Differential updates for components.

chrome/browser/component_updater/component_patcher.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_PATCHER_H_
+#define CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_PATCHER_H_
+
+#include "base/basictypes.h"
+#include "base/files/file_path.h"

[cpu_(ooo_6.6-7.5), 2013/05/29 20:06:44]

I am guessing you can forward declare FilePath here.

[waffles, 2013/06/13 20:55:04]

Done.

+
+class ComponentInstaller;
+
+enum DeltaUpdateResult {

[cpu_(ooo_6.6-7.5), 2013/05/29 20:06:44]

while the all caps constants in enums is a valid style, is best to use the same
style as in the other files in /component_updater/ for example 

Events {
  kManifestCheck,
  kComponentUpdated,
  kManifestError,
  kNetworkError,
  kUnpackError,
  kInstallerError
};

[waffles, 2013/06/13 20:55:04]

Done. We've unified this with the unpacker error codes, since they overlapped
anyways.

+  // Indicates success.
+  DELTA_OK,
+
+  // Either the file doesn't exist or the expected hash is invalid.
+  DELTA_VERIFICATION_INPUT_ERROR,
+
+  // The expected hash and the actual hash don't match.
+  DELTA_VERIFICATION_FAILURE,
+
+  // commands.json is malformed, or references files that don't exist.
+  DELTA_BAD_COMMANDS,
+
+  // commands.json contains an unsupported command.
+  DELTA_UNSUPPORTED_COMMAND,
+
+  // There was a generic I/O error.
+  DELTA_IO_ERROR,
+
+  // The operation (courgette/bsdiff/move/...) failed.
+  DELTA_OPERATION_FAILURE,
+
+  // The process which runs Courgette failed to start or the exit code of
+  // the process could not be retrieved.
+  DELTA_PATCH_PROCESS_FAILURE,
+};
+
+// The type of a patch file.
+enum PatchType {
+  PATCH_TYPE_UNKNOWN,
+  PATCH_TYPE_COURGETTE,
+  PATCH_TYPE_BSDIFF,
+};
+
+// Applies a delta patch to a file.

[cpu_(ooo_6.6-7.5), 2013/05/29 20:06:44]

we can beef a bit this description, like explaining that takes |input_file| and
uses |patch_file| with ...e tc.

[waffles, 2013/06/13 20:55:04]

Done.

+class ComponentPatcher {
+ public:
+  ComponentPatcher() {}
+  virtual DeltaUpdateResult Patch(PatchType patch_type,
+                                  const base::FilePath& input_file,
+                                  const base::FilePath& patch_file,
+                                  const base::FilePath& output_file,
+                                  int* error) = 0;
+  virtual ~ComponentPatcher() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ComponentPatcher);

[cpu_(ooo_6.6-7.5), 2013/05/29 20:06:44]

abstract base classes we normally don't put DISALLOW_COPY_AND_ASSIGN or ctors,
again refer to the style used in component_updater_service.h

[waffles, 2013/06/13 20:55:04]

Done.

+};
+
+class ComponentPatcherCrossPlatform : public ComponentPatcher {
+ public:
+  ComponentPatcherCrossPlatform();
+  virtual DeltaUpdateResult Patch(PatchType patch_type,
+                                  const base::FilePath& input_file,
+                                  const base::FilePath& patch_file,
+                                  const base::FilePath& output_file,
+                                  int* error) OVERRIDE;

[cpu_(ooo_6.6-7.5), 2013/05/29 20:06:44]

use of override macro might require the compiler_specific.h include

[waffles, 2013/06/13 20:55:04]

Done.

+ private:
+  DISALLOW_COPY_AND_ASSIGN(ComponentPatcherCrossPlatform);
+};
+
+// Recreates the content of a full CRX by taking the unpacked files of a
+// differential component update in |input_dir| and patching the installed
+// component files.
+// The resulting files are written into the |unpack_dir| directory.
+DeltaUpdateResult DifferentialUpdatePatch(const base::FilePath& input_dir,
+                                          const base::FilePath& unpack_dir,
+                                          ComponentPatcher* component_patcher,
+                                          ComponentInstaller* installer,
+                                          int* error);
+
+#endif  // CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_PATCHER_H_