Function find_field_delim

src/cut.c:577–622

   and must have room for a trailing NUL byte at BUF[LEN].  */

ATTRIBUTE_PURE
static char *
find_field_delim (char *buf, size_t len)
{
  if (len < delim_mcel.len)
    return NULL;

#if ! __GLIBC__  /* Only S390 has optimized memmem on glibc-2.42  */
  return memmem (buf, len, delim_bytes, delim_mcel.len);
#else
  if (delim_mcel.len == 1)
    return memchr (buf, delim_bytes[0], len);

  char const *p = buf;
  char const *end = buf + len;

  char saved = buf[len];
  buf[len] = '\0'; /* for strstr.  */

  while (p < end)
    {
      char const *nul = memchr (p, '\0', end - p);
      if (!nul)
        {
          char const *match = strstr (p, delim_bytes);
          buf[len] = saved;
          return (char *) match;
        }

      if (p < nul)
        {
          char const *match = strstr (p, delim_bytes);
          if (match)
            {
              buf[len] = saved;
              return (char *) match;
            }
        }

      p = nul + 1;
    }

  buf[len] = saved;
  return NULL;
#endif
}

/* Return the number of trailing bytes in BUF that could be the initial
   bytes of a delimiter split across buffers.  */