Struct MmapOptions 

pub struct MmapOptions { /* private fields */ }

Configuration for creating a memory mapping.

Implementations

impl MmapOptions

pub const fn new() -> Self

Creates a new MmapOptions with default settings (length 0). You must set a length before mapping.

pub const fn len(self, len: usize) -> Self

Sets the length of the mapping in bytes.

pub const fn with_hint(self, addr: usize) -> Self

Sets a hint address for the mapping.

This is a request to the OS to place the mapping at this specific virtual address. The OS is not required to honor this request (on some platforms), or the call may fail if the address is already in use or invalid.

For the best chance of success:

• The address should be aligned to allocation_granularity().
• The address range [hint_addr, hint_addr + len) should be free.

pub const fn populate(self, populate: bool) -> Self

Sets whether to pre-populate (prefault) the page tables.

On Linux, this adds MAP_POPULATE.

pub const fn no_reserve(self, no_reserve: bool) -> Self

Sets whether to reserve swap space (on supported platforms).

On Linux, this adds MAP_NORESERVE.

pub const fn strict(self, strict: bool) -> Self

Sets whether the hint address is strict.

If true, map_anon will return an error if the OS cannot map the memory at the exact requested hint_addr.

pub unsafe fn map_anon(&self) -> Result<Mmap>

Creates an anonymous memory map.

Safety

This function is unsafe because it creates a raw memory mapping which has implications for memory safety (e.g. use-after-free if the Mmap is dropped while valid pointers into it still exist - though Mmap itself is safe, using the raw pointer it yields requires care).

Actually, Mmap owns the memory, so as long as Mmap is alive, the pointer is valid. However, sys_alloc is a low-level crate, so we mark creation as unsafe mostly because of the OS interactions and potential for UB if hint_addr is misused in some extensive contexts (though simply asking for an addr is usually safe).

Errors

Returns an error if the length is 0, or if the system call fails (e.g. out of memory), or if strict hint compliance is requested but cannot be satisfied.

Trait Implementations

impl Clone for MmapOptions

fn clone(&self) -> MmapOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MmapOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for MmapOptions

fn default() -> Self

Returns the “default value” for a type.