2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 static const char copyright[] =
39 "@(#) Copyright (c) 1989, 1993\n\
40 The Regents of the University of California. All rights reserved.\n";
45 static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93";
49 #include <sys/cdefs.h>
50 __FBSDID("$FreeBSD$");
52 #include <sys/param.h>
53 #include <sys/signal.h>
69 void do_write(char *, char *, uid_t);
70 static void usage(void);
71 int term_chk(char *, int *, time_t *, int);
72 void wr_fputs(unsigned char *s);
73 void search_utmp(char *, char *, char *, uid_t);
74 int utmp_chk(char *, char *);
77 main(int argc, char **argv)
82 char tty[MAXPATHLEN], *mytty;
84 (void)setlocale(LC_CTYPE, "");
86 while (getopt(argc, argv, "") != -1)
91 /* check that sender has write enabled */
92 if (isatty(fileno(stdin)))
93 myttyfd = fileno(stdin);
94 else if (isatty(fileno(stdout)))
95 myttyfd = fileno(stdout);
96 else if (isatty(fileno(stderr)))
97 myttyfd = fileno(stderr);
99 errx(1, "can't find your tty");
100 if (!(mytty = ttyname(myttyfd)))
101 errx(1, "can't find your tty's name");
102 if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV)))
103 mytty += strlen(_PATH_DEV);
104 if (term_chk(mytty, &msgsok, &atime, 1))
107 errx(1, "you have write permission turned off");
114 search_utmp(argv[0], tty, mytty, myuid);
115 do_write(tty, mytty, myuid);
118 if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV)))
119 argv[1] += strlen(_PATH_DEV);
120 if (utmp_chk(argv[0], argv[1]))
121 errx(1, "%s is not logged in on %s", argv[0], argv[1]);
122 if (term_chk(argv[1], &msgsok, &atime, 1))
124 if (myuid && !msgsok)
125 errx(1, "%s has messages disabled on %s", argv[0], argv[1]);
126 do_write(argv[1], mytty, myuid);
138 (void)fprintf(stderr, "usage: write user [tty]\n");
143 * utmp_chk - checks that the given user is actually logged in on
147 utmp_chk(char *user, char *tty)
152 if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
153 return(0); /* ignore error, shouldn't happen anyway */
155 while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
156 if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 &&
157 strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
167 * search_utmp - search utmp for the "best" terminal to write to
169 * Ignores terminals with messages disabled, and of the rest, returns
170 * the one with the most recent access time. Returns as value the number
171 * of the user's terminals with messages enabled, or -1 if the user is
172 * not logged in at all.
174 * Special case for writing to yourself - ignore the terminal you're
175 * writing from, unless that's the only terminal with messages enabled.
178 search_utmp(char *user, char *tty, char *mytty, uid_t myuid)
181 time_t bestatime, atime;
182 int ufd, nloggedttys, nttys, msgsok, user_is_me;
183 char atty[UT_LINESIZE + 1];
185 if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0)
188 nloggedttys = nttys = 0;
191 while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u))
192 if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) {
194 (void)strncpy(atty, u.ut_line, UT_LINESIZE);
195 atty[UT_LINESIZE] = '\0';
196 if (term_chk(atty, &msgsok, &atime, 0))
197 continue; /* bad term? skip */
198 if (myuid && !msgsok)
199 continue; /* skip ttys with msgs off */
200 if (strcmp(atty, mytty) == 0) {
202 continue; /* don't write to yourself */
205 if (atime > bestatime) {
207 (void)strcpy(tty, atty);
212 if (nloggedttys == 0)
213 errx(1, "%s is not logged in", user);
215 if (user_is_me) { /* ok, so write to yourself! */
216 (void)strcpy(tty, mytty);
219 errx(1, "%s has messages disabled", user);
220 } else if (nttys > 1) {
221 warnx("%s is logged in more than once; writing to %s", user, tty);
226 * term_chk - check that a terminal exists, and get the message bit
227 * and the access time
230 term_chk(char *tty, int *msgsokP, time_t *atimeP, int showerror)
233 char path[MAXPATHLEN];
235 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
236 if (stat(path, &s) < 0) {
241 *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */
242 *atimeP = s.st_atime;
247 * do_write - actually make the connection
250 do_write(char *tty, char *mytty, uid_t myuid)
256 char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
258 /* Determine our login name before we reopen() stdout */
259 if ((login = getlogin()) == NULL) {
260 if ((pwd = getpwuid(myuid)))
261 login = pwd->pw_name;
266 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
267 if ((freopen(path, "w", stdout)) == NULL)
270 (void)signal(SIGINT, done);
271 (void)signal(SIGHUP, done);
274 if (gethostname(host, sizeof(host)) < 0)
275 (void)strcpy(host, "???");
276 now = time((time_t *)NULL);
279 (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n",
280 login, host, mytty, nows + 11);
282 while (fgets(line, sizeof(line), stdin) != NULL)
287 * done - cleanup and exit
292 (void)printf("EOF\r\n");
297 * wr_fputs - like fputs(), but makes control characters visible and
301 wr_fputs(unsigned char *s)
304 #define PUTC(c) if (putchar(c) == EOF) err(1, NULL);
306 for (; *s != '\0'; ++s) {
309 } else if (((*s & 0x80) && *s < 0xA0) ||
310 /* disable upper controls */
311 (!isprint(*s) && !isspace(*s) &&
312 *s != '\a' && *s != '\b')