323 lines
8.3 KiB
C
323 lines
8.3 KiB
C
/* $NetBSD: write.c,v 1.8 1997/02/11 08:21:03 mrg Exp $ */
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/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static char copyright[] =
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"@(#) Copyright (c) 1989, 1993\n\
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The Regents of the University of California. All rights reserved.\n";
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#endif /* not lint */
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)write.c 8.2 (Berkeley) 4/27/95";
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#endif
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static char *rcsid = "$NetBSD: write.c,v 1.8 1997/02/11 08:21:03 mrg Exp $";
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#endif /* not lint */
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <ctype.h>
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#include <stdio.h>
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#include <string.h>
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#include <signal.h>
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#include <time.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <unistd.h>
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#include <utmp.h>
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#include <err.h>
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void done();
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void do_write __P((char *, char *, uid_t));
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void wr_fputs __P((char *));
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void search_utmp __P((char *, char *, char *, uid_t, int));
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int term_chk __P((char *, int *, time_t *, int));
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int utmp_chk __P((char *, char *));
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int
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main(argc, argv)
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int argc;
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char **argv;
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{
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register char *cp;
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time_t atime;
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uid_t myuid;
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int msgsok, myttyfd;
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char tty[MAXPATHLEN], *mytty;
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/* check that sender has write enabled */
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if (isatty(fileno(stdin)))
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myttyfd = fileno(stdin);
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else if (isatty(fileno(stdout)))
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myttyfd = fileno(stdout);
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else if (isatty(fileno(stderr)))
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myttyfd = fileno(stderr);
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else
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errx(1, "can't find your tty");
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if (!(mytty = ttyname(myttyfd)))
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errx(1, "can't find your tty's name");
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if (cp = strrchr(mytty, '/'))
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mytty = cp + 1;
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if (term_chk(mytty, &msgsok, &atime, 1))
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exit(1);
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if (!msgsok) {
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(void)fprintf(stderr,
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"warning: you have write permission turned off; "
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"no reply possible\n");
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}
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myuid = getuid();
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/* check args */
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switch (argc) {
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case 2:
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search_utmp(argv[1], tty, mytty, myuid, sizeof tty);
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do_write(tty, mytty, myuid);
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break;
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case 3:
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if (!strncmp(argv[2], "/dev/", 5))
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argv[2] += 5;
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if (utmp_chk(argv[1], argv[2]))
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errx(1, "%s is not logged in on %s",
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argv[1], argv[2]);
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if (term_chk(argv[2], &msgsok, &atime, 1))
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exit(1);
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if (myuid && !msgsok)
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errx(1, "%s has messages disabled on %s",
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argv[1], argv[2]);
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do_write(argv[2], mytty, myuid);
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break;
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default:
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(void)fprintf(stderr, "usage: write user [tty]\n");
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exit(1);
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}
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done();
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/* NOTREACHED */
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}
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/*
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* utmp_chk - checks that the given user is actually logged in on
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* the given tty
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*/
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int
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utmp_chk(user, tty)
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char *user, *tty;
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{
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struct utmp u;
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int ufd;
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if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
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return(0); /* ignore error, shouldn't happen anyway */
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while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
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if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
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strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
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(void)close(ufd);
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return(0);
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}
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(void)close(ufd);
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return(1);
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}
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/*
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* search_utmp - search utmp for the "best" terminal to write to
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*
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* Ignores terminals with messages disabled, and of the rest, returns
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* the one with the most recent access time. Returns as value the number
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* of the user's terminals with messages enabled, or -1 if the user is
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* not logged in at all.
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*
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* Special case for writing to yourself - ignore the terminal you're
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* writing from, unless that's the only terminal with messages enabled.
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*/
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void
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search_utmp(user, tty, mytty, myuid, ttylen)
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char *user, *tty, *mytty;
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uid_t myuid;
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int ttylen;
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{
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struct utmp u;
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time_t bestatime, atime;
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int ufd, nloggedttys, nttys, msgsok, user_is_me;
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char atty[UT_LINESIZE + 1];
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if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
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err(1, "%s", _PATH_UTMP);
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nloggedttys = nttys = 0;
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bestatime = 0;
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user_is_me = 0;
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while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
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if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
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++nloggedttys;
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(void)strncpy(atty, u.ut_line, UT_LINESIZE);
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atty[UT_LINESIZE] = '\0';
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if (term_chk(atty, &msgsok, &atime, 0))
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continue; /* bad term? skip */
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if (myuid && !msgsok)
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continue; /* skip ttys with msgs off */
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if (strcmp(atty, mytty) == 0) {
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user_is_me = 1;
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continue; /* don't write to yourself */
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}
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++nttys;
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if (atime > bestatime) {
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bestatime = atime;
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(void)strncpy(tty, atty, ttylen - 1);
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}
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}
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(void)close(ufd);
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if (nloggedttys == 0)
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errx(1, "%s is not logged in", user);
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if (nttys == 0) {
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if (user_is_me) { /* ok, so write to yourself! */
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(void)strncpy(tty, mytty, ttylen - 1);
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return;
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}
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errx(1, "%s has messages disabled", user);
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} else if (nttys > 1)
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warnx("%s is logged in more than once; writing to %s",
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user, tty);
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}
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/*
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* term_chk - check that a terminal exists, and get the message bit
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* and the access time
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*/
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int
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term_chk(tty, msgsokP, atimeP, showerror)
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char *tty;
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int *msgsokP, showerror;
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time_t *atimeP;
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{
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struct stat s;
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char path[MAXPATHLEN];
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(void)snprintf(path, sizeof path, "/dev/%s", tty);
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if (stat(path, &s) < 0) {
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if (showerror)
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warn("%s", path);
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return(1);
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}
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*msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */
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*atimeP = s.st_atime;
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return(0);
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}
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/*
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* do_write - actually make the connection
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*/
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void
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do_write(tty, mytty, myuid)
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char *tty, *mytty;
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uid_t myuid;
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{
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register char *login, *nows;
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register struct passwd *pwd;
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time_t now;
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char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
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/* Determine our login name before the we reopen() stdout */
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if ((login = getlogin()) == NULL)
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if (pwd = getpwuid(myuid))
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login = pwd->pw_name;
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else
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login = "???";
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(void)snprintf(path, sizeof path, "/dev/%s", tty);
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if ((freopen(path, "w", stdout)) == NULL)
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err(1, "%s", path);
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(void)signal(SIGINT, done);
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(void)signal(SIGHUP, done);
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/* print greeting */
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if (gethostname(host, sizeof(host)) < 0)
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(void)strncpy(host, "???", sizeof(host) - 1);
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now = time((time_t *)NULL);
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nows = ctime(&now);
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nows[16] = '\0';
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(void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n",
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login, host, mytty, nows + 11);
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while (fgets(line, sizeof(line), stdin) != NULL)
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wr_fputs(line);
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}
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/*
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* done - cleanup and exit
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*/
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void
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done()
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{
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(void)printf("EOF\r\n");
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exit(0);
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}
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/*
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* wr_fputs - like fputs(), but makes control characters visible and
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* turns \n into \r\n
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*/
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void
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wr_fputs(s)
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register char *s;
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{
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register char c;
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#define PUTC(c) if (putchar(c) == EOF) goto err;
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for (; *s != '\0'; ++s) {
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c = toascii(*s);
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if (c == '\n') {
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PUTC('\r');
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PUTC('\n');
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} else if (!isprint(c) && !isspace(c) && c != '\007') {
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PUTC('^');
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PUTC(c^0x40); /* DEL to ?, others to alpha */
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} else
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PUTC(c);
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}
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return;
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err: err(1, NULL);
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#undef PUTC
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}
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