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/wp-includes/ -> compat.php (source)

   1  <?php
   2  /**
   3   * WordPress implementation for PHP functions either missing from older PHP versions or not included by default.
   4   *
   5   * @package PHP
   6   * @access private
   7   */
   8  
   9  // If gettext isn't available.
  10  if ( ! function_exists( '_' ) ) {
  11      function _( $string ) {
  12          return $string;
  13      }
  14  }
  15  
  16  /**
  17   * Returns whether PCRE/u (PCRE_UTF8 modifier) is available for use.
  18   *
  19   * @ignore
  20   * @since 4.2.2
  21   * @access private
  22   *
  23   * @param bool $set - Used for testing only
  24   *             null   : default - get PCRE/u capability
  25   *             false  : Used for testing - return false for future calls to this function
  26   *             'reset': Used for testing - restore default behavior of this function
  27   */
  28  function _wp_can_use_pcre_u( $set = null ) {
  29      static $utf8_pcre = 'reset';
  30  
  31      if ( null !== $set ) {
  32          $utf8_pcre = $set;
  33      }
  34  
  35      if ( 'reset' === $utf8_pcre ) {
  36          // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- intentional error generated to detect PCRE/u support.
  37          $utf8_pcre = @preg_match( '/^./u', 'a' );
  38      }
  39  
  40      return $utf8_pcre;
  41  }
  42  
  43  if ( ! function_exists( 'mb_substr' ) ) :
  44      /**
  45       * Compat function to mimic mb_substr().
  46       *
  47       * @ignore
  48       * @since 3.2.0
  49       *
  50       * @see _mb_substr()
  51       *
  52       * @param string      $str      The string to extract the substring from.
  53       * @param int         $start    Position to being extraction from in `$str`.
  54       * @param int|null    $length   Optional. Maximum number of characters to extract from `$str`.
  55       *                              Default null.
  56       * @param string|null $encoding Optional. Character encoding to use. Default null.
  57       * @return string Extracted substring.
  58       */
  59  	function mb_substr( $str, $start, $length = null, $encoding = null ) {
  60          return _mb_substr( $str, $start, $length, $encoding );
  61      }
  62  endif;
  63  
  64  /**
  65   * Internal compat function to mimic mb_substr().
  66   *
  67   * Only understands UTF-8 and 8bit.  All other character sets will be treated as 8bit.
  68   * For $encoding === UTF-8, the $str input is expected to be a valid UTF-8 byte sequence.
  69   * The behavior of this function for invalid inputs is undefined.
  70   *
  71   * @ignore
  72   * @since 3.2.0
  73   *
  74   * @param string      $str      The string to extract the substring from.
  75   * @param int         $start    Position to being extraction from in `$str`.
  76   * @param int|null    $length   Optional. Maximum number of characters to extract from `$str`.
  77   *                              Default null.
  78   * @param string|null $encoding Optional. Character encoding to use. Default null.
  79   * @return string Extracted substring.
  80   */
  81  function _mb_substr( $str, $start, $length = null, $encoding = null ) {
  82      if ( null === $encoding ) {
  83          $encoding = get_option( 'blog_charset' );
  84      }
  85  
  86      /*
  87       * The solution below works only for UTF-8, so in case of a different
  88       * charset just use built-in substr().
  89       */
  90      if ( ! in_array( $encoding, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ), true ) ) {
  91          return is_null( $length ) ? substr( $str, $start ) : substr( $str, $start, $length );
  92      }
  93  
  94      if ( _wp_can_use_pcre_u() ) {
  95          // Use the regex unicode support to separate the UTF-8 characters into an array.
  96          preg_match_all( '/./us', $str, $match );
  97          $chars = is_null( $length ) ? array_slice( $match[0], $start ) : array_slice( $match[0], $start, $length );
  98          return implode( '', $chars );
  99      }
 100  
 101      $regex = '/(
 102          [\x00-\x7F]                  # single-byte sequences   0xxxxxxx
 103          | [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx
 104          | \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2
 105          | [\xE1-\xEC][\x80-\xBF]{2}
 106          | \xED[\x80-\x9F][\x80-\xBF]
 107          | [\xEE-\xEF][\x80-\xBF]{2}
 108          | \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3
 109          | [\xF1-\xF3][\x80-\xBF]{3}
 110          | \xF4[\x80-\x8F][\x80-\xBF]{2}
 111      )/x';
 112  
 113      // Start with 1 element instead of 0 since the first thing we do is pop.
 114      $chars = array( '' );
 115      do {
 116          // We had some string left over from the last round, but we counted it in that last round.
 117          array_pop( $chars );
 118  
 119          /*
 120           * Split by UTF-8 character, limit to 1000 characters (last array element will contain
 121           * the rest of the string).
 122           */
 123          $pieces = preg_split( $regex, $str, 1000, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY );
 124  
 125          $chars = array_merge( $chars, $pieces );
 126  
 127          // If there's anything left over, repeat the loop.
 128      } while ( count( $pieces ) > 1 && $str = array_pop( $pieces ) );
 129  
 130      return implode( '', array_slice( $chars, $start, $length ) );
 131  }
 132  
 133  if ( ! function_exists( 'mb_strlen' ) ) :
 134      /**
 135       * Compat function to mimic mb_strlen().
 136       *
 137       * @ignore
 138       * @since 4.2.0
 139       *
 140       * @see _mb_strlen()
 141       *
 142       * @param string      $str      The string to retrieve the character length from.
 143       * @param string|null $encoding Optional. Character encoding to use. Default null.
 144       * @return int String length of `$str`.
 145       */
 146  	function mb_strlen( $str, $encoding = null ) {
 147          return _mb_strlen( $str, $encoding );
 148      }
 149  endif;
 150  
 151  /**
 152   * Internal compat function to mimic mb_strlen().
 153   *
 154   * Only understands UTF-8 and 8bit.  All other character sets will be treated as 8bit.
 155   * For $encoding === UTF-8, the `$str` input is expected to be a valid UTF-8 byte
 156   * sequence. The behavior of this function for invalid inputs is undefined.
 157   *
 158   * @ignore
 159   * @since 4.2.0
 160   *
 161   * @param string      $str      The string to retrieve the character length from.
 162   * @param string|null $encoding Optional. Character encoding to use. Default null.
 163   * @return int String length of `$str`.
 164   */
 165  function _mb_strlen( $str, $encoding = null ) {
 166      if ( null === $encoding ) {
 167          $encoding = get_option( 'blog_charset' );
 168      }
 169  
 170      /*
 171       * The solution below works only for UTF-8, so in case of a different charset
 172       * just use built-in strlen().
 173       */
 174      if ( ! in_array( $encoding, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ), true ) ) {
 175          return strlen( $str );
 176      }
 177  
 178      if ( _wp_can_use_pcre_u() ) {
 179          // Use the regex unicode support to separate the UTF-8 characters into an array.
 180          preg_match_all( '/./us', $str, $match );
 181          return count( $match[0] );
 182      }
 183  
 184      $regex = '/(?:
 185          [\x00-\x7F]                  # single-byte sequences   0xxxxxxx
 186          | [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx
 187          | \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2
 188          | [\xE1-\xEC][\x80-\xBF]{2}
 189          | \xED[\x80-\x9F][\x80-\xBF]
 190          | [\xEE-\xEF][\x80-\xBF]{2}
 191          | \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3
 192          | [\xF1-\xF3][\x80-\xBF]{3}
 193          | \xF4[\x80-\x8F][\x80-\xBF]{2}
 194      )/x';
 195  
 196      // Start at 1 instead of 0 since the first thing we do is decrement.
 197      $count = 1;
 198      do {
 199          // We had some string left over from the last round, but we counted it in that last round.
 200          $count--;
 201  
 202          /*
 203           * Split by UTF-8 character, limit to 1000 characters (last array element will contain
 204           * the rest of the string).
 205           */
 206          $pieces = preg_split( $regex, $str, 1000 );
 207  
 208          // Increment.
 209          $count += count( $pieces );
 210  
 211          // If there's anything left over, repeat the loop.
 212      } while ( $str = array_pop( $pieces ) );
 213  
 214      // Fencepost: preg_split() always returns one extra item in the array.
 215      return --$count;
 216  }
 217  
 218  if ( ! function_exists( 'hash_hmac' ) ) :
 219      /**
 220       * Compat function to mimic hash_hmac().
 221       *
 222       * The Hash extension is bundled with PHP by default since PHP 5.1.2.
 223       * However, the extension may be explicitly disabled on select servers.
 224       * As of PHP 7.4.0, the Hash extension is a core PHP extension and can no
 225       * longer be disabled.
 226       * I.e. when PHP 7.4.0 becomes the minimum requirement, this polyfill
 227       * and the associated `_hash_hmac()` function can be safely removed.
 228       *
 229       * @ignore
 230       * @since 3.2.0
 231       *
 232       * @see _hash_hmac()
 233       *
 234       * @param string $algo       Hash algorithm. Accepts 'md5' or 'sha1'.
 235       * @param string $data       Data to be hashed.
 236       * @param string $key        Secret key to use for generating the hash.
 237       * @param bool   $raw_output Optional. Whether to output raw binary data (true),
 238       *                           or lowercase hexits (false). Default false.
 239       * @return string|false The hash in output determined by `$raw_output`. False if `$algo`
 240       *                      is unknown or invalid.
 241       */
 242  	function hash_hmac( $algo, $data, $key, $raw_output = false ) {
 243          return _hash_hmac( $algo, $data, $key, $raw_output );
 244      }
 245  endif;
 246  
 247  /**
 248   * Internal compat function to mimic hash_hmac().
 249   *
 250   * @ignore
 251   * @since 3.2.0
 252   *
 253   * @param string $algo       Hash algorithm. Accepts 'md5' or 'sha1'.
 254   * @param string $data       Data to be hashed.
 255   * @param string $key        Secret key to use for generating the hash.
 256   * @param bool   $raw_output Optional. Whether to output raw binary data (true),
 257   *                           or lowercase hexits (false). Default false.
 258   * @return string|false The hash in output determined by `$raw_output`. False if `$algo`
 259   *                      is unknown or invalid.
 260   */
 261  function _hash_hmac( $algo, $data, $key, $raw_output = false ) {
 262      $packs = array(
 263          'md5'  => 'H32',
 264          'sha1' => 'H40',
 265      );
 266  
 267      if ( ! isset( $packs[ $algo ] ) ) {
 268          return false;
 269      }
 270  
 271      $pack = $packs[ $algo ];
 272  
 273      if ( strlen( $key ) > 64 ) {
 274          $key = pack( $pack, $algo( $key ) );
 275      }
 276  
 277      $key = str_pad( $key, 64, chr( 0 ) );
 278  
 279      $ipad = ( substr( $key, 0, 64 ) ^ str_repeat( chr( 0x36 ), 64 ) );
 280      $opad = ( substr( $key, 0, 64 ) ^ str_repeat( chr( 0x5C ), 64 ) );
 281  
 282      $hmac = $algo( $opad . pack( $pack, $algo( $ipad . $data ) ) );
 283  
 284      if ( $raw_output ) {
 285          return pack( $pack, $hmac );
 286      }
 287      return $hmac;
 288  }
 289  
 290  if ( ! function_exists( 'hash_equals' ) ) :
 291      /**
 292       * Timing attack safe string comparison
 293       *
 294       * Compares two strings using the same time whether they're equal or not.
 295       *
 296       * Note: It can leak the length of a string when arguments of differing length are supplied.
 297       *
 298       * This function was added in PHP 5.6.
 299       * However, the Hash extension may be explicitly disabled on select servers.
 300       * As of PHP 7.4.0, the Hash extension is a core PHP extension and can no
 301       * longer be disabled.
 302       * I.e. when PHP 7.4.0 becomes the minimum requirement, this polyfill
 303       * can be safely removed.
 304       *
 305       * @since 3.9.2
 306       *
 307       * @param string $a Expected string.
 308       * @param string $b Actual, user supplied, string.
 309       * @return bool Whether strings are equal.
 310       */
 311  	function hash_equals( $a, $b ) {
 312          $a_length = strlen( $a );
 313          if ( strlen( $b ) !== $a_length ) {
 314              return false;
 315          }
 316          $result = 0;
 317  
 318          // Do not attempt to "optimize" this.
 319          for ( $i = 0; $i < $a_length; $i++ ) {
 320              $result |= ord( $a[ $i ] ) ^ ord( $b[ $i ] );
 321          }
 322  
 323          return 0 === $result;
 324      }
 325  endif;
 326  
 327  // random_int() was introduced in PHP 7.0.
 328  if ( ! function_exists( 'random_int' ) ) {
 329      require  ABSPATH . WPINC . '/random_compat/random.php';
 330  }
 331  // sodium_crypto_box() was introduced in PHP 7.2.
 332  if ( ! function_exists( 'sodium_crypto_box' ) ) {
 333      require  ABSPATH . WPINC . '/sodium_compat/autoload.php';
 334  }
 335  
 336  if ( ! function_exists( 'is_countable' ) ) {
 337      /**
 338       * Polyfill for is_countable() function added in PHP 7.3.
 339       *
 340       * Verify that the content of a variable is an array or an object
 341       * implementing the Countable interface.
 342       *
 343       * @since 4.9.6
 344       *
 345       * @param mixed $var The value to check.
 346       * @return bool True if `$var` is countable, false otherwise.
 347       */
 348  	function is_countable( $var ) {
 349          return ( is_array( $var )
 350              || $var instanceof Countable
 351              || $var instanceof SimpleXMLElement
 352              || $var instanceof ResourceBundle
 353          );
 354      }
 355  }
 356  
 357  if ( ! function_exists( 'is_iterable' ) ) {
 358      /**
 359       * Polyfill for is_iterable() function added in PHP 7.1.
 360       *
 361       * Verify that the content of a variable is an array or an object
 362       * implementing the Traversable interface.
 363       *
 364       * @since 4.9.6
 365       *
 366       * @param mixed $var The value to check.
 367       * @return bool True if `$var` is iterable, false otherwise.
 368       */
 369  	function is_iterable( $var ) {
 370          return ( is_array( $var ) || $var instanceof Traversable );
 371      }
 372  }


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