Add FileReader interface and implement FileSystemFileReader

webkit/fileapi/file_system_file_reader.cc

+// 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.
+
+#include "webkit/fileapi/file_system_file_reader.h"
+
+#include "base/file_util_proxy.h"
+#include "base/message_loop_proxy.h"
+#include "base/platform_file.h"
+#include "net/base/file_stream.h"
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "webkit/blob/local_file_reader.h"
+#include "webkit/fileapi/file_system_context.h"
+#include "webkit/fileapi/file_system_operation_interface.h"
+
+using webkit_blob::LocalFileReader;
+
+namespace fileapi {
+
+namespace {
+
+void ReadAdapter(base::WeakPtr<FileSystemFileReader> reader,
+                 net::IOBuffer* buf, int buf_len,
+                 const net::CompletionCallback& callback) {
+  if (!reader.get())
+    return;
+  int rv = reader->Read(buf, buf_len, callback);
+  if (rv != net::ERR_IO_PENDING)
+    callback.Run(rv);
+}
+
+}
+
+FileSystemFileReader::FileSystemFileReader(
+    base::MessageLoopProxy* file_thread_proxy,
+    FileSystemContext* file_system_context,
+    const GURL& url,
+    int64 initial_offset)
+    : file_thread_proxy_(file_thread_proxy),
+      file_system_context_(file_system_context),
+      url_(url),
+      initial_offset_(initial_offset),
+      has_pending_create_snapshot_(false),
+      weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+}
+
+FileSystemFileReader::~FileSystemFileReader() {
+}
+
+int FileSystemFileReader::Read(
+    net::IOBuffer* buf, int buf_len,
+    const net::CompletionCallback& callback) {
+  if (local_file_reader_.get())
+    return local_file_reader_->Read(buf, buf_len, callback);
+  DCHECK(!has_pending_create_snapshot_);
+  FileSystemOperationInterface* operation =
+      file_system_context_->CreateFileSystemOperation(
+          url_, file_thread_proxy_);
+  if (!operation)
+    return net::ERR_INVALID_URL;
+  has_pending_create_snapshot_ = true;
+  operation->CreateSnapshotFile(
+      url_,
+      base::Bind(&FileSystemFileReader::DidCreateSnapshot,
+                 weak_factory_.GetWeakPtr(),
+                 base::Bind(&ReadAdapter, weak_factory_.GetWeakPtr(),
+                            make_scoped_refptr(buf), buf_len, callback),
+                 callback));
+  return net::ERR_IO_PENDING;
+}
+
+void FileSystemFileReader::DidCreateSnapshot(
+    const base::Closure& read_closure,
+    const net::CompletionCallback& callback,
+    base::PlatformFileError file_error,
+    const base::PlatformFileInfo& file_info,
+    const FilePath& platform_path,
+    const scoped_refptr<webkit_blob::ShareableFileReference>& file_ref) {
+  DCHECK(has_pending_create_snapshot_);
+  DCHECK(!local_file_reader_.get());
+  has_pending_create_snapshot_ = false;
+
+  if (file_error != base::PLATFORM_FILE_OK) {
+    callback.Run(LocalFileReader::PlatformFileErrorToNetError(file_error));
+    return;
+  }
+
+  // Keep the reference (if it's non-null) so that the file won't go away.
+  snapshot_ref_ = file_ref;
+
+  local_file_reader_.reset(
+      new LocalFileReader(file_thread_proxy_,
+                          platform_path,
+                          initial_offset_,
+                          base::Time()));
+
+  read_closure.Run();
+}
+
+}  // namespace fileapi