Add write and read/write support to FileStream (renamed from FileInputStream)...

net/base/file_input_stream.h

-// Copyright (c) 2008 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 FileInputStream, a basic interface for reading files
-// synchronously or asynchronously with support for seeking to an offset.
-
-#ifndef NET_BASE_FILE_INPUT_STREAM_H_
-#define NET_BASE_FILE_INPUT_STREAM_H_
-
-#include "net/base/completion_callback.h"
-
-#if defined(OS_WIN)
-typedef void* HANDLE;
-#endif
-
-namespace net {
-
-// TODO(darin): Move this to a more generic location.
-// This explicit mapping matches both FILE_ on Windows and SEEK_ on Linux.
-enum Whence {
-  FROM_BEGIN   = 0,
-  FROM_CURRENT = 1,
-  FROM_END     = 2
-};
-
-class FileInputStream {
- public:
-  FileInputStream();
-  ~FileInputStream();
-
-  // Call this method to close the FileInputStream.  It is OK to call Close
-  // multiple times.  Redundant calls are ignored.
-  void Close();
-
-  // Call this method to open the FileInputStream.  The remaining methods
-  // cannot be used unless this method returns OK.  If the file cannot be
-  // opened then an error code is returned.
-  // NOTE: The underlying file is opened with non-exclusive access.
-  int Open(const std::wstring& path, bool asynchronous_mode);
-
-  // Returns true if Open succeeded and Close has not been called.
-  bool IsOpen() const;
-
-  // Adjust the position from where data is read.  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 Seek while a Read call
-  // has a pending completion.
-  int64 Seek(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.
-  int64 Available();
-
-  // Call this method to read data from the current stream position.  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 opened with |asynchronous_mode| set to true, then a non-null callback
-  // must be passed to this method.  In asynchronous mode, if the read could
-  // not complete synchronously, then ERR_IO_PENDING is returned, and the
-  // callback will be notified on the current thread (via the MessageLoop) when
-  // the read has completed.
-  // 
-  // In the case of an asychronous read, the memory pointed to by |buf| must
-  // remain valid until the callback is notified.  However, 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.
-  // 
-  int Read(char* buf, int buf_len, CompletionCallback* callback);
-
- private:
-  class AsyncContext;
-  friend class AsyncContext;
-
-  // This member is used to support asynchronous reads.  It is non-null when
-  // the FileInputStream was opened with asynchronous_mode set to true.
-  scoped_ptr<AsyncContext> async_context_;
-
-#if defined(OS_WIN)
-  HANDLE handle_;
-#elif defined(OS_POSIX)
-  int fd_;
-#endif
-
-  DISALLOW_COPY_AND_ASSIGN(FileInputStream);
-};
-
-}  // namespace net
-
-#endif  // NET_BASE_FILE_INPUT_STREAM_H_