glibc/sysdeps/generic/strsep.c

/* Copyright (C) 1992, 93, 96, 97, 98, 99 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <string.h>

#undef __strsep
#undef strsep

char *
__strsep (char **stringp, const char *delim)
{
  char *begin, *end;

  begin = *stringp;
  if (begin == NULL)
    return NULL;

  /* A frequent case is when the delimiter string contains only one
     character.  Here we don't need to call the expensive `strpbrk'
     function and instead work using `strchr'.  */
  if (delim[0] == '\0' || delim[1] == '\0')
    {
      char ch = delim[0];

      if (ch == '\0')
	end = NULL;
      else
	{
	  if (*begin == ch)
	    end = begin;
	  else if (*begin == '\0')
	    end = NULL;
	  else
	    end = strchr (begin + 1, ch);
	}
    }
  else
    /* Find the end of the token.  */
    end = strpbrk (begin, delim);

  if (end)
    {
      /* Terminate the token and set *STRINGP past NUL character.  */
      *end++ = '\0';
      *stringp = end;
    }
  else
    /* No more delimiters; this is the last token.  */
    *stringp = NULL;

  return begin;
}
weak_alias (__strsep, strsep)