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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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