thr_write.c revision 36382 
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: uthread_write.c,v 1.5 1998/04/29 09:59:33 jb Exp $
33 *
34 */
35#include <sys/types.h>
36#include <sys/fcntl.h>
37#include <sys/uio.h>
38#include <errno.h>
39#include <unistd.h>
40#ifdef _THREAD_SAFE
41#include <pthread.h>
42#include "pthread_private.h"
43
44ssize_t
45write(int fd, const void *buf, size_t nbytes)
46{
47	int	blocking;
48	int	status;
49	ssize_t n;
50	ssize_t num = 0;
51	ssize_t	ret;
52
53	/* Lock the file descriptor for write: */
54	if ((ret = _thread_fd_lock(fd, FD_WRITE, NULL,
55	    __FILE__, __LINE__)) == 0) {
56		/* Check if file operations are to block */
57		blocking = ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0);
58
59		/*
60		 * Loop while no error occurs and until the expected number
61		 * of bytes are written if performing a blocking write:
62		 */
63		while (ret == 0) {
64			/* Perform a non-blocking write syscall: */
65			n = _thread_sys_write(fd, buf + num, nbytes - num);
66
67			/* Check if one or more bytes were written: */
68			if (n > 0)
69				/*
70				 * Keep a count of the number of bytes
71				 * written:
72				 */
73				num += n;
74
75			/*
76			 * If performing a blocking write, check if the
77			 * write would have blocked or if some bytes
78			 * were written but there are still more to
79			 * write:
80			 */
81			if (blocking && ((n < 0 && (errno == EWOULDBLOCK ||
82			    errno == EAGAIN)) || num < nbytes)) {
83				_thread_run->data.fd.fd = fd;
84				_thread_kern_set_timeout(NULL);
85
86				/* Reset the interrupted operation flag: */
87				_thread_run->interrupted = 0;
88
89				_thread_kern_sched_state(PS_FDW_WAIT,
90				    __FILE__, __LINE__);
91
92				/*
93				 * Check if the operation was
94				 * interrupted by a signal
95				 */
96				if (_thread_run->interrupted) {
97					/* Return an error: */
98					ret = -1;
99				}
100
101			/*
102			 * If performing a non-blocking write or if an
103			 * error occurred, just return whatever the write
104			 * syscall did:
105			 */
106			} else if (!blocking || n < 0) {
107				/* A non-blocking call might return zero: */
108				ret = n;
109				break;
110
111			/* Check if the write has completed: */
112			} else if (num >= nbytes)
113				/* Return the number of bytes written: */
114				ret = num;
115		}
116		_thread_fd_unlock(fd, FD_RDWR);
117	}
118	return (ret);
119}
120#endif
121