1/* $NetBSD: ttymsg.c,v 1.22 2005/08/27 17:16:06 elad 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 35static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 36#else 37__RCSID("$NetBSD: ttymsg.c,v 1.22 2005/08/27 17:16:06 elad 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 */ 63char * 64ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout) 65{ 66 static char errbuf[1024]; 67 char device[MAXNAMLEN]; 68 const char *ptr; 69 int fd, ret; 70 struct iovec localiov[32]; 71 sigset_t nset; 72 int forked = 0; 73 size_t cnt, left, wret; 74 75 _DIAGASSERT(iov != NULL); 76 _DIAGASSERT(iovcnt >= 0); 77 _DIAGASSERT(line != NULL); 78 79 if (iovcnt < 0) { 80 (void)snprintf(errbuf, sizeof(errbuf), 81 "%s: negative iovcnt", __func__); 82 return errbuf; 83 } 84 85 if ((size_t)iovcnt >= sizeof(localiov) / sizeof(localiov[0])) { 86 (void)snprintf(errbuf, sizeof(errbuf), 87 "%s: too many iov's (%d) max is %zu", __func__, 88 iovcnt, sizeof(localiov) / sizeof(localiov[0])); 89 return errbuf; 90 } 91 92 ptr = strncmp(line, "pts/", (size_t)4) == 0 ? line + 4 : line; 93 if (strcspn(ptr, "./") != strlen(ptr)) { 94 /* A slash or dot is an attempt to break security... */ 95 (void)snprintf(errbuf, sizeof(errbuf), 96 "%s: '/' or '.' in \"%s\"", __func__, line); 97 return errbuf; 98 } 99 ret = snprintf(device, sizeof(device), "%s%s", _PATH_DEV, line); 100 if (ret == -1 || ret >= (int)sizeof(device)) { 101 (void) snprintf(errbuf, sizeof(errbuf), 102 "%s: line `%s' too long", __func__, line); 103 return errbuf; 104 } 105 cnt = (size_t)ret; 106 107 /* 108 * open will fail on slip lines or exclusive-use lines 109 * if not running as root; not an error. 110 */ 111 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 112 if (errno == EBUSY || errno == EACCES) 113 return NULL; 114 (void)snprintf(errbuf, sizeof(errbuf), 115 "%s: Cannot open `%s' (%s)", 116 __func__, device, strerror(errno)); 117 return errbuf; 118 } 119 if (!isatty(fd)) { 120 (void)snprintf(errbuf, sizeof(errbuf), 121 "%s: line `%s' is not a tty device", __func__, device); 122 (void)close(fd); 123 return errbuf; 124 } 125 126 for (cnt = left = 0; cnt < (size_t)iovcnt; ++cnt) 127 left += iov[cnt].iov_len; 128 129 for (;;) { 130 wret = writev(fd, iov, iovcnt); 131 if (wret >= left) 132 break; 133 if (wret > 0) { 134 left -= wret; 135 if (iov != localiov) { 136 (void)memcpy(localiov, iov, 137 iovcnt * sizeof(struct iovec)); 138 iov = localiov; 139 } 140 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 141 wret -= iov->iov_len; 142 ++iov; 143 --iovcnt; 144 } 145 if (wret) { 146 iov->iov_base = 147 (char *)iov->iov_base + wret; 148 iov->iov_len -= wret; 149 } 150 continue; 151 } else if (wret == 0) { 152 (void)snprintf(errbuf, sizeof(errbuf), 153 "%s: failed writing %zu bytes to `%s'", __func__, 154 left, device); 155 (void) close(fd); 156 if (forked) 157 _exit(1); 158 return errbuf; 159 } 160 if (errno == EWOULDBLOCK) { 161 pid_t cpid; 162 163 if (forked) { 164 (void)close(fd); 165 _exit(1); 166 } 167 cpid = fork(); 168 if (cpid < 0) { 169 (void)snprintf(errbuf, sizeof(errbuf), 170 "%s: Cannot fork (%s)", __func__, 171 strerror(errno)); 172 (void)close(fd); 173 return errbuf; 174 } 175 if (cpid) { /* parent */ 176 (void)close(fd); 177 return NULL; 178 } 179 forked++; 180 /* wait at most tmout seconds */ 181 (void)signal(SIGALRM, SIG_DFL); 182 (void)signal(SIGTERM, SIG_DFL); /* XXX */ 183 sigfillset(&nset); 184 (void)sigprocmask(SIG_UNBLOCK, &nset, NULL); 185 (void)alarm((u_int)tmout); 186 (void)fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 187 continue; 188 } 189 /* 190 * We get ENODEV on a slip line if we're running as root, 191 * and EIO if the line just went away. 192 */ 193 if (errno == ENODEV || errno == EIO) 194 break; 195 (void) close(fd); 196 if (forked) 197 _exit(1); 198 (void)snprintf(errbuf, sizeof(errbuf), 199 "%s: Write to line `%s' failed (%s)", __func__, 200 device, strerror(errno)); 201 return errbuf; 202 } 203 204 (void) close(fd); 205 if (forked) 206 _exit(0); 207 return NULL; 208} 209