chrome/installer/setup/archive_patch_helper.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_INSTALLER_SETUP_ARCHIVE_PATCH_HELPER_H_
   6 #define CHROME_INSTALLER_SETUP_ARCHIVE_PATCH_HELPER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/files/file_path.h"
  10
  11 namespace installer {
  12
  13 // A helper class that facilitates uncompressing and patching the chrome archive
  14 // and installer.
  15 //
  16 // Chrome's installer is deployed along with a compressed archive containing
  17 // either 1) an uncompressd archive of the product binaries or 2) a patch file
  18 // to be applied to the uncompressed archive of the version being updated. To
  19 // obtain the uncompressed archive, the contents of the compressed archive are
  20 // uncompressed and extracted. Installation proceeds directly if the
  21 // uncompressed archive is found after this step. Otherwise, the patch is
  22 // applied to the previous version's uncompressed archive using either
  23 // Courgette's ensemble patching or bspatch.
  24 //
  25 // Chrome's installer itself may also be deployed as a patch against the
  26 // previous version's saved installer binary. The same process is followed to
  27 // obtain the new installer. The compressed archive unconditionally contains a
  28 // patch file in this case.
  29 class ArchivePatchHelper {
  30  public:
  31   // Constructs an instance that can uncompress |compressed_archive| into
  32   // |working_directory| and optionally apply the extracted patch file to
  33   // |patch_source|, writing the result to |target|.
  34   ArchivePatchHelper(const base::FilePath& working_directory,
  35                      const base::FilePath& compressed_archive,
  36                      const base::FilePath& patch_source,
  37                      const base::FilePath& target);
  38
  39   ~ArchivePatchHelper();
  40
  41   // Uncompresses |compressed_archive| in |working_directory| then applies the
  42   // extracted patch file to |patch_source|, writing the result to |target|.
  43   // Ensemble patching via Courgette is attempted first. If that fails, bspatch
  44   // is attempted. Returns false if uncompression or both patching steps fail.
  45   static bool UncompressAndPatch(const base::FilePath& working_directory,
  46                                  const base::FilePath& compressed_archive,
  47                                  const base::FilePath& patch_source,
  48                                  const base::FilePath& target);
  49
  50   // Uncompresses compressed_archive() into the working directory. On success,
  51   // last_uncompressed_file (if not NULL) is populated with the path to the last
  52   // file extracted from the archive.
  53   bool Uncompress(base::FilePath* last_uncompressed_file);
  54
  55   // Attempts to use courgette to apply last_uncompressed_file() to
  56   // patch_source() to generate target(). Returns false if patching fails.
  57   bool EnsemblePatch();
  58
  59   // Attempts to use bspatch to apply last_uncompressed_file() to patch_source()
  60   // to generate target(). Returns false if patching fails.
  61   bool BinaryPatch();
  62
  63   const base::FilePath& compressed_archive() const {
  64     return compressed_archive_;
  65   }
  66   void set_patch_source(const base::FilePath& patch_source) {
  67     patch_source_ = patch_source;
  68   }
  69   const base::FilePath& patch_source() const {
  70     return patch_source_;
  71   }
  72   const base::FilePath& target() const {
  73     return target_;
  74   }
  75
  76   // Returns the path of the last file extracted by Uncompress().
  77   const base::FilePath& last_uncompressed_file() const {
  78     return last_uncompressed_file_;
  79   }
  80   void set_last_uncompressed_file(
  81       const base::FilePath& last_uncompressed_file) {
  82     last_uncompressed_file_ = last_uncompressed_file;
  83   }
  84
  85  private:
  86   base::FilePath working_directory_;
  87   base::FilePath compressed_archive_;
  88   base::FilePath patch_source_;
  89   base::FilePath target_;
  90   base::FilePath last_uncompressed_file_;
  91
  92   DISALLOW_COPY_AND_ASSIGN(ArchivePatchHelper);
  93 };
  94
  95 }  // namespace installer
  96
  97 #endif  // CHROME_INSTALLER_SETUP_ARCHIVE_PATCH_HELPER_H_