1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef STORAGE_BROWSER_FILEAPI_FILE_STREAM_WRITER_H_ 6 #define STORAGE_BROWSER_FILEAPI_FILE_STREAM_WRITER_H_ 7 8 #include "base/basictypes.h" 9 #include "net/base/completion_callback.h" 10 #include "storage/browser/storage_browser_export.h" 11 12 namespace base { 13 class FilePath; 14 class TaskRunner; 15 } 16 17 namespace net { 18 class IOBuffer; 19 } 20 21 namespace storage { 22 23 // A generic interface for writing to a file-like object. 24 class FileStreamWriter { 25 public: 26 enum OpenOrCreate { OPEN_EXISTING_FILE, CREATE_NEW_FILE }; 27 28 // Creates a writer for the existing file in the path |file_path| starting 29 // from |initial_offset|. Uses |task_runner| for async file operations. 30 STORAGE_EXPORT static FileStreamWriter* CreateForLocalFile( 31 base::TaskRunner* task_runner, 32 const base::FilePath& file_path, 33 int64 initial_offset, 34 OpenOrCreate open_or_create); 35 36 // Closes the file. If there's an in-flight operation, it is canceled (i.e., 37 // the callback function associated with the operation is not called). 38 virtual ~FileStreamWriter() {} 39 40 // Writes to the current cursor position asynchronously. 41 // 42 // Up to buf_len bytes will be written. (In other words, partial 43 // writes are allowed.) If the write completed synchronously, it returns 44 // the number of bytes written. If the operation could not be performed, it 45 // returns an error code. Otherwise, net::ERR_IO_PENDING is returned, and the 46 // callback will be run on the thread where Write() was called when the write 47 // has completed. 48 // 49 // This errors out (either synchronously or via callback) with: 50 // net::ERR_FILE_NOT_FOUND: When the target file is not found. 51 // net::ERR_ACCESS_DENIED: When the target file is a directory or 52 // the writer has no permission on the file. 53 // net::ERR_FILE_NO_SPACE: When the write will result in out of quota 54 // or there is not enough room left on the disk. 55 // 56 // It is invalid to call Write while there is an in-flight async operation. 57 virtual int Write(net::IOBuffer* buf, int buf_len, 58 const net::CompletionCallback& callback) = 0; 59 60 // Cancels an in-flight async operation. 61 // 62 // If the cancel is finished synchronously, it returns net::OK. If the 63 // cancel could not be performed, it returns an error code. Especially when 64 // there is no in-flight operation, net::ERR_UNEXPECTED is returned. 65 // Otherwise, net::ERR_IO_PENDING is returned, and the callback will be run on 66 // the thread where Cancel() was called when the cancel has completed. It is 67 // invalid to call Cancel() more than once on the same async operation. 68 // 69 // In either case, the callback function passed to the in-flight async 70 // operation is dismissed immediately when Cancel() is called, and thus 71 // will never be called. 72 virtual int Cancel(const net::CompletionCallback& callback) = 0; 73 74 // Flushes the data written so far. 75 // 76 // If the flush finished synchronously, it return net::OK. If the flush could 77 // not be performed, it returns an error code. Otherwise, net::ERR_IO_PENDING 78 // is returned, and the callback will be run on the thread where Flush() was 79 // called when the flush has completed. 80 // 81 // It is invalid to call Flush while there is an in-flight async operation. 82 virtual int Flush(const net::CompletionCallback& callback) = 0; 83 }; 84 85 } // namespace storage 86 87 #endif // STORAGE_BROWSER_FILEAPI_FILE_STREAM_WRITER_H_ 88
