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<?php

/**

 * @file

 * Handling of universally unique identifiers.

 */

/**

 * Pattern for detecting a valid UUID.

 */

define('UUID_PATTERN', '[0-9a-f]{8}-([0-9a-f]{4}-){3}[0-9a-f]{12}');

/**

 * Generates an universally unique identifier.

 *

 * This function first checks for the PECL alternative for generating

 * universally unique identifiers. If that doesn't exist, then it falls back on

 * PHP for generating that.

 *

 * @return

 *   An UUID, made up of 32 hex digits and 4 hyphens.

 */

function uuid_generate() {

  $callback = drupal_static(__FUNCTION__);

  if (empty($callback)) {

    if (function_exists('uuid_create') && !function_exists('uuid_make')) {

      $callback = '_uuid_generate_pecl';

    }

    elseif (function_exists('com_create_guid')) {

      $callback = '_uuid_generate_com';

    }

    else {

      $callback = '_uuid_generate_php';

    }

  }

  return $callback();

}

/**

 * Generate all missing UUIDs.

 */

function uuid_sync_all() {

  module_invoke_all('uuid_sync');

}

/**

 * Generates a UUID URI for an entity.

 *

 * @param object $entity

 *   The entity to use for generating the UUID URI.

 * @param string $entity_type

 *   The type of entity being used.

 *

 * @return string

 *  The generated UUID URI or normal URI if entity doesn't support UUIDs.

 */

function uuid_entity_uuid_uri($entity, $entity_type) {

  $entity_info = entity_get_info($entity_type);

  if (empty($entity_info['uuid'])) {

    $uri = $entity_info['uri callback']($entity);

    return $uri['path'];

  }

  if (isset($entity_info['uuid uri callback'])) {

    return $entity_info['uuid uri callback']($entity);

  }

  return "uuid/{$entity_type}/" . $entity->{$entity_info['entity keys']['uuid']};

}

/**

 * Converts an ID URI string to an entity data array.

 *

 * @see uuid_id_uri_array_to_data()

 *

 * @param string $uri

 *  The URI to convert.

 *

 * @return array

 *  The entity data.

 */

function uuid_id_uri_to_data($uri) {

  $parts = explode('/', $uri);

  return uuid_id_uri_array_to_data($parts);

}

/**

 * Converts a URI array to entity data array.

 *

 * @param array $uri

 *  The URI parts, often taken from arg().

 *

 * @return array

 *  The entity data.

 */

function uuid_id_uri_array_to_data($uri) {

  $data = array(

    'request' => $uri,

    'entity_type' => $uri[0],

    'id' => $uri[1],

  );

  drupal_alter('uuid_id_uri_data', $data);

  return $data;

}

/**

 * Converts a UUID URI string to an entity data array.

 *

 * @see uuid_uri_array_to_data()

 *

 * @param string $uri

 *  The URI to convert.

 *

 * @return array

 *  The entity data.

 */

function uuid_uri_to_data($uri, $strip_uuid = TRUE) {

  return uuid_uri_array_to_data(explode('/', $uri));

}

/**

 * Converts a URI array to entity data array.

 *

 * @param array $uri

 *  The URI parts, often taken from arg().

 *

 * @return array

 *  The entity data.

 */

function uuid_uri_array_to_data($uri, $strip_uuid = TRUE) {

  if ($strip_uuid) {

    array_shift($uri);

  }

  $data = array(

    'request' => $uri,

    'entity_type' => $uri[0],

    'uuid' => $uri[1],

  );

  drupal_alter('uuid_uri_data', $data);

  return $data;

}

/**

 * Generates a UUID using the Windows internal GUID generator.

 *

 * @see http://php.net/com_create_guid

 */

function _uuid_generate_com() {

  // Remove {} wrapper and make lower case to keep result consistent.

  return drupal_strtolower(trim(com_create_guid(), '{}'));

}

/**

 * Generates an universally unique identifier using the PECL extension.

 */

function _uuid_generate_pecl() {

  return uuid_create(UUID_TYPE_DEFAULT);

}

/**

 * Generates a UUID v4 (RFC 4122 section 4.4) using PHP code.

 *

 * @see http://www.rfc-editor.org/rfc/rfc4122.txt

 *

 * The UUID layout and fields are defined in section 4.1.2.

 *

 * Note that there are inconsistencies in the RFC with respect to

 * bit numbering. Network Order is correct, so the most significant bit

 * always appears first (in left-to-right sequence). See errata 3546:

 * http://www.rfc-editor.org/errata_search.php?rfc=4122&eid=3546

 *

 * Based on code from http://php.net/uniqid

 */

function _uuid_generate_php() {

  // We limit each generated number to 16 bits (maximum value 0xffff)

  // because mt_rand() returns a *signed* integer, and hence a 32-bit

  // value can only have a 31-bit magnitude. Constructing a 32-bit

  // number from two 16-bit random numbers guarantees that all 32 bits

  // are random.

  return sprintf('%04x%04x-%04x-4%03x-%04x-%04x%04x%04x',

    // 32 bits for "time_low".

    mt_rand(0, 0xffff), mt_rand(0, 0xffff),

    // 16 bits for "time_mid".

    mt_rand(0, 0xffff),

    // 12 bits after the initial 0100 (version 4) for "time_hi_and_version".

    mt_rand(0, 0x0fff),

    // 16 bits in total for "clk_seq_hi_res" and "clk_seq_low", with the

    // most significant 2 bits of clk_seq_hi_res set to '10'. We do a

    // bitwise OR of a random 14-bit value (maximum 0x3fff) with 0x8000

    // (a 16-bit integer with only the most significant bit set).

    mt_rand(0, 0x3fff) | 0x8000,

    // 48 bits for "node".

    mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)

  );

}

// This is wrapped in an if block to avoid conflicts with PECL's uuid_is_valid().

if (!function_exists('uuid_is_valid')) {

  /**

   * Check that a string appears to be in the format of a UUID.

   *

   * @param $uuid

   *  The string to test.

   *

   * @return

   *   TRUE if the string is well formed.

   */

  function uuid_is_valid($uuid) {

    return preg_match('/^' . UUID_PATTERN . '$/', $uuid);

  }

}