string/strtok_r.c

   1 /* Reentrant string tokenizer.  Generic version.
   2    Copyright (C) 1991-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #include <string.h>
  24
  25 #ifndef _LIBC
  26 /* Get specification.  */
  27 # include "strtok_r.h"
  28 # define __strtok_r strtok_r
  29 #endif
  30
  31 /* Parse S into tokens separated by characters in DELIM.
  32    If S is NULL, the saved pointer in SAVE_PTR is used as
  33    the next starting point.  For example:
  34         char s[] = "-abc-=-def";
  35         char *sp;
  36         x = strtok_r(s, "-", &sp);      // x = "abc", sp = "=-def"
  37         x = strtok_r(NULL, "-=", &sp);  // x = "def", sp = NULL
  38         x = strtok_r(NULL, "=", &sp);   // x = NULL
  39                 // s = "abc\0-def\0"
  40 */
  41 char *
  42 __strtok_r (char *s, const char *delim, char **save_ptr)
  43 {
  44   char *end;
  45
  46   if (s == NULL)
  47     s = *save_ptr;
  48
  49   if (*s == '\0')
  50     {
  51       *save_ptr = s;
  52       return NULL;
  53     }
  54
  55   /* Scan leading delimiters.  */
  56   s += strspn (s, delim);
  57   if (*s == '\0')
  58     {
  59       *save_ptr = s;
  60       return NULL;
  61     }
  62
  63   /* Find the end of the token.  */
  64   end = s + strcspn (s, delim);
  65   if (*end == '\0')
  66     {
  67       *save_ptr = end;
  68       return s;
  69     }
  70
  71   /* Terminate the token and make *SAVE_PTR point past it.  */
  72   *end = '\0';
  73   *save_ptr = end + 1;
  74   return s;
  75 }
  76 #ifdef weak_alias
  77 libc_hidden_def (__strtok_r)
  78 weak_alias (__strtok_r, strtok_r)
  79 #endif