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// Copyright 2020 The Fuchsia 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 <lib/fit/result.h>
#include <string>
#include <string_view>
#include <fbl/span.h>
#include <fbl/unique_fd.h>
#include "src/storage/volume_image/utils/reader.h"
namespace storage::volume_image {
// Reader implementation that interacts reads from a file descriptor.
class FdReader final : public Reader {
// On success returns a |FdReader| from a file descriptor pointing to |path|, and whose name is
// |path|.
static fit::result<FdReader, std::string> Create(std::string_view path);
explicit FdReader(fbl::unique_fd fd) : FdReader(std::move(fd), std::string_view()) {}
FdReader(fbl::unique_fd fd, std::string_view name);
FdReader(const FdReader&) = delete;
FdReader(FdReader&&) = default;
FdReader& operator=(const FdReader&) = delete;
FdReader& operator=(FdReader&&) = default;
uint64_t GetMaximumOffset() const override { return maximum_offset_; }
// On success data at [|offset|, |offset| + |buffer.size()|] are read into
// |buffer|.
// On error the returned result to contains a string describing the error.
fit::result<void, std::string> Read(uint64_t offset, fbl::Span<uint8_t> buffer) const final;
// Returns a unique identifier for this |FdReader|.
std::string_view name() const { return name_; }
fbl::unique_fd fd_;
// Stores a unique name for the resource represented by |fd_|, for properly reporting errors.
std::string name_;
uint64_t maximum_offset_ = 0;
} // namespace storage::volume_image