/* $NetBSD: ttymsg.c,v 1.23 2009/01/18 12:13:04 lukem Exp $ */
/*
* Copyright (c) 1989, 1993
* 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. 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.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93";
#else
__RCSID("$NetBSD: ttymsg.c,v 1.23 2009/01/18 12:13:04 lukem Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <sys/uio.h>
#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>
/*
* Display the contents of a uio structure on a terminal. Used by wall(1),
* syslogd(8), and talkd(8). Forks and finishes in child if write would block,
* waiting up to tmout seconds. 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(struct iovec *iov, int iovcnt, const char *line, int tmout)
{
static char errbuf[1024];
char device[MAXNAMLEN];
const char *ptr;
int fd, ret;
struct iovec localiov[32];
sigset_t nset;
int forked = 0;
size_t cnt, left, wret;
_DIAGASSERT(iov != NULL);
_DIAGASSERT(iovcnt >= 0);
_DIAGASSERT(line != NULL);
if (iovcnt < 0) {
(void)snprintf(errbuf, sizeof(errbuf),
"%s: negative iovcnt", __func__);
return errbuf;
}
if ((size_t)iovcnt >= sizeof(localiov) / sizeof(localiov[0])) {
(void)snprintf(errbuf, sizeof(errbuf),
"%s: too many iov's (%d) max is %zu", __func__,
iovcnt, sizeof(localiov) / sizeof(localiov[0]));
return errbuf;
}
ptr = strncmp(line, "pts/", (size_t)4) == 0 ? line + 4 : line;
if (strcspn(ptr, "./") != strlen(ptr)) {
/* A slash or dot is an attempt to break security... */
(void)snprintf(errbuf, sizeof(errbuf),
"%s: '/' or '.' in \"%s\"", __func__, line);
return errbuf;
}
ret = snprintf(device, sizeof(device), "%s%s", _PATH_DEV, line);
if (ret == -1 || ret >= (int)sizeof(device)) {
(void) snprintf(errbuf, sizeof(errbuf),
"%s: line `%s' too long", __func__, line);
return errbuf;
}
cnt = (size_t)ret;
/*
* open will fail on slip lines or exclusive-use lines
* if not running as root; not an error.
*/
if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
if (errno == EBUSY || errno == EACCES)
return NULL;
(void)snprintf(errbuf, sizeof(errbuf),
"%s: Cannot open `%s' (%s)",
__func__, device, strerror(errno));
return errbuf;
}
if (!isatty(fd)) {
(void)snprintf(errbuf, sizeof(errbuf),
"%s: line `%s' is not a tty device", __func__, device);
(void)close(fd);
return errbuf;
}
for (cnt = left = 0; cnt < (size_t)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) {
(void)memcpy(localiov, iov,
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 =
(char *)iov->iov_base + wret;
iov->iov_len -= wret;
}
continue;
} else if (wret == 0) {
(void)snprintf(errbuf, sizeof(errbuf),
"%s: failed writing %zu bytes to `%s'", __func__,
left, device);
(void) close(fd);
if (forked)
_exit(1);
return errbuf;
}
if (errno == EWOULDBLOCK) {
pid_t cpid;
if (forked) {
(void)close(fd);
_exit(1);
}
cpid = fork();
if (cpid < 0) {
(void)snprintf(errbuf, sizeof(errbuf),
"%s: Cannot fork (%s)", __func__,
strerror(errno));
(void)close(fd);
return errbuf;
}
if (cpid) { /* parent */
(void)close(fd);
return NULL;
}
forked++;
/* wait at most tmout seconds */
(void)signal(SIGALRM, SIG_DFL);
(void)signal(SIGTERM, SIG_DFL); /* XXX */
sigfillset(&nset);
(void)sigprocmask(SIG_UNBLOCK, &nset, NULL);
(void)alarm((u_int)tmout);
(void)fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */
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: Write to line `%s' failed (%s)", __func__,
device, strerror(errno));
return errbuf;
}
(void) close(fd);
if (forked)
_exit(0);
return NULL;
}
