1 /* $NetBSD: ttymsg.c,v 1.19 2004/03/29 11:52:39 wiz 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. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 #if 0 35 static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 36 #else 37 __RCSID("$NetBSD: ttymsg.c,v 1.19 2004/03/29 11:52:39 wiz Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <sys/types.h> 42 #include <sys/uio.h> 43 44 #include <assert.h> 45 #include <dirent.h> 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <paths.h> 49 #include <signal.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 #include <util.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 char * 64 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout) 65 { 66 static char errbuf[1024]; 67 char device[MAXNAMLEN]; 68 int cnt, fd, left, wret; 69 struct iovec localiov[6]; 70 sigset_t nset; 71 int forked = 0; 72 73 _DIAGASSERT(iov != NULL); 74 _DIAGASSERT(iovcnt >= 0); 75 _DIAGASSERT(line != NULL); 76 77 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 78 return ("too many iov's (change code in libutil/ttymsg.c)"); 79 80 if (strlcpy(device, _PATH_DEV, sizeof(device)) >= sizeof(device) || 81 strlcat(device, line, sizeof(device)) >= sizeof(device)) { 82 (void) snprintf(errbuf, sizeof(errbuf), "%s: path too long", 83 line); 84 return (errbuf); 85 } 86 if (strcspn(line, "./") != strlen(line)) { 87 /* A slash or dot is an attempt to break security... */ 88 (void) snprintf(errbuf, sizeof(errbuf), "'/' or '.' in \"%s\"", 89 line); 90 return (errbuf); 91 } 92 93 /* 94 * open will fail on slip lines or exclusive-use lines 95 * if not running as root; not an error. 96 */ 97 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 98 if (errno == EBUSY || errno == EACCES) 99 return (NULL); 100 (void) snprintf(errbuf, sizeof(errbuf), 101 "%s: %s", device, strerror(errno)); 102 return (errbuf); 103 } 104 if (!isatty(fd)) { 105 (void) snprintf(errbuf, sizeof(errbuf), 106 "%s: not a tty device", device); 107 (void) close(fd); 108 return (errbuf); 109 } 110 111 for (cnt = left = 0; cnt < iovcnt; ++cnt) 112 left += iov[cnt].iov_len; 113 114 for (;;) { 115 wret = writev(fd, iov, iovcnt); 116 if (wret >= left) 117 break; 118 if (wret >= 0) { 119 left -= wret; 120 if (iov != localiov) { 121 memcpy(localiov, iov, 122 iovcnt * sizeof(struct iovec)); 123 iov = localiov; 124 } 125 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 126 wret -= iov->iov_len; 127 ++iov; 128 --iovcnt; 129 } 130 if (wret) { 131 iov->iov_base = 132 (char *)iov->iov_base + wret; 133 iov->iov_len -= wret; 134 } 135 continue; 136 } 137 if (errno == EWOULDBLOCK) { 138 pid_t cpid; 139 140 if (forked) { 141 (void) close(fd); 142 _exit(1); 143 } 144 cpid = fork(); 145 if (cpid < 0) { 146 (void) snprintf(errbuf, sizeof(errbuf), 147 "fork: %s", strerror(errno)); 148 (void) close(fd); 149 return (errbuf); 150 } 151 if (cpid) { /* parent */ 152 (void) close(fd); 153 return (NULL); 154 } 155 forked++; 156 /* wait at most tmout seconds */ 157 (void) signal(SIGALRM, SIG_DFL); 158 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 159 sigfillset(&nset); 160 (void) sigprocmask(SIG_UNBLOCK, &nset, NULL); 161 (void) alarm((u_int)tmout); 162 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 163 continue; 164 } 165 /* 166 * We get ENODEV on a slip line if we're running as root, 167 * and EIO if the line just went away. 168 */ 169 if (errno == ENODEV || errno == EIO) 170 break; 171 (void) close(fd); 172 if (forked) 173 _exit(1); 174 (void) snprintf(errbuf, sizeof(errbuf), 175 "%s: %s", device, strerror(errno)); 176 return (errbuf); 177 } 178 179 (void) close(fd); 180 if (forked) 181 _exit(0); 182 return (NULL); 183 } 184