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   1  <?php
   2  
   3  /*
   4   * This file is part of the Symfony package.
   5   *
   6   * (c) Fabien Potencier <fabien@symfony.com>
   7   *
   8   * For the full copyright and license information, please view the LICENSE
   9   * file that was distributed with this source code.
  10   */
  11  
  12  namespace Symfony\Component\Filesystem;
  13  
  14  use Symfony\Component\Filesystem\Exception\IOException;
  15  
  16  /**
  17   * LockHandler class provides a simple abstraction to lock anything by means of
  18   * a file lock.
  19   *
  20   * A locked file is created based on the lock name when calling lock(). Other
  21   * lock handlers will not be able to lock the same name until it is released
  22   * (explicitly by calling release() or implicitly when the instance holding the
  23   * lock is destroyed).
  24   *
  25   * @author Grégoire Pineau <lyrixx@lyrixx.info>
  26   * @author Romain Neutron <imprec@gmail.com>
  27   * @author Nicolas Grekas <p@tchwork.com>
  28   */
  29  class LockHandler
  30  {
  31      private $file;
  32      private $handle;
  33  
  34      /**
  35       * @param string      $name     The lock name
  36       * @param string|null $lockPath The directory to store the lock. Default values will use temporary directory
  37       *
  38       * @throws IOException If the lock directory could not be created or is not writable
  39       */
  40      public function __construct($name, $lockPath = null)
  41      {
  42          $lockPath = $lockPath ?: sys_get_temp_dir();
  43  
  44          if (!is_dir($lockPath)) {
  45              $fs = new Filesystem();
  46              $fs->mkdir($lockPath);
  47          }
  48  
  49          if (!is_writable($lockPath)) {
  50              throw new IOException(sprintf('The directory "%s" is not writable.', $lockPath), 0, null, $lockPath);
  51          }
  52  
  53          $this->file = sprintf('%s/sf.%s.%s.lock', $lockPath, preg_replace('/[^a-z0-9\._-]+/i', '-', $name), hash('sha256', $name));
  54      }
  55  
  56      /**
  57       * Lock the resource.
  58       *
  59       * @param bool $blocking Wait until the lock is released
  60       *
  61       * @return bool Returns true if the lock was acquired, false otherwise
  62       *
  63       * @throws IOException If the lock file could not be created or opened
  64       */
  65      public function lock($blocking = false)
  66      {
  67          if ($this->handle) {
  68              return true;
  69          }
  70  
  71          $error = null;
  72  
  73          // Silence error reporting
  74          set_error_handler(function ($errno, $msg) use (&$error) {
  75              $error = $msg;
  76          });
  77  
  78          if (!$this->handle = fopen($this->file, 'r+') ?: fopen($this->file, 'r')) {
  79              if ($this->handle = fopen($this->file, 'x')) {
  80                  chmod($this->file, 0666);
  81              } elseif (!$this->handle = fopen($this->file, 'r+') ?: fopen($this->file, 'r')) {
  82                  usleep(100); // Give some time for chmod() to complete
  83                  $this->handle = fopen($this->file, 'r+') ?: fopen($this->file, 'r');
  84              }
  85          }
  86          restore_error_handler();
  87  
  88          if (!$this->handle) {
  89              throw new IOException($error, 0, null, $this->file);
  90          }
  91  
  92          // On Windows, even if PHP doc says the contrary, LOCK_NB works, see
  93          // https://bugs.php.net/54129
  94          if (!flock($this->handle, LOCK_EX | ($blocking ? 0 : LOCK_NB))) {
  95              fclose($this->handle);
  96              $this->handle = null;
  97  
  98              return false;
  99          }
 100  
 101          return true;
 102      }
 103  
 104      /**
 105       * Release the resource.
 106       */
 107      public function release()
 108      {
 109          if ($this->handle) {
 110              flock($this->handle, LOCK_UN | LOCK_NB);
 111              fclose($this->handle);
 112              $this->handle = null;
 113          }
 114      }
 115  }