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Code review comments from jeffpc
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--- old/usr/src/lib/libc/port/sys/sbrk.c
+++ new/usr/src/lib/libc/port/sys/sbrk.c
1 1 /*
2 2 * CDDL HEADER START
3 3 *
4 4 * The contents of this file are subject to the terms of the
5 5 * Common Development and Distribution License (the "License").
6 6 * You may not use this file except in compliance with the License.
7 7 *
8 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 9 * or http://www.opensolaris.org/os/licensing.
10 10 * See the License for the specific language governing permissions
11 11 * and limitations under the License.
12 12 *
13 13 * When distributing Covered Code, include this CDDL HEADER in each
14 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 15 * If applicable, add the following below this CDDL HEADER, with the
16 16 * fields enclosed by brackets "[]" replaced with your own identifying
17 17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 18 *
19 19 * CDDL HEADER END
20 20 */
21 21
22 22 /*
23 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 24 * Use is subject to license terms.
25 25 */
26 26
27 27 #pragma weak _sbrk = sbrk
28 28 #pragma weak _brk = brk
29 29
30 30 #include "lint.h"
31 31 #include <synch.h>
32 32 #include <errno.h>
33 33 #include <sys/isa_defs.h>
34 34 #include <sys/types.h>
35 35 #include <sys/sysmacros.h>
36 36 #include <inttypes.h>
37 37 #include <unistd.h>
38 38 #include "mtlib.h"
39 39 #include "libc.h"
40 40
41 41 void *_nd = NULL;
42 42 mutex_t __sbrk_lock = DEFAULTMUTEX;
43 43
44 44 extern intptr_t _brk_unlocked(void *);
45 45 void *_sbrk_unlocked(intptr_t);
46 46
47 47 /*
48 48 * The break must always be at least 8-byte aligned
49 49 */
50 50 #if (_MAX_ALIGNMENT < 8)
51 51 #define ALIGNSZ 8
52 52 #else
53 53 #define ALIGNSZ _MAX_ALIGNMENT
54 54 #endif
55 55
56 56 #define BRKALIGN(x) (caddr_t)P2ROUNDUP((uintptr_t)(x), ALIGNSZ)
57 57
58 58 void *
59 59 sbrk(intptr_t addend)
60 60 {
61 61 void *result;
62 62
63 63 if (!primary_link_map) {
64 64 errno = ENOTSUP;
65 65 return ((void *)-1);
66 66 }
67 67 lmutex_lock(&__sbrk_lock);
68 68 result = _sbrk_unlocked(addend);
69 69 lmutex_unlock(&__sbrk_lock);
70 70
71 71 return (result);
72 72 }
73 73
74 74 /*
75 75 * _sbrk_unlocked() aligns the old break, adds the addend, aligns
76 76 * the new break, and calls _brk_unlocked() to set the new break.
77 77 * We must align the old break because _nd may begin life misaligned.
78 78 * The addend can be either positive or negative, so there are two
79 79 * overflow/underflow edge conditions to reject:
80 80 *
81 81 * - the addend is negative and brk + addend < 0.
82 82 * - the addend is positive and brk + addend > ULONG_MAX
83 83 */
84 84 void *
85 85 _sbrk_unlocked(intptr_t addend)
86 86 {
87 87 char *old_brk;
88 88 char *new_brk;
89 89
90 90 if (_nd == NULL) {
91 91 _nd = (void *)_brk_unlocked(0);
92 92 }
93 93
94 94 old_brk = BRKALIGN(_nd);
95 95 new_brk = BRKALIGN(old_brk + addend);
96 96
97 97 if ((addend > 0 && new_brk < old_brk) ||
98 98 (addend < 0 && new_brk > old_brk)) {
99 99 errno = ENOMEM;
100 100 return ((void *)-1);
101 101 }
102 102 if (_brk_unlocked(new_brk) != 0)
103 103 return ((void *)-1);
104 104 _nd = new_brk;
105 105 return (old_brk);
106 106 }
107 107
108 108 /*
109 109 * _sbrk_grow_aligned() aligns the old break to a low_align boundry,
110 110 * adds min_size, aligns to a high_align boundry, and calls _brk_unlocked()
111 111 * to set the new break. The low_aligned-aligned value is returned, and
112 112 * the actual space allocated is returned through actual_size.
113 113 *
114 114 * Unlike sbrk(2), _sbrk_grow_aligned takes an unsigned size, and does
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115 115 * not allow shrinking the heap.
116 116 */
117 117 void *
118 118 _sbrk_grow_aligned(size_t min_size, size_t low_align, size_t high_align,
119 119 size_t *actual_size)
120 120 {
121 121 uintptr_t old_brk;
122 122 uintptr_t ret_brk;
123 123 uintptr_t high_brk;
124 124 uintptr_t new_brk;
125 - int brk_result;
125 + intptr_t brk_result;
126 126
127 127 if (!primary_link_map) {
128 128 errno = ENOTSUP;
129 129 return ((void *)-1);
130 130 }
131 131 if ((low_align & (low_align - 1)) != 0 ||
132 132 (high_align & (high_align - 1)) != 0) {
133 133 errno = EINVAL;
134 134 return ((void *)-1);
135 135 }
136 136 low_align = MAX(low_align, ALIGNSZ);
137 137 high_align = MAX(high_align, ALIGNSZ);
138 138
139 139 lmutex_lock(&__sbrk_lock);
140 140
141 - if (_nd == NULL) {
141 + if (_nd == NULL)
142 142 _nd = (void *)_brk_unlocked(0);
143 - }
144 143
145 144 old_brk = (uintptr_t)BRKALIGN(_nd);
146 145 ret_brk = P2ROUNDUP(old_brk, low_align);
147 146 high_brk = ret_brk + min_size;
148 147 new_brk = P2ROUNDUP(high_brk, high_align);
149 148
150 149 /*
151 150 * Check for overflow
152 151 */
153 152 if (ret_brk < old_brk || high_brk < ret_brk || new_brk < high_brk) {
154 153 lmutex_unlock(&__sbrk_lock);
155 154 errno = ENOMEM;
156 155 return ((void *)-1);
157 156 }
158 157
159 - if ((brk_result = (int)_brk_unlocked((void *)new_brk)) == 0)
158 + if ((brk_result = _brk_unlocked((void *)new_brk)) == 0)
160 159 _nd = (void *)new_brk;
161 160 lmutex_unlock(&__sbrk_lock);
162 161
163 162 if (brk_result != 0)
164 163 return ((void *)-1);
165 164
166 165 if (actual_size != NULL)
167 166 *actual_size = (new_brk - ret_brk);
168 167 return ((void *)ret_brk);
169 168 }
170 169
171 170 int
172 171 brk(void *new_brk)
173 172 {
174 - int result;
173 + intptr_t result;
175 174
176 175 /*
177 176 * brk(2) will return the current brk if given an argument of 0, so we
178 177 * need to fail it here
179 178 */
180 179 if (new_brk == 0) {
181 180 errno = ENOMEM;
182 181 return (-1);
183 182 }
184 183
185 184 if (!primary_link_map) {
186 185 errno = ENOTSUP;
187 186 return (-1);
188 187 }
189 188 /*
190 189 * Need to align this here; _brk_unlocked won't do it for us.
191 190 */
192 191 new_brk = BRKALIGN(new_brk);
193 192
194 193 lmutex_lock(&__sbrk_lock);
195 - if ((result = (int)_brk_unlocked(new_brk)) == 0)
194 + if ((result = _brk_unlocked(new_brk)) == 0)
196 195 _nd = new_brk;
197 196 lmutex_unlock(&__sbrk_lock);
198 197
199 198 return (result);
200 199 }
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