1 /* $NetBSD: ttymsg.c,v 1.23 2009/01/18 12:13:04 lukem Exp $ */
2
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/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 #if 0
35 static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93";
36 #else
37 __RCSID("$NetBSD: ttymsg.c,v 1.23 2009/01/18 12:13:04 lukem Exp $");
38 #endif
39 #endif /* LIBC_SCCS and not lint */
40
41 #include <sys/types.h>
42 #include <sys/uio.h>
43
44 #include <assert.h>
45 #include <dirent.h>
46 #include <errno.h>
47 #include <fcntl.h>
48 #include <paths.h>
49 #include <signal.h>
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53 #include <unistd.h>
54 #include <util.h>
55
56 /*
57 * Display the contents of a uio structure on a terminal. Used by wall(1),
58 * syslogd(8), and talkd(8). Forks and finishes in child if write would block,
59 * waiting up to tmout seconds. Returns pointer to error string on unexpected
60 * error; string is not newline-terminated. Various "normal" errors are
61 * ignored (exclusive-use, lack of permission, etc.).
62 */
63 char *
ttymsg(struct iovec * iov,int iovcnt,const char * line,int tmout)64 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout)
65 {
66 static char errbuf[1024];
67 char device[MAXNAMLEN];
68 const char *ptr;
69 int fd, ret;
70 struct iovec localiov[32];
71 sigset_t nset;
72 int forked = 0;
73 size_t cnt, left, wret;
74
75 _DIAGASSERT(iov != NULL);
76 _DIAGASSERT(iovcnt >= 0);
77 _DIAGASSERT(line != NULL);
78
79 if (iovcnt < 0) {
80 (void)snprintf(errbuf, sizeof(errbuf),
81 "%s: negative iovcnt", __func__);
82 return errbuf;
83 }
84
85 if ((size_t)iovcnt >= sizeof(localiov) / sizeof(localiov[0])) {
86 (void)snprintf(errbuf, sizeof(errbuf),
87 "%s: too many iov's (%d) max is %zu", __func__,
88 iovcnt, sizeof(localiov) / sizeof(localiov[0]));
89 return errbuf;
90 }
91
92 ptr = strncmp(line, "pts/", (size_t)4) == 0 ? line + 4 : line;
93 if (strcspn(ptr, "./") != strlen(ptr)) {
94 /* A slash or dot is an attempt to break security... */
95 (void)snprintf(errbuf, sizeof(errbuf),
96 "%s: '/' or '.' in \"%s\"", __func__, line);
97 return errbuf;
98 }
99 ret = snprintf(device, sizeof(device), "%s%s", _PATH_DEV, line);
100 if (ret == -1 || ret >= (int)sizeof(device)) {
101 (void) snprintf(errbuf, sizeof(errbuf),
102 "%s: line `%s' too long", __func__, line);
103 return errbuf;
104 }
105 cnt = (size_t)ret;
106
107 /*
108 * open will fail on slip lines or exclusive-use lines
109 * if not running as root; not an error.
110 */
111 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
112 if (errno == EBUSY || errno == EACCES)
113 return NULL;
114 (void)snprintf(errbuf, sizeof(errbuf),
115 "%s: Cannot open `%s' (%s)",
116 __func__, device, strerror(errno));
117 return errbuf;
118 }
119 if (!isatty(fd)) {
120 (void)snprintf(errbuf, sizeof(errbuf),
121 "%s: line `%s' is not a tty device", __func__, device);
122 (void)close(fd);
123 return errbuf;
124 }
125
126 for (cnt = left = 0; cnt < (size_t)iovcnt; ++cnt)
127 left += iov[cnt].iov_len;
128
129 for (;;) {
130 wret = writev(fd, iov, iovcnt);
131 if (wret >= left)
132 break;
133 if (wret > 0) {
134 left -= wret;
135 if (iov != localiov) {
136 (void)memcpy(localiov, iov,
137 iovcnt * sizeof(struct iovec));
138 iov = localiov;
139 }
140 for (cnt = 0; wret >= iov->iov_len; ++cnt) {
141 wret -= iov->iov_len;
142 ++iov;
143 --iovcnt;
144 }
145 if (wret) {
146 iov->iov_base =
147 (char *)iov->iov_base + wret;
148 iov->iov_len -= wret;
149 }
150 continue;
151 } else if (wret == 0) {
152 (void)snprintf(errbuf, sizeof(errbuf),
153 "%s: failed writing %zu bytes to `%s'", __func__,
154 left, device);
155 (void) close(fd);
156 if (forked)
157 _exit(1);
158 return errbuf;
159 }
160 if (errno == EWOULDBLOCK) {
161 pid_t cpid;
162
163 if (forked) {
164 (void)close(fd);
165 _exit(1);
166 }
167 cpid = fork();
168 if (cpid < 0) {
169 (void)snprintf(errbuf, sizeof(errbuf),
170 "%s: Cannot fork (%s)", __func__,
171 strerror(errno));
172 (void)close(fd);
173 return errbuf;
174 }
175 if (cpid) { /* parent */
176 (void)close(fd);
177 return NULL;
178 }
179 forked++;
180 /* wait at most tmout seconds */
181 (void)signal(SIGALRM, SIG_DFL);
182 (void)signal(SIGTERM, SIG_DFL); /* XXX */
183 sigfillset(&nset);
184 (void)sigprocmask(SIG_UNBLOCK, &nset, NULL);
185 (void)alarm((u_int)tmout);
186 (void)fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */
187 continue;
188 }
189 /*
190 * We get ENODEV on a slip line if we're running as root,
191 * and EIO if the line just went away.
192 */
193 if (errno == ENODEV || errno == EIO)
194 break;
195 (void) close(fd);
196 if (forked)
197 _exit(1);
198 (void)snprintf(errbuf, sizeof(errbuf),
199 "%s: Write to line `%s' failed (%s)", __func__,
200 device, strerror(errno));
201 return errbuf;
202 }
203
204 (void) close(fd);
205 if (forked)
206 _exit(0);
207 return NULL;
208 }
209