Method allocate

vm-allocator/src/address.rs:166–194

Allocates a range of addresses from the managed region. Returns `Some(allocated_address)` when successful, or `None` if an area of `size` can't be allocated or if alignment isn't a power of two.

(
        &mut self,
        address: Option<GuestAddress>,
        size: GuestUsize,
        align_size: Option<GuestUsize>,
    )

    /// when successful, or `None` if an area of `size` can't be allocated or if alignment isn't
    /// a power of two.
    pub fn allocate(
        &mut self,
        address: Option<GuestAddress>,
        size: GuestUsize,
        align_size: Option<GuestUsize>,
    ) -> Option<GuestAddress> {
        if size == 0 {
            return None;
        }

        let alignment = align_size.unwrap_or(4);
        if !alignment.is_power_of_two() {
            return None;
        }

        let new_addr = match address {
            Some(req_address) => match self.available_range(req_address, size, alignment) {
                Ok(addr) => addr,
                Err(_) => {
                    return None;
                }
            },
            None => self.first_available_range(size, alignment)?,
        };

        self.ranges.insert(new_addr, size);

        Some(new_addr)
    }

    /// Free an already allocated address range.
    /// We can only free a range if it matches exactly an already allocated range.