1 //
2 // Copyright (C) 2016 The Android Open Source Project
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 // http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16
17 #include "update_engine/common/file_fetcher.h"
18
19 #include <algorithm>
20 #include <string>
21
22 #include <base/bind.h>
23 #include <base/format_macros.h>
24 #include <base/location.h>
25 #include <base/logging.h>
26 #include <base/strings/string_util.h>
27 #include <base/strings/stringprintf.h>
28 #include <brillo/streams/file_stream.h>
29
30 #include "update_engine/common/hardware_interface.h"
31 #include "update_engine/common/platform_constants.h"
32
33 using std::string;
34
35 namespace {
36
37 size_t kReadBufferSize = 16 * 1024;
38
39 } // namespace
40
41 namespace chromeos_update_engine {
42
43 // static
SupportedUrl(const string & url)44 bool FileFetcher::SupportedUrl(const string& url) {
45 // Note that we require the file path to start with a "/".
46 return base::StartsWith(
47 url, "file:///", base::CompareCase::INSENSITIVE_ASCII);
48 }
49
~FileFetcher()50 FileFetcher::~FileFetcher() {
51 LOG_IF(ERROR, transfer_in_progress_)
52 << "Destroying the fetcher while a transfer is in progress.";
53 CleanUp();
54 }
55
56 // Begins the transfer, which must not have already been started.
BeginTransfer(const string & url)57 void FileFetcher::BeginTransfer(const string& url) {
58 CHECK(!transfer_in_progress_);
59
60 if (!SupportedUrl(url)) {
61 LOG(ERROR) << "Unsupported file URL: " << url;
62 // No HTTP error code when the URL is not supported.
63 http_response_code_ = 0;
64 CleanUp();
65 if (delegate_)
66 delegate_->TransferComplete(this, false);
67 return;
68 }
69
70 string file_path = url.substr(strlen("file://"));
71 stream_ =
72 brillo::FileStream::Open(base::FilePath(file_path),
73 brillo::Stream::AccessMode::READ,
74 brillo::FileStream::Disposition::OPEN_EXISTING,
75 nullptr);
76
77 if (!stream_) {
78 LOG(ERROR) << "Couldn't open " << file_path;
79 http_response_code_ = kHttpResponseNotFound;
80 CleanUp();
81 if (delegate_)
82 delegate_->TransferComplete(this, false);
83 return;
84 }
85 http_response_code_ = kHttpResponseOk;
86
87 if (offset_)
88 stream_->SetPosition(offset_, nullptr);
89 bytes_copied_ = 0;
90 transfer_in_progress_ = true;
91 ScheduleRead();
92 }
93
TerminateTransfer()94 void FileFetcher::TerminateTransfer() {
95 CleanUp();
96 if (delegate_) {
97 // Note that after the callback returns this object may be destroyed.
98 delegate_->TransferTerminated(this);
99 }
100 }
101
ScheduleRead()102 void FileFetcher::ScheduleRead() {
103 if (transfer_paused_ || ongoing_read_ || !transfer_in_progress_)
104 return;
105
106 buffer_.resize(kReadBufferSize);
107 size_t bytes_to_read = buffer_.size();
108 if (data_length_ >= 0) {
109 bytes_to_read = std::min(static_cast<uint64_t>(bytes_to_read),
110 data_length_ - bytes_copied_);
111 }
112
113 if (!bytes_to_read) {
114 OnReadDoneCallback(0);
115 return;
116 }
117
118 ongoing_read_ = stream_->ReadAsync(
119 buffer_.data(),
120 bytes_to_read,
121 base::Bind(&FileFetcher::OnReadDoneCallback, base::Unretained(this)),
122 base::Bind(&FileFetcher::OnReadErrorCallback, base::Unretained(this)),
123 nullptr);
124
125 if (!ongoing_read_) {
126 LOG(ERROR) << "Unable to schedule an asynchronous read from the stream.";
127 CleanUp();
128 if (delegate_)
129 delegate_->TransferComplete(this, false);
130 }
131 }
132
OnReadDoneCallback(size_t bytes_read)133 void FileFetcher::OnReadDoneCallback(size_t bytes_read) {
134 ongoing_read_ = false;
135 if (bytes_read == 0) {
136 CleanUp();
137 if (delegate_)
138 delegate_->TransferComplete(this, true);
139 } else {
140 bytes_copied_ += bytes_read;
141 if (delegate_)
142 delegate_->ReceivedBytes(this, buffer_.data(), bytes_read);
143 ScheduleRead();
144 }
145 }
146
OnReadErrorCallback(const brillo::Error * error)147 void FileFetcher::OnReadErrorCallback(const brillo::Error* error) {
148 LOG(ERROR) << "Asynchronous read failed: " << error->GetMessage();
149 CleanUp();
150 if (delegate_)
151 delegate_->TransferComplete(this, false);
152 }
153
Pause()154 void FileFetcher::Pause() {
155 if (transfer_paused_) {
156 LOG(ERROR) << "Fetcher already paused.";
157 return;
158 }
159 transfer_paused_ = true;
160 }
161
Unpause()162 void FileFetcher::Unpause() {
163 if (!transfer_paused_) {
164 LOG(ERROR) << "Resume attempted when fetcher not paused.";
165 return;
166 }
167 transfer_paused_ = false;
168 ScheduleRead();
169 }
170
CleanUp()171 void FileFetcher::CleanUp() {
172 if (stream_) {
173 stream_->CancelPendingAsyncOperations();
174 stream_->CloseBlocking(nullptr);
175 stream_.reset();
176 }
177 // Destroying the |stream_| releases the callback, so we don't have any
178 // ongoing read at this point.
179 ongoing_read_ = false;
180 buffer_ = brillo::Blob();
181
182 transfer_in_progress_ = false;
183 transfer_paused_ = false;
184 }
185
186 } // namespace chromeos_update_engine
187