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who.c revision 1.3 
      1 /*	$NetBSD: who.c,v 1.3 1994/11/14 05:13:17 jtc Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Michael Fischbein.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #ifndef lint
     40 static char copyright[] =
     41 "@(#) Copyright (c) 1989, 1993\n\
     42 	The Regents of the University of California.  All rights reserved.\n";
     43 #endif /* not lint */
     44 
     45 #ifndef lint
     46 #if 0
     47 static char sccsid[] = "@(#)who.c	8.1 (Berkeley) 6/6/93";
     48 #endif
     49 static char rcsid[] = "$NetBSD: who.c,v 1.3 1994/11/14 05:13:17 jtc Exp $";
     50 #endif /* not lint */
     51 
     52 #include <sys/types.h>
     53 #include <sys/file.h>
     54 #include <sys/time.h>
     55 #include <pwd.h>
     56 #include <utmp.h>
     57 #include <stdio.h>
     58 
     59 main(argc, argv)
     60 	int argc;
     61 	char **argv;
     62 {
     63 	register char *p;
     64 	struct utmp usr;
     65 	struct passwd *pw;
     66 	FILE *ufp, *file();
     67 	char *t, *rindex(), *strcpy(), *strncpy(), *ttyname();
     68 	time_t time();
     69 
     70 	switch (argc) {
     71 	case 1:					/* who */
     72 		ufp = file(_PATH_UTMP);
     73 		/* only entries with both name and line fields */
     74 		while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
     75 			if (*usr.ut_name && *usr.ut_line)
     76 				output(&usr);
     77 		break;
     78 	case 2:					/* who utmp_file */
     79 		ufp = file(argv[1]);
     80 		/* all entries */
     81 		while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
     82 			output(&usr);
     83 		break;
     84 	case 3:					/* who am i */
     85 		ufp = file(_PATH_UTMP);
     86 
     87 		/* search through the utmp and find an entry for this tty */
     88 		if (p = ttyname(0)) {
     89 			/* strip any directory component */
     90 			if (t = rindex(p, '/'))
     91 				p = t + 1;
     92 			while (fread((char *)&usr, sizeof(usr), 1, ufp) == 1)
     93 				if (usr.ut_name && !strcmp(usr.ut_line, p)) {
     94 					output(&usr);
     95 					exit(0);
     96 				}
     97 			/* well, at least we know what the tty is */
     98 			(void)strncpy(usr.ut_line, p, UT_LINESIZE);
     99 		} else
    100 			(void)strcpy(usr.ut_line, "tty??");
    101 		pw = getpwuid(getuid());
    102 		(void)strncpy(usr.ut_name, pw ? pw->pw_name : "?", UT_NAMESIZE);
    103 		(void)time(&usr.ut_time);
    104 		*usr.ut_host = '\0';
    105 		output(&usr);
    106 		break;
    107 	default:
    108 		(void)fprintf(stderr, "usage: who [ file ]\n       who am i\n");
    109 		exit(1);
    110 	}
    111 	exit(0);
    112 }
    113 
    114 output(up)
    115 	struct utmp *up;
    116 {
    117 	char *ctime();
    118 
    119 	(void)printf("%-*.*s %-*.*s", UT_NAMESIZE, UT_NAMESIZE, up->ut_name,
    120 	    UT_LINESIZE, UT_LINESIZE, up->ut_line);
    121 	(void)printf("%.12s", ctime(&up->ut_time) + 4);
    122 	if (*up->ut_host)
    123 		printf("\t(%.*s)", UT_HOSTSIZE, up->ut_host);
    124 	(void)putchar('\n');
    125 }
    126 
    127 FILE *
    128 file(name)
    129 	char *name;
    130 {
    131 	extern int errno;
    132 	FILE *ufp;
    133 	char *strerror();
    134 
    135 	if (!(ufp = fopen(name, "r"))) {
    136 		(void)fprintf(stderr, "who: %s: %s.\n", name, strerror(errno));
    137 		exit(1);
    138 	}
    139 	return(ufp);
    140 }
    141