1 /* $OpenBSD: uthread_write.c,v 1.10 2003/12/22 00:33:42 brad Exp $ */
2 /*
3 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 * must display the following acknowledgement:
16 * This product includes software developed by John Birrell.
17 * 4. Neither the name of the author nor the names of any co-contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $FreeBSD: uthread_write.c,v 1.12 1999/08/28 00:03:54 peter Exp $
34 *
35 */
36 #include <sys/types.h>
37 #include <sys/fcntl.h>
38 #include <sys/uio.h>
39 #include <errno.h>
40 #include <unistd.h>
41 #ifdef _THREAD_SAFE
42 #include <pthread.h>
43 #include "pthread_private.h"
44
45 ssize_t
write(int fd,const void * buf,size_t nbytes)46 write(int fd, const void *buf, size_t nbytes)
47 {
48 struct pthread *curthread = _get_curthread();
49 int blocking;
50 int type;
51 size_t num = 0;
52 ssize_t n;
53 ssize_t ret;
54
55 /* This is a cancellation point: */
56 _thread_enter_cancellation_point();
57
58 /* POSIX says to do just this: */
59 if (nbytes == 0)
60 ret = 0;
61
62 /* Lock the file descriptor for write: */
63 else if ((ret = _FD_LOCK(fd, FD_WRITE, NULL)) == 0) {
64 /* Get the read/write mode type: */
65 type = _thread_fd_table[fd]->flags & O_ACCMODE;
66
67 /* Check if the file is not open for write: */
68 if (type != O_WRONLY && type != O_RDWR) {
69 /* File is not open for write: */
70 errno = EBADF;
71 ret = -1;
72 }
73
74 else {
75 /* Check if file operations are to block */
76 blocking = ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0);
77
78 /*
79 * Loop while no error occurs and until the expected number
80 * of bytes are written if performing a blocking write:
81 */
82 while (ret == 0) {
83 /* Perform a non-blocking write syscall: */
84 n = _thread_sys_write(fd, (caddr_t)buf + num,
85 nbytes - num);
86
87 /* Check if one or more bytes were written: */
88 if (n > 0)
89 /*
90 * Keep a count of the number of bytes
91 * written:
92 */
93 num += n;
94
95 /*
96 * If performing a blocking write, check if the
97 * write would have blocked or if some bytes
98 * were written but there are still more to
99 * write:
100 */
101 if (blocking && ((n < 0 && (errno == EWOULDBLOCK ||
102 errno == EAGAIN)) || (n > 0 && num < nbytes))) {
103 curthread->data.fd.fd = fd;
104 _thread_kern_set_timeout(NULL);
105
106 /* Reset the interrupted operation flag: */
107 curthread->interrupted = 0;
108
109 _thread_kern_sched_state(PS_FDW_WAIT,
110 __FILE__, __LINE__);
111
112 /*
113 * Check if the operation was
114 * interrupted by a signal
115 */
116 if (curthread->interrupted) {
117 if (num > 0) {
118 /* Return partial success: */
119 ret = num;
120 } else {
121 /* Return an error: */
122 errno = EINTR;
123 ret = -1;
124 }
125 }
126
127 /*
128 * If performing a non-blocking write,
129 * just return whatever the write syscall did:
130 */
131 } else if (!blocking) {
132 /* A non-blocking call might return zero: */
133 ret = n;
134 break;
135
136 /*
137 * If there was an error, return partial success
138 * (if any bytes were written) or else the error:
139 */
140 } else if (n <= 0) {
141 if (num > 0)
142 ret = num;
143 else
144 ret = n;
145 if (n == 0)
146 break;
147
148 /* Check if the write has completed: */
149 } else if (num >= nbytes)
150 /* Return the number of bytes written: */
151 ret = num;
152 }
153 }
154 _FD_UNLOCK(fd, FD_WRITE);
155 }
156
157 /* No longer in a cancellation point: */
158 _thread_leave_cancellation_point();
159
160 return (ret);
161 }
162 #endif
163