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 #include <sys/cdefs.h> 35 36 __FBSDID("$FreeBSD$"); 37 38 #ifndef lint 39 static const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 40 #endif 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 #include "ttymsg.h" 55 56 /* 57 * Display the contents of a uio structure on a terminal. Used by wall(1), 58 * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 59 * waiting up to tmout seconds. Returns pointer to error string on unexpected 60 * error; string is not newline-terminated. Various "normal" errors are 61 * ignored (exclusive-use, lack of permission, etc.). 62 */ 63 const char * 64 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout) 65 { 66 struct iovec localiov[7]; 67 ssize_t left, wret; 68 int cnt, fd; 69 static char device[MAXNAMLEN] = _PATH_DEV; 70 static char errbuf[1024]; 71 char *p; 72 int forked; 73 74 forked = 0; 75 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0]))) 76 return ("too many iov's (change code in wall/ttymsg.c)"); 77 78 p = device + sizeof(_PATH_DEV) - 1; 79 strlcpy(p, line, sizeof(device)); 80 if (strncmp(p, "pts/", 4) == 0) 81 p += 4; 82 if (strchr(p, '/') != NULL) { 83 /* A slash is an attempt to break security... */ 84 (void) snprintf(errbuf, sizeof(errbuf), 85 "Too many '/' in \"%s\"", device); 86 return (errbuf); 87 } 88 89 /* 90 * open will fail on slip lines or exclusive-use lines 91 * if not running as root; not an error. 92 */ 93 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 94 if (errno == EBUSY || errno == EACCES) 95 return (NULL); 96 (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device, 97 strerror(errno)); 98 return (errbuf); 99 } 100 101 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt) 102 left += iov[cnt].iov_len; 103 104 for (;;) { 105 wret = writev(fd, iov, iovcnt); 106 if (wret >= left) 107 break; 108 if (wret >= 0) { 109 left -= wret; 110 if (iov != localiov) { 111 bcopy(iov, localiov, 112 iovcnt * sizeof(struct iovec)); 113 iov = localiov; 114 } 115 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) { 116 wret -= iov->iov_len; 117 ++iov; 118 --iovcnt; 119 } 120 if (wret) { 121 iov->iov_base = (char *)iov->iov_base + wret; 122 iov->iov_len -= wret; 123 } 124 continue; 125 } 126 if (errno == EWOULDBLOCK) { 127 int cpid; 128 129 if (forked) { 130 (void) close(fd); 131 _exit(1); 132 } 133 cpid = fork(); 134 if (cpid < 0) { 135 (void) snprintf(errbuf, sizeof(errbuf), 136 "fork: %s", strerror(errno)); 137 (void) close(fd); 138 return (errbuf); 139 } 140 if (cpid) { /* parent */ 141 (void) close(fd); 142 return (NULL); 143 } 144 forked++; 145 /* wait at most tmout seconds */ 146 (void) signal(SIGALRM, SIG_DFL); 147 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 148 (void) sigsetmask(0); 149 (void) alarm((u_int)tmout); 150 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 151 continue; 152 } 153 /* 154 * We get ENODEV on a slip line if we're running as root, 155 * and EIO if the line just went away. 156 */ 157 if (errno == ENODEV || errno == EIO) 158 break; 159 (void) close(fd); 160 if (forked) 161 _exit(1); 162 (void) snprintf(errbuf, sizeof(errbuf), 163 "%s: %s", device, strerror(errno)); 164 return (errbuf); 165 } 166 167 (void) close(fd); 168 if (forked) 169 _exit(0); 170 return (NULL); 171 } 172