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| 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/storage/webkit_storage_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_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_ | |
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