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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 32 __FBSDID("$FreeBSD$"); 33 34 #ifndef lint 35 static const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 36 #endif 37 38 #include <sys/types.h> 39 #include <sys/uio.h> 40 #include <dirent.h> 41 #include <errno.h> 42 #include <fcntl.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 char device[MAXNAMLEN]; 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 strlcpy(device, _PATH_DEV, sizeof(device)); 75 p = device + sizeof(_PATH_DEV) - 1; 76 strlcpy(p, line, sizeof(device) - sizeof(_PATH_DEV)); 77 if (strncmp(p, "pts/", 4) == 0) 78 p += 4; 79 if (strchr(p, '/') != NULL) { 80 /* A slash is an attempt to break security... */ 81 (void) snprintf(errbuf, sizeof(errbuf), 82 "Too many '/' in \"%s\"", device); 83 return (errbuf); 84 } 85 86 /* 87 * open will fail on slip lines or exclusive-use lines 88 * if not running as root; not an error. 89 */ 90 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 91 if (errno == EBUSY || errno == EACCES) 92 return (NULL); 93 (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device, 94 strerror(errno)); 95 return (errbuf); 96 } 97 98 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt) 99 left += iov[cnt].iov_len; 100 101 for (;;) { 102 wret = writev(fd, iov, iovcnt); 103 if (wret >= left) 104 break; 105 if (wret >= 0) { 106 left -= wret; 107 if (iov != localiov) { 108 bcopy(iov, localiov, 109 iovcnt * sizeof(struct iovec)); 110 iov = localiov; 111 } 112 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) { 113 wret -= iov->iov_len; 114 ++iov; 115 --iovcnt; 116 } 117 if (wret) { 118 iov->iov_base = (char *)iov->iov_base + wret; 119 iov->iov_len -= wret; 120 } 121 continue; 122 } 123 if (errno == EWOULDBLOCK) { 124 int cpid; 125 126 if (forked) { 127 (void) close(fd); 128 _exit(1); 129 } 130 cpid = fork(); 131 if (cpid < 0) { 132 (void) snprintf(errbuf, sizeof(errbuf), 133 "fork: %s", strerror(errno)); 134 (void) close(fd); 135 return (errbuf); 136 } 137 if (cpid) { /* parent */ 138 (void) close(fd); 139 return (NULL); 140 } 141 forked++; 142 /* wait at most tmout seconds */ 143 (void) signal(SIGALRM, SIG_DFL); 144 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 145 (void) sigsetmask(0); 146 (void) alarm((u_int)tmout); 147 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 148 continue; 149 } 150 /* 151 * We get ENODEV on a slip line if we're running as root, 152 * and EIO if the line just went away. 153 */ 154 if (errno == ENODEV || errno == EIO) 155 break; 156 (void) close(fd); 157 if (forked) 158 _exit(1); 159 (void) snprintf(errbuf, sizeof(errbuf), 160 "%s: %s", device, strerror(errno)); 161 return (errbuf); 162 } 163 164 (void) close(fd); 165 if (forked) 166 _exit(0); 167 return (NULL); 168 } 169