1 /* $NetBSD: ttymsg.c,v 1.4 1997/02/11 08:42:03 mrg 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 39 #endif 40 static char rcsid[] = "$NetBSD: ttymsg.c,v 1.4 1997/02/11 08:42:03 mrg Exp $"; 41 #endif /* not lint */ 42 43 #include <sys/types.h> 44 #include <sys/uio.h> 45 #include <signal.h> 46 #include <fcntl.h> 47 #include <dirent.h> 48 #include <errno.h> 49 #include <paths.h> 50 #include <unistd.h> 51 #include <stdio.h> 52 #include <string.h> 53 #include <stdlib.h> 54 55 /* 56 * Display the contents of a uio structure on a terminal. Used by wall(1), 57 * syslogd(8), 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 register int cnt, fd, left, wret; 72 struct iovec localiov[6]; 73 int forked = 0; 74 75 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 76 return ("too many iov's (change code in wall/ttymsg.c)"); 77 78 (void)strncpy(device + sizeof(_PATH_DEV) - 1, line, 79 sizeof(device) - sizeof(_PATH_DEV)); 80 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 81 /* A slash is an attempt to break security... */ 82 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 83 device); 84 return (errbuf); 85 } 86 87 /* 88 * open will fail on slip lines or exclusive-use lines 89 * if not running as root; not an error. 90 */ 91 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 92 if (errno == EBUSY || errno == EACCES) 93 return (NULL); 94 (void) snprintf(errbuf, sizeof(errbuf), 95 "%s: %s", device, strerror(errno)); 96 return (errbuf); 97 } 98 99 for (cnt = left = 0; cnt < iovcnt; ++cnt) 100 left += iov[cnt].iov_len; 101 102 for (;;) { 103 wret = writev(fd, iov, iovcnt); 104 if (wret >= left) 105 break; 106 if (wret >= 0) { 107 left -= wret; 108 if (iov != localiov) { 109 bcopy(iov, localiov, 110 iovcnt * sizeof(struct iovec)); 111 iov = localiov; 112 } 113 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 114 wret -= iov->iov_len; 115 ++iov; 116 --iovcnt; 117 } 118 if (wret) { 119 iov->iov_base += wret; 120 iov->iov_len -= wret; 121 } 122 continue; 123 } 124 if (errno == EWOULDBLOCK) { 125 int cpid, off = 0; 126 127 if (forked) { 128 (void) close(fd); 129 _exit(1); 130 } 131 cpid = fork(); 132 if (cpid < 0) { 133 (void) snprintf(errbuf, sizeof(errbuf), 134 "fork: %s", strerror(errno)); 135 (void) close(fd); 136 return (errbuf); 137 } 138 if (cpid) { /* parent */ 139 (void) close(fd); 140 return (NULL); 141 } 142 forked++; 143 /* wait at most tmout seconds */ 144 (void) signal(SIGALRM, SIG_DFL); 145 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 146 (void) sigsetmask(0); 147 (void) alarm((u_int)tmout); 148 (void) fcntl(fd, O_NONBLOCK, &off); 149 continue; 150 } 151 /* 152 * We get ENODEV on a slip line if we're running as root, 153 * and EIO if the line just went away. 154 */ 155 if (errno == ENODEV || errno == EIO) 156 break; 157 (void) close(fd); 158 if (forked) 159 _exit(1); 160 (void) snprintf(errbuf, sizeof(errbuf), 161 "%s: %s", device, strerror(errno)); 162 return (errbuf); 163 } 164 165 (void) close(fd); 166 if (forked) 167 _exit(0); 168 return (NULL); 169 } 170