1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * Miscellaneous C routines for copying data around without
29 * descending into assembler. Compilers are pretty good at
30 * scheduling instructions, and humans are pretty hopeless at
31 * writing correct assembler.
32 */
33
34 #include <sys/types.h>
35 #include <sys/systm.h>
36 #include <sys/errno.h>
37 #include <sys/param.h>
38
39 /*
40 * copyinstr_noerr and copyoutstr_noerr can be implemented completely
41 * in C on machines with shared user and kernel context.
42 */
43 static int
copystr_nofault(const char * src,char * dst,size_t maxlength,size_t * lencopied)44 copystr_nofault(const char *src, char *dst, size_t maxlength,
45 size_t *lencopied)
46 {
47 int error = 0;
48 size_t leftover;
49
50 if ((leftover = maxlength) == 0)
51 error = ENAMETOOLONG;
52 else
53 do {
54 leftover--;
55 if ((*dst++ = *src++) == '\0')
56 break;
57 if (leftover == 0) {
58 error = ENAMETOOLONG;
59 break;
60 }
61 /*CONSTCOND*/
62 } while (1);
63
64 if (lencopied)
65 *lencopied = maxlength - leftover;
66 return (error);
67 }
68
69
70 int
copyinstr_noerr(const char * uaddr,char * kaddr,size_t maxlength,size_t * lencopied)71 copyinstr_noerr(const char *uaddr, char *kaddr, size_t maxlength,
72 size_t *lencopied)
73 {
74 char *ua = (char *)uaddr;
75
76 ASSERT((uintptr_t)kaddr > kernelbase);
77
78 if ((uintptr_t)ua > kernelbase) {
79 /*
80 * force fault at kernelbase
81 */
82 ua = (char *)kernelbase;
83 }
84 return (copystr_nofault(ua, kaddr, maxlength, lencopied));
85 }
86
87 int
copyoutstr_noerr(const char * kaddr,char * uaddr,size_t maxlength,size_t * lencopied)88 copyoutstr_noerr(const char *kaddr, char *uaddr, size_t maxlength,
89 size_t *lencopied)
90 {
91 char *ua = (char *)uaddr;
92
93 ASSERT((uintptr_t)kaddr > kernelbase);
94
95 if ((uintptr_t)ua > kernelbase) {
96 /*
97 * force fault at kernelbase
98 */
99 ua = (char *)kernelbase;
100 }
101 return (copystr_nofault(kaddr, ua, maxlength, lencopied));
102 }
103