os161/common/libc/string/strtok_r.c
2015-12-23 00:50:04 +00:00

97 lines
2.8 KiB
C

/*
* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
* The President and Fellows of Harvard College.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* This file is shared between libc and the kernel, so don't put anything
* in here that won't work in both contexts.
*/
#ifdef _KERNEL
#include <types.h>
#include <lib.h>
#else
#include <string.h>
#endif
/*
* Standard C string function: tokenize a string splitting based on a
* list of separator characters. Reentrant version.
*
* The "context" argument should point to a "char *" that is preserved
* between calls to strtok_r that wish to operate on same string.
*/
char *
strtok_r(char *string, const char *seps, char **context)
{
char *head; /* start of word */
char *tail; /* end of word */
/* If we're starting up, initialize context */
if (string) {
*context = string;
}
/* Get potential start of this next word */
head = *context;
if (head == NULL) {
return NULL;
}
/* Skip any leading separators */
while (*head && strchr(seps, *head)) {
head++;
}
/* Did we hit the end? */
if (*head == 0) {
/* Nothing left */
*context = NULL;
return NULL;
}
/* skip over word */
tail = head;
while (*tail && !strchr(seps, *tail)) {
tail++;
}
/* Save head for next time in context */
if (*tail == 0) {
*context = NULL;
}
else {
*tail = 0;
tail++;
*context = tail;
}
/* Return current word */
return head;
}