Struct wasmtime_runtime::Mmap

pub struct Mmap { /* private fields */ }

A simple struct consisting of a page-aligned pointer to page-aligned and initially-zeroed memory and a length.

Implementations

impl Mmap

pub fn with_at_least(size: usize) -> Result<Self>

Create a new Mmap pointing to at least size bytes of page-aligned accessible memory.

pub fn from_file(path: &Path) -> Result<Self>

Creates a new Mmap by opening the file located at path and mapping it into memory.

The memory is mapped in read-only mode for the entire file. If portions of the file need to be modified then the region crate can be use to alter permissions of each page.

The memory mapping and the length of the file within the mapping are returned.

pub fn accessible_reserved( accessible_size: usize, mapping_size: usize ) -> Result<Self>

Create a new Mmap pointing to accessible_size bytes of page-aligned accessible memory, within a reserved mapping of mapping_size bytes. accessible_size and mapping_size must be native page-size multiples.

Panics

This function will panic if accessible_size is greater than mapping_size or if either of them are not page-aligned.

pub fn make_accessible(&mut self, start: usize, len: usize) -> Result<()>

Make the memory starting at start and extending for len bytes accessible. start and len must be native page-size multiples and describe a range within self’s reserved memory.

Panics

This function will panic if start or len is not page aligned or if either are outside the bounds of this mapping.

pub unsafe fn slice(&self, range: Range<usize>) -> &[u8]

Return the allocated memory as a slice of u8.

Safety

The caller must ensure that the range of bytes is accessible to the program and additionally has previously been initialized.

Panics

Panics of the range provided is outside of the limits of this mmap.

pub unsafe fn slice_mut(&mut self, range: Range<usize>) -> &mut [u8]

Return the allocated memory as a mutable slice of u8.

Safety

The caller must ensure that the range of bytes is accessible to the program and additionally has previously been initialized.

Panics

Panics of the range provided is outside of the limits of this mmap.

pub fn as_ptr(&self) -> *const u8

Return the allocated memory as a pointer to u8.

pub fn as_mut_ptr(&mut self) -> *mut u8

Return the allocated memory as a mutable pointer to u8.

pub fn len(&self) -> usize

Return the length of the allocated memory.

This is the byte length of this entire mapping which includes both addressible and non-addressible memory.

pub fn is_empty(&self) -> bool

Return whether any memory has been allocated or reserved.

pub unsafe fn make_executable( &self, range: Range<usize>, enable_branch_protection: bool ) -> Result<()>

Makes the specified range within this Mmap to be read/execute.

Unsafety

This method is unsafe as it’s generally not valid to simply make memory executable, so it’s up to the caller to ensure that everything is in order and this doesn’t overlap with other memory that should only be read or only read/write.

Panics

Panics of range is out-of-bounds or not page-aligned.

pub unsafe fn make_readonly(&self, range: Range<usize>) -> Result<()>

Makes the specified range within this Mmap to be readonly.

pub fn original_file(&self) -> Option<&Arc<File>>

Returns the underlying file that this mmap is mapping, if present.

Trait Implementations

impl Debug for Mmap

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

Formats the value using the given formatter.