term-utils/ttymsg.c

   1 /*
   2  * Copyright (c) 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * Modified Sun Mar 12 10:39:22 1995, faith@cs.unc.edu for Linux
  34  *
  35  */
  36
  37  /* 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
  38   * - added Native Language Support
  39   * Sun Mar 21 1999 - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  40   * - fixed strerr(errno) in gettext calls
  41   */
  42
  43 #include <sys/types.h>
  44 #include <sys/param.h>
  45 #include <sys/uio.h>
  46 #include <signal.h>
  47 #include <fcntl.h>
  48 #include <dirent.h>
  49 #include <errno.h>
  50 #include <paths.h>
  51 #include <unistd.h>
  52 #include <stdio.h>
  53 #include <string.h>
  54 #include <stdlib.h>
  55
  56 #include "nls.h"
  57 #include "closestream.h"
  58 #include "pathnames.h"
  59 #include "ttymsg.h"
  60
  61 #define ERR_BUFLEN      (MAXNAMLEN + 1024)
  62
  63 /*
  64  * Display the contents of a uio structure on a terminal.  Used by wall(1),
  65  * syslogd(8), and talkd(8).  Forks and finishes in child if write would block,
  66  * waiting up to tmout seconds.  Returns pointer to error string on unexpected
  67  * error; string is not newline-terminated.  Various "normal" errors are
  68  * ignored (exclusive-use, lack of permission, etc.).
  69  */
  70 char *
  71 ttymsg(struct iovec *iov, size_t iovcnt, char *line, int tmout) {
  72         static char device[MAXNAMLEN];
  73         static char errbuf[ERR_BUFLEN];
  74         size_t cnt, left;
  75         ssize_t wret;
  76         struct iovec localiov[6];
  77         int fd, forked = 0;
  78         ssize_t len = 0;
  79
  80         if (iovcnt > ARRAY_SIZE(localiov)) {
  81                 snprintf(errbuf, sizeof(errbuf), _("internal error: too many iov's"));
  82                 return errbuf;
  83         }
  84
  85         /* The old code here rejected the line argument when it contained a '/',
  86            saying: "A slash may be an attempt to break security...".
  87            However, if a user can control the line argument here
  88            then he can make this routine write to /dev/hda or /dev/sda
  89            already. So, this test was worthless, and these days it is
  90            also wrong since people use /dev/pts/xxx. */
  91
  92         len = snprintf(device, sizeof(device), "%s%s", _PATH_DEV, line);
  93         if (len < 0 || (size_t)len >= sizeof(device)) {
  94                 snprintf(errbuf, sizeof(errbuf), _("excessively long line arg"));
  95                 return errbuf;
  96         }
  97
  98         /*
  99          * open will fail on slip lines or exclusive-use lines
 100          * if not running as root; not an error.
 101          */
 102         if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
 103                 if (errno == EBUSY || errno == EACCES)
 104                         return NULL;
 105
 106                 len = snprintf(errbuf, sizeof(errbuf), "%s: %m", device);
 107                 if (len < 0 || (size_t)len >= sizeof(errbuf))
 108                         snprintf(errbuf, sizeof(errbuf), _("open failed"));
 109                 return errbuf;
 110         }
 111
 112         for (cnt = left = 0; cnt < iovcnt; ++cnt)
 113                 left += iov[cnt].iov_len;
 114
 115         for (;;) {
 116                 wret = writev(fd, iov, iovcnt);
 117                 if (wret >= (ssize_t) left)
 118                         break;
 119                 if (wret >= 0) {
 120                         left -= wret;
 121                         if (iov != localiov) {
 122                                 memmove(localiov, iov,
 123                                     iovcnt * sizeof(struct iovec));
 124                                 iov = localiov;
 125                         }
 126                         for (cnt = 0; wret >= (ssize_t) iov->iov_len; ++cnt) {
 127                                 wret -= iov->iov_len;
 128                                 ++iov;
 129                                 --iovcnt;
 130                         }
 131                         if (wret) {
 132                                 iov->iov_base = (char *) iov->iov_base + wret;
 133                                 iov->iov_len -= wret;
 134                         }
 135                         continue;
 136                 }
 137                 if (errno == EWOULDBLOCK) {
 138                         int cpid, flags;
 139                         sigset_t sigmask;
 140
 141                         if (forked) {
 142                                 close(fd);
 143                                 _exit(EXIT_FAILURE);
 144                         }
 145                         cpid = fork();
 146                         if (cpid < 0) {
 147                                 len = snprintf(errbuf, sizeof(errbuf), _("fork: %m"));
 148                                 if (len < 0 || (size_t)len >= sizeof(errbuf))
 149                                         snprintf(errbuf, sizeof(errbuf), _("cannot fork"));
 150                                 close(fd);
 151                                 return errbuf;
 152                         }
 153                         if (cpid) {     /* parent */
 154                                 close(fd);
 155                                 return NULL;
 156                         }
 157                         forked++;
 158                         /* wait at most tmout seconds */
 159                         signal(SIGALRM, SIG_DFL);
 160                         signal(SIGTERM, SIG_DFL); /* XXX */
 161                         sigemptyset(&sigmask);
 162                         sigprocmask (SIG_SETMASK, &sigmask, NULL);
 163                         alarm((u_int)tmout);
 164                         flags = fcntl(fd, F_GETFL);
 165                         fcntl(flags, F_SETFL, (long) (flags & ~O_NONBLOCK));
 166                         continue;
 167                 }
 168                 /*
 169                  * We get ENODEV on a slip line if we're running as root,
 170                  * and EIO if the line just went away.
 171                  */
 172                 if (errno == ENODEV || errno == EIO)
 173                         break;
 174                 if (close_fd(fd) != 0)
 175                         warn(_("write failed: %s"), device);
 176                 if (forked)
 177                         _exit(EXIT_FAILURE);
 178
 179                 len = snprintf(errbuf, sizeof(errbuf), "%s: %m", device);
 180                 if (len < 0 || (size_t)len >= sizeof(errbuf))
 181                         snprintf(errbuf, sizeof(errbuf),
 182                                         _("%s: BAD ERROR, message is "
 183                                           "far too long"), device);
 184                 return errbuf;
 185         }
 186
 187         if (forked)
 188                 _exit(EXIT_SUCCESS);
 189         return NULL;
 190 }