1 /*	$OpenBSD: ttymsg.c,v 1.3 1996/10/25 06:06:30 downsj Exp $	*/
2 /*	$NetBSD: ttymsg.c,v 1.3 1994/11/17 07:17:55 jtc Exp $	*/
3 
4 /*
5  * Copyright (c) 1989, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
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.
23  *
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
34  * SUCH DAMAGE.
35  */
36 
37 
38 #include "config.h"
39 
40 #include <sys/types.h>
41 #include <sys/uio.h>
42 #ifdef HAVE_DIRENT_H
43 # include <dirent.h>
44 #elif defined(HAVE_SYS_HNDIR_H)
45 # include <sys/ndir.h>
46 #elif defined(HAVE_SYS_HDIR_H)
47 # include <sys/dir.h>
48 #elif defined(HAVE_NDIR_H)
49 # include <ndir.h>
50 #else
51 # define MAXNAMLEN 128
52 # warning Using MAXNAMLEN of 128
53 #endif
54 #ifndef MAXNAMLEN
55 #include <limits.h>
56 #define MAXNAMLEN NAME_MAX
57 #endif
58 #include <errno.h>
59 #include <fcntl.h>
60 #ifdef HAVE_PATHS_H
61 # include <paths.h>
62 #endif
63 #include <signal.h>
64 #include <stdio.h>
65 #include <string.h>
66 #include <unistd.h>
67 #include <strings.h>
68 
69 #ifndef _PATH_DEV
70 #define _PATH_DEV "/dev/"
71 /* #warning Using "/dev/" for _PATH_DEV */
72 #endif
73 
74 #ifndef sigsetmask
75 int sigsetmask(int);
76 #endif
77 
78 /*
79  * Display the contents of a uio structure on a terminal.  Used by wall(1),
80  * syslogd(8), and talkd(8).  Forks and finishes in child if write would block,
81  * waiting up to tmout seconds.  Returns pointer to error string on unexpected
82  * error; string is not newline-terminated.  Various "normal" errors are
83  * ignored (exclusive-use, lack of permission, etc.).
84  */
85 char *
ttymsg(struct iovec * iov,int iovcnt,char * line,int tmout)86 ttymsg(struct iovec *iov, int iovcnt, char *line, int tmout)
87 {
88 	static char device[MAXNAMLEN] = { _PATH_DEV };
89 	static char errbuf[1024];
90 	register int cnt, fd, left, wret;
91 	struct iovec localiov[6];
92 	int forked = 0;
93 
94 
95 	if (iovcnt > sizeof(localiov) / sizeof(localiov[0]))
96 		return ("too many iov's (change code in wall/ttymsg.c)");
97 
98 	/*
99 	 * Ignore lines that start with "ftp" or "uucp".
100 	 */
101 	if ((strncmp(line, "ftp", 3) == 0)
102 	    || (strncmp(line, "uucp", 4) == 0))
103 		return (NULL);
104 
105 	(void) strcpy(device + sizeof(_PATH_DEV) - 1, line);
106 
107 #ifndef HAVE_LINUX
108 	if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) {
109 		/* A slash is an attempt to break security... */
110 		(void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"",
111 		    device);
112 		return (errbuf);
113 	}
114 #endif
115 
116 	/*
117 	 * open will fail on slip lines or exclusive-use lines
118 	 * if not running as root; not an error.
119 	 */
120 	if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
121 		if (errno == EBUSY || errno == EACCES)
122 			return (NULL);
123 		(void) snprintf(errbuf, sizeof(errbuf),
124 		    "%s: %s", device, strerror(errno));
125 		return (errbuf);
126 	}
127 
128 	for (cnt = left = 0; cnt < iovcnt; ++cnt)
129 		left += iov[cnt].iov_len;
130 
131 	for (;;) {
132 		wret = writev(fd, iov, iovcnt);
133 		if (wret >= left)
134 			break;
135 		if (wret >= 0) {
136 			left -= wret;
137 			if (iov != localiov) {
138 				bcopy(iov, localiov,
139 				    iovcnt * sizeof(struct iovec));
140 				iov = localiov;
141 			}
142 			for (cnt = 0; wret >= iov->iov_len; ++cnt) {
143 				wret -= iov->iov_len;
144 				++iov;
145 				--iovcnt;
146 			}
147 			/* we assume writev() writes whole chunks.  posix? */
148 			continue;
149 		}
150 		if (errno == EWOULDBLOCK) {
151 			int cpid, off = 0;
152 
153 			if (forked) {
154 				(void) close(fd);
155 				_exit(1);
156 			}
157 			cpid = fork();
158 			if (cpid < 0) {
159 				(void) snprintf(errbuf, sizeof(errbuf),
160 				    "fork: %s", strerror(errno));
161 				(void) close(fd);
162 				return (errbuf);
163 			}
164 			if (cpid) {	/* parent */
165 				(void) close(fd);
166 				return (NULL);
167 			}
168 			forked++;
169 			/* wait at most tmout seconds */
170 			(void) signal(SIGALRM, SIG_DFL);
171 			(void) signal(SIGTERM, SIG_DFL); /* XXX */
172 			sigsetmask(0);
173 			(void) alarm((u_int)tmout);
174 			(void) fcntl(fd, O_NONBLOCK, &off);
175 			continue;
176 		}
177 		/*
178 		 * We get ENODEV on a slip line if we're running as root,
179 		 * and EIO if the line just went away.
180 		 */
181 		if (errno == ENODEV || errno == EIO)
182 			break;
183 		(void) close(fd);
184 		if (forked)
185 			_exit(1);
186 		(void) snprintf(errbuf, sizeof(errbuf),
187 		    "%s: %s", device, strerror(errno));
188 		return (errbuf);
189 	}
190 
191 	(void) close(fd);
192 	if (forked)
193 		_exit(0);
194 	return (NULL);
195 }
196