1 /* 2 * Copyright (c) 1989 The Regents of the University of California. 3 * 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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #ifndef lint 35 static char sccsid[] = "@(#)ttymsg.c 5.8 (Berkeley) 7/1/91"; 36 #endif /* not lint */ 37 38 #include <sys/types.h> 39 #include <sys/uio.h> 40 #include <signal.h> 41 #include <fcntl.h> 42 #include <dirent.h> 43 #include <errno.h> 44 #include <paths.h> 45 #include <unistd.h> 46 #include <stdio.h> 47 #include <string.h> 48 #include <stdlib.h> 49 50 /* 51 * Display the contents of a uio structure on a terminal. Used by wall(1) 52 * and syslogd(8). Forks and finishes in child if write would block, waiting 53 * at most five minutes. Returns pointer to error string on unexpected error; 54 * string is not newline-terminated. Various "normal" errors are ignored 55 * (exclusive-use, lack of permission, etc.). 56 */ 57 char * 58 ttymsg(iov, iovcnt, line) 59 struct iovec *iov; 60 int iovcnt; 61 char *line; 62 { 63 static char device[MAXNAMLEN] = _PATH_DEV; 64 static char errbuf[1024]; 65 register int cnt, fd, left, wret; 66 struct iovec localiov[6]; 67 int forked = 0; 68 69 if (iovcnt > 6) 70 return ("too many iov's (change code in wall/ttymsg.c)"); 71 /* 72 * open will fail on slip lines or exclusive-use lines 73 * if not running as root; not an error. 74 */ 75 (void) strcpy(device + sizeof(_PATH_DEV) - 1, line); 76 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 77 if (errno == EBUSY || errno == EACCES) 78 return (NULL); 79 (void) snprintf(errbuf, sizeof(errbuf), 80 "%s: %s", device, strerror(errno)); 81 return (errbuf); 82 } 83 84 for (cnt = left = 0; cnt < iovcnt; ++cnt) 85 left += iov[cnt].iov_len; 86 87 for (;;) { 88 wret = writev(fd, iov, iovcnt); 89 if (wret >= left) 90 break; 91 if (wret >= 0) { 92 left -= wret; 93 if (iov != localiov) { 94 bcopy(iov, localiov, 95 iovcnt * sizeof(struct iovec)); 96 iov = localiov; 97 } 98 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 99 wret -= iov->iov_len; 100 ++iov; 101 --iovcnt; 102 } 103 if (wret) { 104 iov->iov_base += wret; 105 iov->iov_len -= wret; 106 } 107 continue; 108 } 109 if (errno == EWOULDBLOCK) { 110 int cpid, off = 0; 111 112 if (forked) { 113 (void) close(fd); 114 _exit(1); 115 } 116 cpid = fork(); 117 if (cpid < 0) { 118 (void) snprintf(errbuf, sizeof(errbuf), 119 "fork: %s", strerror(errno)); 120 (void) close(fd); 121 return (errbuf); 122 } 123 if (cpid) { /* parent */ 124 (void) close(fd); 125 return (NULL); 126 } 127 forked++; 128 /* wait at most 5 minutes */ 129 (void) signal(SIGALRM, SIG_DFL); 130 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 131 (void) sigsetmask(0); 132 (void) alarm((u_int)(60 * 5)); 133 (void) fcntl(fd, O_NONBLOCK, &off); 134 continue; 135 } 136 /* 137 * We get ENODEV on a slip line if we're running as root, 138 * and EIO if the line just went away. 139 */ 140 if (errno == ENODEV || errno == EIO) 141 break; 142 (void) close(fd); 143 if (forked) 144 _exit(1); 145 (void) snprintf(errbuf, sizeof(errbuf), 146 "%s: %s", device, strerror(errno)); 147 return (errbuf); 148 } 149 150 (void) close(fd); 151 if (forked) 152 _exit(0); 153 return (NULL); 154 } 155