curl/lib/curl_memrchr.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/

#include "curl_setup.h"

#include <curl/curl.h>

#include "curl_memrchr.h"
#include "curl_memory.h"

/* The last #include file should be: */
#include "memdebug.h"

#ifndef HAVE_MEMRCHR

/*
 * Curl_memrchr()
 *
 * Our memrchr() function clone for systems which lack this function. The
 * memrchr() function is like the memchr() function, except that it searches
 * backwards from the end of the n bytes pointed to by s instead of forward
 * from the beginning.
 */

void *
Curl_memrchr(const void *s, int c, size_t n)
{
  if(n > 0) {
    const unsigned char *p = s;
    const unsigned char *q = s;

    p += n - 1;

    while(p >= q) {
      if(*p == (unsigned char)c)
        return (void *)p;
      p--;
    }
  }
  return NULL;
}

#endif /* HAVE_MEMRCHR */