1 /* $NetBSD: ttymsg.c,v 1.11 1998/09/27 00:00:16 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 40 #else 41 __RCSID("$NetBSD: ttymsg.c,v 1.11 1998/09/27 00:00:16 christos Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <sys/types.h> 46 #include <sys/uio.h> 47 #include <signal.h> 48 #include <fcntl.h> 49 #include <dirent.h> 50 #include <errno.h> 51 #include <paths.h> 52 #include <unistd.h> 53 #include <stdio.h> 54 #include <string.h> 55 #include <stdlib.h> 56 #include <util.h> 57 58 /* 59 * Display the contents of a uio structure on a terminal. Used by wall(1), 60 * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 61 * waiting up to tmout seconds. Returns pointer to error string on unexpected 62 * error; string is not newline-terminated. Various "normal" errors are 63 * ignored (exclusive-use, lack of permission, etc.). 64 */ 65 char * 66 ttymsg(iov, iovcnt, line, tmout) 67 struct iovec *iov; 68 int iovcnt; 69 const char *line; 70 int tmout; 71 { 72 static char device[MAXNAMLEN] = _PATH_DEV; 73 static char errbuf[1024]; 74 int cnt, fd, left, wret; 75 struct iovec localiov[6]; 76 sigset_t nset; 77 int forked = 0; 78 79 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 80 return ("too many iov's (change code in libutil/ttymsg.c)"); 81 82 (void)strncpy(device + sizeof(_PATH_DEV) - 1, line, 83 sizeof(device) - sizeof(_PATH_DEV)); 84 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 85 /* A slash is an attempt to break security... */ 86 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 87 device); 88 return (errbuf); 89 } 90 91 /* 92 * open will fail on slip lines or exclusive-use lines 93 * if not running as root; not an error. 94 */ 95 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 96 if (errno == EBUSY || errno == EACCES) 97 return (NULL); 98 (void) snprintf(errbuf, sizeof(errbuf), 99 "%s: %s", device, strerror(errno)); 100 return (errbuf); 101 } 102 103 for (cnt = left = 0; cnt < iovcnt; ++cnt) 104 left += iov[cnt].iov_len; 105 106 for (;;) { 107 wret = writev(fd, iov, iovcnt); 108 if (wret >= left) 109 break; 110 if (wret >= 0) { 111 left -= wret; 112 if (iov != localiov) { 113 memcpy(localiov, iov, 114 iovcnt * sizeof(struct iovec)); 115 iov = localiov; 116 } 117 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 118 wret -= iov->iov_len; 119 ++iov; 120 --iovcnt; 121 } 122 if (wret) { 123 iov->iov_base = 124 (char *)iov->iov_base + wret; 125 iov->iov_len -= wret; 126 } 127 continue; 128 } 129 if (errno == EWOULDBLOCK) { 130 int cpid, off = 0; 131 132 if (forked) { 133 (void) close(fd); 134 _exit(1); 135 } 136 cpid = fork(); 137 if (cpid < 0) { 138 (void) snprintf(errbuf, sizeof(errbuf), 139 "fork: %s", strerror(errno)); 140 (void) close(fd); 141 return (errbuf); 142 } 143 if (cpid) { /* parent */ 144 (void) close(fd); 145 return (NULL); 146 } 147 forked++; 148 /* wait at most tmout seconds */ 149 (void) signal(SIGALRM, SIG_DFL); 150 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 151 sigfillset(&nset); 152 (void) sigprocmask(SIG_UNBLOCK, &nset, NULL); 153 (void) alarm((u_int)tmout); 154 (void) fcntl(fd, O_NONBLOCK, &off); 155 continue; 156 } 157 /* 158 * We get ENODEV on a slip line if we're running as root, 159 * and EIO if the line just went away. 160 */ 161 if (errno == ENODEV || errno == EIO) 162 break; 163 (void) close(fd); 164 if (forked) 165 _exit(1); 166 (void) snprintf(errbuf, sizeof(errbuf), 167 "%s: %s", device, strerror(errno)); 168 return (errbuf); 169 } 170 171 (void) close(fd); 172 if (forked) 173 _exit(0); 174 return (NULL); 175 } 176