wall.tproj/ttymsg.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.0 (the 'License').  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License."
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * Copyright (c) 1989, 1993
  26  *      The Regents of the University of California.  All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  * 3. All advertising materials mentioning features or use of this software
  37  *    must display the following acknowledgement:
  38  *      This product includes software developed by the University of
  39  *      California, Berkeley and its contributors.
  40  * 4. Neither the name of the University nor the names of its contributors
  41  *    may be used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  */
  56
  57
  58 #include <sys/types.h>
  59 #include <sys/uio.h>
  60 #include <signal.h>
  61 #include <fcntl.h>
  62 #include <dirent.h>
  63 #include <errno.h>
  64 #include <paths.h>
  65 #include <unistd.h>
  66 #include <stdio.h>
  67 #include <string.h>
  68 #include <stdlib.h>
  69
  70 /*
  71  * Display the contents of a uio structure on a terminal.  Used by wall(1),
  72  * syslogd(8), and talkd(8).  Forks and finishes in child if write would block,
  73  * waiting up to tmout seconds.  Returns pointer to error string on unexpected
  74  * error; string is not newline-terminated.  Various "normal" errors are
  75  * ignored (exclusive-use, lack of permission, etc.).
  76  */
  77 char *
  78 ttymsg(iov, iovcnt, line, tmout)
  79         struct iovec *iov;
  80         int iovcnt;
  81         char *line;
  82         int tmout;
  83 {
  84         static char device[MAXNAMLEN] = _PATH_DEV;
  85         static char errbuf[1024];
  86         register int cnt, fd, left, wret;
  87         struct iovec localiov[6];
  88         int forked = 0;
  89
  90         if (iovcnt > sizeof(localiov) / sizeof(localiov[0]))
  91                 return ("too many iov's (change code in wall/ttymsg.c)");
  92
  93         (void) strcpy(device + sizeof(_PATH_DEV) - 1, line);
  94         if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) {
  95                 /* A slash is an attempt to break security... */
  96                 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"",
  97                     device);
  98                 return (errbuf);
  99         }
 100
 101         /*
 102          * open will fail on slip lines or exclusive-use lines
 103          * if not running as root; not an error.
 104          */
 105         if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
 106                 if (errno == EBUSY || errno == EACCES)
 107                         return (NULL);
 108                 (void) snprintf(errbuf, sizeof(errbuf),
 109                     "%s: %s", device, strerror(errno));
 110                 return (errbuf);
 111         }
 112
 113         for (cnt = left = 0; cnt < iovcnt; ++cnt)
 114                 left += iov[cnt].iov_len;
 115
 116         for (;;) {
 117                 wret = writev(fd, iov, iovcnt);
 118                 if (wret >= left)
 119                         break;
 120                 if (wret >= 0) {
 121                         left -= wret;
 122                         if (iov != localiov) {
 123                                 bcopy(iov, localiov,
 124                                     iovcnt * sizeof(struct iovec));
 125                                 iov = localiov;
 126                         }
 127                         for (cnt = 0; wret >= iov->iov_len; ++cnt) {
 128                                 wret -= iov->iov_len;
 129                                 ++iov;
 130                                 --iovcnt;
 131                         }
 132                         if (wret) {
 133                                 iov->iov_base += wret;
 134                                 iov->iov_len -= wret;
 135                         }
 136                         continue;
 137                 }
 138                 if (errno == EWOULDBLOCK) {
 139                         int cpid, off = 0;
 140
 141                         if (forked) {
 142                                 (void) close(fd);
 143                                 _exit(1);
 144                         }
 145                         cpid = fork();
 146                         if (cpid < 0) {
 147                                 (void) snprintf(errbuf, sizeof(errbuf),
 148                                     "fork: %s", strerror(errno));
 149                                 (void) close(fd);
 150                                 return (errbuf);
 151                         }
 152                         if (cpid) {     /* parent */
 153                                 (void) close(fd);
 154                                 return (NULL);
 155                         }
 156                         forked++;
 157                         /* wait at most tmout seconds */
 158                         (void) signal(SIGALRM, SIG_DFL);
 159                         (void) signal(SIGTERM, SIG_DFL); /* XXX */
 160                         (void) sigsetmask(0);
 161                         (void) alarm((u_int)tmout);
 162                         (void) fcntl(fd, O_NONBLOCK, &off);
 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 }