ttymsg.c revision 286269
1241675Suqs/* 2241675Suqs * Copyright (c) 1989, 1993 3241675Suqs * The Regents of the University of California. All rights reserved. 4241675Suqs * 5241675Suqs * Redistribution and use in source and binary forms, with or without 6241675Suqs * modification, are permitted provided that the following conditions 7241675Suqs * are met: 8241675Suqs * 1. Redistributions of source code must retain the above copyright 9241675Suqs * notice, this list of conditions and the following disclaimer. 10241675Suqs * 2. Redistributions in binary form must reproduce the above copyright 11241675Suqs * notice, this list of conditions and the following disclaimer in the 12241675Suqs * documentation and/or other materials provided with the distribution. 13241675Suqs * 4. Neither the name of the University nor the names of its contributors 14241675Suqs * may be used to endorse or promote products derived from this software 15241675Suqs * without specific prior written permission. 16241675Suqs * 17241675Suqs * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18241675Suqs * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19241675Suqs * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20241675Suqs * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21241675Suqs * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22241675Suqs * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23241675Suqs * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24241675Suqs * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25241675Suqs * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26241675Suqs * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27241675Suqs * SUCH DAMAGE. 28241675Suqs */ 29241675Suqs 30241675Suqs#include <sys/cdefs.h> 31241675Suqs 32241675Suqs__FBSDID("$FreeBSD: stable/10/usr.bin/wall/ttymsg.c 286269 2015-08-04 03:06:23Z pfg $"); 33241675Suqs 34241675Suqs#ifndef lint 35241675Suqsstatic const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 36241675Suqs#endif 37241675Suqs 38241675Suqs#include <sys/types.h> 39241675Suqs#include <sys/uio.h> 40241675Suqs#include <dirent.h> 41241675Suqs#include <errno.h> 42241675Suqs#include <fcntl.h> 43241675Suqs#include <paths.h> 44241675Suqs#include <signal.h> 45241675Suqs#include <stdio.h> 46241675Suqs#include <string.h> 47241675Suqs#include <stdlib.h> 48241675Suqs#include <unistd.h> 49241675Suqs 50241675Suqs#include "ttymsg.h" 51241675Suqs 52241675Suqs/* 53241675Suqs * Display the contents of a uio structure on a terminal. Used by wall(1), 54241675Suqs * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 55241675Suqs * waiting up to tmout seconds. Returns pointer to error string on unexpected 56241675Suqs * error; string is not newline-terminated. Various "normal" errors are 57241675Suqs * ignored (exclusive-use, lack of permission, etc.). 58241675Suqs */ 59241675Suqsconst char * 60241675Suqsttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout) 61241675Suqs{ 62241675Suqs struct iovec localiov[7]; 63241675Suqs ssize_t left, wret; 64241675Suqs int cnt, fd; 65241675Suqs char device[MAXNAMLEN] = _PATH_DEV; 66241675Suqs static char errbuf[1024]; 67241675Suqs char *p; 68241675Suqs int forked; 69241675Suqs 70241675Suqs forked = 0; 71241675Suqs if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0]))) 72241675Suqs return ("too many iov's (change code in wall/ttymsg.c)"); 73241675Suqs 74241675Suqs strlcat(device, line, sizeof(device)); 75241675Suqs p = device + sizeof(_PATH_DEV) - 1; 76241675Suqs if (strncmp(p, "pts/", 4) == 0) 77241675Suqs p += 4; 78241675Suqs if (strchr(p, '/') != NULL) { 79241675Suqs /* A slash is an attempt to break security... */ 80241675Suqs (void) snprintf(errbuf, sizeof(errbuf), 81241675Suqs "Too many '/' in \"%s\"", device); 82241675Suqs return (errbuf); 83241675Suqs } 84241675Suqs 85241675Suqs /* 86241675Suqs * open will fail on slip lines or exclusive-use lines 87241675Suqs * if not running as root; not an error. 88241675Suqs */ 89241675Suqs if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 90241675Suqs if (errno == EBUSY || errno == EACCES) 91241675Suqs return (NULL); 92241675Suqs (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device, 93241675Suqs strerror(errno)); 94241675Suqs return (errbuf); 95 } 96 97 for (cnt = 0, left = 0; cnt < iovcnt; ++cnt) 98 left += iov[cnt].iov_len; 99 100 for (;;) { 101 wret = writev(fd, iov, iovcnt); 102 if (wret >= left) 103 break; 104 if (wret >= 0) { 105 left -= wret; 106 if (iov != localiov) { 107 bcopy(iov, localiov, 108 iovcnt * sizeof(struct iovec)); 109 iov = localiov; 110 } 111 for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) { 112 wret -= iov->iov_len; 113 ++iov; 114 --iovcnt; 115 } 116 if (wret) { 117 iov->iov_base = (char *)iov->iov_base + wret; 118 iov->iov_len -= wret; 119 } 120 continue; 121 } 122 if (errno == EWOULDBLOCK) { 123 int cpid; 124 125 if (forked) { 126 (void) close(fd); 127 _exit(1); 128 } 129 cpid = fork(); 130 if (cpid < 0) { 131 (void) snprintf(errbuf, sizeof(errbuf), 132 "fork: %s", strerror(errno)); 133 (void) close(fd); 134 return (errbuf); 135 } 136 if (cpid) { /* parent */ 137 (void) close(fd); 138 return (NULL); 139 } 140 forked++; 141 /* wait at most tmout seconds */ 142 (void) signal(SIGALRM, SIG_DFL); 143 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 144 (void) sigsetmask(0); 145 (void) alarm((u_int)tmout); 146 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 147 continue; 148 } 149 /* 150 * We get ENODEV on a slip line if we're running as root, 151 * and EIO if the line just went away. 152 */ 153 if (errno == ENODEV || errno == EIO) 154 break; 155 (void) close(fd); 156 if (forked) 157 _exit(1); 158 (void) snprintf(errbuf, sizeof(errbuf), 159 "%s: %s", device, strerror(errno)); 160 return (errbuf); 161 } 162 163 (void) close(fd); 164 if (forked) 165 _exit(0); 166 return (NULL); 167} 168