1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1989, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33
34__FBSDID("$FreeBSD$");
35
36#ifndef lint
37static const char sccsid[] = "@(#)ttymsg.c	8.2 (Berkeley) 11/16/93";
38#endif
39
40#include <sys/types.h>
41#include <sys/uio.h>
42#include <dirent.h>
43#include <errno.h>
44#include <fcntl.h>
45#include <paths.h>
46#include <signal.h>
47#include <stdio.h>
48#include <string.h>
49#include <stdlib.h>
50#include <unistd.h>
51
52#include "ttymsg.h"
53
54/*
55 * Display the contents of a uio structure on a terminal.  Used by wall(1),
56 * syslogd(8), and talkd(8).  Forks and finishes in child if write would block,
57 * waiting up to tmout seconds.  Returns pointer to error string on unexpected
58 * error; string is not newline-terminated.  Various "normal" errors are
59 * ignored (exclusive-use, lack of permission, etc.).
60 */
61const char *
62ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout)
63{
64	struct iovec localiov[TTYMSG_IOV_MAX];
65	ssize_t left, wret;
66	int cnt, fd;
67	char device[MAXNAMLEN] = _PATH_DEV;
68	static char errbuf[1024];
69	char *p;
70	int forked;
71
72	forked = 0;
73	if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0])))
74		return ("too many iov's (change code in wall/ttymsg.c)");
75
76	strlcat(device, line, sizeof(device));
77	p = device + sizeof(_PATH_DEV) - 1;
78	if (strncmp(p, "pts/", 4) == 0)
79		p += 4;
80	if (strchr(p, '/') != NULL) {
81		/* A slash is an attempt to break security... */
82		(void) snprintf(errbuf, sizeof(errbuf),
83		    "Too many '/' in \"%s\"", device);
84		return (errbuf);
85	}
86
87	/*
88	 * open will fail on slip lines or exclusive-use lines
89	 * if not running as root; not an error.
90	 */
91	if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
92		if (errno == EBUSY || errno == EACCES)
93			return (NULL);
94		(void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device,
95		    strerror(errno));
96		return (errbuf);
97	}
98
99	for (cnt = 0, left = 0; cnt < iovcnt; ++cnt)
100		left += iov[cnt].iov_len;
101
102	for (;;) {
103		wret = writev(fd, iov, iovcnt);
104		if (wret >= left)
105			break;
106		if (wret >= 0) {
107			left -= wret;
108			if (iov != localiov) {
109				bcopy(iov, localiov,
110				    iovcnt * sizeof(struct iovec));
111				iov = localiov;
112			}
113			for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) {
114				wret -= iov->iov_len;
115				++iov;
116				--iovcnt;
117			}
118			if (wret) {
119				iov->iov_base = (char *)iov->iov_base + wret;
120				iov->iov_len -= wret;
121			}
122			continue;
123		}
124		if (errno == EWOULDBLOCK) {
125			int cpid;
126
127			if (forked) {
128				(void) close(fd);
129				_exit(1);
130			}
131			cpid = fork();
132			if (cpid < 0) {
133				(void) snprintf(errbuf, sizeof(errbuf),
134				    "fork: %s", strerror(errno));
135				(void) close(fd);
136				return (errbuf);
137			}
138			if (cpid) {	/* parent */
139				(void) close(fd);
140				return (NULL);
141			}
142			forked++;
143			/* wait at most tmout seconds */
144			(void) signal(SIGALRM, SIG_DFL);
145			(void) signal(SIGTERM, SIG_DFL); /* XXX */
146			(void) sigsetmask(0);
147			(void) alarm((u_int)tmout);
148			(void) fcntl(fd, F_SETFL, 0);	/* clear O_NONBLOCK */
149			continue;
150		}
151		/*
152		 * We get ENODEV on a slip line if we're running as root,
153		 * and EIO if the line just went away.
154		 */
155		if (errno == ENODEV || errno == EIO)
156			break;
157		(void) close(fd);
158		if (forked)
159			_exit(1);
160		(void) snprintf(errbuf, sizeof(errbuf),
161		    "%s: %s", device, strerror(errno));
162		return (errbuf);
163	}
164
165	(void) close(fd);
166	if (forked)
167		_exit(0);
168	return (NULL);
169}
170