thr_write.c revision 50476 
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 AUTHOR 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 * $FreeBSD: head/lib/libkse/thread/thr_write.c 50476 1999-08-28 00:22:10Z peter $
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	type;
49	ssize_t n;
50	ssize_t num = 0;
51	ssize_t	ret;
52
53	/* POSIX says to do just this: */
54	if (nbytes == 0)
55		return (0);
56
57	/* Lock the file descriptor for write: */
58	if ((ret = _FD_LOCK(fd, FD_WRITE, NULL)) == 0) {
59		/* Get the read/write mode type: */
60		type = _thread_fd_table[fd]->flags & O_ACCMODE;
61
62		/* Check if the file is not open for write: */
63		if (type != O_WRONLY && type != O_RDWR) {
64			/* File is not open for write: */
65			errno = EBADF;
66			_FD_UNLOCK(fd, FD_WRITE);
67			return (-1);
68		}
69
70		/* Check if file operations are to block */
71		blocking = ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0);
72
73		/*
74		 * Loop while no error occurs and until the expected number
75		 * of bytes are written if performing a blocking write:
76		 */
77		while (ret == 0) {
78			/* Perform a non-blocking write syscall: */
79			n = _thread_sys_write(fd, buf + num, nbytes - num);
80
81			/* Check if one or more bytes were written: */
82			if (n > 0)
83				/*
84				 * Keep a count of the number of bytes
85				 * written:
86				 */
87				num += n;
88
89			/*
90			 * If performing a blocking write, check if the
91			 * write would have blocked or if some bytes
92			 * were written but there are still more to
93			 * write:
94			 */
95			if (blocking && ((n < 0 && (errno == EWOULDBLOCK ||
96			    errno == EAGAIN)) || (n >= 0 && num < nbytes))) {
97				_thread_run->data.fd.fd = fd;
98				_thread_kern_set_timeout(NULL);
99
100				/* Reset the interrupted operation flag: */
101				_thread_run->interrupted = 0;
102
103				_thread_kern_sched_state(PS_FDW_WAIT,
104				    __FILE__, __LINE__);
105
106				/*
107				 * Check if the operation was
108				 * interrupted by a signal
109				 */
110				if (_thread_run->interrupted) {
111					/* Return an error: */
112					ret = -1;
113				}
114
115			/*
116			 * If performing a non-blocking write or if an
117			 * error occurred, just return whatever the write
118			 * syscall did:
119			 */
120			} else if (!blocking || n < 0) {
121				/* A non-blocking call might return zero: */
122				ret = n;
123				break;
124
125			/* Check if the write has completed: */
126			} else if (num >= nbytes)
127				/* Return the number of bytes written: */
128				ret = num;
129		}
130		_FD_UNLOCK(fd, FD_RDWR);
131	}
132	return (ret);
133}
134#endif
135