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.
5 #ifndef WEBKIT_BLOB_FILE_STREAM_READER_H_
6 #define WEBKIT_BLOB_FILE_STREAM_READER_H_
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"
24 class FileSystemContext;
28 namespace webkit_blob {
30 // A generic interface for reading a file-like object.
31 class FileStreamReader {
33 // Creates a new FileReader for a local file |file_path|.
34 // |initial_offset| specifies the offset in the file where the first read
35 // should start. If the given offset is out of the file range any
36 // read operation may error out with net::ERR_REQUEST_RANGE_NOT_SATISFIABLE.
37 // |expected_modification_time| specifies the expected last modification
38 // If the value is non-null, the reader will check the underlying file's
39 // actual modification time to see if the file has been modified, and if
40 // it does any succeeding read operations should fail with
41 // ERR_UPLOAD_FILE_CHANGED error.
42 WEBKIT_STORAGE_BROWSER_EXPORT static FileStreamReader*
43 CreateForLocalFile(base::TaskRunner* task_runner,
44 const base::FilePath& file_path,
46 const base::Time& expected_modification_time);
48 // Creates a new reader for a filesystem URL |url| form |initial_offset|.
49 // |expected_modification_time| specifies the expected last modification if
50 // the value is non-null, the reader will check the underlying file's actual
51 // modification time to see if the file has been modified, and if it does any
52 // succeeding read operations should fail with ERR_UPLOAD_FILE_CHANGED error.
53 WEBKIT_STORAGE_BROWSER_EXPORT static FileStreamReader*
54 CreateForFileSystemFile(fileapi::FileSystemContext* context,
55 const fileapi::FileSystemURL& url,
57 const base::Time& expected_modification_time);
59 // It is valid to delete the reader at any time. If the stream is deleted
60 // while it has a pending read, its callback will not be called.
61 virtual ~FileStreamReader() {}
63 // Reads from the current cursor position asynchronously.
65 // Up to buf_len bytes will be copied into buf. (In other words, partial
66 // reads are allowed.) Returns the number of bytes copied, 0 if at
67 // end-of-file, or an error code if the operation could not be performed.
68 // If the read could not complete synchronously, then ERR_IO_PENDING is
69 // returned, and the callback will be run on the thread where Read()
70 // was called, when the read has completed.
72 // It is invalid to call Read while there is an in-flight Read operation.
74 // If the stream is deleted while it has an in-flight Read operation
75 // |callback| will not be called.
76 virtual int Read(net::IOBuffer* buf, int buf_len,
77 const net::CompletionCallback& callback) = 0;
79 // Returns the length of the file if it could successfully retrieve the
80 // file info *and* its last modification time equals to
81 // expected modification time (rv >= 0 cases).
82 // Otherwise, a negative error code is returned (rv < 0 cases).
83 // If the stream is deleted while it has an in-flight GetLength operation
84 // |callback| will not be called.
85 // Note that the return type is int64 to return a larger file's size (a file
86 // larger than 2G) but an error code should fit in the int range (may be
87 // smaller than int64 range).
88 virtual int64 GetLength(const net::Int64CompletionCallback& callback) = 0;
91 } // namespace webkit_blob
93 #endif // WEBKIT_BLOB_FILE_STREAM_READER_H_