string/strsep.c

   1 /* Copyright (C) 1992-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19
  20 #undef __strsep
  21 #undef strsep
  22
  23 char *
  24 __strsep (char **stringp, const char *delim)
  25 {
  26   char *begin, *end;
  27
  28   begin = *stringp;
  29   if (begin == NULL)
  30     return NULL;
  31
  32   /* A frequent case is when the delimiter string contains only one
  33      character.  Here we don't need to call the expensive `strpbrk'
  34      function and instead work using `strchr'.  */
  35   if (delim[0] == '\0' || delim[1] == '\0')
  36     {
  37       char ch = delim[0];
  38
  39       if (ch == '\0')
  40         end = NULL;
  41       else
  42         {
  43           if (*begin == ch)
  44             end = begin;
  45           else if (*begin == '\0')
  46             end = NULL;
  47           else
  48             end = strchr (begin + 1, ch);
  49         }
  50     }
  51   else
  52     /* Find the end of the token.  */
  53     end = strpbrk (begin, delim);
  54
  55   if (end)
  56     {
  57       /* Terminate the token and set *STRINGP past NUL character.  */
  58       *end++ = '\0';
  59       *stringp = end;
  60     }
  61   else
  62     /* No more delimiters; this is the last token.  */
  63     *stringp = NULL;
  64
  65   return begin;
  66 }
  67 weak_alias (__strsep, strsep)
  68 strong_alias (__strsep, __strsep_g)
  69 libc_hidden_def (__strsep_g)