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#ifndef UPDATE_ENGINE_COMMON_FILE_FETCHER_H_
18#define UPDATE_ENGINE_COMMON_FILE_FETCHER_H_
19
20#include <memory>
21#include <string>
22#include <utility>
23
24#include <base/logging.h>
25#include <base/macros.h>
26#include <brillo/message_loops/message_loop.h>
27#include <brillo/streams/stream.h>
28
29#include "update_engine/common/http_fetcher.h"
30
31// This is a concrete implementation of HttpFetcher that reads files
32// asynchronously.
33
34namespace chromeos_update_engine {
35
36class FileFetcher : public HttpFetcher {
37 public:
38  // Returns whether the passed url is supported.
39  static bool SupportedUrl(const std::string& url);
40
41  FileFetcher() : HttpFetcher(nullptr) {}
42
43  // Cleans up all internal state. Does not notify delegate.
44  ~FileFetcher() override;
45
46  // HttpFetcher overrides.
47  void SetOffset(off_t offset) override { offset_ = offset; }
48  void SetLength(size_t length) override { data_length_ = length; }
49  void UnsetLength() override { SetLength(0); }
50
51  // Begins the transfer if it hasn't already begun.
52  void BeginTransfer(const std::string& url) override;
53
54  // If the transfer is in progress, aborts the transfer early. The transfer
55  // cannot be resumed.
56  void TerminateTransfer() override;
57
58  // Ignore all extra headers for files.
59  void SetHeader(const std::string& header_name,
60                 const std::string& header_value) override {};
61
62  // Suspend the asynchronous file read.
63  void Pause() override;
64
65  // Resume the suspended file read.
66  void Unpause() override;
67
68  size_t GetBytesDownloaded() override {
69    return static_cast<size_t>(bytes_copied_);
70  }
71
72  // Ignore all the time limits for files.
73  void set_low_speed_limit(int low_speed_bps, int low_speed_sec) override {}
74  void set_connect_timeout(int connect_timeout_seconds) override {}
75  void set_max_retry_count(int max_retry_count) override {}
76
77 private:
78  // Cleans up the fetcher, resetting its status to a newly constructed one.
79  void CleanUp();
80
81  // Schedule a new asynchronous read if the stream is not paused and no other
82  // read is in process. This method can be called at any point.
83  void ScheduleRead();
84
85  // Called from the main loop when a single read from |stream_| succeeds or
86  // fails, calling OnReadDoneCallback() and OnReadErrorCallback() respectively.
87  void OnReadDoneCallback(size_t bytes_read);
88  void OnReadErrorCallback(const brillo::Error* error);
89
90  // Whether the transfer was started and didn't finish yet.
91  bool transfer_in_progress_{false};
92
93  // Whether the transfer is paused.
94  bool transfer_paused_{false};
95
96  // Whether there's an ongoing asynchronous read. When this value is true, the
97  // the |buffer_| is being used by the |stream_|.
98  bool ongoing_read_{false};
99
100  // Total number of bytes copied.
101  uint64_t bytes_copied_{0};
102
103  // The offset inside the file where the read should start.
104  uint64_t offset_{0};
105
106  // The length of the data or -1 if unknown (will read until EOF).
107  int64_t data_length_{-1};
108
109  brillo::StreamPtr stream_;
110
111  // The buffer used for reading from the stream.
112  brillo::Blob buffer_;
113
114  DISALLOW_COPY_AND_ASSIGN(FileFetcher);
115};
116
117}  // namespace chromeos_update_engine
118
119#endif  // UPDATE_ENGINE_COMMON_FILE_FETCHER_H_
120