes.insert(fs_iter.GetStat().st_ino);
     if (fs_iter.GetStat().st_size == 0)
       continue;
 
     LOG(INFO) << "Encoding file " << fs_iter.GetPartialPath();
 
+    bool should_diff_from_source = true;
+    string src_path = old_root + fs_iter.GetPartialPath();
+    if (utils::FileExists(src_path.c_str())) {
+      struct stat src_stbuf;
+      TEST_AND_RETURN_FALSE_ERRNO(0 == stat(src_path.c_str(), &src_stbuf));
+      should_diff_from_source = !utils::SetContainsKey(visited_src_inodes,

[petkov, 2011/02/15 06:01:38]

Add a comment what this is trying to catch and what action is taken?

+                                                       src_stbuf.st_ino);
+      visited_src_inodes.insert(src_stbuf.st_ino);
+    }
+
     TEST_AND_RETURN_FALSE(DeltaReadFile(graph,
                                         Vertex::kInvalidIndex,
                                         blocks,
-                                        old_root,
+                                        (should_diff_from_source ?
+                                         old_root :
+                                         "/-!@:&*nonexistent_path"),

[petkov, 2011/02/15 06:01:38]

This feels a bit of a hack. Maybe use an empty string and check for it
explicitly in DeltaReadFile?

                                         new_root,
                                         fs_iter.GetPartialPath(),
                                         data_fd,
                                         data_file_size));
   }
   return true;
 }
 
 // This class allocates non-existent temp blocks, starting from
 // kTempBlockStart. Other code is responsible for converting these
@@ skipping 1428 matching lines @@
   dummy_extent->set_start_block(kSparseHole);
   dummy_extent->set_num_blocks((signature_blob_length + kBlockSize - 1) /
                                kBlockSize);
 }
 
 const char* const kBsdiffPath = "bsdiff";
 const char* const kBspatchPath = "bspatch";
 const char* const kDeltaMagic = "CrAU";
 
 };  // namespace chromeos_update_engine