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Annotation of src/usr.bin/users/users.c, Revision 1.9

1.9     ! deraadt     1: /*     $OpenBSD: users.c,v 1.8 2003/10/16 16:57:37 tedu 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>
                     34: #include <utmp.h>
                     35: #include <stdio.h>
                     36: #include <stdlib.h>
                     37: #include <string.h>
                     38: #include <err.h>
                     39:
                     40: typedef char   namebuf[UT_NAMESIZE];
                     41:
1.5       millert    42: int scmp(const void *, const void *);
1.1       deraadt    43:
                     44: int
1.6       deraadt    45: main(int argc, char *argv[])
1.1       deraadt    46: {
                     47:        namebuf *names = NULL;
1.4       mpech      48:        int ncnt = 0;
                     49:        int nmax = 0;
1.1       deraadt    50:        int cnt;
                     51:        struct utmp utmp;
                     52:        int ch;
                     53:
1.3       millert    54:        while ((ch = getopt(argc, argv, "")) != -1)
1.1       deraadt    55:                switch(ch) {
                     56:                case '?':
                     57:                default:
                     58:                        (void)fprintf(stderr, "usage: users\n");
                     59:                        exit(1);
                     60:                }
                     61:        argc -= optind;
                     62:        argv += optind;
                     63:
                     64:        if (!freopen(_PATH_UTMP, "r", stdin)) {
                     65:                err(1, "can't open %s", _PATH_UTMP);
                     66:                /* NOTREACHED */
                     67:        }
                     68:
                     69:        while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) {
                     70:                if (*utmp.ut_name) {
                     71:                        if (ncnt >= nmax) {
1.8       tedu       72:                                size_t newmax = nmax + 32;
                     73:                                namebuf *newnames;
1.1       deraadt    74:
1.8       tedu       75:                                newnames = realloc(names,
                     76:                                    sizeof(*names) * newmax);
                     77:
                     78:                                if (newnames == NULL) {
1.1       deraadt    79:                                        err(1, NULL);
                     80:                                        /* NOTREACHED */
                     81:                                }
1.8       tedu       82:                                names = newnames;
                     83:                                nmax = newmax;
1.1       deraadt    84:                        }
                     85:
                     86:                        (void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
                     87:                        ++ncnt;
                     88:                }
                     89:        }
                     90:
                     91:        if (ncnt) {
                     92:                qsort(names, ncnt, UT_NAMESIZE, scmp);
                     93:                (void)printf("%.*s", UT_NAMESIZE, names[0]);
                     94:                for (cnt = 1; cnt < ncnt; ++cnt)
                     95:                        if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE))
                     96:                                (void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
                     97:                (void)printf("\n");
                     98:        }
                     99:        exit(0);
                    100: }
                    101:
                    102: int
1.6       deraadt   103: scmp(const void *p, const void *q)
1.1       deraadt   104: {
                    105:        return(strncmp((char *) p, (char *) q, UT_NAMESIZE));
                    106: }