// Copyright (c) 2012 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.
// This file defines FileStream, a basic interface for reading and writing files
// synchronously or asynchronously with support for seeking to an offset.
// Note that even when used asynchronously, only one operation is supported at
// a time.
#ifndef NET_BASE_FILE_STREAM_H_
#define NET_BASE_FILE_STREAM_H_
#include "base/files/file.h"
#include "base/platform_file.h"
#include "base/task_runner.h"
#include "net/base/completion_callback.h"
#include "net/base/file_stream_whence.h"
#include "net/base/net_export.h"
#include "net/base/net_log.h"
namespace base {
class FilePath;
}
namespace net {
class IOBuffer;
class NET_EXPORT FileStream {
public:
// Creates a |FileStream| with a new |BoundNetLog| (based on |net_log|)
// attached. |net_log| may be NULL if no logging is needed.
// Uses |task_runner| for asynchronous operations.
FileStream(net::NetLog* net_log,
const scoped_refptr<base::TaskRunner>& task_runner);
// Same as above, but runs async tasks in base::WorkerPool.
explicit FileStream(net::NetLog* net_log);
// Construct a FileStream with an existing file handle and opening flags.
// |file| is valid file handle.
// |flags| is a bitfield of base::PlatformFileFlags when the file handle was
// opened.
// |net_log| is the net log pointer to use to create a |BoundNetLog|. May be
// NULL if logging is not needed.
// Uses |task_runner| for asynchronous operations.
// Note: the new FileStream object takes ownership of the PlatformFile and
// will close it on destruction.
// This constructor is deprecated.
// TODO(rvargas): remove all references to PlatformFile.
FileStream(base::PlatformFile file,
int flags,
net::NetLog* net_log,
const scoped_refptr<base::TaskRunner>& task_runner);
// Same as above, but runs async tasks in base::WorkerPool.
// This constructor is deprecated.
FileStream(base::PlatformFile file, int flags, net::NetLog* net_log);
// Non-deprecated versions of the previous two constructors.
FileStream(base::File file,
net::NetLog* net_log,
const scoped_refptr<base::TaskRunner>& task_runner);
FileStream(base::File file, net::NetLog* net_log);
// The underlying file is closed automatically.
virtual ~FileStream();
// Call this method to open the FileStream asynchronously. The remaining
// methods cannot be used unless the file is opened successfully. Returns
// ERR_IO_PENDING if the operation is started. If the operation cannot be
// started then an error code is returned.
//
// Once the operation is done, |callback| will be run on the thread where
// Open() was called, with the result code. open_flags is a bitfield of
// base::PlatformFileFlags.
//
// If the file stream is not closed manually, the underlying file will be
// automatically closed when FileStream is destructed in an asynchronous
// manner (i.e. the file stream is closed in the background but you don't
// know when).
virtual int Open(const base::FilePath& path, int open_flags,
const CompletionCallback& callback);
// Call this method to open the FileStream synchronously.
// The remaining methods cannot be used unless this method returns OK. If
// the file cannot be opened then an error code is returned. open_flags is
// a bitfield of base::PlatformFileFlags
//
// If the file stream is not closed manually, the underlying file will be
// automatically closed when FileStream is destructed.
virtual int OpenSync(const base::FilePath& path, int open_flags);
// Returns ERR_IO_PENDING and closes the file asynchronously, calling
// |callback| when done.
// It is invalid to request any asynchronous operations while there is an
// in-flight asynchronous operation.
virtual int Close(const CompletionCallback& callback);
// Closes the file immediately and returns OK. If the file is open
// asynchronously, Close(const CompletionCallback&) should be used instead.
virtual int CloseSync();
// Returns true if Open succeeded and Close has not been called.
virtual bool IsOpen() const;
// Adjust the position from where data is read asynchronously.
// Upon success, ERR_IO_PENDING is returned and |callback| will be run
// on the thread where Seek() was called with the the stream position
// relative to the start of the file. Otherwise, an error code is returned.
// It is invalid to request any asynchronous operations while there is an
// in-flight asynchronous operation.
virtual int Seek(Whence whence, int64 offset,
const Int64CompletionCallback& callback);
// Adjust the position from where data is read synchronously.
// Upon success, the stream position relative to the start of the file is
// returned. Otherwise, an error code is returned. It is not valid to
// call SeekSync while a Read call has a pending completion.
virtual int64 SeekSync(Whence whence, int64 offset);
// Returns the number of bytes available to read from the current stream
// position until the end of the file. Otherwise, an error code is returned.
virtual int64 Available();
// Call this method to read data from the current stream 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.
//
// The file must be opened with PLATFORM_FILE_ASYNC, and a non-null
// callback must be passed to this method. 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 valid to destroy or close the file stream while there is an
// asynchronous read in progress. That will cancel the read and allow
// the buffer to be freed.
//
// It is invalid to request any asynchronous operations while there is an
// in-flight asynchronous operation.
//
// This method must not be called if the stream was opened WRITE_ONLY.
virtual int Read(IOBuffer* buf, int buf_len,
const CompletionCallback& callback);
// Call this method to read data from the current stream position
// synchronously. 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.
//
// The file must not be opened with PLATFORM_FILE_ASYNC.
// This method must not be called if the stream was opened WRITE_ONLY.
virtual int ReadSync(char* buf, int buf_len);
// Performs the same as ReadSync, but ensures that exactly buf_len bytes
// are copied into buf. A partial read may occur, but only as a result of
// end-of-file or fatal error. Returns the number of bytes copied into buf,
// 0 if at end-of-file and no bytes have been read into buf yet,
// or an error code if the operation could not be performed.
virtual int ReadUntilComplete(char *buf, int buf_len);
// Call this method to write data at the current stream position
// asynchronously. Up to buf_len bytes will be written from buf. (In
// other words, partial writes are allowed.) Returns the number of
// bytes written, or an error code if the operation could not be
// performed.
//
// The file must be opened with PLATFORM_FILE_ASYNC, and a non-null
// callback must be passed to this method. If the write could not
// complete synchronously, then ERR_IO_PENDING is returned, and the
// callback will be run on the thread where Write() was called when
// the write has completed.
//
// It is valid to destroy or close the file stream while there is an
// asynchronous write in progress. That will cancel the write and allow
// the buffer to be freed.
//
// It is invalid to request any asynchronous operations while there is an
// in-flight asynchronous operation.
//
// This method must not be called if the stream was opened READ_ONLY.
//
// Zero byte writes are not allowed.
virtual int Write(IOBuffer* buf, int buf_len,
const CompletionCallback& callback);
// Call this method to write data at the current stream position
// synchronously. Up to buf_len bytes will be written from buf. (In
// other words, partial writes are allowed.) Returns the number of
// bytes written, or an error code if the operation could not be
// performed.
//
// The file must not be opened with PLATFORM_FILE_ASYNC.
// This method must not be called if the stream was opened READ_ONLY.
//
// Zero byte writes are not allowed.
virtual int WriteSync(const char* buf, int buf_len);
// Truncates the file to be |bytes| length. This is only valid for writable
// files. After truncation the file stream is positioned at |bytes|. The new
// position is returned, or a value < 0 on error.
// WARNING: one may not truncate a file beyond its current length on any
// platform with this call.
virtual int64 Truncate(int64 bytes);
// Forces out a filesystem sync on this file to make sure that the file was
// written out to disk and is not currently sitting in the buffer. This does
// not have to be called, it just forces one to happen at the time of
// calling.
//
// The file must be opened with PLATFORM_FILE_ASYNC, and a non-null
// callback must be passed to this method. If the write could not
// complete synchronously, then ERR_IO_PENDING is returned, and the
// callback will be run on the thread where Flush() was called when
// the write has completed.
//
// It is valid to destroy or close the file stream while there is an
// asynchronous flush in progress. That will cancel the flush and allow
// the buffer to be freed.
//
// It is invalid to request any asynchronous operations while there is an
// in-flight asynchronous operation.
//
// This method should not be called if the stream was opened READ_ONLY.
virtual int Flush(const CompletionCallback& callback);
// Forces out a filesystem sync on this file to make sure that the file was
// written out to disk and is not currently sitting in the buffer. This does
// not have to be called, it just forces one to happen at the time of
// calling.
//
// Returns an error code if the operation could not be performed.
//
// This method should not be called if the stream was opened READ_ONLY.
virtual int FlushSync();
// Turns on UMA error statistics gathering.
void EnableErrorStatistics();
// Sets the source reference for net-internals logging.
// Creates source dependency events between |owner_bound_net_log| and
// |bound_net_log_|. Each gets an event showing the dependency on the other.
// If only one of those is valid, it gets an event showing that a change
// of ownership happened, but without details.
void SetBoundNetLogSource(const net::BoundNetLog& owner_bound_net_log);
// Returns the underlying platform file for testing.
const base::File& GetFileForTesting() const;
private:
class Context;
net::BoundNetLog bound_net_log_;
// Context performing I/O operations. It was extracted into a separate class
// to perform asynchronous operations because FileStream can be destroyed
// before completion of an async operation. Also if a FileStream is destroyed
// without explicitly calling Close, the file should be closed asynchronously
// without delaying FileStream's destructor.
scoped_ptr<Context> context_;
DISALLOW_COPY_AND_ASSIGN(FileStream);
};
} // namespace net
#endif // NET_BASE_FILE_STREAM_H_