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. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)ttymsg.c 8.2 (Berkeley) 11/16/93
30 * $FreeBSD: src/usr.bin/wall/ttymsg.c,v 1.4.2.3 2001/10/18 08:08:17 des Exp $
31 * $DragonFly: src/usr.bin/wall/ttymsg.c,v 1.3 2005/08/08 16:39:17 joerg Exp $
32 */
33
34 #include <sys/types.h>
35 #include <sys/uio.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <limits.h>
39 #include <paths.h>
40 #include <signal.h>
41 #include <stdio.h>
42 #include <string.h>
43 #include <stdlib.h>
44 #include <unistd.h>
45
46 #include "ttymsg.h"
47
48 /*
49 * Display the contents of a uio structure on a terminal. Used by wall(1),
50 * syslogd(8), and talkd(8). Forks and finishes in child if write would block,
51 * waiting up to tmout seconds. Returns pointer to error string on unexpected
52 * error; string is not newline-terminated. Various "normal" errors are
53 * ignored (exclusive-use, lack of permission, etc.).
54 */
55 const char *
ttymsg(struct iovec * iov,int iovcnt,const char * line,int tmout)56 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout)
57 {
58 struct iovec localiov[7];
59 ssize_t left, wret;
60 int cnt, fd;
61 static char device[PATH_MAX] = _PATH_DEV;
62 static char errbuf[1024];
63 char *p;
64 int forked;
65
66 forked = 0;
67 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0])))
68 return ("too many iov's (change code in wall/ttymsg.c)");
69
70 p = device + sizeof(_PATH_DEV) - 1;
71 strlcpy(p, line, sizeof(device));
72 if (!strncmp(p, "pts/", 4))
73 p += 4;
74 if (strchr(p, '/') != NULL) {
75 /* A slash is an attempt to break security... */
76 (void) snprintf(errbuf, sizeof(errbuf),
77 "Too many '/' in \"%s\"", device);
78 return (errbuf);
79 }
80
81 /*
82 * open will fail on slip lines or exclusive-use lines
83 * if not running as root; not an error.
84 */
85 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
86 if (errno == EBUSY || errno == EACCES)
87 return (NULL);
88 (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device,
89 strerror(errno));
90 return (errbuf);
91 }
92
93 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt)
94 left += iov[cnt].iov_len;
95
96 for (;;) {
97 wret = writev(fd, iov, iovcnt);
98 if (wret >= left)
99 break;
100 if (wret >= 0) {
101 left -= wret;
102 if (iov != localiov) {
103 bcopy(iov, localiov,
104 iovcnt * sizeof(struct iovec));
105 iov = localiov;
106 }
107 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) {
108 wret -= iov->iov_len;
109 ++iov;
110 --iovcnt;
111 }
112 if (wret) {
113 iov->iov_base = (char *)iov->iov_base + wret;
114 iov->iov_len -= wret;
115 }
116 continue;
117 }
118 if (errno == EWOULDBLOCK) {
119 int cpid;
120
121 if (forked) {
122 (void) close(fd);
123 _exit(1);
124 }
125 cpid = fork();
126 if (cpid < 0) {
127 (void) snprintf(errbuf, sizeof(errbuf),
128 "fork: %s", strerror(errno));
129 (void) close(fd);
130 return (errbuf);
131 }
132 if (cpid) { /* parent */
133 (void) close(fd);
134 return (NULL);
135 }
136 forked++;
137 /* wait at most tmout seconds */
138 (void) signal(SIGALRM, SIG_DFL);
139 (void) signal(SIGTERM, SIG_DFL); /* XXX */
140 (void) sigsetmask(0);
141 (void) alarm((u_int)tmout);
142 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */
143 continue;
144 }
145 /*
146 * We get ENODEV on a slip line if we're running as root,
147 * and EIO if the line just went away.
148 */
149 if (errno == ENODEV || errno == EIO)
150 break;
151 (void) close(fd);
152 if (forked)
153 _exit(1);
154 (void) snprintf(errbuf, sizeof(errbuf),
155 "%s: %s", device, strerror(errno));
156 return (errbuf);
157 }
158
159 (void) close(fd);
160 if (forked)
161 _exit(0);
162 return (NULL);
163 }
164