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Code review comments from jeffpc


 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         int 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 
 145         old_brk = (uintptr_t)BRKALIGN(_nd);
 146         ret_brk = P2ROUNDUP(old_brk, low_align);
 147         high_brk = ret_brk + min_size;
 148         new_brk = P2ROUNDUP(high_brk, high_align);
 149 
 150         /*
 151          * Check for overflow
 152          */
 153         if (ret_brk < old_brk || high_brk < ret_brk || new_brk < high_brk) {
 154                 lmutex_unlock(&__sbrk_lock);
 155                 errno = ENOMEM;
 156                 return ((void *)-1);
 157         }
 158 
 159         if ((brk_result = (int)_brk_unlocked((void *)new_brk)) == 0)
 160                 _nd = (void *)new_brk;
 161         lmutex_unlock(&__sbrk_lock);
 162 
 163         if (brk_result != 0)
 164                 return ((void *)-1);
 165 
 166         if (actual_size != NULL)
 167                 *actual_size = (new_brk - ret_brk);
 168         return ((void *)ret_brk);
 169 }
 170 
 171 int
 172 brk(void *new_brk)
 173 {
 174         int result;
 175 
 176         /*
 177          * brk(2) will return the current brk if given an argument of 0, so we
 178          * need to fail it here
 179          */
 180         if (new_brk == 0) {
 181                 errno = ENOMEM;
 182                 return (-1);
 183         }
 184 
 185         if (!primary_link_map) {
 186                 errno = ENOTSUP;
 187                 return (-1);
 188         }
 189         /*
 190          * Need to align this here;  _brk_unlocked won't do it for us.
 191          */
 192         new_brk = BRKALIGN(new_brk);
 193 
 194         lmutex_lock(&__sbrk_lock);
 195         if ((result = (int)_brk_unlocked(new_brk)) == 0)
 196                 _nd = new_brk;
 197         lmutex_unlock(&__sbrk_lock);
 198 
 199         return (result);
 200 }


 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 }