fileapi: Add modification time check for FileSystemFileStreamReader

webkit/fileapi/file_system_file_stream_reader.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WEBKIT_FILEAPI_FILE_SYSTEM_FILE_STREAM_READER_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_FILE_STREAM_READER_H_
 
 #include "base/bind.h"
 #include "base/memory/ref_counted.h"
 #include "base/platform_file.h"
+#include "base/time.h"
 #include "webkit/fileapi/file_system_url.h"
+#include "webkit/fileapi/fileapi_export.h"
 #include "webkit/blob/file_stream_reader.h"
 #include "webkit/blob/shareable_file_reference.h"
 
 class FilePath;
 
 namespace base {
 class SequencedTaskRunner;
 }
 
 namespace webkit_blob {
 class LocalFileStreamReader;
 }
 
 namespace fileapi {
 
 class FileSystemContext;
 
 // TODO(kinaba,satorux): This generic implementation would work for any
 // filesystems but remote filesystem should implement its own reader
 // rather than relying on FileSystemOperation::GetSnapshotFile() which
 // may force downloading the entire contents for remote files.
-class FileSystemFileStreamReader : public webkit_blob::FileStreamReader {
+class FILEAPI_EXPORT_PRIVATE FileSystemFileStreamReader
+    : public webkit_blob::FileStreamReader {
  public:
   // Creates a new FileReader for a filesystem URL |url| form |initial_offset|.
+  // |expected_modification_time| specifies the expected last modification if
+  // the value is non-null, the reader will check the underlying file's actual
+  // modification time to see if the file has been modified, and if it does any
+  // succeeding read operations should fail with ERR_UPLOAD_FILE_CHANGED error.
   FileSystemFileStreamReader(FileSystemContext* file_system_context,
                              const FileSystemURL& url,
-                             int64 initial_offset);
+                             int64 initial_offset,
+                             const base::Time& expected_modification_time);
   virtual ~FileSystemFileStreamReader();
 
   // FileStreamReader overrides.
   virtual int Read(net::IOBuffer* buf, int buf_len,
                    const net::CompletionCallback& callback) OVERRIDE;
   virtual int GetLength(
       const net::Int64CompletionCallback& callback) OVERRIDE;
 
  private:
   int CreateSnapshot(const base::Closure& callback,
                      const net::CompletionCallback& error_callback);
   void DidCreateSnapshot(
       const base::Closure& callback,
       const net::CompletionCallback& error_callback,
       base::PlatformFileError file_error,
       const base::PlatformFileInfo& file_info,
       const FilePath& platform_path,
       const scoped_refptr<webkit_blob::ShareableFileReference>& file_ref);
 
   scoped_refptr<FileSystemContext> file_system_context_;
   FileSystemURL url_;
   const int64 initial_offset_;
+  const base::Time expected_modification_time_;
   scoped_ptr<webkit_blob::LocalFileStreamReader> local_file_reader_;
   scoped_refptr<webkit_blob::ShareableFileReference> snapshot_ref_;
   bool has_pending_create_snapshot_;
   base::WeakPtrFactory<FileSystemFileStreamReader> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FileSystemFileStreamReader);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_FILE_STREAM_READER_H_