ref: 3a91086edd50be172bf1f2305967e145d3c4faf8
dir: /src/libc/arch/amd64/darwin/_getheap.c/
static char heap[16384]; void * _getheap(void) { return heap; } void * _brk(void *addr) { static char *cur = heap; char *p = addr; if (p < heap || p > &heap[sizeof(heap) - 1]) return (void *)-1; return cur = p; }