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/types.h>
33 #include <sys/stat.h>
34 #include <sys/uio.h>
35
36 #include <dirent.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <paths.h>
40 #include <signal.h>
41 #include <stdbool.h>
42 #include <stdio.h>
43 #include <string.h>
44 #include <stdlib.h>
45 #include <unistd.h>
46
47 #include "ttymsg.h"
48
49 /*
50 * Display the contents of a uio structure on a terminal. If shout is
51 * non-zero, do so even if the terminal has messages disabled. Used by
52 * wall(1), syslogd(8), and talkd(8). Forks and finishes in child if
53 * write would block, waiting up to timeout seconds. Various "normal"
54 * errors are ignored (exclusive-use, lack of permission, etc.).
55 */
56 int
ttymsg(struct iovec * iov,int iovcnt,const char * tty,int timeout,bool shout)57 ttymsg(struct iovec *iov, int iovcnt, const char *tty, int timeout,
58 bool shout)
59 {
60 struct iovec localiov[TTYMSG_IOV_MAX];
61 struct stat sb;
62 ssize_t wret;
63 size_t resid;
64 int cnt, dd, fd, serrno;
65 int forked;
66
67 forked = 0;
68 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0]))) {
69 errno = EFBIG;
70 return (-1);
71 }
72
73 dd = open(_PATH_DEV, O_SEARCH | O_DIRECTORY);
74 if (dd < 0)
75 return (-1);
76 fd = openat(dd, tty, O_WRONLY | O_NONBLOCK | O_RESOLVE_BENEATH);
77 if (fd < 0) {
78 serrno = errno;
79 close(dd);
80 /*
81 * open will fail on slip lines or exclusive-use lines
82 * if not running as root; not an error.
83 */
84 if (serrno == EBUSY || serrno == EACCES)
85 return (0);
86 errno = serrno;
87 return (-1);
88 }
89 close(dd);
90 if (!shout) {
91 if (fstat(fd, &sb) != 0) {
92 serrno = errno;
93 close(fd);
94 errno = serrno;
95 return (-1);
96 }
97 if ((sb.st_mode & S_IWGRP) == 0) {
98 close(fd);
99 return (0);
100 }
101 }
102
103 for (cnt = 0, resid = 0; cnt < iovcnt; ++cnt)
104 resid += iov[cnt].iov_len;
105
106 do {
107 wret = writev(fd, iov, iovcnt);
108 if (wret >= 0) {
109 resid -= wret;
110 if (iov != localiov) {
111 bcopy(iov, localiov,
112 iovcnt * sizeof(struct iovec));
113 iov = localiov;
114 }
115 while ((size_t)wret >= iov->iov_len) {
116 wret -= iov->iov_len;
117 ++iov;
118 --iovcnt;
119 }
120 if (wret) {
121 iov->iov_base = (char *)iov->iov_base + wret;
122 iov->iov_len -= wret;
123 }
124 continue;
125 }
126 if (errno == EWOULDBLOCK) {
127 int cpid;
128
129 if (forked) {
130 (void) close(fd);
131 _exit(1);
132 }
133 cpid = fork();
134 if (cpid < 0) {
135 serrno = errno;
136 (void) close(fd);
137 errno = serrno;
138 return (-1);
139 }
140 if (cpid) { /* parent */
141 (void) close(fd);
142 return (0);
143 }
144 forked++;
145 /* wait at most timeout seconds */
146 (void) signal(SIGALRM, SIG_DFL);
147 (void) signal(SIGTERM, SIG_DFL); /* XXX */
148 (void) sigsetmask(0);
149 (void) alarm((u_int)timeout);
150 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */
151 continue;
152 }
153 /*
154 * We get ENODEV on a slip line if we're running as root,
155 * and EIO if the line just went away.
156 */
157 serrno = errno;
158 if (serrno == ENODEV || serrno == EIO)
159 break;
160 (void) close(fd);
161 if (forked)
162 _exit(1);
163 errno = serrno;
164 return (-1);
165 } while (resid > 0);
166
167 (void) close(fd);
168 if (forked)
169 _exit(0);
170 return (0);
171 }
172