source/modules/juce_core/files/juce_TemporaryFile.cpp

   1 /*
   2   ==============================================================================
   3
   4    This file is part of the JUCE library.
   5    Copyright (c) 2022 - Raw Material Software Limited
   6
   7    JUCE is an open source library subject to commercial or open-source
   8    licensing.
   9
  10    The code included in this file is provided under the terms of the ISC license
  11    http://www.isc.org/downloads/software-support-policy/isc-license. Permission
  12    To use, copy, modify, and/or distribute this software for any purpose with or
  13    without fee is hereby granted provided that the above copyright notice and
  14    this permission notice appear in all copies.
  15
  16    JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
  17    EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
  18    DISCLAIMED.
  19
  20   ==============================================================================
  21 */
  22
  23 namespace juce
  24 {
  25
  26 // Using Random::getSystemRandom() can be a bit dangerous in multithreaded contexts!
  27 class LockedRandom
  28 {
  29 public:
  30     int nextInt()
  31     {
  32         const ScopedLock lock (mutex);
  33         return random.nextInt();
  34     }
  35
  36 private:
  37     CriticalSection mutex;
  38     Random random;
  39 };
  40
  41 static LockedRandom lockedRandom;
  42
  43 static File createTempFile (const File& parentDirectory, String name,
  44                             const String& suffix, int optionFlags)
  45 {
  46     if ((optionFlags & TemporaryFile::useHiddenFile) != 0)
  47         name = "." + name;
  48
  49     return parentDirectory.getNonexistentChildFile (name, suffix, (optionFlags & TemporaryFile::putNumbersInBrackets) != 0);
  50 }
  51
  52 TemporaryFile::TemporaryFile (const String& suffix, const int optionFlags)
  53     : temporaryFile (createTempFile (File::getSpecialLocation (File::tempDirectory),
  54                                      "temp_" + String::toHexString (lockedRandom.nextInt()),
  55                                      suffix, optionFlags)),
  56       targetFile()
  57 {
  58 }
  59
  60 TemporaryFile::TemporaryFile (const File& target, const int optionFlags)
  61     : temporaryFile (createTempFile (target.getParentDirectory(),
  62                                      target.getFileNameWithoutExtension()
  63                                        + "_temp" + String::toHexString (lockedRandom.nextInt()),
  64                                      target.getFileExtension(), optionFlags)),
  65       targetFile (target)
  66 {
  67     // If you use this constructor, you need to give it a valid target file!
  68     jassert (targetFile != File());
  69 }
  70
  71 TemporaryFile::TemporaryFile (const File& target, const File& temporary)
  72     : temporaryFile (temporary), targetFile (target)
  73 {
  74 }
  75
  76 TemporaryFile::~TemporaryFile()
  77 {
  78     if (! deleteTemporaryFile())
  79     {
  80         /* Failed to delete our temporary file! The most likely reason for this would be
  81            that you've not closed an output stream that was being used to write to file.
  82
  83            If you find that something beyond your control is changing permissions on
  84            your temporary files and preventing them from being deleted, you may want to
  85            call TemporaryFile::deleteTemporaryFile() to detect those error cases and
  86            handle them appropriately.
  87         */
  88         jassertfalse;
  89     }
  90 }
  91
  92 //==============================================================================
  93 bool TemporaryFile::overwriteTargetFileWithTemporary() const
  94 {
  95     // This method only works if you created this object with the constructor
  96     // that takes a target file!
  97     jassert (targetFile != File());
  98
  99     if (temporaryFile.exists())
 100     {
 101         // Have a few attempts at overwriting the file before giving up..
 102         for (int i = 5; --i >= 0;)
 103         {
 104             if (temporaryFile.replaceFileIn (targetFile))
 105                 return true;
 106
 107             Thread::sleep (100);
 108         }
 109     }
 110     else
 111     {
 112         // There's no temporary file to use. If your write failed, you should
 113         // probably check, and not bother calling this method.
 114         jassertfalse;
 115     }
 116
 117     return false;
 118 }
 119
 120 bool TemporaryFile::deleteTemporaryFile() const
 121 {
 122     // Have a few attempts at deleting the file before giving up..
 123     for (int i = 5; --i >= 0;)
 124     {
 125         if (temporaryFile.isDirectory() ? temporaryFile.deleteRecursively() : temporaryFile.deleteFile())
 126             return true;
 127
 128         Thread::sleep (50);
 129     }
 130
 131     return false;
 132 }
 133
 134 } // namespace juce