thr_close.c revision 17706 
1/*
2 * Copyright (c) 1995 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 */
33#include <stdlib.h>
34#include <unistd.h>
35#include <fcntl.h>
36#include <sys/stat.h>
37#ifdef _THREAD_SAFE
38#include <pthread.h>
39#include "pthread_private.h"
40
41int
42close(int fd)
43{
44	int		flags;
45	int		ret;
46	int		status;
47	struct stat	sb;
48
49	/* Lock the file descriptor while the file is closed: */
50	if ((ret = _thread_fd_lock(fd, FD_RDWR, NULL, __FILE__, __LINE__)) == 0) {
51		/* Block signals: */
52		_thread_kern_sig_block(&status);
53
54		/* Get file descriptor status. */
55		fstat(fd, &sb);
56
57		/*
58		 * Check if the file should be left as blocking.
59		 *
60		 * This is so that the file descriptors shared with a parent
61		 * process aren't left set to non-blocking if the child
62		 * closes them prior to exit.  An example where this causes
63		 * problems with /bin/sh is when a child closes stdin.
64		 *
65		 * Setting a file as blocking causes problems if a threaded
66		 * parent accesses the file descriptor before the child exits.
67		 * Once the threaded parent receives a SIGCHLD then it resets
68		 * all of its files to non-blocking, and so it is then safe
69		 * to access them.
70		 *
71		 * Pipes are not set to blocking when they are closed, as
72		 * the parent and child will normally close the file
73		 * descriptor of the end of the pipe that they are not
74		 * using, which would then cause any reads to block
75		 * indefinitely.
76		 */
77		if ((S_ISREG(sb.st_mode) || S_ISCHR(sb.st_mode)) && (_thread_fd_table[fd]->flags & O_NONBLOCK) == 0) {
78			/* Get the current flags: */
79			flags = _thread_sys_fcntl(fd, F_GETFL, NULL);
80			/* Clear the nonblocking file descriptor flag: */
81			_thread_sys_fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
82		}
83
84		/* Close the file descriptor: */
85		ret = _thread_sys_close(fd);
86
87		/* Free the file descriptor table entry: */
88		free(_thread_fd_table[fd]);
89		_thread_fd_table[fd] = NULL;
90
91		/* Unblock signals again: */
92		_thread_kern_sig_unblock(status);
93	}
94	return (ret);
95}
96#endif
97