fixes for utf-8 to/from unicode conversion

The functions utf8_to unicode and unicode_to_utf8 didn't work correctly
with some 3 and 4 byte strings. This exchanges those functions against
two more sophisticated ones. It also adds unit testing for them.

darcs-hash:20060221212605-7ad00-7bfefe8c9615d5a7f3b33c279ce79d4200d4778c.gz

1 files changed, 251 insertions, 46 deletions

diff --git a/inc/utf8.php b/inc/utf8.php
index 3a223d3fb..ecb2dc89b 100644
--- a/inc/utf8.php
+++ b/inc/utf8.php
@@ -382,61 +382,266 @@ function utf8_tohtml ($str) {
 }
 
 /**
- * This function returns any UTF-8 encoded text as a list of
- * Unicode values:
+ * Takes an UTF-8 string and returns an array of ints representing the
+ * Unicode characters. Astral planes are supported ie. the ints in the
+ * output can be > 0xFFFF. Occurrances of the BOM are ignored. Surrogates
+ * are not allowed.
  *
- * @author Scott Michael Reynen <scott@randomchaos.com>
- * @link   http://www.randomchaos.com/document.php?source=php_and_unicode
- * @see    unicode_to_utf8()
+ * If $strict is set to true the function returns false if the input
+ * string isn't a valid UTF-8 octet sequence and raises a PHP error at
+ * level E_USER_WARNING
+ *
+ * Note: this function has been modified slightly in this library to
+ * trigger errors on encountering bad bytes
+ *
+ * @author <hsivonen@iki.fi>
+ * @author Harry Fuecks <hfuecks@gmail.com>
+ * @param  string  UTF-8 encoded string
+ * @param  boolean Check for invalid sequences?
+ * @return mixed array of unicode code points or FALSE if UTF-8 invalid
+ * @see    unicode_to_utf8
+ * @link   http://hsivonen.iki.fi/php-utf8/
+ * @link   http://sourceforge.net/projects/phputf8/
  */
-function utf8_to_unicode( &$str ) {
-  $unicode = array();
-  $values = array();
-  $lookingFor = 1;
-
-  for ($i = 0; $i < strlen( $str ); $i++ ) {
-    $thisValue = ord( $str[ $i ] );
-    if ( $thisValue < 128 ) $unicode[] = $thisValue;
-    else {
-      if ( count( $values ) == 0 ) $lookingFor = ( $thisValue < 224 ) ? 2 : 3;
-      $values[] = $thisValue;
-      if ( count( $values ) == $lookingFor ) {
-  $number = ( $lookingFor == 3 ) ?
-    ( ( $values[0] % 16 ) * 4096 ) + ( ( $values[1] % 64 ) * 64 ) + ( $values[2] % 64 ):
-    ( ( $values[0] % 32 ) * 64 ) + ( $values[1] % 64 );
-  $unicode[] = $number;
-  $values = array();
-  $lookingFor = 1;
-      }
+function utf8_to_unicode($str,$strict=false) {
+    $mState = 0;     // cached expected number of octets after the current octet
+                     // until the beginning of the next UTF8 character sequence
+    $mUcs4  = 0;     // cached Unicode character
+    $mBytes = 1;     // cached expected number of octets in the current sequence
+
+    $out = array();
+
+    $len = strlen($str);
+
+    for($i = 0; $i < $len; $i++) {
+
+        $in = ord($str{$i});
+
+        if ( $mState == 0) {
+
+            // When mState is zero we expect either a US-ASCII character or a
+            // multi-octet sequence.
+            if (0 == (0x80 & ($in))) {
+                // US-ASCII, pass straight through.
+                $out[] = $in;
+                $mBytes = 1;
+
+            } else if (0xC0 == (0xE0 & ($in))) {
+                // First octet of 2 octet sequence
+                $mUcs4 = ($in);
+                $mUcs4 = ($mUcs4 & 0x1F) << 6;
+                $mState = 1;
+                $mBytes = 2;
+
+            } else if (0xE0 == (0xF0 & ($in))) {
+                // First octet of 3 octet sequence
+                $mUcs4 = ($in);
+                $mUcs4 = ($mUcs4 & 0x0F) << 12;
+                $mState = 2;
+                $mBytes = 3;
+
+            } else if (0xF0 == (0xF8 & ($in))) {
+                // First octet of 4 octet sequence
+                $mUcs4 = ($in);
+                $mUcs4 = ($mUcs4 & 0x07) << 18;
+                $mState = 3;
+                $mBytes = 4;
+
+            } else if (0xF8 == (0xFC & ($in))) {
+                /* First octet of 5 octet sequence.
+                 *
+                 * This is illegal because the encoded codepoint must be either
+                 * (a) not the shortest form or
+                 * (b) outside the Unicode range of 0-0x10FFFF.
+                 * Rather than trying to resynchronize, we will carry on until the end
+                 * of the sequence and let the later error handling code catch it.
+                 */
+                $mUcs4 = ($in);
+                $mUcs4 = ($mUcs4 & 0x03) << 24;
+                $mState = 4;
+                $mBytes = 5;
+
+            } else if (0xFC == (0xFE & ($in))) {
+                // First octet of 6 octet sequence, see comments for 5 octet sequence.
+                $mUcs4 = ($in);
+                $mUcs4 = ($mUcs4 & 1) << 30;
+                $mState = 5;
+                $mBytes = 6;
+
+            } elseif($strict) {
+                /* Current octet is neither in the US-ASCII range nor a legal first
+                 * octet of a multi-octet sequence.
+                 */
+                trigger_error(
+                        'utf8_to_unicode: Illegal sequence identifier '.
+                            'in UTF-8 at byte '.$i,
+                        E_USER_WARNING
+                    );
+                return FALSE;
+
+            }
+
+        } else {
+
+            // When mState is non-zero, we expect a continuation of the multi-octet
+            // sequence
+            if (0x80 == (0xC0 & ($in))) {
+
+                // Legal continuation.
+                $shift = ($mState - 1) * 6;
+                $tmp = $in;
+                $tmp = ($tmp & 0x0000003F) << $shift;
+                $mUcs4 |= $tmp;
+
+                /**
+                 * End of the multi-octet sequence. mUcs4 now contains the final
+                 * Unicode codepoint to be output
+                 */
+                if (0 == --$mState) {
+
+                    /*
+                     * Check for illegal sequences and codepoints.
+                     */
+                    // From Unicode 3.1, non-shortest form is illegal
+                    if (((2 == $mBytes) && ($mUcs4 < 0x0080)) ||
+                        ((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
+                        ((4 == $mBytes) && ($mUcs4 < 0x10000)) ||
+                        (4 < $mBytes) ||
+                        // From Unicode 3.2, surrogate characters are illegal
+                        (($mUcs4 & 0xFFFFF800) == 0xD800) ||
+                        // Codepoints outside the Unicode range are illegal
+                        ($mUcs4 > 0x10FFFF)) {
+
+                        if($strict){
+                            trigger_error(
+                                    'utf8_to_unicode: Illegal sequence or codepoint '.
+                                        'in UTF-8 at byte '.$i,
+                                    E_USER_WARNING
+                                );
+
+                            return FALSE;
+                        }
+
+                    }
+
+                    if (0xFEFF != $mUcs4) {
+                        // BOM is legal but we don't want to output it
+                        $out[] = $mUcs4;
+                    }
+
+                    //initialize UTF8 cache
+                    $mState = 0;
+                    $mUcs4  = 0;
+                    $mBytes = 1;
+                }
+
+            } elseif($strict) {
+                /**
+                 *((0xC0 & (*in) != 0x80) && (mState != 0))
+                 * Incomplete multi-octet sequence.
+                 */
+                trigger_error(
+                        'utf8_to_unicode: Incomplete multi-octet '.
+                        '   sequence in UTF-8 at byte '.$i,
+                        E_USER_WARNING
+                    );
+
+                return FALSE;
+            }
+        }
     }
-  }
-  return $unicode;
+    return $out;
 }
 
 /**
- * This function converts a Unicode array back to its UTF-8 representation
+ * Takes an array of ints representing the Unicode characters and returns
+ * a UTF-8 string. Astral planes are supported ie. the ints in the
+ * input can be > 0xFFFF. Occurrances of the BOM are ignored. Surrogates
+ * are not allowed.
  *
- * @author Scott Michael Reynen <scott@randomchaos.com>
- * @link   http://www.randomchaos.com/document.php?source=php_and_unicode
- * @see    utf8_to_unicode()
+ * If $strict is set to true the function returns false if the input
+ * array contains ints that represent surrogates or are outside the
+ * Unicode range and raises a PHP error at level E_USER_WARNING
+ *
+ * Note: this function has been modified slightly in this library to use
+ * output buffering to concatenate the UTF-8 string (faster) as well as
+ * reference the array by it's keys
+ *
+ * @param  array of unicode code points representing a string
+ * @param  boolean Check for invalid sequences?
+ * @return mixed UTF-8 string or FALSE if array contains invalid code points
+ * @author <hsivonen@iki.fi>
+ * @author Harry Fuecks <hfuecks@gmail.com>
+ * @see    utf8_to_unicode
+ * @link   http://hsivonen.iki.fi/php-utf8/
+ * @link   http://sourceforge.net/projects/phputf8/
  */
-function unicode_to_utf8( &$str ) {
-  if (!is_array($str)) return '';
-
-  $utf8 = '';
-  foreach( $str as $unicode ) {
-    if ( $unicode < 128 ) {
-      $utf8.= chr( $unicode );
-    } elseif ( $unicode < 2048 ) {
-      $utf8.= chr( 192 +  ( ( $unicode - ( $unicode % 64 ) ) / 64 ) );
-      $utf8.= chr( 128 + ( $unicode % 64 ) );
-    } else {
-      $utf8.= chr( 224 + ( ( $unicode - ( $unicode % 4096 ) ) / 4096 ) );
-      $utf8.= chr( 128 + ( ( ( $unicode % 4096 ) - ( $unicode % 64 ) ) / 64 ) );
-      $utf8.= chr( 128 + ( $unicode % 64 ) );
+function unicode_to_utf8($arr,$strict=false) {
+    if (!is_array($arr)) return '';
+    ob_start();
+
+    foreach (array_keys($arr) as $k) {
+
+        # ASCII range (including control chars)
+        if ( ($arr[$k] >= 0) && ($arr[$k] <= 0x007f) ) {
+
+            echo chr($arr[$k]);
+
+        # 2 byte sequence
+        } else if ($arr[$k] <= 0x07ff) {
+
+            echo chr(0xc0 | ($arr[$k] >> 6));
+            echo chr(0x80 | ($arr[$k] & 0x003f));
+
+        # Byte order mark (skip)
+        } else if($arr[$k] == 0xFEFF) {
+
+            // nop -- zap the BOM
+
+        # Test for illegal surrogates
+        } else if ($arr[$k] >= 0xD800 && $arr[$k] <= 0xDFFF) {
+
+            // found a surrogate
+            if($strict){
+                trigger_error(
+                    'unicode_to_utf8: Illegal surrogate '.
+                        'at index: '.$k.', value: '.$arr[$k],
+                    E_USER_WARNING
+                    );
+                return FALSE;
+            }
+
+        # 3 byte sequence
+        } else if ($arr[$k] <= 0xffff) {
+
+            echo chr(0xe0 | ($arr[$k] >> 12));
+            echo chr(0x80 | (($arr[$k] >> 6) & 0x003f));
+            echo chr(0x80 | ($arr[$k] & 0x003f));
+
+        # 4 byte sequence
+        } else if ($arr[$k] <= 0x10ffff) {
+
+            echo chr(0xf0 | ($arr[$k] >> 18));
+            echo chr(0x80 | (($arr[$k] >> 12) & 0x3f));
+            echo chr(0x80 | (($arr[$k] >> 6) & 0x3f));
+            echo chr(0x80 | ($arr[$k] & 0x3f));
+
+        } elseif($strict) {
+
+            trigger_error(
+                'unicode_to_utf8: Codepoint out of Unicode range '.
+                    'at index: '.$k.', value: '.$arr[$k],
+                E_USER_WARNING
+                );
+
+            // out of range
+            return FALSE;
+        }
     }
-  }
-  return $utf8;
+
+    $result = ob_get_contents();
+    ob_end_clean();
+    return $result;
 }
 
 /**