/*
* 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 enabeling daemons
* to use write.
* - ANSIed it since I was working on it anyway.
* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
* - added Native Language Support
*
*/
#include <stdio.h>
#include <unistd.h>
#include <utmp.h>
#include <errno.h>
#include <ctype.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 <sys/file.h>
#include <sys/time.h>
#include <paths.h>
#include "pathnames.h"
#include "carefulputc.h"
#include "nls.h"
void search_utmp(char *, char *, char *, uid_t);
void do_write(char *, char *, uid_t);
void wr_fputs(char *);
static void done(int);
int term_chk(char *, int *, time_t *, int);
int utmp_chk(char *, char *);
static gid_t myegid;
int
main(int argc, char **argv) {
time_t atime;
uid_t myuid;
int msgsok, myttyfd;
char tty[MAXPATHLEN], *mytty;
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
myegid = getegid();
/* check that sender has write enabled */
if (isatty(fileno(stdin)))
myttyfd = fileno(stdin);
else if (isatty(fileno(stdout)))
myttyfd = fileno(stdout);
else if (isatty(fileno(stderr)))
myttyfd = fileno(stderr);
else {
myttyfd = -1;
}
if (myttyfd != -1) {
if (!(mytty = ttyname(myttyfd))) {
(void)fprintf(stderr, _("write: can't find your tty's name\n"));
exit(1);
}
/* We may have /dev/ttyN but also /dev/pts/xx.
Below, term_chk() will put "/dev/" in front, so remove that part. */
if (!strncmp(mytty, "/dev/", 5))
mytty += 5;
if (term_chk(mytty, &msgsok, &atime, 1))
exit(1);
if (!msgsok) {
(void)fprintf(stderr,
_("write: you have write permission turned off.\n"));
exit(1);
}
} else {
mytty = "<no tty>";
}
myuid = getuid();
/* check args */
switch (argc) {
case 2:
search_utmp(argv[1], tty, mytty, myuid);
do_write(tty, mytty, myuid);
break;
case 3:
if (!strncmp(argv[2], "/dev/", 5))
argv[2] += 5;
if (utmp_chk(argv[1], argv[2])) {
(void)fprintf(stderr,
_("write: %s is not logged in on %s.\n"),
argv[1], argv[2]);
exit(1);
}
if (term_chk(argv[2], &msgsok, &atime, 1))
exit(1);
if (myuid && !msgsok) {
(void)fprintf(stderr,
_("write: %s has messages disabled on %s\n"),
argv[1], argv[2]);
exit(1);
}
do_write(argv[2], mytty, myuid);
break;
default:
(void)fprintf(stderr, _("usage: write user [tty]\n"));
exit(1);
}
done(0);
/* NOTREACHED */
return 0;
}
/*
* utmp_chk - checks that the given user is actually logged in on
* the given tty
*/
int utmp_chk(char *user, char *tty)
{
struct utmp u;
struct utmp *uptr;
int res = 1;
utmpname(_PATH_UTMP);
setutent();
while ((uptr = getutent())) {
memcpy(&u, uptr, sizeof(u));
if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
strncmp(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.
*/
void search_utmp(char *user, char *tty, char *mytty, uid_t myuid)
{
struct utmp u;
struct utmp *uptr;
time_t bestatime, atime;
int nloggedttys, nttys, msgsok, 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(user, u.ut_name, sizeof(u.ut_name)) == 0) {
++nloggedttys;
(void)strncpy(atty, u.ut_line, sizeof(u.ut_line));
atty[sizeof(u.ut_line)] = '\0';
if (term_chk(atty, &msgsok, &atime, 0))
continue; /* bad term? skip */
if (myuid && !msgsok)
continue; /* skip ttys with msgs off */
if (strcmp(atty, mytty) == 0) {
user_is_me = 1;
continue; /* don't write to yourself */
}
if (u.ut_type != USER_PROCESS)
continue; /* it's not a valid entry */
++nttys;
if (atime > bestatime) {
bestatime = atime;
(void)strcpy(tty, atty);
}
}
}
endutent();
if (nloggedttys == 0) {
(void)fprintf(stderr, _("write: %s is not logged in\n"), user);
exit(1);
}
if (nttys == 0) {
if (user_is_me) { /* ok, so write to yourself! */
(void)strcpy(tty, mytty);
return;
}
(void)fprintf(stderr,
_("write: %s has messages disabled\n"), user);
exit(1);
} else if (nttys > 1) {
(void)fprintf(stderr,
_("write: %s is logged in more than once; writing to %s\n"),
user, tty);
}
}
/*
* term_chk - check that a terminal exists, and get the message bit
* and the access time
*/
int term_chk(char *tty, int *msgsokP, time_t *atimeP, int showerror)
{
struct stat s;
char path[MAXPATHLEN];
if (strlen(tty) + 6 > sizeof(path))
return(1);
(void)sprintf(path, "/dev/%s", tty);
if (stat(path, &s) < 0) {
if (showerror)
(void)fprintf(stderr,
"write: %s: %s\n", path, strerror(errno));
return(1);
}
/* group write bit and group ownership */
*msgsokP = (s.st_mode & (S_IWRITE >> 3)) && myegid == s.st_gid;
*atimeP = s.st_atime;
return(0);
}
/*
* do_write - actually make the connection
*/
void do_write(char *tty, char *mytty, uid_t myuid) {
char *login, *pwuid, *nows;
struct passwd *pwd;
time_t now;
char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
/* Determine our login name(s) before the we reopen() stdout */
if ((pwd = getpwuid(myuid)) != NULL)
pwuid = pwd->pw_name;
else
pwuid = "???";
if ((login = getlogin()) == NULL)
login = pwuid;
if (strlen(tty) + 6 > sizeof(path))
exit(1);
(void)sprintf(path, "/dev/%s", tty);
if ((freopen(path, "w", stdout)) == NULL) {
(void)fprintf(stderr, "write: %s: %s\n",
path, strerror(errno));
exit(1);
}
(void)signal(SIGINT, done);
(void)signal(SIGHUP, done);
/* print greeting */
if (gethostname(host, sizeof(host)) < 0)
(void)strcpy(host, "???");
now = time((time_t *)NULL);
nows = ctime(&now);
nows[16] = '\0';
printf("\r\n\007\007\007");
if (strcmp(login, pwuid))
(void)printf(_("Message from %s@%s (as %s) on %s at %s ..."),
login, host, pwuid, mytty, nows + 11);
else
(void)printf(_("Message from %s@%s on %s at %s ..."),
login, host, mytty, nows + 11);
printf("\r\n");
while (fgets(line, sizeof(line), stdin) != NULL)
wr_fputs(line);
}
/*
* done - cleanup and exit
*/
static void
done(int dummy) {
(void)printf("EOF\r\n");
exit(0);
}
/*
* wr_fputs - like fputs(), but makes control characters visible and
* turns \n into \r\n.
*/
void
wr_fputs(char *s) {
char c;
#define PUTC(c) if (carefulputc(c,stdout) == EOF) goto err;
while(*s) {
c = *s++;
if (c == '\n')
PUTC('\r');
PUTC(c);
}
return;
err:
fprintf(stderr, "write: %s\n", strerror(errno));
exit(1);
#undef PUTC
}
