Function pool_init

examples/stdlib.c:1796–1822

* Pool init. */

 * Pool init.
 */
static struct malloc_pool_s *pool_init(struct malloc_pool_s *pool)
{
    pool = (pool == NULL? &malloc_pool: pool);
    if (pool->base != NULL)
        return pool;
    if (mutex_lock(&pool->mutex) < 0)
        return pool;
    if (pool->base != NULL)
    {
        mutex_unlock(&pool->mutex);
        return pool;
    }
    uintptr_t hint = 0xaaa00000000ull;
    (void)getrandom(&hint, sizeof(uint32_t), 0);
    hint &= ~(MA_PAGE_SIZE-1);
    void *ptr = mmap((void *)hint, MA_MAX_SIZE, PROT_NONE,
        MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
    if (ptr == MAP_FAILED)
        panic("mmap() failed");
    pool->base   = (uint8_t *)ptr;
    pool->mmap   = 0;
    pool->end    = UINT32_MAX;
    pool->root   = MA_NIL;
    pool->flags  = MAP_PRIVATE | MAP_ANONYMOUS;
    mutex_unlock(&pool->mutex);
    return pool;
}

/*
 * Fix the interval-tree invariant (RB-tree augmentation).