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