1 /* $OpenBSD: atomicio.c,v 1.9 2007/09/07 14:50:44 tobias Exp $ */
2 
3 /*
4  * Copyright (c) 2006 Damien Miller. All rights reserved.
5  * Copyright (c) 2005 Anil Madhavapeddy. All rights reserved.
6  * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 #include <sys/param.h>
33 
34 #include <errno.h>
35 #include <poll.h>
36 #include <unistd.h>
37 
38 #include "atomicio.h"
39 
40 /*
41  * ensure all of data on socket comes through. f==read || f==vwrite
42  */
43 size_t
atomicio(ssize_t (* f)(int,void *,size_t),int fd,void * _s,size_t n)44 atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
45 {
46 	char *s = _s;
47 	size_t pos = 0;
48 	ssize_t res;
49 	struct pollfd pfd;
50 
51 	pfd.fd = fd;
52 	pfd.events = f == read ? POLLIN : POLLOUT;
53 	while (n > pos) {
54 		res = (f) (fd, s + pos, n - pos);
55 		switch (res) {
56 		case -1:
57 			if (errno == EINTR)
58 				continue;
59 			if (errno == EAGAIN) {
60 				(void) poll(&pfd, 1, -1);
61 				continue;
62 			}
63 			return (0);
64 		case 0:
65 			errno = EPIPE;
66 			return (pos);
67 		default:
68 			pos += (size_t)res;
69 		}
70 	}
71 	return (pos);
72 }
73