Bug in users command

[John F Haugh II]

I think there is a bug in the code for "users" in the 4.3-reno
source.  The problem is that the first user name is always printed
as is the last user name.  If there is exactly one user on the
system, and the user is logged on more than once, you get the
user name twice.

Here is the code, as I have modified it to run on SCO Xenix.  The
file was short enough that a diff didn't seem warranted.  The problem
was in the for-while loop that was at the end of main().  I replaced
it with a simpler for loop.
--
/*
 * Copyright (c) 1980, 1987 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted provided
 * that: (1) source distributions retain this entire copyright notice and
 * comment, and (2) distributions including binaries display the following
 * acknowledgement:  ``This product includes software developed by the
 * University of California, Berkeley and its contributors'' in the
 * documentation or other materials provided with the distribution and in
 * all advertising materials mentioning features or use of this software.
 * 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)users.c	5.9 (Berkeley) 6/1/90";
#endif /* not lint */

#include <sys/types.h>
#include <errno.h>
#include <utmp.h>
#include <stdio.h>

#define	MAXUSERS	200

#ifndef	UT_NAMESIZE
#define	UT_NAMESIZE	(sizeof ((struct utmp *) 0)->ut_name)
#endif

#ifndef	_PATH_UTMP
#define	_PATH_UTMP	"/etc/utmp"
#endif

main()
{
	register int cnt, ncnt;
	struct utmp utmp;
	char names[MAXUSERS][UT_NAMESIZE];
	int scmp();

	if (!freopen(_PATH_UTMP, "r", stdin)) {
		(void)fprintf(stderr, "users: can't open %s.\n", _PATH_UTMP);
		exit(1);
	}
	for (ncnt = 0;
	    fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1;)
		if (*utmp.ut_name) {
#ifdef	USER_PROCESS
			if (utmp.ut_type != USER_PROCESS)
				continue;
#endif
			if (ncnt == MAXUSERS) {
				(void)fprintf(stderr,
				    "users: too many users.\n");
				break;
			}
			(void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
			++ncnt;
		}

	if (ncnt) {
		qsort(names, ncnt, UT_NAMESIZE, scmp);
		(void)printf("%s", names[0]);
		for (cnt = 1; cnt < ncnt; ++cnt) {
			if (! strncmp (names[cnt - 1], names[cnt], UT_NAMESIZE))
				continue;

			(void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
		}
		(void)printf("\n");
	}
	exit(0);
}

scmp(p, q)
	char *p, *q;
{
	return(strcmp(p, q));
}
--
-- 
John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh
Ma Bell: (512) 832-8832                           Domain: jfh at rpp386.cactus.org
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