xref: /freebsd/usr.sbin/bhyve/iov.c (revision aa1a8ff2d6dbc51ef058f46f3db5a8bb77967145)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2016 Jakub Klama <jceel@FreeBSD.org>.
5  * Copyright (c) 2018 Alexander Motin <mav@FreeBSD.org>
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  *    in this position and unchanged.
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 AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 #include <sys/param.h>
32 #include <sys/types.h>
33 #include <sys/uio.h>
34 
35 #include <stdlib.h>
36 #include <string.h>
37 #include "iov.h"
38 
39 void
40 seek_iov(const struct iovec *iov1, int niov1, struct iovec *iov2, int *niov2,
41     size_t seek)
42 {
43 	size_t remainder = 0;
44 	size_t left = seek;
45 	int i, j;
46 
47 	for (i = 0; i < niov1; i++) {
48 		size_t toseek = MIN(left, iov1[i].iov_len);
49 		left -= toseek;
50 
51 		if (toseek == iov1[i].iov_len)
52 			continue;
53 
54 		if (left == 0) {
55 			remainder = toseek;
56 			break;
57 		}
58 	}
59 
60 	for (j = i; j < niov1; j++) {
61 		iov2[j - i].iov_base = (char *)iov1[j].iov_base + remainder;
62 		iov2[j - i].iov_len = iov1[j].iov_len - remainder;
63 		remainder = 0;
64 	}
65 
66 	*niov2 = j - i;
67 }
68 
69 size_t
70 count_iov(const struct iovec *iov, int niov)
71 {
72 	size_t total = 0;
73 	int i;
74 
75 	for (i = 0; i < niov; i++)
76 		total += iov[i].iov_len;
77 
78 	return (total);
79 }
80 
81 void
82 truncate_iov(struct iovec *iov, int *niov, size_t length)
83 {
84 	size_t done = 0;
85 	int i;
86 
87 	for (i = 0; i < *niov; i++) {
88 		size_t toseek = MIN(length - done, iov[i].iov_len);
89 		done += toseek;
90 
91 		if (toseek <= iov[i].iov_len) {
92 			iov[i].iov_len = toseek;
93 			*niov = i + 1;
94 			return;
95 		}
96 	}
97 }
98 
99 ssize_t
100 iov_to_buf(const struct iovec *iov, int niov, void **buf)
101 {
102 	size_t ptr, total;
103 	int i;
104 
105 	total = count_iov(iov, niov);
106 	*buf = realloc(*buf, total);
107 	if (*buf == NULL)
108 		return (-1);
109 
110 	for (i = 0, ptr = 0; i < niov; i++) {
111 		memcpy((uint8_t *)*buf + ptr, iov[i].iov_base, iov[i].iov_len);
112 		ptr += iov[i].iov_len;
113 	}
114 
115 	return (total);
116 }
117 
118 ssize_t
119 buf_to_iov(const void *buf, size_t buflen, const struct iovec *iov, int niov,
120     size_t seek)
121 {
122 	struct iovec *diov;
123 	size_t off = 0, len;
124 	int  i;
125 
126 	if (seek > 0) {
127 		int ndiov;
128 
129 		diov = malloc(sizeof(struct iovec) * niov);
130 		seek_iov(iov, niov, diov, &ndiov, seek);
131 		iov = diov;
132 		niov = ndiov;
133 	}
134 
135 	for (i = 0; i < niov && off < buflen; i++) {
136 		len = MIN(iov[i].iov_len, buflen - off);
137 		memcpy(iov[i].iov_base, (const uint8_t *)buf + off, len);
138 		off += len;
139 	}
140 
141 	if (seek > 0)
142 		free(diov);
143 
144 	return ((ssize_t)off);
145 }
146 
147