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Annotation of src/usr.bin/users/users.c, Revision 1.11

1.11    ! doug        1: /*     $OpenBSD: users.c,v 1.10 2013/11/15 22:20:04 millert Exp $      */
1.1       deraadt     2: /*     $NetBSD: users.c,v 1.5 1994/12/20 15:58:19 jtc Exp $    */
                      3:
                      4: /*
                      5:  * Copyright (c) 1980, 1987, 1993
                      6:  *     The Regents of the University of California.  All rights reserved.
                      7:  *
                      8:  * Redistribution and use in source and binary forms, with or without
                      9:  * modification, are permitted provided that the following conditions
                     10:  * are met:
                     11:  * 1. Redistributions of source code must retain the above copyright
                     12:  *    notice, this list of conditions and the following disclaimer.
                     13:  * 2. Redistributions in binary form must reproduce the above copyright
                     14:  *    notice, this list of conditions and the following disclaimer in the
                     15:  *    documentation and/or other materials provided with the distribution.
1.7       millert    16:  * 3. Neither the name of the University nor the names of its contributors
1.1       deraadt    17:  *    may be used to endorse or promote products derived from this software
                     18:  *    without specific prior written permission.
                     19:  *
                     20:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     21:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     22:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     23:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     24:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     25:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     26:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     27:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     28:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     29:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     30:  * SUCH DAMAGE.
                     31:  */
                     32:
                     33: #include <sys/types.h>
1.10      millert    34:
                     35: #include <err.h>
1.1       deraadt    36: #include <stdio.h>
                     37: #include <stdlib.h>
                     38: #include <string.h>
1.10      millert    39: #include <unistd.h>
                     40: #include <utmp.h>
1.1       deraadt    41:
                     42: typedef char   namebuf[UT_NAMESIZE];
                     43:
1.5       millert    44: int scmp(const void *, const void *);
1.1       deraadt    45:
                     46: int
1.6       deraadt    47: main(int argc, char *argv[])
1.1       deraadt    48: {
                     49:        namebuf *names = NULL;
1.4       mpech      50:        int ncnt = 0;
                     51:        int nmax = 0;
1.1       deraadt    52:        int cnt;
                     53:        struct utmp utmp;
                     54:        int ch;
                     55:
1.3       millert    56:        while ((ch = getopt(argc, argv, "")) != -1)
1.1       deraadt    57:                switch(ch) {
                     58:                case '?':
                     59:                default:
                     60:                        (void)fprintf(stderr, "usage: users\n");
                     61:                        exit(1);
                     62:                }
                     63:        argc -= optind;
                     64:        argv += optind;
                     65:
                     66:        if (!freopen(_PATH_UTMP, "r", stdin)) {
                     67:                err(1, "can't open %s", _PATH_UTMP);
                     68:                /* NOTREACHED */
                     69:        }
                     70:
                     71:        while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) {
                     72:                if (*utmp.ut_name) {
                     73:                        if (ncnt >= nmax) {
1.8       tedu       74:                                size_t newmax = nmax + 32;
                     75:                                namebuf *newnames;
1.1       deraadt    76:
1.11    ! doug       77:                                newnames = reallocarray(names, newmax,
        !            78:                                    sizeof(*names));
1.8       tedu       79:
                     80:                                if (newnames == NULL) {
1.1       deraadt    81:                                        err(1, NULL);
                     82:                                        /* NOTREACHED */
                     83:                                }
1.8       tedu       84:                                names = newnames;
                     85:                                nmax = newmax;
1.1       deraadt    86:                        }
                     87:
                     88:                        (void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
                     89:                        ++ncnt;
                     90:                }
                     91:        }
                     92:
                     93:        if (ncnt) {
                     94:                qsort(names, ncnt, UT_NAMESIZE, scmp);
                     95:                (void)printf("%.*s", UT_NAMESIZE, names[0]);
                     96:                for (cnt = 1; cnt < ncnt; ++cnt)
                     97:                        if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE))
                     98:                                (void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
                     99:                (void)printf("\n");
                    100:        }
                    101:        exit(0);
                    102: }
                    103:
                    104: int
1.6       deraadt   105: scmp(const void *p, const void *q)
1.1       deraadt   106: {
                    107:        return(strncmp((char *) p, (char *) q, UT_NAMESIZE));
                    108: }