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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * @(#) Copyright (c) 1989, 1993 The Regents of the University of California. All rights reserved.
33 * @(#)write.c 8.1 (Berkeley) 6/6/93
34 * $FreeBSD: src/usr.bin/write/write.c,v 1.12 1999/08/28 01:07:48 peter Exp $
35 * $DragonFly: src/usr.bin/write/write.c,v 1.7 2005/08/30 22:02:36 liamfoy Exp $
38 #include <sys/param.h>
53 #include "utmpentry.h"
55 static void done(int);
56 static void do_write(const char *, const char *, uid_t, int *);
57 static void usage(void);
58 static int term_chk(const char *, int *, time_t *, int);
59 static void wr_fputs(unsigned char *s);
60 static void search_utmp(const char *, char *, size_t, const char *, uid_t);
61 static int utmp_chk(const char *, const char *);
64 main(int argc, char **argv)
68 int msgsok, mymsgok, myttyfd;
69 char tty[MAXPATHLEN], *mytty;
71 setlocale(LC_CTYPE, "");
73 /* check that sender has write enabled */
74 if (isatty(fileno(stdin)))
75 myttyfd = fileno(stdin);
76 else if (isatty(fileno(stdout)))
77 myttyfd = fileno(stdout);
78 else if (isatty(fileno(stderr)))
79 myttyfd = fileno(stderr);
81 errx(1, "can't find your tty");
82 if (!(mytty = ttyname(myttyfd)))
83 errx(1, "can't find your tty's name");
84 if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV)))
85 mytty += strlen(_PATH_DEV);
86 if (term_chk(mytty, &mymsgok, &atime, 1))
89 warnx("you have write permission turned off (man mesg)");
96 search_utmp(argv[1], tty, sizeof tty, mytty, myuid);
97 do_write(tty, mytty, myuid, &mymsgok);
100 if (!strncmp(argv[2], _PATH_DEV, strlen(_PATH_DEV)))
101 argv[2] += strlen(_PATH_DEV);
102 if (utmp_chk(argv[1], argv[2]))
103 errx(1, "%s is not logged in on %s", argv[1], argv[2]);
104 if (term_chk(argv[2], &msgsok, &atime, 1))
106 if (myuid && !msgsok)
107 errx(1, "%s has messages disabled on %s", argv[1], argv[2]);
108 do_write(argv[2], mytty, myuid, &mymsgok);
120 fprintf(stderr, "usage: write user [tty]\n");
125 * utmp_chk - checks that the given user is actually logged in on
129 utmp_chk(const char *user, const char *tty)
131 struct utmpentry *ep;
133 getutentries(NULL, &ep);
135 for (; ep; ep = ep->next) {
136 if (strcmp(user, ep->name) == 0 &&
137 strcmp(tty, ep->line) == 0) {
146 * search_utmp - search utmp for the "best" terminal to write to
148 * Ignores terminals with messages disabled, and of the rest, returns
149 * the one with the most recent access time. Returns as value the number
150 * of the user's terminals with messages enabled, or -1 if the user is
151 * not logged in at all.
153 * Special case for writing to yourself - ignore the terminal you're
154 * writing from, unless that's the only terminal with messages enabled.
157 search_utmp(const char *user, char *tty, size_t ttyl, const char *mytty, uid_t myuid)
159 struct utmpentry *ep;
160 time_t bestatime, atime;
161 int nloggedttys, nttys, msgsok, user_is_me;
163 getutentries(NULL, &ep);
165 nloggedttys = nttys = 0;
168 for (; ep; ep = ep->next)
169 if (strcmp(user, ep->name) == 0) {
171 if (term_chk(ep->line, &msgsok, &atime, 0))
172 continue; /* bad term? skip */
173 if (myuid && !msgsok)
174 continue; /* skip ttys with msgs off */
175 if (strcmp(ep->line, mytty) == 0) {
177 continue; /* don't write to yourself */
180 if (atime > bestatime) {
182 strlcpy(tty, ep->line, ttyl);
186 if (nloggedttys == 0)
187 errx(1, "%s is not logged in", user);
189 if (user_is_me) { /* ok, so write to yourself! */
190 strlcpy(tty, mytty, ttyl);
193 errx(1, "%s has messages disabled", user);
194 } else if (nttys > 1) {
195 warnx("%s is logged in more than once; writing to %s", user, tty);
200 * term_chk - check that a terminal exists, and get the message bit
201 * and the access time
204 term_chk(const char *tty, int *msgsokP, time_t *atimeP, int showerror)
207 char path[MAXPATHLEN];
209 snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
210 if (stat(path, &s) < 0) {
215 *msgsokP = (s.st_mode & S_IWGRP) != 0; /* group write bit */
216 *atimeP = s.st_atime;
221 * do_write - actually make the connection
224 do_write(const char *tty, const char *mytty, uid_t myuid, int *mymsgok)
230 char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
232 /* Determine our login name before we reopen() stdout */
233 if ((login = getlogin()) == NULL) {
234 if ((pwd = getpwuid(myuid)))
235 login = pwd->pw_name;
240 snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
241 if ((freopen(path, "w", stdout)) == NULL)
244 signal(SIGINT, done);
245 signal(SIGHUP, done);
248 if (gethostname(host, sizeof(host)) < 0)
249 strlcpy(host, "???", sizeof host);
253 printf("\r\n\007\007\007Message from %s@%s on %s at %s (%s %s replies)...\r\n",
254 login, host, mytty, nows + 11, login, *mymsgok == 0 ? "does not accept" : "accepts");
256 while (fgets(line, sizeof(line), stdin) != NULL)
261 * done - cleanup and exit
271 * wr_fputs - like fputs(), but makes control characters visible and
275 wr_fputs(unsigned char *s)
278 #define PUTC(c) if (putchar(c) == EOF) err(1, NULL);
280 for (; *s != '\0'; ++s) {
283 } else if (((*s & 0x80) && *s < 0xA0) ||
284 /* disable upper controls */
285 (!isprint(*s) && !isspace(*s) &&
286 *s != '\a' && *s != '\b')