freebsd-skq/lib/libc_r/uthread/uthread_close.c
deischen 8347fcb52d Remove much of the dereferencing of the fd table entries to look
at file flags and replace it with functions that will avoid null
pointer checks.

MFC to be done by archie ;-)

PR:		42100
Reviewed by:	archie, robert
MFC after:	3 days
2002-08-29 23:06:07 +00:00

116 lines
3.9 KiB
C

/*
* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
* 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 John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <pthread.h>
#include "pthread_private.h"
__weak_reference(__close, close);
int
_close(int fd)
{
int flags;
int ret;
struct stat sb;
struct fd_table_entry *entry;
if ((fd == _thread_kern_pipe[0]) || (fd == _thread_kern_pipe[1])) {
/*
* Don't allow silly programs to close the kernel pipe.
*/
errno = EBADF;
ret = -1;
}
/*
* Lock the file descriptor while the file is closed and get
* the file descriptor status:
*/
else if (((ret = _FD_LOCK(fd, FD_RDWR, NULL)) == 0) &&
((ret = __sys_fstat(fd, &sb)) == 0)) {
/*
* Check if the file should be left as blocking.
*
* This is so that the file descriptors shared with a parent
* process aren't left set to non-blocking if the child
* closes them prior to exit. An example where this causes
* problems with /bin/sh is when a child closes stdin.
*
* Setting a file as blocking causes problems if a threaded
* parent accesses the file descriptor before the child exits.
* Once the threaded parent receives a SIGCHLD then it resets
* all of its files to non-blocking, and so it is then safe
* to access them.
*
* Pipes are not set to blocking when they are closed, as
* the parent and child will normally close the file
* descriptor of the end of the pipe that they are not
* using, which would then cause any reads to block
* indefinitely.
*/
if ((S_ISREG(sb.st_mode) || S_ISCHR(sb.st_mode))
&& (_thread_fd_getflags(fd) & O_NONBLOCK) == 0) {
/* Get the current flags: */
flags = __sys_fcntl(fd, F_GETFL, NULL);
/* Clear the nonblocking file descriptor flag: */
__sys_fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
}
/* XXX: Assumes well behaved threads. */
/* XXX: Defer real close to avoid race condition */
entry = _thread_fd_table[fd];
_thread_fd_table[fd] = NULL;
free(entry);
/* Close the file descriptor: */
ret = __sys_close(fd);
}
return (ret);
}
int
__close(int fd)
{
int ret;
_thread_enter_cancellation_point();
ret = _close(fd);
_thread_leave_cancellation_point();
return ret;
}