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 WEBKIT_BLOB_FILE_STREAM_READER_H_ 6 #define WEBKIT_BLOB_FILE_STREAM_READER_H_ 7 8 #include "base/basictypes.h" 9 #include "base/compiler_specific.h" 10 #include "net/base/completion_callback.h" 11 #include "webkit/browser/webkit_storage_browser_export.h" 12 13 namespace net { 14 class IOBuffer; 15 } 16 17 namespace webkit_blob { 18 19 // A generic interface for reading a file-like object. 20 class WEBKIT_STORAGE_BROWSER_EXPORT FileStreamReader { 21 public: 22 // It is valid to delete the reader at any time. If the stream is deleted 23 // while it has a pending read, its callback will not be called. 24 virtual ~FileStreamReader() {} 25 26 // Reads from the current cursor position asynchronously. 27 // 28 // Up to buf_len bytes will be copied into buf. (In other words, partial 29 // reads are allowed.) Returns the number of bytes copied, 0 if at 30 // end-of-file, or an error code if the operation could not be performed. 31 // If the read could not complete synchronously, then ERR_IO_PENDING is 32 // returned, and the callback will be run on the thread where Read() 33 // was called, when the read has completed. 34 // 35 // It is invalid to call Read while there is an in-flight Read operation. 36 // 37 // If the stream is deleted while it has an in-flight Read operation 38 // |callback| will not be called. 39 virtual int Read(net::IOBuffer* buf, int buf_len, 40 const net::CompletionCallback& callback) = 0; 41 42 // Returns the length of the file if it could successfully retrieve the 43 // file info *and* its last modification time equals to 44 // expected modification time (rv >= 0 cases). 45 // Otherwise, a negative error code is returned (rv < 0 cases). 46 // If the stream is deleted while it has an in-flight GetLength operation 47 // |callback| will not be called. 48 // Note that the return type is int64 to return a larger file's size (a file 49 // larger than 2G) but an error code should fit in the int range (may be 50 // smaller than int64 range). 51 virtual int64 GetLength(const net::Int64CompletionCallback& callback) = 0; 52 }; 53 54 } // namespace webkit_blob 55 56 #endif // WEBKIT_BLOB_FILE_STREAM_READER_H_ 57
