lib/strtok_r.c

   1 /* Reentrant string tokenizer.  Generic version.
   2    Copyright (C) 1991, 1996-1999, 2001, 2004, 2007, 2009-2024 Free Software
   3    Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    This file is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation; either version 2.1 of the
   9    License, or (at your option) any later version.
  10
  11    This file is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #include <string.h>
  24
  25 #ifdef _LIBC
  26 # undef strtok_r
  27 # undef __strtok_r
  28 #else
  29 # define __strtok_r strtok_r
  30 # define __rawmemchr strchr
  31 #endif
  32
  33 /* Parse S into tokens separated by characters in DELIM.
  34    If S is NULL, the saved pointer in SAVE_PTR is used as
  35    the next starting point.  For example:
  36         char s[] = "-abc-=-def";
  37         char *sp;
  38         x = strtok_r(s, "-", &sp);      // x = "abc", sp = "=-def"
  39         x = strtok_r(NULL, "-=", &sp);  // x = "def", sp = NULL
  40         x = strtok_r(NULL, "=", &sp);   // x = NULL
  41                 // s = "abc\0-def\0"
  42 */
  43 char *
  44 __strtok_r (char *s, const char *delim, char **save_ptr)
  45 {
  46   char *token;
  47
  48   if (s == NULL)
  49     s = *save_ptr;
  50
  51   /* Scan leading delimiters.  */
  52   s += strspn (s, delim);
  53   if (*s == '\0')
  54     {
  55       *save_ptr = s;
  56       return NULL;
  57     }
  58
  59   /* Find the end of the token.  */
  60   token = s;
  61   s = strpbrk (token, delim);
  62   if (s == NULL)
  63     /* This token finishes the string.  */
  64     *save_ptr = __rawmemchr (token, '\0');
  65   else
  66     {
  67       /* Terminate the token and make *SAVE_PTR point past it.  */
  68       *s = '\0';
  69       *save_ptr = s + 1;
  70     }
  71   return token;
  72 }
  73 #ifdef weak_alias
  74 libc_hidden_def (__strtok_r)
  75 weak_alias (__strtok_r, strtok_r)
  76 #endif