1 /* $NetBSD: ttymsg.c,v 1.21 2005/01/08 06:43:16 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. 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 1.21 2005/01/08 06:43:16 christos 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 const char *ptr; 69 int cnt, fd, left, wret; 70 struct iovec localiov[32]; 71 sigset_t nset; 72 int forked = 0; 73 74 _DIAGASSERT(iov != NULL); 75 _DIAGASSERT(iovcnt >= 0); 76 _DIAGASSERT(line != NULL); 77 78 if (iovcnt >= sizeof(localiov) / sizeof(localiov[0])) { 79 (void)snprintf(errbuf, sizeof(errbuf), 80 "%s: too many iov's (%d) max is %zu", __func__, 81 iovcnt, sizeof(localiov) / sizeof(localiov[0])); 82 return errbuf; 83 } 84 85 ptr = strncmp(line, "pts/", 4) == 0 ? line + 4 : line; 86 if (strcspn(ptr, "./") != strlen(ptr)) { 87 /* A slash or dot is an attempt to break security... */ 88 (void)snprintf(errbuf, sizeof(errbuf), 89 "%s: '/' or '.' in \"%s\"", __func__, line); 90 return errbuf; 91 } 92 cnt = snprintf(device, sizeof(device), "%s%s", _PATH_DEV, line); 93 if (cnt == -1 || cnt >= sizeof(device)) { 94 (void) snprintf(errbuf, sizeof(errbuf), 95 "%s: line `%s' too long", __func__, line); 96 return errbuf; 97 } 98 99 /* 100 * open will fail on slip lines or exclusive-use lines 101 * if not running as root; not an error. 102 */ 103 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 104 if (errno == EBUSY || errno == EACCES) 105 return NULL; 106 (void)snprintf(errbuf, sizeof(errbuf), 107 "%s: Cannot open `%s' (%s)", 108 __func__, device, strerror(errno)); 109 return errbuf; 110 } 111 if (!isatty(fd)) { 112 (void)snprintf(errbuf, sizeof(errbuf), 113 "%s: line `%s' is not a tty device", __func__, device); 114 (void)close(fd); 115 return errbuf; 116 } 117 118 for (cnt = left = 0; cnt < iovcnt; ++cnt) 119 left += iov[cnt].iov_len; 120 121 for (;;) { 122 wret = writev(fd, iov, iovcnt); 123 if (wret >= left) 124 break; 125 if (wret > 0) { 126 left -= wret; 127 if (iov != localiov) { 128 (void)memcpy(localiov, iov, 129 iovcnt * sizeof(struct iovec)); 130 iov = localiov; 131 } 132 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 133 wret -= iov->iov_len; 134 ++iov; 135 --iovcnt; 136 } 137 if (wret) { 138 iov->iov_base = 139 (char *)iov->iov_base + wret; 140 iov->iov_len -= wret; 141 } 142 continue; 143 } else if (wret == 0) { 144 (void)snprintf(errbuf, sizeof(errbuf), 145 "%s: failed writing %d bytes to `%s'", __func__, 146 left, device); 147 (void) close(fd); 148 if (forked) 149 _exit(1); 150 return errbuf; 151 } 152 if (errno == EWOULDBLOCK) { 153 pid_t cpid; 154 155 if (forked) { 156 (void)close(fd); 157 _exit(1); 158 } 159 cpid = fork(); 160 if (cpid < 0) { 161 (void)snprintf(errbuf, sizeof(errbuf), 162 "%s: Cannot fork (%s)", __func__, 163 strerror(errno)); 164 (void)close(fd); 165 return errbuf; 166 } 167 if (cpid) { /* parent */ 168 (void)close(fd); 169 return NULL; 170 } 171 forked++; 172 /* wait at most tmout seconds */ 173 (void)signal(SIGALRM, SIG_DFL); 174 (void)signal(SIGTERM, SIG_DFL); /* XXX */ 175 sigfillset(&nset); 176 (void)sigprocmask(SIG_UNBLOCK, &nset, NULL); 177 (void)alarm((u_int)tmout); 178 (void)fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 179 continue; 180 } 181 /* 182 * We get ENODEV on a slip line if we're running as root, 183 * and EIO if the line just went away. 184 */ 185 if (errno == ENODEV || errno == EIO) 186 break; 187 (void) close(fd); 188 if (forked) 189 _exit(1); 190 (void)snprintf(errbuf, sizeof(errbuf), 191 "%s: Write to line `%s' failed (%s)", __func__, 192 device, strerror(errno)); 193 return errbuf; 194 } 195 196 (void) close(fd); 197 if (forked) 198 _exit(0); 199 return NULL; 200 } 201