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 (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #pragma weak _sbrk = sbrk
28 #pragma weak _brk = brk
29
30 #include "lint.h"
31 #include <synch.h>
32 #include <errno.h>
33 #include <sys/isa_defs.h>
34 #include <sys/types.h>
35 #include <sys/sysmacros.h>
36 #include <inttypes.h>
37 #include <unistd.h>
38 #include "mtlib.h"
39 #include "libc.h"
40
41 void *_nd = NULL;
42 mutex_t __sbrk_lock = DEFAULTMUTEX;
43
44 extern intptr_t _brk_unlocked(void *);
45 void *_sbrk_unlocked(intptr_t);
46
47 /*
48 * The break must always be at least 8-byte aligned
49 */
50 #if (_MAX_ALIGNMENT < 8)
51 #define ALIGNSZ 8
52 #else
53 #define ALIGNSZ _MAX_ALIGNMENT
54 #endif
55
56 #define BRKALIGN(x) (caddr_t)P2ROUNDUP((uintptr_t)(x), ALIGNSZ)
57
58 void *
59 sbrk(intptr_t addend)
60 {
61 void *result;
62
63 if (!primary_link_map) {
64 errno = ENOTSUP;
65 return ((void *)-1);
66 }
67 lmutex_lock(&__sbrk_lock);
68 result = _sbrk_unlocked(addend);
69 lmutex_unlock(&__sbrk_lock);
70
71 return (result);
72 }
73
74 /*
75 * _sbrk_unlocked() aligns the old break, adds the addend, aligns
76 * the new break, and calls _brk_unlocked() to set the new break.
77 * We must align the old break because _nd may begin life misaligned.
78 * The addend can be either positive or negative, so there are two
79 * overflow/underflow edge conditions to reject:
80 *
81 * - the addend is negative and brk + addend < 0.
82 * - the addend is positive and brk + addend > ULONG_MAX
83 */
84 void *
85 _sbrk_unlocked(intptr_t addend)
86 {
87 char *old_brk;
88 char *new_brk;
89
90 if (_nd == NULL) {
91 _nd = (void *)_brk_unlocked(0);
92 }
93
94 old_brk = BRKALIGN(_nd);
95 new_brk = BRKALIGN(old_brk + addend);
96
97 if ((addend > 0 && new_brk < old_brk) ||
98 (addend < 0 && new_brk > old_brk)) {
99 errno = ENOMEM;
100 return ((void *)-1);
101 }
102 if (_brk_unlocked(new_brk) != 0)
103 return ((void *)-1);
104 _nd = new_brk;
105 return (old_brk);
106 }
107
108 /*
109 * _sbrk_grow_aligned() aligns the old break to a low_align boundry,
110 * adds min_size, aligns to a high_align boundry, and calls _brk_unlocked()
111 * to set the new break. The low_aligned-aligned value is returned, and
112 * the actual space allocated is returned through actual_size.
113 *
114 * Unlike sbrk(2), _sbrk_grow_aligned takes an unsigned size, and does
115 * not allow shrinking the heap.
116 */
117 void *
118 _sbrk_grow_aligned(size_t min_size, size_t low_align, size_t high_align,
119 size_t *actual_size)
120 {
121 uintptr_t old_brk;
122 uintptr_t ret_brk;
123 uintptr_t high_brk;
124 uintptr_t new_brk;
125 intptr_t brk_result;
126
127 if (!primary_link_map) {
128 errno = ENOTSUP;
129 return ((void *)-1);
130 }
131 if ((low_align & (low_align - 1)) != 0 ||
132 (high_align & (high_align - 1)) != 0) {
133 errno = EINVAL;
134 return ((void *)-1);
135 }
136 low_align = MAX(low_align, ALIGNSZ);
137 high_align = MAX(high_align, ALIGNSZ);
138
139 lmutex_lock(&__sbrk_lock);
140
141 if (_nd == NULL)
142 _nd = (void *)_brk_unlocked(0);
143
144 old_brk = (uintptr_t)BRKALIGN(_nd);
145 ret_brk = P2ROUNDUP(old_brk, low_align);
146 high_brk = ret_brk + min_size;
147 new_brk = P2ROUNDUP(high_brk, high_align);
148
149 /*
150 * Check for overflow
151 */
152 if (ret_brk < old_brk || high_brk < ret_brk || new_brk < high_brk) {
153 lmutex_unlock(&__sbrk_lock);
154 errno = ENOMEM;
155 return ((void *)-1);
156 }
157
158 if ((brk_result = _brk_unlocked((void *)new_brk)) == 0)
159 _nd = (void *)new_brk;
160 lmutex_unlock(&__sbrk_lock);
161
162 if (brk_result != 0)
163 return ((void *)-1);
164
165 if (actual_size != NULL)
166 *actual_size = (new_brk - ret_brk);
167 return ((void *)ret_brk);
168 }
169
170 int
171 brk(void *new_brk)
172 {
173 intptr_t result;
174
175 /*
176 * brk(2) will return the current brk if given an argument of 0, so we
177 * need to fail it here
178 */
179 if (new_brk == 0) {
180 errno = ENOMEM;
181 return (-1);
182 }
183
184 if (!primary_link_map) {
185 errno = ENOTSUP;
186 return (-1);
187 }
188 /*
189 * Need to align this here; _brk_unlocked won't do it for us.
190 */
191 new_brk = BRKALIGN(new_brk);
192
193 lmutex_lock(&__sbrk_lock);
194 if ((result = _brk_unlocked(new_brk)) == 0)
195 _nd = new_brk;
196 lmutex_unlock(&__sbrk_lock);
197
198 return (result);
199 }