freebsd-skq/usr.bin/window/wwspawn.c
joerg 1288f941f7 Make window(1) actually work again. It has been broken for quite some
time now.

For whatever reason, the kernel seems to have generated SIGIOs
previously without an initial fcntl(...,F_SETOWN), but does no longer.
This caused window(1) to wait indefinitely for input.

Also, undo rev 1.3 of wwspawn.c, it was not well-thought, and
apparently not even tested at all.  The blindly (even in a nonsensical
place like the comment on top of the function) applied replacement of
vfork() by fork() totally ignored that window(1) *does* abuse the
feature of vfork() where a modification of the parent's address space
is possible (in this case, to notify the parent of an erred exec*).
Also, with vfork(), it is guaranteed that the parent is only woken up
after the exec*() happened, where the replacement by fork() made the
parent to almost always become runnable again before the child, in
which case the parent simply told `subprocess died'.  Unfortunately,
working around _this_ seems to be a lot more of redesign work compared
to little gained value, so i think relying on the specifics of vfork()
is the simpler way.

Submitted by:	Philipp Mergenthaler <un1i@rz.uni-karlsruhe.de>
1999-03-02 19:08:09 +00:00

86 lines
2.7 KiB
C

/*
* Copyright (c) 1983, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Edward Wang at The University of California, Berkeley.
*
* 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
static char sccsid[] = "@(#)wwspawn.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
#include "ww.h"
#include <signal.h>
/*
* There is a dead lock with vfork and closing of pseudo-ports.
* So we have to be sneaky about error reporting.
*/
wwspawn(wp, file, argv)
register struct ww *wp;
char *file;
char **argv;
{
int pid;
int ret;
char erred = 0;
int s;
s = sigblock(sigmask(SIGCHLD));
switch (pid = vfork()) {
case -1:
wwerrno = WWE_SYS;
ret = -1;
break;
case 0:
if (wwenviron(wp) >= 0)
execvp(file, argv);
erred = 1;
_exit(1);
default:
if (erred) {
wwerrno = WWE_SYS;
ret = -1;
} else {
wp->ww_pid = pid;
wp->ww_state = WWS_HASPROC;
ret = pid;
}
}
(void) sigsetmask(s);
if (wp->ww_socket >= 0) {
(void) close(wp->ww_socket);
wp->ww_socket = -1;
}
return ret;
}