File: /www/sites/representsale.com/index/wp-includes/compat-utf8.php
<?php
/**
* Finds spans of valid and invalid UTF-8 bytes in a given string.
*
* This is a low-level tool to power various UTF-8 functionality.
* It scans through a string until it finds invalid byte spans.
* When it does this, it does three things:
*
* - Assigns `$at` to the position after the last successful code point.
* - Assigns `$invalid_length` to the length of the maximal subpart of
* the invalid bytes starting at `$at`.
* - Returns how many code points were successfully scanned.
*
* This information is enough to build a number of useful UTF-8 functions.
*
* Example:
*
* // ñ is U+F1, which in `ISO-8859-1`/`latin1`/`Windows-1252`/`cp1252` is 0xF1.
* "Pi\xF1a" === $pineapple = mb_convert_encoding( "Piña", 'Windows-1252', 'UTF-8' );
* $at = $invalid_length = 0;
*
* // The first step finds the invalid 0xF1 byte.
* 2 === _wp_scan_utf8( $pineapple, $at, $invalid_length );
* $at === 2; $invalid_length === 1;
*
* // The second step continues to the end of the string.
* 1 === _wp_scan_utf8( $pineapple, $at, $invalid_length );
* $at === 4; $invalid_length === 0;
*
* Note! This functions many arguments are passed without and “options”
* array. This choice is based on the fact that this is a low-level function
* and there’s no need to create an array of items on every invocation.
*
* @since 6.9.0
* @access private
*
* @param string $bytes UTF-8 encoded string which might include invalid spans of bytes.
* @param int $at Where to start scanning.
* @param int $invalid_length Will be set to how many bytes are to be ignored after `$at`.
* @param int|null $max_bytes Stop scanning after this many bytes have been seen.
* @param int|null $max_code_points Stop scanning after this many code points have been seen.
* @return int How many code points were successfully scanned.
*/
function _wp_scan_utf8( string $bytes, int &$at, int &$invalid_length, ?int $max_bytes = null, ?int $max_code_points = null ): int {
$byte_length = strlen( $bytes );
$end = min( $byte_length, $at + ( $max_bytes ?? PHP_INT_MAX ) );
$invalid_length = 0;
$count = 0;
$max_count = $max_code_points ?? PHP_INT_MAX;
for ( $i = $at; $i < $end && $count <= $max_count; $i++ ) {
/*
* Quickly skip past US-ASCII bytes, all of which are valid UTF-8.
*
* This optimization step improves the speed from 10x to 100x
* depending on whether the JIT has optimized the function.
*/
$ascii_byte_count = strspn(
$bytes,
"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f" .
"\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f" .
" !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f",
$i,
$end - $i
);
if ( $count + $ascii_byte_count >= $max_count ) {
$at = $i + ( $max_count - $count );
$count = $max_count;
return $count;
}
$count += $ascii_byte_count;
$i += $ascii_byte_count;
if ( $i >= $end ) {
$at = $end;
return $count;
}
/**
* The above fast-track handled all single-byte UTF-8 characters. What
* follows MUST be a multibyte sequence otherwise there’s invalid UTF-8.
*
* Therefore everything past here is checking those multibyte sequences.
*
* It may look like there’s a need to check against the max bytes here,
* but since each match of a single character returns, this functions will
* bail already if crossing the max-bytes threshold. This function SHALL
* NOT return in the middle of a multi-byte character, so if a character
* falls on each side of the max bytes, the entire character will be scanned.
*
* Because it’s possible that there are truncated characters, the use of
* the null-coalescing operator with "\xC0" is a convenience for skipping
* length checks on every continuation bytes. This works because 0xC0 is
* always invalid in a UTF-8 string, meaning that if the string has been
* truncated, it will find 0xC0 and reject as invalid UTF-8.
*
* > [The following table] lists all of the byte sequences that are well-formed
* > in UTF-8. A range of byte values such as A0..BF indicates that any byte
* > from A0 to BF (inclusive) is well-formed in that position. Any byte value
* > outside of the ranges listed is ill-formed.
*
* > Table 3-7. Well-Formed UTF-8 Byte Sequences
* ╭─────────────────────┬────────────┬──────────────┬─────────────┬──────────────╮
* │ Code Points │ First Byte │ Second Byte │ Third Byte │ Fourth Byte │
* ├─────────────────────┼────────────┼──────────────┼─────────────┼──────────────┤
* │ U+0000..U+007F │ 00..7F │ │ │ │
* │ U+0080..U+07FF │ C2..DF │ 80..BF │ │ │
* │ U+0800..U+0FFF │ E0 │ A0..BF │ 80..BF │ │
* │ U+1000..U+CFFF │ E1..EC │ 80..BF │ 80..BF │ │
* │ U+D000..U+D7FF │ ED │ 80..9F │ 80..BF │ │
* │ U+E000..U+FFFF │ EE..EF │ 80..BF │ 80..BF │ │
* │ U+10000..U+3FFFF │ F0 │ 90..BF │ 80..BF │ 80..BF │
* │ U+40000..U+FFFFF │ F1..F3 │ 80..BF │ 80..BF │ 80..BF │
* │ U+100000..U+10FFFF │ F4 │ 80..8F │ 80..BF │ 80..BF │
* ╰─────────────────────┴────────────┴──────────────┴─────────────┴──────────────╯
*
* @see https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-3/#G27506
*/
// Valid two-byte code points.
$b1 = ord( $bytes[ $i ] );
$b2 = ord( $bytes[ $i + 1 ] ?? "\xC0" );
if ( $b1 >= 0xC2 && $b1 <= 0xDF && $b2 >= 0x80 && $b2 <= 0xBF ) {
++$count;
++$i;
continue;
}
// Valid three-byte code points.
$b3 = ord( $bytes[ $i + 2 ] ?? "\xC0" );
if ( $b3 < 0x80 || $b3 > 0xBF ) {
goto invalid_utf8;
}
if (
( 0xE0 === $b1 && $b2 >= 0xA0 && $b2 <= 0xBF ) ||
( $b1 >= 0xE1 && $b1 <= 0xEC && $b2 >= 0x80 && $b2 <= 0xBF ) ||
( 0xED === $b1 && $b2 >= 0x80 && $b2 <= 0x9F ) ||
( $b1 >= 0xEE && $b1 <= 0xEF && $b2 >= 0x80 && $b2 <= 0xBF )
) {
++$count;
$i += 2;
continue;
}
// Valid four-byte code points.
$b4 = ord( $bytes[ $i + 3 ] ?? "\xC0" );
if ( $b4 < 0x80 || $b4 > 0xBF ) {
goto invalid_utf8;
}
if (
( 0xF0 === $b1 && $b2 >= 0x90 && $b2 <= 0xBF ) ||
( $b1 >= 0xF1 && $b1 <= 0xF3 && $b2 >= 0x80 && $b2 <= 0xBF ) ||
( 0xF4 === $b1 && $b2 >= 0x80 && $b2 <= 0x8F )
) {
++$count;
$i += 3;
continue;
}
/**
* When encountering invalid byte sequences, Unicode suggests finding the
* maximal subpart of a text and replacing that subpart with a single
* replacement character.
*
* > This practice is more secure because it does not result in the
* > conversion consuming parts of valid sequences as though they were
* > invalid. It also guarantees at least one replacement character will
* > occur for each instance of an invalid sequence in the original text.
* > Furthermore, this practice can be defined consistently for better
* > interoperability between different implementations of conversion.
*
* @see https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-5/#G40630
*/
invalid_utf8:
$at = $i;
$invalid_length = 1;
// Single-byte and two-byte characters.
if ( ( 0x00 === ( $b1 & 0x80 ) ) || ( 0xC0 === ( $b1 & 0xE0 ) ) ) {
return $count;
}
$b2 = ord( $bytes[ $i + 1 ] ?? "\xC0" );
$b3 = ord( $bytes[ $i + 2 ] ?? "\xC0" );
// Find the maximal subpart and skip past it.
if ( 0xE0 === ( $b1 & 0xF0 ) ) {
// Three-byte characters.
$b2_valid = (
( 0xE0 === $b1 && $b2 >= 0xA0 && $b2 <= 0xBF ) ||
( $b1 >= 0xE1 && $b1 <= 0xEC && $b2 >= 0x80 && $b2 <= 0xBF ) ||
( 0xED === $b1 && $b2 >= 0x80 && $b2 <= 0x9F ) ||
( $b1 >= 0xEE && $b1 <= 0xEF && $b2 >= 0x80 && $b2 <= 0xBF )
);
$invalid_length = min( $end - $i, $b2_valid ? 2 : 1 );
return $count;
} elseif ( 0xF0 === ( $b1 & 0xF8 ) ) {
// Four-byte characters.
$b2_valid = (
( 0xF0 === $b1 && $b2 >= 0x90 && $b2 <= 0xBF ) ||
( $b1 >= 0xF1 && $b1 <= 0xF3 && $b2 >= 0x80 && $b2 <= 0xBF ) ||
( 0xF4 === $b1 && $b2 >= 0x80 && $b2 <= 0x8F )
);
$b3_valid = $b3 >= 0x80 && $b3 <= 0xBF;
$invalid_length = min( $end - $i, $b2_valid ? ( $b3_valid ? 3 : 2 ) : 1 );
return $count;
}
return $count;
}
$at = $i;
return $count;
}
/**
* Fallback mechanism for safely validating UTF-8 bytes.
*
* @since 6.9.0
* @access private
*
* @see wp_is_valid_utf8()
*
* @param string $bytes String which might contain text encoded as UTF-8.
* @return bool Whether the provided bytes can decode as valid UTF-8.
*/
function _wp_is_valid_utf8_fallback( string $bytes ): bool {
$bytes_length = strlen( $bytes );
if ( 0 === $bytes_length ) {
return true;
}
$next_byte_at = 0;
$invalid_length = 0;
_wp_scan_utf8( $bytes, $next_byte_at, $invalid_length );
return $bytes_length === $next_byte_at && 0 === $invalid_length;
}
/**
* Fallback mechanism for replacing invalid spans of UTF-8 bytes.
*
* Example:
*
* 'Pi�a' === _wp_scrub_utf8_fallback( "Pi\xF1a" ); // “ñ” is 0xF1 in Windows-1252.
*
* @since 6.9.0
* @access private
*
* @see wp_scrub_utf8()
*
* @param string $bytes UTF-8 encoded string which might contain spans of invalid bytes.
* @return string Input string with spans of invalid bytes swapped with the replacement character.
*/
function _wp_scrub_utf8_fallback( string $bytes ): string {
$bytes_length = strlen( $bytes );
$next_byte_at = 0;
$was_at = 0;
$invalid_length = 0;
$scrubbed = '';
while ( $next_byte_at <= $bytes_length ) {
_wp_scan_utf8( $bytes, $next_byte_at, $invalid_length );
if ( $next_byte_at >= $bytes_length ) {
if ( 0 === $was_at ) {
return $bytes;
}
return $scrubbed . substr( $bytes, $was_at, $next_byte_at - $was_at - $invalid_length );
}
$scrubbed .= substr( $bytes, $was_at, $next_byte_at - $was_at );
$scrubbed .= "\u{FFFD}";
$next_byte_at += $invalid_length;
$was_at = $next_byte_at;
}
return $scrubbed;
}