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logutmp.c revision 1.2 
      1 /*
      2  * Portions Copyright (c) 1988, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  * Portions Copyright (c) 1996, Jason Downs.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. All advertising materials mentioning features or use of this software
     15  *    must display the following acknowledgement:
     16  *	This product includes software developed by the University of
     17  *	California, Berkeley and its contributors.
     18  * 4. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/types.h>
     36 
     37 #include <fcntl.h>
     38 #include <stdio.h>
     39 #include <stdlib.h>
     40 #include <string.h>
     41 #include <ttyent.h>
     42 #include <unistd.h>
     43 #include <utmp.h>
     44 #include <util.h>
     45 
     46 typedef struct utmp UTMP;
     47 
     48 static int fd = -1;
     49 static int topslot = -1;
     50 
     51 /*
     52  * Special versions of login()/logout() which hold the utmp file open,
     53  * for use with ftpd.
     54  */
     55 
     56 void
     57 login(const UTMP *ut)
     58 {
     59 	UTMP ubuf;
     60 
     61 	/*
     62 	 * First, loop through /etc/ttys, if needed, to initialize the
     63 	 * top of the tty slots, since ftpd has no tty.
     64 	 */
     65 	if (topslot < 0) {
     66 		topslot = 0;
     67 		while (getttyent() != (struct ttyent *)NULL)
     68 			topslot++;
     69 	}
     70 	if ((topslot < 0) || ((fd < 0)
     71 	    && (fd = open(_PATH_UTMP, O_RDWR|O_CREAT, 0644)) < 0))
     72 	    	return;
     73 
     74 	/*
     75 	 * Now find a slot that's not in use...
     76 	 */
     77 	(void)lseek(fd, (off_t)(topslot * sizeof(UTMP)), SEEK_SET);
     78 
     79 	while (1) {
     80 		if (read(fd, &ubuf, sizeof(UTMP)) == sizeof(UTMP)) {
     81 			if (!ubuf.ut_name[0]) {
     82 				(void)lseek(fd, -(off_t)sizeof(UTMP), SEEK_CUR);
     83 				break;
     84 			}
     85 			topslot++;
     86 		} else {
     87 			(void)lseek(fd, (off_t)(topslot * sizeof(UTMP)),
     88 			    SEEK_SET);
     89 			break;
     90 		}
     91 	}
     92 
     93 	(void)write(fd, ut, sizeof(UTMP));
     94 }
     95 
     96 int
     97 logout(const char *line)
     98 {
     99 	UTMP ut;
    100 	int rval;
    101 
    102 	rval = 0;
    103 	if (fd < 0)
    104 		return(rval);
    105 
    106 	(void)lseek(fd, 0, SEEK_SET);
    107 
    108 	while (read(fd, &ut, sizeof(UTMP)) == sizeof(UTMP)) {
    109 		if (!ut.ut_name[0]
    110 		    || strncmp(ut.ut_line, line, UT_LINESIZE))
    111 			continue;
    112 		memset(ut.ut_name, 0, UT_NAMESIZE);
    113 		memset(ut.ut_host, 0, UT_HOSTSIZE);
    114 		(void)time(&ut.ut_time);
    115 		(void)lseek(fd, -(off_t)sizeof(UTMP), SEEK_CUR);
    116 		(void)write(fd, &ut, sizeof(UTMP));
    117 		rval = 1;
    118 	}
    119 	return(rval);
    120 }
    121