1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. 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 8.2 (Berkeley) 11/16/93"; 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 * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 53 * waiting up to tmout seconds. Returns pointer to error string on unexpected 54 * error; string is not newline-terminated. Various "normal" errors are 55 * ignored (exclusive-use, lack of permission, etc.). 56 */ 57 char * 58 ttymsg(iov, iovcnt, line, tmout) 59 struct iovec *iov; 60 int iovcnt; 61 char *line; 62 int tmout; 63 { 64 static char device[MAXNAMLEN] = _PATH_DEV; 65 static char errbuf[1024]; 66 register int cnt, fd, left, wret; 67 struct iovec localiov[6]; 68 int forked = 0; 69 70 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 71 return ("too many iov's (change code in wall/ttymsg.c)"); 72 73 (void) strcpy(device + sizeof(_PATH_DEV) - 1, line); 74 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 75 /* A slash is an attempt to break security... */ 76 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 77 device); 78 return (errbuf); 79 } 80 81 /* 82 * open will fail on slip lines or exclusive-use lines 83 * if not running as root; not an error. 84 */ 85 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 86 if (errno == EBUSY || errno == EACCES) 87 return (NULL); 88 (void) snprintf(errbuf, sizeof(errbuf), 89 "%s: %s", device, strerror(errno)); 90 return (errbuf); 91 } 92 93 for (cnt = left = 0; cnt < iovcnt; ++cnt) 94 left += iov[cnt].iov_len; 95 96 for (;;) { 97 wret = writev(fd, iov, iovcnt); 98 if (wret >= left) 99 break; 100 if (wret >= 0) { 101 left -= wret; 102 if (iov != localiov) { 103 bcopy(iov, localiov, 104 iovcnt * sizeof(struct iovec)); 105 iov = localiov; 106 } 107 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 108 wret -= iov->iov_len; 109 ++iov; 110 --iovcnt; 111 } 112 if (wret) { 113 iov->iov_base += wret; 114 iov->iov_len -= wret; 115 } 116 continue; 117 } 118 if (errno == EWOULDBLOCK) { 119 int cpid, off = 0; 120 121 if (forked) { 122 (void) close(fd); 123 _exit(1); 124 } 125 cpid = fork(); 126 if (cpid < 0) { 127 (void) snprintf(errbuf, sizeof(errbuf), 128 "fork: %s", strerror(errno)); 129 (void) close(fd); 130 return (errbuf); 131 } 132 if (cpid) { /* parent */ 133 (void) close(fd); 134 return (NULL); 135 } 136 forked++; 137 /* wait at most tmout seconds */ 138 (void) signal(SIGALRM, SIG_DFL); 139 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 140 (void) sigsetmask(0); 141 (void) alarm((u_int)tmout); 142 (void) fcntl(fd, O_NONBLOCK, &off); 143 continue; 144 } 145 /* 146 * We get ENODEV on a slip line if we're running as root, 147 * and EIO if the line just went away. 148 */ 149 if (errno == ENODEV || errno == EIO) 150 break; 151 (void) close(fd); 152 if (forked) 153 _exit(1); 154 (void) snprintf(errbuf, sizeof(errbuf), 155 "%s: %s", device, strerror(errno)); 156 return (errbuf); 157 } 158 159 (void) close(fd); 160 if (forked) 161 _exit(0); 162 return (NULL); 163 } 164