read_file.cc revision cedac228d2dd51db4b79ea1e72c7f249408ee061 
1// Copyright 2014 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#include "chrome/browser/chromeos/file_system_provider/operations/read_file.h"
6
7#include <limits>
8#include <string>
9
10#include "chrome/common/extensions/api/file_system_provider.h"
11#include "chrome/common/extensions/api/file_system_provider_internal.h"
12
13namespace chromeos {
14namespace file_system_provider {
15namespace operations {
16namespace {
17
18// Convert |value| into |output|. If parsing fails, then returns a negative
19// value. Otherwise returns number of bytes written to the buffer.
20int CopyRequestValueToBuffer(scoped_ptr<RequestValue> value,
21                             net::IOBuffer* buffer,
22                             int buffer_offset,
23                             int buffer_length) {
24  using extensions::api::file_system_provider_internal::
25      ReadFileRequestedSuccess::Params;
26
27  const Params* params = value->read_file_success_params();
28  if (!params)
29    return -1;
30
31  const size_t chunk_size = params->data.length();
32
33  // Check for overflows.
34  if (chunk_size > static_cast<size_t>(buffer_length) - buffer_offset)
35    return -1;
36
37  memcpy(buffer->data() + buffer_offset, params->data.c_str(), chunk_size);
38
39  return chunk_size;
40}
41
42}  // namespace
43
44ReadFile::ReadFile(
45    extensions::EventRouter* event_router,
46    const ProvidedFileSystemInfo& file_system_info,
47    int file_handle,
48    net::IOBuffer* buffer,
49    int64 offset,
50    int length,
51    const ProvidedFileSystemInterface::ReadChunkReceivedCallback& callback)
52    : Operation(event_router, file_system_info),
53      file_handle_(file_handle),
54      buffer_(buffer),
55      offset_(offset),
56      length_(length),
57      current_offset_(0),
58      callback_(callback) {
59}
60
61ReadFile::~ReadFile() {
62}
63
64bool ReadFile::Execute(int request_id) {
65  scoped_ptr<base::ListValue> values(new base::ListValue);
66  values->AppendInteger(file_handle_);
67  values->AppendDouble(offset_);
68  values->AppendInteger(length_);
69  return SendEvent(
70      request_id,
71      extensions::api::file_system_provider::OnReadFileRequested::kEventName,
72      values.Pass());
73}
74
75void ReadFile::OnSuccess(int /* request_id */,
76                         scoped_ptr<RequestValue> result,
77                         bool has_next) {
78  const int copy_result = CopyRequestValueToBuffer(
79      result.Pass(), buffer_, current_offset_, length_);
80  DCHECK_LE(0, copy_result);
81  DCHECK(!has_next || copy_result > 0);
82  if (copy_result > 0)
83    current_offset_ += copy_result;
84  callback_.Run(copy_result, has_next, base::File::FILE_OK);
85}
86
87void ReadFile::OnError(int /* request_id */, base::File::Error error) {
88  callback_.Run(0 /* chunk_length */, false /* has_next */, error);
89}
90
91}  // namespace operations
92}  // namespace file_system_provider
93}  // namespace chromeos
94