root/common/libc/string/strtok_r.c

DEFINITIONS

1. strtok_r

   1 /*
   2  * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
   3  *      The President and Fellows of Harvard College.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  30 /*
  31  * This file is shared between libc and the kernel, so don't put anything
  32  * in here that won't work in both contexts.
  33  */
  35 #ifdef _KERNEL
  36 #include <types.h>
  37 #include <lib.h>
  38 #else
  39 #include <string.h>
  40 #endif
  42 /*
  43  * Standard C string function: tokenize a string splitting based on a
  44  * list of separator characters. Reentrant version.
  45  *
  46  * The "context" argument should point to a "char *" that is preserved
  47  * between calls to strtok_r that wish to operate on same string.
  48  */
  49 char *
strtok_r(char *string, const char *seps, char **context)
  51 {
  52         char *head;  /* start of word */
  53         char *tail;  /* end of word */
  55         /* If we're starting up, initialize context */
  56         if (string) {
  57                 *context = string;
  58         }
  60         /* Get potential start of this next word */
head = *context;
  62         if (head == NULL) {
  63                 return NULL;
  64         }
  66         /* Skip any leading separators */
  67         while (*head && strchr(seps, *head)) {
head++;
  69         }
  71         /* Did we hit the end? */
  72         if (*head == 0) {
  73                 /* Nothing left */
  74                 *context = NULL;
  75                 return NULL;
  76         }
  78         /* skip over word */
tail = head;
  80         while (*tail && !strchr(seps, *tail)) {
tail++;
  82         }
  84         /* Save head for next time in context */
  85         if (*tail == 0) {
  86                 *context = NULL;
  87         }
  88         else {
  89                 *tail = 0;
tail++;
  91                 *context = tail;
  92         }
  94         /* Return current word */
  95         return head;
  96 }