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calculates offset from start for small allocations

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rwarr627 2020-06-08 19:17:53 -07:00
parent 467ba8440f
commit 9ef16cdcdb
1 changed files with 20 additions and 3 deletions
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23
h_malloc.c
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@ -1635,18 +1635,35 @@ EXPORT size_t h_malloc_object_size(void *p) {
return 0;
}
thread_unseal_metadata();
void *slab_region_start = get_slab_region_start();
if (p >= slab_region_start && p < ro.slab_region_end) {
struct slab_size_class_info size_class_info = slab_size_class(p);
size_t class = size_class_info.class;
size_t size_class = size_classes[class];
struct size_class *c = &ro.size_class_metadata[size_class_info.arena][class];
mutex_lock(&c->lock);
struct slab_metadata *metadata = get_metadata(c, p);
size_t slab_size = get_slab_size(size_class_slots[class], size_class);
void *slab = get_slab(c, slab_size, metadata);
size_t slot = libdivide_u32_do((const char *)p - (const char *)slab, &c->size_divisor);
void *start = slot_pointer(size_class, slab, slot);
size_t offset = (const char *)p - (const char *)start;
mutex_unlock(&c->lock);
thread_seal_metadata();
size_t size = slab_usable_size(p);
return size ? size - canary_size : 0;
return size ? size - canary_size - offset : 0;
}
if (unlikely(slab_region_start == NULL)) {
return SIZE_MAX;
}
thread_unseal_metadata();
struct region_allocator *ra = ro.region_allocator;
mutex_lock(&ra->lock);
struct region_metadata *region = regions_find(p);