1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 33 34 #include <sys/types.h> 35 #include <sys/uio.h> 36 #include <dirent.h> 37 #include <errno.h> 38 #include <fcntl.h> 39 #include <paths.h> 40 #include <signal.h> 41 #include <stdio.h> 42 #include <string.h> 43 #include <stdlib.h> 44 #include <unistd.h> 45 46 #include "ttymsg.h" 47 48 /* 49 * Display the contents of a uio structure on a terminal. Used by wall(1), 50 * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 51 * waiting up to tmout seconds. Returns pointer to error string on unexpected 52 * error; string is not newline-terminated. Various "normal" errors are 53 * ignored (exclusive-use, lack of permission, etc.). 54 */ 55 const char * 56 ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout) 57 { 58 struct iovec localiov[TTYMSG_IOV_MAX]; 59 ssize_t left, wret; 60 int cnt, fd; 61 char device[MAXNAMLEN] = _PATH_DEV; 62 static char errbuf[1024]; 63 char *p; 64 int forked; 65 66 forked = 0; 67 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0]))) 68 return ("too many iov's (change code in wall/ttymsg.c)"); 69 70 strlcat(device, line, sizeof(device)); 71 p = device + sizeof(_PATH_DEV) - 1; 72 if (strncmp(p, "pts/", 4) == 0) 73 p += 4; 74 if (strchr(p, '/') != NULL) { 75 /* A slash is an attempt to break security... */ 76 (void) snprintf(errbuf, sizeof(errbuf), 77 "Too many '/' in \"%s\"", device); 78 return (errbuf); 79 } 80 81 /* 82 * open will fail on slip lines or exclusive-use lines 83 * if not running as root; not an error. 84 */ 85 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 86 if (errno == EBUSY || errno == EACCES) 87 return (NULL); 88 (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device, 89 strerror(errno)); 90 return (errbuf); 91 } 92 93 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt) 94 left += iov[cnt].iov_len; 95 96 for (;;) { 97 wret = writev(fd, iov, iovcnt); 98 if (wret >= left) 99 break; 100 if (wret >= 0) { 101 left -= wret; 102 if (iov != localiov) { 103 bcopy(iov, localiov, 104 iovcnt * sizeof(struct iovec)); 105 iov = localiov; 106 } 107 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) { 108 wret -= iov->iov_len; 109 ++iov; 110 --iovcnt; 111 } 112 if (wret) { 113 iov->iov_base = (char *)iov->iov_base + wret; 114 iov->iov_len -= wret; 115 } 116 continue; 117 } 118 if (errno == EWOULDBLOCK) { 119 int cpid; 120 121 if (forked) { 122 (void) close(fd); 123 _exit(1); 124 } 125 cpid = fork(); 126 if (cpid < 0) { 127 (void) snprintf(errbuf, sizeof(errbuf), 128 "fork: %s", strerror(errno)); 129 (void) close(fd); 130 return (errbuf); 131 } 132 if (cpid) { /* parent */ 133 (void) close(fd); 134 return (NULL); 135 } 136 forked++; 137 /* wait at most tmout seconds */ 138 (void) signal(SIGALRM, SIG_DFL); 139 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 140 (void) sigsetmask(0); 141 (void) alarm((u_int)tmout); 142 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 143 continue; 144 } 145 /* 146 * We get ENODEV on a slip line if we're running as root, 147 * and EIO if the line just went away. 148 */ 149 if (errno == ENODEV || errno == EIO) 150 break; 151 (void) close(fd); 152 if (forked) 153 _exit(1); 154 (void) snprintf(errbuf, sizeof(errbuf), 155 "%s: %s", device, strerror(errno)); 156 return (errbuf); 157 } 158 159 (void) close(fd); 160 if (forked) 161 _exit(0); 162 return (NULL); 163 } 164