NetBSD/usr.sbin/sup/source/nxtarg.c

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/* $NetBSD: nxtarg.c,v 1.4 1997/06/17 21:38:23 christos Exp $ */
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/*
* 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,brk);
* char *p,*q,*brk;
* 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 "brk".
* 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 "brk" 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"
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char _argbreak;
char *nxtarg (q,brk)
char **q,*brk;
{
register char *front,*back;
front = *q; /* start of string */
/* leading blanks and tabs */
while (*front && (*front == ' ' || *front == '\t')) front++;
/* find break character at end */
if (brk == 0) brk = " ";
back = skipto (front, brk);
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_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);
}