1 /* $NetBSD: ttymsg.c,v 1.14 1999/09/20 04:48:11 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. 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 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 40 #else 41 __RCSID("$NetBSD: ttymsg.c,v 1.14 1999/09/20 04:48:11 lukem Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <sys/types.h> 46 #include <sys/uio.h> 47 48 #include <assert.h> 49 #include <dirent.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <paths.h> 53 #include <signal.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <unistd.h> 58 #include <util.h> 59 60 /* 61 * Display the contents of a uio structure on a terminal. Used by wall(1), 62 * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 63 * waiting up to tmout seconds. Returns pointer to error string on unexpected 64 * error; string is not newline-terminated. Various "normal" errors are 65 * ignored (exclusive-use, lack of permission, etc.). 66 */ 67 char * 68 ttymsg(iov, iovcnt, line, tmout) 69 struct iovec *iov; 70 int iovcnt; 71 const char *line; 72 int tmout; 73 { 74 static char device[MAXNAMLEN] = _PATH_DEV; 75 static char errbuf[1024]; 76 int cnt, fd, left, wret; 77 struct iovec localiov[6]; 78 sigset_t nset; 79 int forked = 0; 80 81 _DIAGASSERT(iov != NULL); 82 _DIAGASSERT(iovcnt >= 0); 83 _DIAGASSERT(line != NULL); 84 85 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 86 return ("too many iov's (change code in libutil/ttymsg.c)"); 87 88 (void)strncpy(device + sizeof(_PATH_DEV) - 1, line, 89 sizeof(device) - sizeof(_PATH_DEV)); 90 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 91 /* A slash is an attempt to break security... */ 92 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 93 device); 94 return (errbuf); 95 } 96 97 /* 98 * open will fail on slip lines or exclusive-use lines 99 * if not running as root; not an error. 100 */ 101 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 102 if (errno == EBUSY || errno == EACCES) 103 return (NULL); 104 (void) snprintf(errbuf, sizeof(errbuf), 105 "%s: %s", device, strerror(errno)); 106 return (errbuf); 107 } 108 109 for (cnt = left = 0; cnt < iovcnt; ++cnt) 110 left += iov[cnt].iov_len; 111 112 for (;;) { 113 wret = writev(fd, iov, iovcnt); 114 if (wret >= left) 115 break; 116 if (wret >= 0) { 117 left -= wret; 118 if (iov != localiov) { 119 memcpy(localiov, iov, 120 iovcnt * sizeof(struct iovec)); 121 iov = localiov; 122 } 123 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 124 wret -= iov->iov_len; 125 ++iov; 126 --iovcnt; 127 } 128 if (wret) { 129 iov->iov_base = 130 (char *)iov->iov_base + wret; 131 iov->iov_len -= wret; 132 } 133 continue; 134 } 135 if (errno == EWOULDBLOCK) { 136 int cpid, off = 0; 137 138 if (forked) { 139 (void) close(fd); 140 _exit(1); 141 } 142 cpid = fork(); 143 if (cpid < 0) { 144 (void) snprintf(errbuf, sizeof(errbuf), 145 "fork: %s", strerror(errno)); 146 (void) close(fd); 147 return (errbuf); 148 } 149 if (cpid) { /* parent */ 150 (void) close(fd); 151 return (NULL); 152 } 153 forked++; 154 /* wait at most tmout seconds */ 155 (void) signal(SIGALRM, SIG_DFL); 156 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 157 sigfillset(&nset); 158 (void) sigprocmask(SIG_UNBLOCK, &nset, NULL); 159 (void) alarm((u_int)tmout); 160 (void) fcntl(fd, O_NONBLOCK, &off); 161 continue; 162 } 163 /* 164 * We get ENODEV on a slip line if we're running as root, 165 * and EIO if the line just went away. 166 */ 167 if (errno == ENODEV || errno == EIO) 168 break; 169 (void) close(fd); 170 if (forked) 171 _exit(1); 172 (void) snprintf(errbuf, sizeof(errbuf), 173 "%s: %s", device, strerror(errno)); 174 return (errbuf); 175 } 176 177 (void) close(fd); 178 if (forked) 179 _exit(0); 180 return (NULL); 181 } 182