mirror of
https://github.com/freebsd/freebsd-src
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358 lines
9.2 KiB
C
358 lines
9.2 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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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. 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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#include <sys/param.h>
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#include <sys/capsicum.h>
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#include <sys/filio.h>
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#include <sys/signal.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <capsicum_helpers.h>
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#include <ctype.h>
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#include <err.h>
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#include <errno.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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#include <unistd.h>
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#include <utmpx.h>
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#include <wchar.h>
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#include <wctype.h>
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void done(int);
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void do_write(int, char *, char *, const char *);
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static void usage(void) __dead2;
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int term_chk(int, char *, int *, time_t *, int);
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void wr_fputs(wchar_t *s);
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void search_utmp(int, 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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unsigned long cmds[] = { TIOCGETA, TIOCGWINSZ, FIODGNAME };
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cap_rights_t rights;
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struct passwd *pwd;
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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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const char *login;
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int devfd;
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(void)setlocale(LC_CTYPE, "");
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devfd = open(_PATH_DEV, O_RDONLY);
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if (devfd < 0)
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err(1, "open(/dev)");
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cap_rights_init(&rights, CAP_FCNTL, CAP_FSTAT, CAP_IOCTL, CAP_LOOKUP,
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CAP_PWRITE);
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if (caph_rights_limit(devfd, &rights) < 0)
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err(1, "can't limit devfd rights");
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/*
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* Can't use capsicum helpers here because we need the additional
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* FIODGNAME ioctl.
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*/
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cap_rights_init(&rights, CAP_FCNTL, CAP_FSTAT, CAP_IOCTL, CAP_READ,
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CAP_WRITE);
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if (caph_rights_limit(STDIN_FILENO, &rights) < 0 ||
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caph_rights_limit(STDOUT_FILENO, &rights) < 0 ||
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caph_rights_limit(STDERR_FILENO, &rights) < 0 ||
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caph_ioctls_limit(STDIN_FILENO, cmds, nitems(cmds)) < 0 ||
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caph_ioctls_limit(STDOUT_FILENO, cmds, nitems(cmds)) < 0 ||
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caph_ioctls_limit(STDERR_FILENO, cmds, nitems(cmds)) < 0 ||
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caph_fcntls_limit(STDIN_FILENO, CAP_FCNTL_GETFL) < 0 ||
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caph_fcntls_limit(STDOUT_FILENO, CAP_FCNTL_GETFL) < 0 ||
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caph_fcntls_limit(STDERR_FILENO, CAP_FCNTL_GETFL) < 0)
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err(1, "can't limit stdio rights");
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caph_cache_catpages();
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caph_cache_tzdata();
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/*
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* Cache UTX database fds.
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*/
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setutxent();
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/*
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* Determine our login name before we reopen() stdout
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* and before entering capability sandbox.
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*/
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myuid = getuid();
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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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if (caph_enter() < 0)
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err(1, "cap_enter");
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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(devfd, 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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/* check args */
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switch (argc) {
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case 1:
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search_utmp(devfd, argv[0], tty, mytty, myuid);
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do_write(devfd, tty, mytty, login);
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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(devfd, 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(devfd, argv[1], mytty, login);
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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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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(int devfd, 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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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(devfd, 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(int devfd, char *tty, int *msgsokP, time_t *atimeP, int showerror)
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{
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struct stat s;
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if (fstatat(devfd, tty, &s, 0) < 0) {
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if (showerror)
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warn("%s%s", _PATH_DEV, tty);
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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(int devfd, char *tty, char *mytty, const char *login)
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{
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char *nows;
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time_t now;
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char host[MAXHOSTNAMELEN];
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wchar_t line[512];
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int fd;
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fd = openat(devfd, tty, O_WRONLY);
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if (fd < 0)
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err(1, "openat(%s%s)", _PATH_DEV, tty);
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fclose(stdout);
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stdout = fdopen(fd, "w");
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if (stdout == NULL)
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err(1, "%s%s", _PATH_DEV, tty);
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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 (fgetws(line, sizeof(line)/sizeof(wchar_t), 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(wchar_t *s)
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{
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#define PUTC(c) if (putwchar(c) == WEOF) err(1, NULL);
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for (; *s != L'\0'; ++s) {
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if (*s == L'\n') {
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PUTC(L'\r');
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PUTC(L'\n');
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} else if (iswprint(*s) || iswspace(*s)) {
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PUTC(*s);
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} else {
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wprintf(L"<0x%X>", *s);
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}
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}
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return;
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#undef PUTC
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}
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