lib/strsep.c

   1 /* Copyright (C) 2004, 2007, 2009-2024 Free Software Foundation, Inc.
   2
   3    Written by Yoann Vandoorselaere <yoann@prelude-ids.org>.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifdef HAVE_CONFIG_H
  19 # include <config.h>
  20 #endif
  21
  22 /* Specification.  */
  23 #include <string.h>
  24
  25 char *
  26 strsep (char **stringp, const char *delim)
  27 {
  28   char *start = *stringp;
  29   char *ptr;
  30
  31   if (start == NULL)
  32     return NULL;
  33
  34   /* Optimize the case of no delimiters.  */
  35   if (delim[0] == '\0')
  36     {
  37       *stringp = NULL;
  38       return start;
  39     }
  40
  41   /* Optimize the case of one delimiter.  */
  42   if (delim[1] == '\0')
  43     ptr = strchr (start, delim[0]);
  44   else
  45     /* The general case.  */
  46     ptr = strpbrk (start, delim);
  47   if (ptr == NULL)
  48     {
  49       *stringp = NULL;
  50       return start;
  51     }
  52
  53   *ptr = '\0';
  54   *stringp = ptr + 1;
  55
  56   return start;
  57 }