thr_close.c revision 48046 
1/*
2 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
3 * 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 John Birrell.
16 * 4. Neither the name of the author nor the names of any co-contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $Id$
33 */
34#include <errno.h>
35#include <stdlib.h>
36#include <unistd.h>
37#include <fcntl.h>
38#include <sys/stat.h>
39#ifdef _THREAD_SAFE
40#include <pthread.h>
41#include "pthread_private.h"
42
43int
44close(int fd)
45{
46	int		flags;
47	int		ret;
48	int		status;
49	struct stat	sb;
50	struct fd_table_entry	*entry;
51
52	if ((fd == _thread_kern_pipe[0]) || (fd == _thread_kern_pipe[1])) {
53		/*
54		 * Don't allow silly programs to close the kernel pipe.
55		 */
56		errno = EBADF;
57		ret = -1;
58	}
59	/*
60	 * Lock the file descriptor while the file is closed and get
61	 * the file descriptor status:
62	 */
63	else if (((ret = _FD_LOCK(fd, FD_RDWR, NULL)) == 0) &&
64	    ((ret = _thread_sys_fstat(fd, &sb)) == 0)) {
65		/*
66		 * Check if the file should be left as blocking.
67		 *
68		 * This is so that the file descriptors shared with a parent
69		 * process aren't left set to non-blocking if the child
70		 * closes them prior to exit.  An example where this causes
71		 * problems with /bin/sh is when a child closes stdin.
72		 *
73		 * Setting a file as blocking causes problems if a threaded
74		 * parent accesses the file descriptor before the child exits.
75		 * Once the threaded parent receives a SIGCHLD then it resets
76		 * all of its files to non-blocking, and so it is then safe
77		 * to access them.
78		 *
79		 * Pipes are not set to blocking when they are closed, as
80		 * the parent and child will normally close the file
81		 * descriptor of the end of the pipe that they are not
82		 * using, which would then cause any reads to block
83		 * indefinitely.
84		 */
85		if ((S_ISREG(sb.st_mode) || S_ISCHR(sb.st_mode)) && (_thread_fd_table[fd]->flags & O_NONBLOCK) == 0) {
86			/* Get the current flags: */
87			flags = _thread_sys_fcntl(fd, F_GETFL, NULL);
88			/* Clear the nonblocking file descriptor flag: */
89			_thread_sys_fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
90		}
91
92		/* XXX: Assumes well behaved threads. */
93		/* XXX: Defer real close to avoid race condition */
94		entry = _thread_fd_table[fd];
95		_thread_fd_table[fd] = NULL;
96		free(entry);
97
98		/* Close the file descriptor: */
99		ret = _thread_sys_close(fd);
100	}
101	return (ret);
102}
103#endif
104