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 * 4. 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
30 #include <sys/cdefs.h>
31
32 __FBSDID("$FreeBSD$");
33
34 #ifndef lint
35 static const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93";
36 #endif
37
38 #include <sys/types.h>
39 #include <sys/uio.h>
40 #include <dirent.h>
41 #include <errno.h>
42 #include <fcntl.h>
43 #include <paths.h>
44 #include <signal.h>
45 #include <stdio.h>
46 #include <string.h>
47 #include <stdlib.h>
48 #include <unistd.h>
49
50 #include "ttymsg.h"
51
52 /*
53 * Display the contents of a uio structure on a terminal. Used by wall(1),
54 * syslogd(8), and talkd(8). Forks and finishes in child if write would block,
55 * waiting up to tmout seconds. Returns pointer to error string on unexpected
56 * error; string is not newline-terminated. Various "normal" errors are
57 * ignored (exclusive-use, lack of permission, etc.).
58 */
59 const char *
ttymsg(struct iovec * iov,int iovcnt,const char * line,int tmout)60 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout)
61 {
62 struct iovec localiov[7];
63 ssize_t left, wret;
64 int cnt, fd;
65 static char device[MAXNAMLEN] = _PATH_DEV;
66 static char errbuf[1024];
67 char *p;
68 int forked;
69
70 forked = 0;
71 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0])))
72 return ("too many iov's (change code in wall/ttymsg.c)");
73
74 p = device + sizeof(_PATH_DEV) - 1;
75 strlcpy(p, line, sizeof(device));
76 if (strncmp(p, "pts/", 4) == 0)
77 p += 4;
78 if (strchr(p, '/') != NULL) {
79 /* A slash is an attempt to break security... */
80 (void) snprintf(errbuf, sizeof(errbuf),
81 "Too many '/' in \"%s\"", device);
82 return (errbuf);
83 }
84
85 /*
86 * open will fail on slip lines or exclusive-use lines
87 * if not running as root; not an error.
88 */
89 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
90 if (errno == EBUSY || errno == EACCES)
91 return (NULL);
92 (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device,
93 strerror(errno));
94 return (errbuf);
95 }
96
97 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt)
98 left += iov[cnt].iov_len;
99
100 for (;;) {
101 wret = writev(fd, iov, iovcnt);
102 if (wret >= left)
103 break;
104 if (wret >= 0) {
105 left -= wret;
106 if (iov != localiov) {
107 bcopy(iov, localiov,
108 iovcnt * sizeof(struct iovec));
109 iov = localiov;
110 }
111 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) {
112 wret -= iov->iov_len;
113 ++iov;
114 --iovcnt;
115 }
116 if (wret) {
117 iov->iov_base = (char *)iov->iov_base + wret;
118 iov->iov_len -= wret;
119 }
120 continue;
121 }
122 if (errno == EWOULDBLOCK) {
123 int cpid;
124
125 if (forked) {
126 (void) close(fd);
127 _exit(1);
128 }
129 cpid = fork();
130 if (cpid < 0) {
131 (void) snprintf(errbuf, sizeof(errbuf),
132 "fork: %s", strerror(errno));
133 (void) close(fd);
134 return (errbuf);
135 }
136 if (cpid) { /* parent */
137 (void) close(fd);
138 return (NULL);
139 }
140 forked++;
141 /* wait at most tmout seconds */
142 (void) signal(SIGALRM, SIG_DFL);
143 (void) signal(SIGTERM, SIG_DFL); /* XXX */
144 (void) sigsetmask(0);
145 (void) alarm((u_int)tmout);
146 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */
147 continue;
148 }
149 /*
150 * We get ENODEV on a slip line if we're running as root,
151 * and EIO if the line just went away.
152 */
153 if (errno == ENODEV || errno == EIO)
154 break;
155 (void) close(fd);
156 if (forked)
157 _exit(1);
158 (void) snprintf(errbuf, sizeof(errbuf),
159 "%s: %s", device, strerror(errno));
160 return (errbuf);
161 }
162
163 (void) close(fd);
164 if (forked)
165 _exit(0);
166 return (NULL);
167 }
168