uuid.inc

   1 <?php
   2
   3 /**
   4  * @file
   5  * Handling of universally unique identifiers.
   6  */
   7
   8 /**
   9  * Generates an universally unique identifier.
  10  *
  11  * This function first checks for the PECL alternative for generating
  12  * universally unique identifiers. If that doesn't exist, then it falls back on
  13  * PHP for generating that.
  14  *
  15  * @return
  16  *   An UUID, made up of 32 hex digits and 4 hyphens.
  17  */
  18 function uuid_generate() {
  19   $callback = drupal_static(__FUNCTION__);
  20
  21   if (empty($callback)) {
  22     if (function_exists('uuid_create') && !function_exists('uuid_make')) {
  23       $callback = '_uuid_generate_pecl';
  24     }
  25     elseif (function_exists('com_create_guid')) {
  26       $callback = '_uuid_generate_com';
  27     }
  28     else {
  29       $callback = '_uuid_generate_php';
  30     }
  31   }
  32   return $callback();
  33 }
  34
  35 /**
  36  * Generate all missing UUIDs.
  37  */
  38 function uuid_sync_all() {
  39   module_invoke_all('uuid_sync');
  40 }
  41
  42 /**
  43  * Check that a string appears to be in the format of a UUID.
  44  *
  45  * @param $uuid
  46  *  The string to test.
  47  *
  48  * @return
  49  *   TRUE if the string is well formed.
  50  */
  51 function uuid_is_valid($uuid) {
  52   return preg_match("/^[0-9a-f]{8}-([0-9a-f]{4}-){3}[0-9a-f]{12}$/", $uuid);
  53 }
  54
  55 /**
  56  * Generates a UUID using the Windows internal GUID generator.
  57  *
  58  * @see http://php.net/com_create_guid
  59  */
  60 function _uuid_generate_com() {
  61   // Remove {} wrapper and make lower case to keep result consistent.
  62   return drupal_strtolower(trim(com_create_guid(), '{}'));
  63 }
  64
  65 /**
  66  * Generates an universally unique identifier using the PECL extension.
  67  */
  68 function _uuid_generate_pecl() {
  69   return uuid_create(UUID_TYPE_DEFAULT);
  70 }
  71
  72 /**
  73  * Generates a UUID v4 using PHP code.
  74  *
  75  * @see http://php.net/uniqid#65879
  76  */
  77 function _uuid_generate_php() {
  78   // The field names refer to RFC 4122 section 4.1.2.
  79   return sprintf('%04x%04x-%04x-%03x4-%04x-%04x%04x%04x',
  80     // 32 bits for "time_low".
  81     mt_rand(0, 65535), mt_rand(0, 65535),
  82     // 16 bits for "time_mid".
  83     mt_rand(0, 65535),
  84     // 12 bits before the 0100 of (version) 4 for "time_hi_and_version".
  85     mt_rand(0, 4095),
  86     bindec(substr_replace(sprintf('%016b', mt_rand(0, 65535)), '01', 6, 2)),
  87     // 8 bits, the last two of which (positions 6 and 7) are 01, for "clk_seq_hi_res"
  88     // (hence, the 2nd hex digit after the 3rd hyphen can only be 1, 5, 9 or d)
  89     // 8 bits for "clk_seq_low" 48 bits for "node".
  90     mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(0, 65535)
  91   );
  92 }