1 /* $OpenBSD: ttymsg.c,v 1.14 2003/07/31 18:21:42 avsm Exp $ */ 2 /* $NetBSD: ttymsg.c,v 1.3 1994/11/17 07:17:55 jtc Exp $ */ 3 4 /* 5 * Copyright (c) 1989, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #ifndef lint 34 #if 0 35 static const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 36 #endif 37 static const char rcsid[] = "$OpenBSD: ttymsg.c,v 1.14 2003/07/31 18:21:42 avsm Exp $"; 38 #endif /* not lint */ 39 40 #include <sys/types.h> 41 #include <sys/uio.h> 42 #include <signal.h> 43 #include <fcntl.h> 44 #include <dirent.h> 45 #include <errno.h> 46 #include <paths.h> 47 #include <unistd.h> 48 #include <stdio.h> 49 #include <string.h> 50 #include <stdlib.h> 51 #include <sys/stat.h> 52 53 char *ttymsg(struct iovec *, int, char *, int); 54 55 /* 56 * Display the contents of a uio structure on a terminal. Used by wall(1) 57 * and talkd(8). Forks and finishes in child if write would block, 58 * waiting up to tmout seconds. Returns pointer to error string on unexpected 59 * error; string is not newline-terminated. Various "normal" errors are 60 * ignored (exclusive-use, lack of permission, etc.). 61 */ 62 char * 63 ttymsg(iov, iovcnt, line, tmout) 64 struct iovec *iov; 65 int iovcnt; 66 char *line; 67 int tmout; 68 { 69 static char device[MAXNAMLEN] = _PATH_DEV; 70 static char errbuf[1024]; 71 int cnt, fd, left, wret; 72 struct iovec localiov[6]; 73 int forked = 0; 74 struct stat st; 75 sigset_t mask; 76 77 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 78 return ("too many iov's (change code in wall/ttymsg.c)"); 79 80 /* 81 * Ignore lines that start with "ftp" or "uucp". 82 */ 83 if ((strncmp(line, "ftp", 3) == 0) || 84 (strncmp(line, "uucp", 4) == 0)) 85 return (NULL); 86 87 (void) strlcpy(device + sizeof(_PATH_DEV) - 1, line, 88 sizeof(device) - (sizeof(_PATH_DEV) - 1)); 89 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 90 /* A slash is an attempt to break security... */ 91 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 92 device); 93 return (errbuf); 94 } 95 96 if (getuid()) { 97 if (stat(device, &st) < 0) 98 return (NULL); 99 if ((st.st_mode & S_IWGRP) == 0) 100 return (NULL); 101 } 102 103 /* 104 * open will fail on slip lines or exclusive-use lines 105 * if not running as root; not an error. 106 */ 107 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 108 if (errno == EBUSY || errno == EACCES) 109 return (NULL); 110 (void) snprintf(errbuf, sizeof(errbuf), 111 "%s: %s", device, strerror(errno)); 112 return (errbuf); 113 } 114 115 for (cnt = left = 0; cnt < iovcnt; ++cnt) 116 left += iov[cnt].iov_len; 117 118 for (;;) { 119 wret = writev(fd, iov, iovcnt); 120 if (wret >= left) 121 break; 122 if (wret >= 0) { 123 left -= wret; 124 if (iov != localiov) { 125 bcopy(iov, localiov, 126 iovcnt * sizeof(struct iovec)); 127 iov = localiov; 128 } 129 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 130 wret -= iov->iov_len; 131 ++iov; 132 --iovcnt; 133 } 134 if (wret) { 135 iov->iov_base += wret; 136 iov->iov_len -= wret; 137 } 138 continue; 139 } 140 if (errno == EWOULDBLOCK) { 141 int off = 0; 142 pid_t cpid; 143 144 if (forked) { 145 (void) close(fd); 146 _exit(1); 147 } 148 cpid = fork(); 149 if (cpid < 0) { 150 (void) snprintf(errbuf, sizeof(errbuf), 151 "fork: %s", strerror(errno)); 152 (void) close(fd); 153 return (errbuf); 154 } 155 if (cpid) { /* parent */ 156 (void) close(fd); 157 return (NULL); 158 } 159 forked++; 160 /* wait at most tmout seconds */ 161 (void) signal(SIGALRM, SIG_DFL); 162 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 163 (void) sigemptyset(&mask); 164 (void) sigprocmask(SIG_SETMASK, &mask, NULL); 165 (void) alarm((u_int)tmout); 166 (void) fcntl(fd, O_NONBLOCK, &off); 167 continue; 168 } 169 /* 170 * We get ENODEV on a slip line if we're running as root, 171 * and EIO if the line just went away. 172 */ 173 if (errno == ENODEV || errno == EIO) 174 break; 175 (void) close(fd); 176 if (forked) 177 _exit(1); 178 (void) snprintf(errbuf, sizeof(errbuf), 179 "%s: %s", device, strerror(errno)); 180 return (errbuf); 181 } 182 183 (void) close(fd); 184 if (forked) 185 _exit(0); 186 return (NULL); 187 } 188