libs/libc/string/lib_strlcat.c

/****************************************************************************
 * libs/libc/string/lib_strlcat.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <string.h>

#include "libc.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: strlcat
 *
 * Description:
 *   The strlcat() function appends at most (dstsize-strlen(dst)-1)
 *   characters of src to dst (dstsize being the size of the string buffer
 *   dst).
 *
 * Returned Value:
 *   Returns min{dstsize,strlen(dst)} + strlen(src).
 *
 ****************************************************************************/

#if !defined(CONFIG_LIBC_ARCH_STRLCAT) && defined(LIBC_BUILD_STRLCAT)
#undef strlcat /* See mm/README.txt */
size_t strlcat(FAR char *dst, FAR const char *src, size_t dsize)
{
  FAR const char *odst = dst;
  FAR const char *osrc = src;
  size_t n = dsize;
  size_t dlen;

  /* Find the end of dst and adjust bytes left but don't go past end. */

  while (n-- != 0 && *dst != '\0')
    {
      dst++;
    }

  dlen = dst - odst;
  n = dsize - dlen;

  if (n-- == 0)
    {
      return dlen + strlen(src);
    }

  while (*src != '\0')
    {
      if (n != 0)
        {
          *dst++ = *src;
          n--;
        }

      src++;
    }

  *dst = '\0';

  /* Count does not include NUL */

  return dlen + (src - osrc);
}
#endif