update_engine: Add MtdFileDescriptor and UbiFileDescriptor
We send a pure file descriptor to ExtentWriter. This CL changes that to
use FileDescriptor. At the same time, the CL adds two other
FileDescriptor classes MtdFileDescriptor and UbiFileDescriptor to work
with raw NAND and UBI devices. Both of these classes support either read
only or sequential write, but not both at the same time. Seek operation
is possible in read only mode.
These classes are conditionally included if USE_mtd is not '0'.
BUG=chromium:426742
TEST=unittest
TEST=USE=mtd emerge update_engine, make sure there is MtdFileDescriptor
in /usr/sbin/update_engine
TEST=emerge --unmerge android_mtdutils; USE=-mtd emerge update_engine
make sure there is no UbiFileDescriptor in that same file
Change-Id: If3ba43677d93dc4f3cea037f19866c8b546b2cae
Reviewed-on: https://chromium-review.googlesource.com/229004
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Nam Nguyen <namnguyen@chromium.org>
Tested-by: Nam Nguyen <namnguyen@chromium.org>
diff --git a/mtd_file_descriptor.h b/mtd_file_descriptor.h
new file mode 100644
index 0000000..4694016
--- /dev/null
+++ b/mtd_file_descriptor.h
@@ -0,0 +1,71 @@
+// Copyright 2014 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_MTD_FILE_DESCRIPTOR_H_
+#define UPDATE_ENGINE_MTD_FILE_DESCRIPTOR_H_
+
+// This module defines file descriptors that deal with NAND media. We are
+// concerned with raw NAND access (as MTD device), and through UBI layer.
+
+#include <mtdutils.h>
+
+#include "update_engine/file_descriptor.h"
+
+namespace chromeos_update_engine {
+
+// A class defining the file descriptor API for raw MTD device. This file
+// descriptor supports either random read, or sequential write but not both at
+// once.
+class MtdFileDescriptor : public EintrSafeFileDescriptor {
+ public:
+ MtdFileDescriptor();
+
+ static bool IsMtd(const char* path);
+
+ bool Open(const char* path, int flags, mode_t mode) override;
+ bool Open(const char* path, int flags) override;
+ ssize_t Read(void* buf, size_t count) override;
+ ssize_t Write(const void* buf, size_t count) override;
+ off64_t Seek(off64_t offset, int whence) override;
+ void Reset() override;
+
+ private:
+ std::unique_ptr<MtdReadContext, decltype(&mtd_read_close)> read_ctx_;
+ std::unique_ptr<MtdWriteContext, decltype(&mtd_write_close)> write_ctx_;
+};
+
+// TODO(namnguyen) This is a placeholder struct. This struct, and the
+// UbiFileDescriptor class below will need finalized later.
+struct UbiVolumeInfo {
+ uint64_t size;
+};
+
+// A file descriptor to update a UBI volume, similar to MtdFileDescriptor.
+// Once the file descriptor is opened for write, the volume is marked as being
+// updated. The volume will not be usable until an update is completed. See
+// UBI_IOCVOLUP ioctl operation.
+// TODO(namnguyen) Again, this needs fleshed out when we have better library to
+// interact with UBI volumes. I would expect this class to be very similar to
+// MtdFileDescriptor, with two different contexts to bridge C-C++ divide.
+class UbiFileDescriptor : public EintrSafeFileDescriptor {
+ public:
+ static bool IsUbi(const char* path);
+
+ bool Open(const char* path, int flags, mode_t mode) override;
+ bool Open(const char* path, int flags) override;
+ ssize_t Read(void* buf, size_t count) override;
+ ssize_t Write(const void* buf, size_t count) override;
+ off64_t Seek(off64_t offset, int whence) override;
+ void Reset() override;
+
+ private:
+ std::unique_ptr<UbiVolumeInfo> CreateWriteContext(const char* path);
+
+ std::unique_ptr<UbiVolumeInfo> read_ctx_;
+ std::unique_ptr<UbiVolumeInfo> write_ctx_;
+};
+
+} // namespace chromeos_update_engine
+
+#endif // UPDATE_ENGINE_MTD_FILE_DESCRIPTOR_H_