bsd/libkern/strsep.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   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  * 4. 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 REGENTS 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 REGENTS 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  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)strsep.c    8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 /* __FBSDID("$FreeBSD: src/sys/libkern/strsep.c,v 1.7 2004/04/07 20:46:10 imp Exp $"); */
  35
  36 #include <sys/param.h>
  37 #include <libkern/libkern.h>
  38
  39 /*
  40  * Get next token from string *stringp, where tokens are possibly-empty
  41  * strings separated by characters from delim.
  42  *
  43  * Writes NULs into the string at *stringp to end tokens.
  44  * delim need not remain constant from call to call.
  45  * On return, *stringp points past the last NUL written (if there might
  46  * be further tokens), or is NULL (if there are definitely no more tokens).
  47  *
  48  * If *stringp is NULL, strsep returns NULL.
  49  */
  50 char *
  51 strsep(stringp, delim)
  52         char **stringp;
  53         const char *delim;
  54 {
  55         char *s;
  56         const char *spanp;
  57         int c, sc;
  58         char *tok;
  59
  60         if ((s = *stringp) == NULL)
  61                 return (NULL);
  62         for (tok = s;;) {
  63                 c = *s++;
  64                 spanp = delim;
  65                 do {
  66                         if ((sc = *spanp++) == c) {
  67                                 if (c == 0)
  68                                         s = NULL;
  69                                 else
  70                                         s[-1] = 0;
  71                                 *stringp = s;
  72                                 return (tok);
  73                         }
  74                 } while (sc != 0);
  75         }
  76         /* NOTREACHED */
  77 }