5095053036
Because our implementation guarantees the strings inside struct utmpx to be null terminated, we don't need to copy everything out, which makes the code nicer to read. Also set WARNS to 6 and add $FreeBSD$ to keep SVN happy.
324 lines
8.1 KiB
C
324 lines
8.1 KiB
C
/*
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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 const 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
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#if 0
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#ifndef lint
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static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93";
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#endif
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#endif
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/signal.h>
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#include <sys/stat.h>
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#include <sys/file.h>
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#include <sys/time.h>
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#include <ctype.h>
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#include <err.h>
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#include <locale.h>
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#include <paths.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define _ULOG_POSIX_NAMES
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#include <ulog.h>
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#include <unistd.h>
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void done(int);
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void do_write(char *, char *, uid_t);
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static void usage(void);
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int term_chk(char *, int *, time_t *, int);
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void wr_fputs(unsigned char *s);
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void search_utmp(char *, char *, char *, uid_t);
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int utmp_chk(char *, char *);
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int
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main(int argc, char **argv)
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{
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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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(void)setlocale(LC_CTYPE, "");
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while (getopt(argc, argv, "") != -1)
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usage();
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argc -= optind;
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argv += optind;
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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 (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV)))
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mytty += strlen(_PATH_DEV);
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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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errx(1, "you have write permission turned off");
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myuid = getuid();
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/* check args */
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switch (argc) {
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case 1:
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search_utmp(argv[0], tty, mytty, myuid);
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do_write(tty, mytty, myuid);
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break;
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case 2:
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if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV)))
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argv[1] += strlen(_PATH_DEV);
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if (utmp_chk(argv[0], argv[1]))
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errx(1, "%s is not logged in on %s", argv[0], argv[1]);
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if (term_chk(argv[1], &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", argv[0], argv[1]);
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do_write(argv[1], mytty, myuid);
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break;
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default:
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usage();
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}
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done(0);
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return (0);
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}
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static void
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usage(void)
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{
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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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/*
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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(char *user, char *tty)
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{
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struct utmpx lu, *u;
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strncpy(lu.ut_line, tty, sizeof lu.ut_line);
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setutxent();
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while ((u = getutxline(&lu)) != NULL)
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if (u->ut_type == USER_PROCESS &&
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strcmp(user, u->ut_user) == 0) {
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endutxent();
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return(0);
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}
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endutxent();
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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(char *user, char *tty, char *mytty, uid_t myuid)
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{
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struct utmpx *u;
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time_t bestatime, atime;
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int nloggedttys, nttys, msgsok, user_is_me;
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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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setutxent();
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while ((u = getutxent()) != NULL)
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if (u->ut_type == USER_PROCESS &&
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strcmp(user, u->ut_user) == 0) {
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++nloggedttys;
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if (term_chk(u->ut_line, &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(u->ut_line, 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)strlcpy(tty, u->ut_line, MAXPATHLEN);
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}
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}
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endutxent();
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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)strlcpy(tty, mytty, MAXPATHLEN);
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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", user, tty);
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}
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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(char *tty, int *msgsokP, time_t *atimeP, int showerror)
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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), "%s%s", _PATH_DEV, 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(char *tty, char *mytty, uid_t myuid)
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{
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const char *login;
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char *nows;
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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 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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}
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(void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, 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)strcpy(host, "???");
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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(int n __unused)
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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(unsigned char *s)
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{
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#define PUTC(c) if (putchar(c) == EOF) err(1, NULL);
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for (; *s != '\0'; ++s) {
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if (*s == '\n') {
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PUTC('\r');
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} else if (((*s & 0x80) && *s < 0xA0) ||
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/* disable upper controls */
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(!isprint(*s) && !isspace(*s) &&
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*s != '\a' && *s != '\b')
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) {
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if (*s & 0x80) {
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*s &= ~0x80;
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PUTC('M');
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PUTC('-');
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}
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if (iscntrl(*s)) {
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*s ^= 0x40;
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PUTC('^');
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}
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}
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PUTC(*s);
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}
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return;
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#undef PUTC
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}
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