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 * @(#)ttymsg.c 8.2 (Berkeley) 11/16/93 34 * $FreeBSD: src/usr.bin/wall/ttymsg.c,v 1.4.2.3 2001/10/18 08:08:17 des Exp $ 35 * $DragonFly: src/usr.bin/wall/ttymsg.c,v 1.3 2005/08/08 16:39:17 joerg Exp $ 36 */ 37 38 #include <sys/types.h> 39 #include <sys/uio.h> 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <limits.h> 43 #include <paths.h> 44 #include <signal.h> 45 #include <stdio.h> 46 #include <string.h> 47 #include <stdlib.h> 48 #include <unistd.h> 49 50 #include "ttymsg.h" 51 52 /* 53 * Display the contents of a uio structure on a terminal. Used by wall(1), 54 * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 55 * waiting up to tmout seconds. Returns pointer to error string on unexpected 56 * error; string is not newline-terminated. Various "normal" errors are 57 * ignored (exclusive-use, lack of permission, etc.). 58 */ 59 const char * 60 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout) 61 { 62 struct iovec localiov[7]; 63 ssize_t left, wret; 64 int cnt, fd; 65 static char device[PATH_MAX] = _PATH_DEV; 66 static char errbuf[1024]; 67 char *p; 68 int forked; 69 70 forked = 0; 71 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0]))) 72 return ("too many iov's (change code in wall/ttymsg.c)"); 73 74 p = device + sizeof(_PATH_DEV) - 1; 75 strlcpy(p, line, sizeof(device)); 76 if (!strncmp(p, "pts/", 4)) 77 p += 4; 78 if (strchr(p, '/') != NULL) { 79 /* A slash is an attempt to break security... */ 80 (void) snprintf(errbuf, sizeof(errbuf), 81 "Too many '/' in \"%s\"", device); 82 return (errbuf); 83 } 84 85 /* 86 * open will fail on slip lines or exclusive-use lines 87 * if not running as root; not an error. 88 */ 89 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 90 if (errno == EBUSY || errno == EACCES) 91 return (NULL); 92 (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device, 93 strerror(errno)); 94 return (errbuf); 95 } 96 97 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt) 98 left += iov[cnt].iov_len; 99 100 for (;;) { 101 wret = writev(fd, iov, iovcnt); 102 if (wret >= left) 103 break; 104 if (wret >= 0) { 105 left -= wret; 106 if (iov != localiov) { 107 bcopy(iov, localiov, 108 iovcnt * sizeof(struct iovec)); 109 iov = localiov; 110 } 111 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) { 112 wret -= iov->iov_len; 113 ++iov; 114 --iovcnt; 115 } 116 if (wret) { 117 iov->iov_base = (char *)iov->iov_base + wret; 118 iov->iov_len -= wret; 119 } 120 continue; 121 } 122 if (errno == EWOULDBLOCK) { 123 int cpid; 124 125 if (forked) { 126 (void) close(fd); 127 _exit(1); 128 } 129 cpid = fork(); 130 if (cpid < 0) { 131 (void) snprintf(errbuf, sizeof(errbuf), 132 "fork: %s", strerror(errno)); 133 (void) close(fd); 134 return (errbuf); 135 } 136 if (cpid) { /* parent */ 137 (void) close(fd); 138 return (NULL); 139 } 140 forked++; 141 /* wait at most tmout seconds */ 142 (void) signal(SIGALRM, SIG_DFL); 143 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 144 (void) sigsetmask(0); 145 (void) alarm((u_int)tmout); 146 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 147 continue; 148 } 149 /* 150 * We get ENODEV on a slip line if we're running as root, 151 * and EIO if the line just went away. 152 */ 153 if (errno == ENODEV || errno == EIO) 154 break; 155 (void) close(fd); 156 if (forked) 157 _exit(1); 158 (void) snprintf(errbuf, sizeof(errbuf), 159 "%s: %s", device, strerror(errno)); 160 return (errbuf); 161 } 162 163 (void) close(fd); 164 if (forked) 165 _exit(0); 166 return (NULL); 167 } 168