1/* $OpenBSD: atomicio.c,v 1.11 2012/12/04 02:24:47 deraadt Exp $ */
2/*
3 * Copyright (c) 2006 Damien Miller. All rights reserved.
4 * Copyright (c) 2005 Anil Madhavapeddy. All rights reserved.
5 * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <errno.h>
30#include <poll.h>
31#include <unistd.h>
32
33#include "atomicio.h"
34
35/*
36 * ensure all of data on socket comes through. f==read || f==vwrite
37 */
38size_t
39atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
40{
41	char *s = _s;
42	size_t pos = 0;
43	ssize_t res;
44	struct pollfd pfd;
45
46	pfd.fd = fd;
47	pfd.events = f == read ? POLLIN : POLLOUT;
48	while (n > pos) {
49		res = (f) (fd, s + pos, n - pos);
50		switch (res) {
51		case -1:
52			if (errno == EINTR)
53				continue;
54			if ((errno == EAGAIN) || (errno == ENOBUFS)) {
55				(void)poll(&pfd, 1, -1);
56				continue;
57			}
58			return 0;
59		case 0:
60			errno = EPIPE;
61			return pos;
62		default:
63			pos += (size_t)res;
64		}
65	}
66	return (pos);
67}
68