NetBSD/lib/libutil/ttymsg.c

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1993-03-21 12:45:37 +03:00
/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
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/*static char sccsid[] = "from: @(#)ttymsg.c 5.8 (Berkeley) 7/1/91";*/
static char rcsid[] = "$Id: ttymsg.c,v 1.2 1993/08/01 18:03:09 mycroft Exp $";
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#endif /* not lint */
#include <sys/types.h>
#include <sys/uio.h>
#include <signal.h>
#include <fcntl.h>
#include <dirent.h>
#include <errno.h>
#include <paths.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
/*
* Display the contents of a uio structure on a terminal. Used by wall(1)
* and syslogd(8). Forks and finishes in child if write would block, waiting
* at most five minutes. Returns pointer to error string on unexpected error;
* string is not newline-terminated. Various "normal" errors are ignored
* (exclusive-use, lack of permission, etc.).
*/
char *
ttymsg(iov, iovcnt, line)
struct iovec *iov;
int iovcnt;
char *line;
{
static char device[MAXNAMLEN] = _PATH_DEV;
static char errbuf[1024];
register int cnt, fd, left, wret;
struct iovec localiov[6];
int forked = 0;
if (iovcnt > 6)
return ("too many iov's (change code in wall/ttymsg.c)");
/*
* open will fail on slip lines or exclusive-use lines
* if not running as root; not an error.
*/
(void) strcpy(device + sizeof(_PATH_DEV) - 1, line);
if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
if (errno == EBUSY || errno == EACCES)
return (NULL);
(void) snprintf(errbuf, sizeof(errbuf),
"%s: %s", device, strerror(errno));
return (errbuf);
}
for (cnt = left = 0; cnt < iovcnt; ++cnt)
left += iov[cnt].iov_len;
for (;;) {
wret = writev(fd, iov, iovcnt);
if (wret >= left)
break;
if (wret >= 0) {
left -= wret;
if (iov != localiov) {
bcopy(iov, localiov,
iovcnt * sizeof(struct iovec));
iov = localiov;
}
for (cnt = 0; wret >= iov->iov_len; ++cnt) {
wret -= iov->iov_len;
++iov;
--iovcnt;
}
if (wret) {
iov->iov_base += wret;
iov->iov_len -= wret;
}
continue;
}
if (errno == EWOULDBLOCK) {
int cpid, off = 0;
if (forked) {
(void) close(fd);
_exit(1);
}
cpid = fork();
if (cpid < 0) {
(void) snprintf(errbuf, sizeof(errbuf),
"fork: %s", strerror(errno));
(void) close(fd);
return (errbuf);
}
if (cpid) { /* parent */
(void) close(fd);
return (NULL);
}
forked++;
/* wait at most 5 minutes */
(void) signal(SIGALRM, SIG_DFL);
(void) signal(SIGTERM, SIG_DFL); /* XXX */
(void) sigsetmask(0);
(void) alarm((u_int)(60 * 5));
(void) fcntl(fd, O_NONBLOCK, &off);
continue;
}
/*
* We get ENODEV on a slip line if we're running as root,
* and EIO if the line just went away.
*/
if (errno == ENODEV || errno == EIO)
break;
(void) close(fd);
if (forked)
_exit(1);
(void) snprintf(errbuf, sizeof(errbuf),
"%s: %s", device, strerror(errno));
return (errbuf);
}
(void) close(fd);
if (forked)
_exit(0);
return (NULL);
}