freebsd-dev/usr.bin/write/write.c
1999-07-04 17:26:16 +00:00

334 lines
8.4 KiB
C

/*
* 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.
*/
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93";
#endif
static const char rcsid[] =
"$Id: write.c,v 1.10 1997/09/15 00:40:34 ache Exp $";
#endif /* not lint */
#include <sys/param.h>
#include <sys/signal.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/time.h>
#include <ctype.h>
#include <err.h>
#include <locale.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <utmp.h>
void done __P((int));
void do_write __P((char *, char *, uid_t));
static void usage __P((void));
int term_chk __P((char *, int *, time_t *, int));
void wr_fputs __P((unsigned char *s));
void search_utmp __P((char *, char *, char *, uid_t));
int utmp_chk __P((char *, char *));
int
main(argc, argv)
int argc;
char **argv;
{
register char *cp;
time_t atime;
uid_t myuid;
int msgsok, myttyfd;
char tty[MAXPATHLEN], *mytty;
(void)setlocale(LC_CTYPE, "");
/* 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
errx(1, "can't find your tty");
if (!(mytty = ttyname(myttyfd)))
errx(1, "can't find your tty's name");
if ((cp = rindex(mytty, '/')))
mytty = cp + 1;
if (term_chk(mytty, &msgsok, &atime, 1))
exit(1);
if (!msgsok)
errx(1, "you have write permission turned off");
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], _PATH_DEV, strlen(_PATH_DEV)))
argv[2] += strlen(_PATH_DEV);
if (utmp_chk(argv[1], argv[2]))
errx(1, "%s is not logged in on %s", argv[1], argv[2]);
if (term_chk(argv[2], &msgsok, &atime, 1))
exit(1);
if (myuid && !msgsok)
errx(1, "%s has messages disabled on %s", argv[1], argv[2]);
do_write(argv[2], mytty, myuid);
break;
default:
usage();
}
done(0);
return (0);
}
static void
usage()
{
(void)fprintf(stderr, "usage: write user [tty]\n");
exit(1);
}
/*
* utmp_chk - checks that the given user is actually logged in on
* the given tty
*/
int
utmp_chk(user, tty)
char *user, *tty;
{
struct utmp u;
int ufd;
if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
return(0); /* ignore error, shouldn't happen anyway */
while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
(void)close(ufd);
return(0);
}
(void)close(ufd);
return(1);
}
/*
* 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(user, tty, mytty, myuid)
char *user, *tty, *mytty;
uid_t myuid;
{
struct utmp u;
time_t bestatime, atime;
int ufd, nloggedttys, nttys, msgsok, user_is_me;
char atty[UT_LINESIZE + 1];
if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
err(1, "utmp");
nloggedttys = nttys = 0;
bestatime = 0;
user_is_me = 0;
while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
++nloggedttys;
(void)strncpy(atty, u.ut_line, UT_LINESIZE);
atty[UT_LINESIZE] = '\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 */
}
++nttys;
if (atime > bestatime) {
bestatime = atime;
(void)strcpy(tty, atty);
}
}
(void)close(ufd);
if (nloggedttys == 0)
errx(1, "%s is not logged in", user);
if (nttys == 0) {
if (user_is_me) { /* ok, so write to yourself! */
(void)strcpy(tty, mytty);
return;
}
errx(1, "%s has messages disabled", user);
} else if (nttys > 1) {
warnx("%s is logged in more than once; writing to %s", user, tty);
}
}
/*
* term_chk - check that a terminal exists, and get the message bit
* and the access time
*/
int
term_chk(tty, msgsokP, atimeP, showerror)
char *tty;
int *msgsokP, showerror;
time_t *atimeP;
{
struct stat s;
char path[MAXPATHLEN];
(void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
if (stat(path, &s) < 0) {
if (showerror)
warn("%s", path);
return(1);
}
*msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */
*atimeP = s.st_atime;
return(0);
}
/*
* do_write - actually make the connection
*/
void
do_write(tty, mytty, myuid)
char *tty, *mytty;
uid_t myuid;
{
register char *login, *nows;
register struct passwd *pwd;
time_t now;
char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
/* Determine our login name before the we reopen() stdout */
if ((login = getlogin()) == NULL) {
if ((pwd = getpwuid(myuid)))
login = pwd->pw_name;
else
login = "???";
}
(void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
if ((freopen(path, "w", stdout)) == NULL)
err(1, "%s", path);
(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';
(void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n",
login, host, mytty, nows + 11);
while (fgets(line, sizeof(line), stdin) != NULL)
wr_fputs(line);
}
/*
* done - cleanup and exit
*/
void
done(n)
int n; /* signal number */
{
(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(s)
register unsigned char *s;
{
#define PUTC(c) if (putchar(c) == EOF) err(1, NULL);
for (; *s != '\0'; ++s) {
if (*s == '\n') {
PUTC('\r');
} else if (((*s & 0x80) && *s < 0xA0) ||
/* disable upper controls */
(!isprint(*s) && !isspace(*s) &&
*s != '\a' && *s != '\b')
) {
if (*s & 0x80) {
*s &= ~0x80;
PUTC('M');
PUTC('-');
}
if (iscntrl(*s)) {
*s ^= 0x40;
PUTC('^');
}
}
PUTC(*s);
}
return;
#undef PUTC
}