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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef STORAGE_BROWSER_FILE_SYSTEM_FILE_STREAM_READER_H_
#define STORAGE_BROWSER_FILE_SYSTEM_FILE_STREAM_READER_H_
#include <stdint.h>
#include <memory>
#include "base/compiler_specific.h"
#include "base/component_export.h"
#include "base/files/file.h"
#include "base/functional/callback_forward.h"
#include "base/functional/callback_helpers.h"
#include "base/memory/weak_ptr.h"
#include "components/file_access/scoped_file_access.h"
#include "components/file_access/scoped_file_access_delegate.h"
#include "components/services/storage/public/cpp/filesystem/filesystem_proxy.h"
#include "net/base/completion_once_callback.h"
namespace base {
class FilePath;
class TaskRunner;
class Time;
} // namespace base
namespace net {
class IOBuffer;
}
namespace storage {
// A generic interface for reading a file-like object.
class FileStreamReader {
public:
// Creates a new FileReader for a local file |file_path|.
// |initial_offset| specifies the offset in the file where the first read
// should start. If the given offset is out of the file range any
// read operation may error out with net::ERR_REQUEST_RANGE_NOT_SATISFIABLE.
// |expected_modification_time| specifies the expected last modification
// If the value is non-null, the reader will check the underlying file's
// actual modification time to see if the file has been modified, and if
// it does any succeeding read operations should fail with
// ERR_UPLOAD_FILE_CHANGED error.
COMPONENT_EXPORT(STORAGE_BROWSER)
static std::unique_ptr<FileStreamReader> CreateForLocalFile(
scoped_refptr<base::TaskRunner> task_runner,
const base::FilePath& file_path,
int64_t initial_offset,
const base::Time& expected_modification_time,
file_access::ScopedFileAccessDelegate::RequestFilesAccessIOCallback
file_access = base::NullCallback());
// Verify if the underlying file has not been modified.
COMPONENT_EXPORT(STORAGE_BROWSER)
static bool VerifySnapshotTime(const base::Time& expected_modification_time,
const base::File::Info& file_info);
// It is valid to delete the reader at any time. If the stream is deleted
// while it has a pending read, its callback will not be called.
virtual ~FileStreamReader() = default;
// Reads from the current cursor position asynchronously.
//
// Up to buf_len bytes will be copied into buf. (In other words, partial
// reads are allowed.) Returns the number of bytes copied, 0 if at
// end-of-file, or an error code if the operation could not be performed.
// If the read could not complete synchronously, then ERR_IO_PENDING is
// returned, and the callback will be run on the thread where Read()
// was called, when the read has completed.
//
// It is invalid to call Read while there is an in-flight Read operation.
//
// If the stream is deleted while it has an in-flight Read operation
// |callback| will not be called.
virtual int Read(net::IOBuffer* buf,
int buf_len,
net::CompletionOnceCallback callback) = 0;
// Returns the length of the file if it could successfully retrieve the
// file info *and* its last modification time equals to
// expected modification time (rv >= 0 cases).
// Otherwise, a negative error code is returned (rv < 0 cases).
// If the stream is deleted while it has an in-flight GetLength operation
// |callback| will not be called.
// Note that the return type is int64_t to return a larger file's size (a file
// larger than 2G) but an error code should fit in the int range (may be
// smaller than int64_t range).
virtual int64_t GetLength(net::Int64CompletionOnceCallback callback) = 0;
};
} // namespace storage
#endif // STORAGE_BROWSER_FILE_SYSTEM_FILE_STREAM_READER_H_
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