/*	$NetBSD: nxtarg.c,v 1.6 2009/10/16 12:41:37 christos Exp $	*/

/*
 * Copyright (c) 1991 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator   or   Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the rights
 * to redistribute these changes.
 */
/*
 *  nxtarg -- strip off arguments from a string
 *
 *  Usage:  p = nxtarg (&q,sep);
 *	char *p,*q,*sep;
 *	extern char _argbreak;
 *
 *	q is pointer to next argument in string
 *	after call, p points to string containing argument,
 *	q points to remainder of string
 *
 *  Leading blanks and tabs are skipped; the argument ends at the
 *  first occurence of one of the characters in the string "sep".
 *  When such a character is found, it is put into the external
 *  variable "_argbreak", and replaced by a null character; if the
 *  arg string ends before that, then the null character is
 *  placed into _argbreak;
 *  If "sep" is 0, then " " is substituted.
 *
 *  HISTORY
 * 01-Jul-83  Steven Shafer (sas) at Carnegie-Mellon University
 *	Bug fix: added check for "back >= front" in loop to chop trailing
 *	white space.
 *
 * 20-Nov-79  Steven Shafer (sas) at Carnegie-Mellon University
 *	Rewritten for VAX.  By popular demand, a table of break characters
 *	has been added (implemented as a string passed into nxtarg).
 *
 *  Originally	from klg (Ken Greer); IUS/SUS UNIX.
 */
#include "supcdefs.h"
#include "supextern.h"

char _argbreak;

char *
nxtarg(char **q, const char *sep)
{
	char *front, *back;
	front = *q;		/* start of string */
	/* leading blanks and tabs */
	while (*front && (*front == ' ' || *front == '\t'))
		front++;
	/* find break character at end */
	if (sep == 0)
		sep = " ";
	back = skipto(front, sep);
	_argbreak = *back;
	*q = (*back ? back + 1 : back);	/* next arg start loc */
	/* elim trailing blanks and tabs */
	back -= 1;
	while ((back >= front) && (*back == ' ' || *back == '\t'))
		back--;
	back++;
	if (*back)
		*back = '\0';
	return (front);
}