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 } 200