atomicio.c revision 181111 
1/* $OpenBSD: atomicio.c,v 1.25 2007/06/25 12:02:27 dtucker 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 "includes.h"
30
31#include <sys/param.h>
32#include <sys/uio.h>
33
34#include <errno.h>
35#ifdef HAVE_POLL_H
36#include <poll.h>
37#else
38# ifdef HAVE_SYS_POLL_H
39#  include <sys/poll.h>
40# endif
41#endif
42#include <string.h>
43#include <unistd.h>
44
45#include "atomicio.h"
46
47/*
48 * ensure all of data on socket comes through. f==read || f==vwrite
49 */
50size_t
51atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
52{
53	char *s = _s;
54	size_t pos = 0;
55	ssize_t res;
56	struct pollfd pfd;
57
58	pfd.fd = fd;
59	pfd.events = f == read ? POLLIN : POLLOUT;
60	while (n > pos) {
61		res = (f) (fd, s + pos, n - pos);
62		switch (res) {
63		case -1:
64			if (errno == EINTR)
65				continue;
66			if (errno == EAGAIN || errno == EWOULDBLOCK) {
67				(void)poll(&pfd, 1, -1);
68				continue;
69			}
70			return 0;
71		case 0:
72			errno = EPIPE;
73			return pos;
74		default:
75			pos += (size_t)res;
76		}
77	}
78	return (pos);
79}
80
81/*
82 * ensure all of data on socket comes through. f==readv || f==writev
83 */
84size_t
85atomiciov(ssize_t (*f) (int, const struct iovec *, int), int fd,
86    const struct iovec *_iov, int iovcnt)
87{
88	size_t pos = 0, rem;
89	ssize_t res;
90	struct iovec iov_array[IOV_MAX], *iov = iov_array;
91	struct pollfd pfd;
92
93	if (iovcnt > IOV_MAX) {
94		errno = EINVAL;
95		return 0;
96	}
97	/* Make a copy of the iov array because we may modify it below */
98	memcpy(iov, _iov, iovcnt * sizeof(*_iov));
99
100#ifndef BROKEN_READV_COMPARISON
101	pfd.fd = fd;
102	pfd.events = f == readv ? POLLIN : POLLOUT;
103#endif
104	for (; iovcnt > 0 && iov[0].iov_len > 0;) {
105		res = (f) (fd, iov, iovcnt);
106		switch (res) {
107		case -1:
108			if (errno == EINTR)
109				continue;
110			if (errno == EAGAIN || errno == EWOULDBLOCK) {
111#ifndef BROKEN_READV_COMPARISON
112				(void)poll(&pfd, 1, -1);
113#endif
114				continue;
115			}
116			return 0;
117		case 0:
118			errno = EPIPE;
119			return pos;
120		default:
121			rem = (size_t)res;
122			pos += rem;
123			/* skip completed iov entries */
124			while (iovcnt > 0 && rem >= iov[0].iov_len) {
125				rem -= iov[0].iov_len;
126				iov++;
127				iovcnt--;
128			}
129			/* This shouldn't happen... */
130			if (rem > 0 && (iovcnt <= 0 || rem > iov[0].iov_len)) {
131				errno = EFAULT;
132				return 0;
133			}
134			if (iovcnt == 0)
135				break;
136			/* update pointer in partially complete iov */
137			iov[0].iov_base = ((char *)iov[0].iov_base) + rem;
138			iov[0].iov_len -= rem;
139		}
140	}
141	return pos;
142}
143