src/base/utils/io.h

   1 /*
   2  * Bittorrent Client using Qt and libtorrent.
   3  * Copyright (C) 2020  Mike Tzou (Chocobo1)
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version 2
   8  * of the License, or (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  18  *
  19  * In addition, as a special exception, the copyright holders give permission to
  20  * link this program with the OpenSSL project's "OpenSSL" library (or with
  21  * modified versions of it that use the same license as the "OpenSSL" library),
  22  * and distribute the linked executables. You must obey the GNU General Public
  23  * License in all respects for all of the code used other than "OpenSSL".  If you
  24  * modify file(s), you may extend this exception to your version of the file(s),
  25  * but you are not obligated to do so. If you do not wish to do so, delete this
  26  * exception statement from your version.
  27  */
  28
  29 #pragma once
  30
  31 #include <iterator>
  32 #include <memory>
  33
  34 #include <libtorrent/fwd.hpp>
  35
  36 #include <QIODevice>
  37
  38 #include "base/3rdparty/expected.hpp"
  39 #include "base/pathfwd.h"
  40
  41 class QByteArray;
  42 class QFileDevice;
  43 class QString;
  44
  45 namespace Utils::IO
  46 {
  47     // A wrapper class that satisfy LegacyOutputIterator requirement
  48     class FileDeviceOutputIterator
  49     {
  50     public:
  51         // std::iterator_traits
  52         using iterator_category = std::output_iterator_tag;
  53         using difference_type = void;
  54         using value_type = void;
  55         using pointer = void;
  56         using reference = void;
  57
  58         explicit FileDeviceOutputIterator(QFileDevice &device, int bufferSize = (4 * 1024));
  59         FileDeviceOutputIterator(const FileDeviceOutputIterator &other) = default;
  60         ~FileDeviceOutputIterator();
  61
  62         // mimic std::ostream_iterator behavior
  63         FileDeviceOutputIterator &operator=(char c);
  64
  65         constexpr FileDeviceOutputIterator &operator*()
  66         {
  67             return *this;
  68         }
  69
  70         constexpr FileDeviceOutputIterator &operator++()
  71         {
  72             return *this;
  73         }
  74
  75         constexpr FileDeviceOutputIterator &operator++(int)
  76         {
  77             return *this;
  78         }
  79
  80     private:
  81         QFileDevice *m_device = nullptr;
  82         std::shared_ptr<QByteArray> m_buffer;
  83         int m_bufferSize = 0;
  84     };
  85
  86     struct ReadError
  87     {
  88         enum Code
  89         {
  90             NotExist,
  91             ExceedSize,
  92             Failed,  // `read()` operation failed
  93             SizeMismatch
  94         };
  95
  96         Code status = {};
  97         QString message;
  98     };
  99
 100     // TODO: define a specific type for `additionalMode`
 101     // providing `size` is explicit and is strongly recommended
 102     nonstd::expected<QByteArray, ReadError> readFile(const Path &path, qint64 size, QIODevice::OpenMode additionalMode = {});
 103
 104     nonstd::expected<void, QString> saveToFile(const Path &path, const QByteArray &data);
 105     nonstd::expected<void, QString> saveToFile(const Path &path, const lt::entry &data);
 106     nonstd::expected<Path, QString> saveToTempFile(const QByteArray &data);
 107     nonstd::expected<Path, QString> saveToTempFile(const lt::entry &data);
 108 }