/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* Modified for Linux, Mon Mar 8 18:16:24 1993, faith@cs.unc.edu
* Wed Jun 22 21:41:56 1994, faith@cs.unc.edu:
* Added fix from Mike Grupenhoff (kashmir@umiacs.umd.edu)
* Mon Jul 1 17:01:39 MET DST 1996, janl@math.uio.no:
* - Added fix from David.Chapell@mail.trincoll.edu enabling daemons
* to use write.
* - ANSIed it since I was working on it anyway.
* 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
* - added Native Language Support
*
*/
#include <stdio.h>
#include <unistd.h>
#include <utmp.h>
#include <errno.h>
#include <time.h>
#include <pwd.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <paths.h>
#include <getopt.h>
#include "c.h"
#include "carefulputc.h"
#include "closestream.h"
#include "nls.h"
#include "strutils.h"
#include "xalloc.h"
static sig_atomic_t signal_received = 0;
struct write_control {
uid_t src_uid;
const char *src_login;
char *src_tty;
const char *dst_login;
char dst_tty[PATH_MAX];
};
static void __attribute__ ((__noreturn__)) usage(FILE * out)
{
fputs(USAGE_HEADER, out);
fprintf(out,
_(" %s [options] <user> [<ttyname>]\n"),
program_invocation_short_name);
fputs(USAGE_SEPARATOR, out);
fputs(_("Send a message to another user.\n"), out);
fputs(USAGE_OPTIONS, out);
fputs(USAGE_HELP, out);
fputs(USAGE_VERSION, out);
fprintf(out, USAGE_MAN_TAIL("write(1)"));
exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}
/*
* term_chk - check that a terminal exists, and get the message bit
* and the access time
*/
static int term_chk(char *tty, int *msgsokP, time_t * atimeP, int showerror)
{
struct stat s;
char path[PATH_MAX];
if (strlen(tty) + 6 > sizeof(path))
return 1;
sprintf(path, "/dev/%s", tty);
if (stat(path, &s) < 0) {
if (showerror)
warn("%s", path);
return 1;
}
if (getuid() == 0) /* root can always write */
*msgsokP = 1;
else
*msgsokP = (s.st_mode & S_IWGRP) && (getegid() == s.st_gid);
if (atimeP)
*atimeP = s.st_atime;
return 0;
}
/*
* utmp_chk - checks that the given user is actually logged in on
* the given tty
*/
static int utmp_chk(const struct write_control *ctl)
{
struct utmp u;
struct utmp *uptr;
int res = 1;
utmpname(_PATH_UTMP);
setutent();
while ((uptr = getutent())) {
memcpy(&u, uptr, sizeof(u));
if (strncmp(ctl->dst_login, u.ut_user, sizeof(u.ut_user)) == 0 &&
strncmp(ctl->dst_tty, u.ut_line, sizeof(u.ut_line)) == 0) {
res = 0;
break;
}
}
endutent();
return res;
}
/*
* search_utmp - search utmp for the "best" terminal to write to
*
* Ignores terminals with messages disabled, and of the rest, returns
* the one with the most recent access time. Returns as value the number
* of the user's terminals with messages enabled, or -1 if the user is
* not logged in at all.
*
* Special case for writing to yourself - ignore the terminal you're
* writing from, unless that's the only terminal with messages enabled.
*/
static void search_utmp(struct write_control *ctl)
{
struct utmp u;
struct utmp *uptr;
time_t bestatime, atime;
int nloggedttys, nttys, msgsok = 0, user_is_me;
char atty[sizeof(u.ut_line) + 1];
utmpname(_PATH_UTMP);
setutent();
nloggedttys = nttys = 0;
bestatime = 0;
user_is_me = 0;
while ((uptr = getutent())) {
memcpy(&u, uptr, sizeof(u));
if (strncmp(ctl->dst_login, u.ut_user, sizeof(u.ut_user)) == 0) {
++nloggedttys;
xstrncpy(atty, u.ut_line, sizeof(atty));
if (term_chk(atty, &msgsok, &atime, 0))
/* bad term? skip */
continue;
if (ctl->src_uid && !msgsok)
/* skip ttys with msgs off */
continue;
if (strcmp(atty, ctl->src_tty) == 0) {
user_is_me = 1;
/* don't write to yourself */
continue;
}
if (u.ut_type != USER_PROCESS)
/* it's not a valid entry */
continue;
++nttys;
if (atime > bestatime) {
bestatime = atime;
xstrncpy(ctl->dst_tty, atty, sizeof(ctl->dst_tty));
}
}
}
endutent();
if (nloggedttys == 0)
errx(EXIT_FAILURE, _("%s is not logged in"), ctl->dst_login);
if (nttys == 0) {
if (user_is_me) {
/* ok, so write to yourself! */
xstrncpy(ctl->dst_tty, ctl->src_tty, sizeof(ctl->dst_tty));
return;
}
errx(EXIT_FAILURE, _("%s has messages disabled"), ctl->dst_login);
} else if (nttys > 1) {
warnx(_("%s is logged in more than once; writing to %s"),
ctl->dst_login, ctl->dst_tty);
}
}
/*
* signal_handler - cause write loop to exit
*/
static void signal_handler(int signo)
{
signal_received = signo;
}
/*
* wr_fputs - like fputs(), but makes control characters visible and
* turns \n into \r\n.
*/
static void wr_fputs(char *s)
{
char c;
#define PUTC(c) if (fputc_careful(c, stdout, '^') == EOF) \
err(EXIT_FAILURE, _("carefulputc failed"));
while (*s) {
c = *s++;
if (c == '\n')
PUTC('\r');
PUTC(c);
}
return;
#undef PUTC
}
/*
* do_write - actually make the connection
*/
static void do_write(const struct write_control *ctl)
{
char *login, *pwuid, *nows;
struct passwd *pwd;
time_t now;
char path[PATH_MAX], *host, line[512];
struct sigaction sigact;
/* Determine our login name(s) before the we reopen() stdout */
if ((pwd = getpwuid(ctl->src_uid)) != NULL)
pwuid = pwd->pw_name;
else
pwuid = "???";
if ((login = getlogin()) == NULL)
login = pwuid;
if (strlen(ctl->dst_tty) + 6 > sizeof(path))
errx(EXIT_FAILURE, _("tty path %s too long"), ctl->dst_tty);
snprintf(path, sizeof(path), "/dev/%s", ctl->dst_tty);
if ((freopen(path, "w", stdout)) == NULL)
err(EXIT_FAILURE, "%s", path);
sigact.sa_handler = signal_handler;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = 0;
sigaction(SIGINT, &sigact, NULL);
sigaction(SIGHUP, &sigact, NULL);
/* print greeting */
host = xgethostname();
if (!host)
host = xstrdup("???");
now = time((time_t *) NULL);
nows = ctime(&now);
nows[16] = '\0';
printf("\r\n\007\007\007");
if (strcmp(login, pwuid))
printf(_("Message from %s@%s (as %s) on %s at %s ..."),
login, host, pwuid, ctl->src_tty, nows + 11);
else
printf(_("Message from %s@%s on %s at %s ..."),
login, host, ctl->src_tty, nows + 11);
free(host);
printf("\r\n");
while (fgets(line, sizeof(line), stdin) != NULL) {
if (signal_received)
break;
wr_fputs(line);
}
printf("EOF\r\n");
}
int main(int argc, char **argv)
{
int msgsok = 0, src_fd, c;
struct write_control ctl = { 0 };
static const struct option longopts[] = {
{"version", no_argument, NULL, 'V'},
{"help", no_argument, NULL, 'h'},
{NULL, 0, NULL, 0}
};
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
atexit(close_stdout);
while ((c = getopt_long(argc, argv, "Vh", longopts, NULL)) != -1)
switch (c) {
case 'V':
printf(UTIL_LINUX_VERSION);
return EXIT_SUCCESS;
case 'h':
usage(stdout);
default:
usage(stderr);
}
/* check that sender has write enabled */
if (isatty(STDIN_FILENO))
src_fd = STDIN_FILENO;
else if (isatty(STDOUT_FILENO))
src_fd = STDOUT_FILENO;
else if (isatty(STDERR_FILENO))
src_fd = STDERR_FILENO;
else
src_fd = -1;
if (src_fd != -1) {
if (!(ctl.src_tty = ttyname(src_fd)))
errx(EXIT_FAILURE,
_("can't find your tty's name"));
/*
* We may have /dev/ttyN but also /dev/pts/xx. Below,
* term_chk() will put "/dev/" in front, so remove that
* part.
*/
if (!strncmp(ctl.src_tty, "/dev/", 5))
ctl.src_tty += 5;
if (term_chk(ctl.src_tty, &msgsok, NULL, 1))
exit(EXIT_FAILURE);
if (!msgsok)
errx(EXIT_FAILURE,
_("you have write permission turned off"));
msgsok = 0;
} else
ctl.src_tty = "<no tty>";
ctl.src_uid = getuid();
/* check args */
switch (argc) {
case 2:
ctl.dst_login = argv[1];
search_utmp(&ctl);
do_write(&ctl);
break;
case 3:
ctl.dst_login = argv[1];
if (!strncmp(argv[2], "/dev/", 5))
xstrncpy(ctl.dst_tty, argv[2] + 5, sizeof(ctl.dst_tty));
else
xstrncpy(ctl.dst_tty, argv[2], sizeof(ctl.dst_tty));
if (utmp_chk(&ctl))
errx(EXIT_FAILURE,
_("%s is not logged in on %s"),
ctl.dst_login, ctl.dst_tty);
if (term_chk(ctl.dst_tty, &msgsok, NULL, 1))
exit(EXIT_FAILURE);
if (ctl.src_uid && !msgsok)
errx(EXIT_FAILURE,
_("%s has messages disabled on %s"),
ctl.dst_login, ctl.dst_tty);
do_write(&ctl);
break;
default:
usage(stderr);
}
return EXIT_SUCCESS;
}
