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
33 #ifndef lint
34 static const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93";
35 #endif
36
37 #include <sys/types.h>
38 #include <sys/uio.h>
39 #include <dirent.h>
40 #include <errno.h>
41 #include <fcntl.h>
42 #include <paths.h>
43 #include <signal.h>
44 #include <stdio.h>
45 #include <string.h>
46 #include <stdlib.h>
47 #include <unistd.h>
48
49 #include "ttymsg.h"
50
51 /*
52 * Display the contents of a uio structure on a terminal. Used by wall(1),
53 * syslogd(8), and talkd(8). Forks and finishes in child if write would block,
54 * waiting up to tmout seconds. Returns pointer to error string on unexpected
55 * error; string is not newline-terminated. Various "normal" errors are
56 * ignored (exclusive-use, lack of permission, etc.).
57 */
58 const char *
ttymsg(struct iovec * iov,int iovcnt,const char * line,int tmout)59 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout)
60 {
61 struct iovec localiov[TTYMSG_IOV_MAX];
62 ssize_t left, wret;
63 int cnt, fd;
64 char device[MAXNAMLEN] = _PATH_DEV;
65 static char errbuf[1024];
66 char *p;
67 int forked;
68
69 forked = 0;
70 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0])))
71 return ("too many iov's (change code in wall/ttymsg.c)");
72
73 strlcat(device, line, sizeof(device));
74 p = device + sizeof(_PATH_DEV) - 1;
75 if (strncmp(p, "pts/", 4) == 0)
76 p += 4;
77 if (strchr(p, '/') != NULL) {
78 /* A slash is an attempt to break security... */
79 (void) snprintf(errbuf, sizeof(errbuf),
80 "Too many '/' in \"%s\"", device);
81 return (errbuf);
82 }
83
84 /*
85 * open will fail on slip lines or exclusive-use lines
86 * if not running as root; not an error.
87 */
88 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
89 if (errno == EBUSY || errno == EACCES)
90 return (NULL);
91 (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device,
92 strerror(errno));
93 return (errbuf);
94 }
95
96 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt)
97 left += iov[cnt].iov_len;
98
99 for (;;) {
100 wret = writev(fd, iov, iovcnt);
101 if (wret >= left)
102 break;
103 if (wret >= 0) {
104 left -= wret;
105 if (iov != localiov) {
106 bcopy(iov, localiov,
107 iovcnt * sizeof(struct iovec));
108 iov = localiov;
109 }
110 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) {
111 wret -= iov->iov_len;
112 ++iov;
113 --iovcnt;
114 }
115 if (wret) {
116 iov->iov_base = (char *)iov->iov_base + wret;
117 iov->iov_len -= wret;
118 }
119 continue;
120 }
121 if (errno == EWOULDBLOCK) {
122 int cpid;
123
124 if (forked) {
125 (void) close(fd);
126 _exit(1);
127 }
128 cpid = fork();
129 if (cpid < 0) {
130 (void) snprintf(errbuf, sizeof(errbuf),
131 "fork: %s", strerror(errno));
132 (void) close(fd);
133 return (errbuf);
134 }
135 if (cpid) { /* parent */
136 (void) close(fd);
137 return (NULL);
138 }
139 forked++;
140 /* wait at most tmout seconds */
141 (void) signal(SIGALRM, SIG_DFL);
142 (void) signal(SIGTERM, SIG_DFL); /* XXX */
143 (void) sigsetmask(0);
144 (void) alarm((u_int)tmout);
145 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */
146 continue;
147 }
148 /*
149 * We get ENODEV on a slip line if we're running as root,
150 * and EIO if the line just went away.
151 */
152 if (errno == ENODEV || errno == EIO)
153 break;
154 (void) close(fd);
155 if (forked)
156 _exit(1);
157 (void) snprintf(errbuf, sizeof(errbuf),
158 "%s: %s", device, strerror(errno));
159 return (errbuf);
160 }
161
162 (void) close(fd);
163 if (forked)
164 _exit(0);
165 return (NULL);
166 }
167