infra.c

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/*
   +----------------------------------------------------------------------+
   | Copyright (c) The PHP Group                                          |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | https://www.php.net/license/3_01.txt                                 |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Authors: Niels Dossche <nielsdos@php.net>                            |
   +----------------------------------------------------------------------+
*/
 
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
 
#include "php.h"
#if defined(HAVE_LIBXML) && defined(HAVE_DOM)
#include "infra.h"
 
/* https://infra.spec.whatwg.org/#ascii-whitespace */
const char *ascii_whitespace = "\x09\x0A\x0C\x0D\x20";
 
/* https://infra.spec.whatwg.org/#strip-and-collapse-ascii-whitespace */
zend_string *dom_strip_and_collapse_ascii_whitespace(zend_string *input)
{
    if (input == zend_empty_string) {
        return input;
    }
 
    ZEND_ASSERT(!ZSTR_IS_INTERNED(input));
    ZEND_ASSERT(GC_REFCOUNT(input) == 1);
 
    char *write_ptr = ZSTR_VAL(input);
 
    const char *start = ZSTR_VAL(input);
    const char *current = start;
    const char *end = current + ZSTR_LEN(input);
 
    current += strspn(current, ascii_whitespace);
 
    while (current < end) {
        /* Copy non-whitespace */
        size_t non_whitespace_len = strcspn(current, ascii_whitespace);
        /* If the pointers are equal, we still haven't encountered collapsable or strippable whitespace. */
        if (write_ptr != current) {
            memmove(write_ptr, current, non_whitespace_len);
        }
        current += non_whitespace_len;
        write_ptr += non_whitespace_len;
 
        /* Skip whitespace */
        current += strspn(current, ascii_whitespace);
        if (current < end) {
            /* Only make a space when we're not yet at the end of the input, because that means more non-whitespace
             * input is to come. */
            *write_ptr++ = ' ';
        }
    }
 
    *write_ptr = '\0';
 
    size_t len = write_ptr - start;
    if (len != ZSTR_LEN(input)) {
        return zend_string_truncate(input, len, false);
    } else {
        /* Forget the hash value since we may have transformed non-space-whitespace into spaces. */
        zend_string_forget_hash_val(input);
        return input;
    }
}
 
#endif  /* HAVE_LIBXML && HAVE_DOM */