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/* $OpenBSD: users.c,v 1.14 2018/08/03 16:02:53 deraadt Exp $ */
/* $NetBSD: users.c,v 1.5 1994/12/20 15:58:19 jtc Exp $ */
/*
* Copyright (c) 1980, 1987, 1993
* The Regents of the University of California. All rights reserved.
*
* 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 REGENTS 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 REGENTS 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.
*/
#include <sys/types.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <utmp.h>
typedef char namebuf[UT_NAMESIZE];
int scmp(const void *, const void *);
int
main(int argc, char *argv[])
{
namebuf *names = NULL;
int ncnt = 0;
int nmax = 0;
int cnt;
struct utmp utmp;
int ch;
if (unveil(_PATH_UTMP, "r") == -1)
err(1, "unveil");
if (pledge("stdio rpath", NULL) == -1)
err(1, "pledge");
while ((ch = getopt(argc, argv, "")) != -1)
switch(ch) {
case '?':
default:
(void)fprintf(stderr, "usage: users\n");
exit(1);
}
argc -= optind;
argv += optind;
if (!freopen(_PATH_UTMP, "r", stdin)) {
err(1, "can't open %s", _PATH_UTMP);
/* NOTREACHED */
}
while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) {
if (*utmp.ut_name) {
if (ncnt >= nmax) {
size_t newmax = nmax + 32;
namebuf *newnames;
newnames = reallocarray(names, newmax,
sizeof(*names));
if (newnames == NULL) {
err(1, NULL);
/* NOTREACHED */
}
names = newnames;
nmax = newmax;
}
(void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
++ncnt;
}
}
if (ncnt) {
qsort(names, ncnt, UT_NAMESIZE, scmp);
(void)printf("%.*s", UT_NAMESIZE, names[0]);
for (cnt = 1; cnt < ncnt; ++cnt)
if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE))
(void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
(void)printf("\n");
}
exit(0);
}
int
scmp(const void *p, const void *q)
{
return(strncmp((char *) p, (char *) q, UT_NAMESIZE));
}
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