xref: /openssh-portable/atomicio.c (revision 258e6ca0)
1 /* $OpenBSD: atomicio.c,v 1.30 2019/01/24 02:42:23 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 #include <limits.h>
45 
46 #include "atomicio.h"
47 
48 /*
49  * ensure all of data on socket comes through. f==read || f==vwrite
50  */
51 size_t
atomicio6(ssize_t (* f)(int,void *,size_t),int fd,void * _s,size_t n,int (* cb)(void *,size_t),void * cb_arg)52 atomicio6(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n,
53     int (*cb)(void *, size_t), void *cb_arg)
54 {
55 	char *s = _s;
56 	size_t pos = 0;
57 	ssize_t res;
58 	struct pollfd pfd;
59 
60 	pfd.fd = fd;
61 #ifndef BROKEN_READ_COMPARISON
62 	pfd.events = f == read ? POLLIN : POLLOUT;
63 #else
64 	pfd.events = POLLIN|POLLOUT;
65 #endif
66 	while (n > pos) {
67 		res = (f) (fd, s + pos, n - pos);
68 		switch (res) {
69 		case -1:
70 			if (errno == EINTR) {
71 				/* possible SIGALARM, update callback */
72 				if (cb != NULL && cb(cb_arg, 0) == -1) {
73 					errno = EINTR;
74 					return pos;
75 				}
76 				continue;
77 			} else if (errno == EAGAIN || errno == EWOULDBLOCK) {
78 				(void)poll(&pfd, 1, -1);
79 				continue;
80 			}
81 			return 0;
82 		case 0:
83 			errno = EPIPE;
84 			return pos;
85 		default:
86 			pos += (size_t)res;
87 			if (cb != NULL && cb(cb_arg, (size_t)res) == -1) {
88 				errno = EINTR;
89 				return pos;
90 			}
91 		}
92 	}
93 	return pos;
94 }
95 
96 size_t
atomicio(ssize_t (* f)(int,void *,size_t),int fd,void * _s,size_t n)97 atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
98 {
99 	return atomicio6(f, fd, _s, n, NULL, NULL);
100 }
101 
102 /*
103  * ensure all of data on socket comes through. f==readv || f==writev
104  */
105 size_t
atomiciov6(ssize_t (* f)(int,const struct iovec *,int),int fd,const struct iovec * _iov,int iovcnt,int (* cb)(void *,size_t),void * cb_arg)106 atomiciov6(ssize_t (*f) (int, const struct iovec *, int), int fd,
107     const struct iovec *_iov, int iovcnt,
108     int (*cb)(void *, size_t), void *cb_arg)
109 {
110 	size_t pos = 0, rem;
111 	ssize_t res;
112 	struct iovec iov_array[IOV_MAX], *iov = iov_array;
113 	struct pollfd pfd;
114 
115 	if (iovcnt < 0 || iovcnt > IOV_MAX) {
116 		errno = EINVAL;
117 		return 0;
118 	}
119 	/* Make a copy of the iov array because we may modify it below */
120 	memcpy(iov, _iov, (size_t)iovcnt * sizeof(*_iov));
121 
122 	pfd.fd = fd;
123 #ifndef BROKEN_READV_COMPARISON
124 	pfd.events = f == readv ? POLLIN : POLLOUT;
125 #else
126 	pfd.events = POLLIN|POLLOUT;
127 #endif
128 	for (; iovcnt > 0 && iov[0].iov_len > 0;) {
129 		res = (f) (fd, iov, iovcnt);
130 		switch (res) {
131 		case -1:
132 			if (errno == EINTR) {
133 				/* possible SIGALARM, update callback */
134 				if (cb != NULL && cb(cb_arg, 0) == -1) {
135 					errno = EINTR;
136 					return pos;
137 				}
138 				continue;
139 			} else if (errno == EAGAIN || errno == EWOULDBLOCK) {
140 				(void)poll(&pfd, 1, -1);
141 				continue;
142 			}
143 			return 0;
144 		case 0:
145 			errno = EPIPE;
146 			return pos;
147 		default:
148 			rem = (size_t)res;
149 			pos += rem;
150 			/* skip completed iov entries */
151 			while (iovcnt > 0 && rem >= iov[0].iov_len) {
152 				rem -= iov[0].iov_len;
153 				iov++;
154 				iovcnt--;
155 			}
156 			/* This shouldn't happen... */
157 			if (rem > 0 && (iovcnt <= 0 || rem > iov[0].iov_len)) {
158 				errno = EFAULT;
159 				return 0;
160 			}
161 			if (iovcnt == 0)
162 				break;
163 			/* update pointer in partially complete iov */
164 			iov[0].iov_base = ((char *)iov[0].iov_base) + rem;
165 			iov[0].iov_len -= rem;
166 		}
167 		if (cb != NULL && cb(cb_arg, (size_t)res) == -1) {
168 			errno = EINTR;
169 			return pos;
170 		}
171 	}
172 	return pos;
173 }
174 
175 size_t
atomiciov(ssize_t (* f)(int,const struct iovec *,int),int fd,const struct iovec * _iov,int iovcnt)176 atomiciov(ssize_t (*f) (int, const struct iovec *, int), int fd,
177     const struct iovec *_iov, int iovcnt)
178 {
179 	return atomiciov6(f, fd, _iov, iovcnt, NULL, NULL);
180 }
181