update_engine: Introduce FilesystemInterface abstraction.
The interaction with the filesystem in the payload generation process
is hard-coded in several places, making it hard to mock out or use a
different filesystem like squashfs for delta generation. For example,
the metadata, regular file data and non-file data are handled by three
different functions in a similar way, but with different code.
This patch introcudes a filesystem abstraction to map files or
pseudo-files (like the metadata, free-space, etc) into the same interface.
The interface includes three implementations: for parsing ext2 filesystems
using ext2fs (already used by the metadata parsing but not by the file
data processing), a raw one for monolitic partitions like the kernel
and a fake one used for testing without requiring to build/parse a real
ext2 filesystem.
BUG=chromium:331965
TEST=FEATURES=test emerge-link update_engine
Change-Id: I1e14cf8f3883c8e9a1d471c8193c8da60776aa7c
Reviewed-on: https://chromium-review.googlesource.com/275803
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
diff --git a/payload_generator/fake_filesystem.h b/payload_generator/fake_filesystem.h
new file mode 100644
index 0000000..10b6683
--- /dev/null
+++ b/payload_generator/fake_filesystem.h
@@ -0,0 +1,48 @@
+// Copyright 2015 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.
+
+#ifndef UPDATE_ENGINE_PAYLOAD_GENERATOR_FAKE_FILESYSTEM_H_
+#define UPDATE_ENGINE_PAYLOAD_GENERATOR_FAKE_FILESYSTEM_H_
+
+// A fake filesystem interface implementation allowing the user to add arbitrary
+// files/metadata.
+
+#include "update_engine/payload_generator/filesystem_interface.h"
+
+#include <string>
+#include <vector>
+
+#include "update_engine/update_metadata.pb.h"
+
+namespace chromeos_update_engine {
+
+class FakeFilesystem : public FilesystemInterface {
+ public:
+ FakeFilesystem(uint64_t block_size, uint64_t block_count);
+ virtual ~FakeFilesystem() = default;
+
+ // FilesystemInterface overrides.
+ size_t GetBlockSize() const override;
+ size_t GetBlockCount() const override;
+ bool GetFiles(std::vector<File>* files) const override;
+
+ // Fake methods.
+
+ // Add a file to the list of fake files.
+ void AddFile(const std::string& filename, const std::vector<Extent> extents);
+
+ private:
+ FakeFilesystem() = default;
+
+ uint64_t block_size_;
+ uint64_t block_count_;
+
+ std::vector<File> files_;
+
+ DISALLOW_COPY_AND_ASSIGN(FakeFilesystem);
+};
+
+} // namespace chromeos_update_engine
+
+#endif // UPDATE_ENGINE_PAYLOAD_GENERATOR_FAKE_FILESYSTEM_H_