1/*
2 * Copyright (c) 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35
36__FBSDID("$FreeBSD: src/usr.bin/wall/ttymsg.c,v 1.12 2006/01/27 08:52:14 ume Exp $");
37
38#ifndef lint
39__attribute__((__used__))
40static const char sccsid[] = "@(#)ttymsg.c	8.2 (Berkeley) 11/16/93";
41#endif
42
43#include <sys/types.h>
44#include <sys/uio.h>
45#include <dirent.h>
46#include <errno.h>
47#include <fcntl.h>
48#include <paths.h>
49#include <signal.h>
50#include <stdio.h>
51#include <string.h>
52#include <stdlib.h>
53#include <unistd.h>
54
55#include "ttymsg.h"
56
57/*
58 * Display the contents of a uio structure on a terminal.  Used by wall(1),
59 * syslogd(8), and talkd(8).  Forks and finishes in child if write would block,
60 * waiting up to tmout seconds.  Returns pointer to error string on unexpected
61 * error; string is not newline-terminated.  Various "normal" errors are
62 * ignored (exclusive-use, lack of permission, etc.).
63 */
64const char *
65ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout)
66{
67	struct iovec localiov[7];
68	ssize_t left, wret;
69	int cnt, fd;
70	static char device[MAXNAMLEN] = _PATH_DEV;
71	static char errbuf[1024];
72	char *p;
73	int forked;
74
75	forked = 0;
76	if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0])))
77		return ("too many iov's (change code in wall/ttymsg.c)");
78
79	p = device + sizeof(_PATH_DEV) - 1;
80#ifdef __APPLE__
81	/* radar:13145432 */
82	strlcpy(p, line, sizeof(device) - (sizeof(_PATH_DEV) - 1));
83#else
84	strlcpy(p, line, sizeof(device));
85#endif
86	if (strncmp(p, "pts/", 4) == 0)
87		p += 4;
88	if (strchr(p, '/') != NULL) {
89		/* A slash is an attempt to break security... */
90		(void) snprintf(errbuf, sizeof(errbuf),
91		    "Too many '/' in \"%s\"", device);
92		return (errbuf);
93	}
94
95	/*
96	 * open will fail on slip lines or exclusive-use lines
97	 * if not running as root; not an error.
98	 */
99	if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
100		if (errno == EBUSY || errno == EACCES)
101			return (NULL);
102		(void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device,
103		    strerror(errno));
104		return (errbuf);
105	}
106
107	for (cnt = 0, left = 0; cnt < iovcnt; ++cnt)
108		left += iov[cnt].iov_len;
109
110	for (;;) {
111		wret = writev(fd, iov, iovcnt);
112		if (wret >= left)
113			break;
114		if (wret >= 0) {
115			left -= wret;
116			if (iov != localiov) {
117				bcopy(iov, localiov,
118				    iovcnt * sizeof(struct iovec));
119				iov = localiov;
120			}
121			for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) {
122				wret -= iov->iov_len;
123				++iov;
124				--iovcnt;
125			}
126			if (wret) {
127				iov->iov_base = (char *)iov->iov_base + wret;
128				iov->iov_len -= wret;
129			}
130			continue;
131		}
132		if (errno == EWOULDBLOCK) {
133			int cpid;
134
135			if (forked) {
136				(void) close(fd);
137				_exit(1);
138			}
139			cpid = fork();
140			if (cpid < 0) {
141				(void) snprintf(errbuf, sizeof(errbuf),
142				    "fork: %s", strerror(errno));
143				(void) close(fd);
144				return (errbuf);
145			}
146			if (cpid) {	/* parent */
147				(void) close(fd);
148				return (NULL);
149			}
150			forked++;
151			/* wait at most tmout seconds */
152			(void) signal(SIGALRM, SIG_DFL);
153			(void) signal(SIGTERM, SIG_DFL); /* XXX */
154			(void) sigsetmask(0);
155			(void) alarm((u_int)tmout);
156			(void) fcntl(fd, F_SETFL, 0);	/* clear O_NONBLOCK */
157			continue;
158		}
159		/*
160		 * We get ENODEV on a slip line if we're running as root,
161		 * and EIO if the line just went away.
162		 */
163		if (errno == ENODEV || errno == EIO)
164			break;
165		(void) close(fd);
166		if (forked)
167			_exit(1);
168		(void) snprintf(errbuf, sizeof(errbuf),
169		    "%s: %s", device, strerror(errno));
170		return (errbuf);
171	}
172
173	(void) close(fd);
174	if (forked)
175		_exit(0);
176	return (NULL);
177}
178