Struct sparse_mmap::unix::SparseMapping

pub struct SparseMapping { /* private fields */ }

A reserved virtual address range that may be partially populated with memory mappings.

Implementations

impl SparseMapping

pub fn new(len: usize) -> Result<Self, Error>

Reserves a sparse mapping range with the given size.

The range will be aligned to the largest system page size that’s smaller or equal to len.

pub fn is_local(&self) -> bool

Returns true if the mapping is local to the current process.

pub fn as_ptr(&self) -> *mut c_void

Returns the pointer to the beginning of the sparse mapping.

pub fn len(&self) -> usize

Returns the length of the mapping, in bytes.

pub fn alloc(&self, offset: usize, len: usize) -> Result<(), Error>

Allocates private, writable memory at the given offset within the mapping.

pub fn map_zero(&self, offset: usize, len: usize) -> Result<(), Error>

Maps read-only zero pages at the given offset within the mapping.

pub fn map_file( &self, offset: usize, len: usize, file_mapping: impl AsFd, file_offset: u64, writable: bool, ) -> Result<(), Error>

Maps a portion of a file mapping at offset.

pub unsafe fn mmap( &self, offset: usize, len: usize, prot: i32, map_flags: i32, fd: impl AsFd, file_offset: i64, ) -> Result<(), Error>

Maps memory into the mapping, passing parameters through to the mmap syscall.

Safety

This routine is safe to use as long as the caller ensures map_flags excludes any flags that render the memory region non-unmappable (e.g., MAP_LOCKED). Misuse may lead to system resource issues, such as falsely perceived out-of-memory conditions.

pub unsafe fn mmap_anonymous( &self, offset: usize, len: usize, prot: i32, map_flags: i32, ) -> Result<()>

Maps anonymous memory into the mapping, with parameters for the mmap syscall.

Safety

This routine is safe to use as long as the caller ensures map_flags excludes any flags that render the memory region non-unmappable (e.g., MAP_LOCKED). Misuse may lead to system resource issues, such as falsely perceived out-of-memory conditions.

pub fn unmap(&self, offset: usize, len: usize) -> Result<()>

Unmaps memory from the mapping.

impl SparseMapping

pub fn page_size() -> usize

Gets the supported page size for sparse mappings.

pub fn write_at( &self, offset: usize, data: &[u8], ) -> Result<(), SparseMappingError>

Tries to write into the sparse mapping.

pub fn read_at( &self, offset: usize, data: &mut [u8], ) -> Result<(), SparseMappingError>

Tries to read from the sparse mapping.

pub fn read_plain<T: FromBytes>( &self, offset: usize, ) -> Result<T, SparseMappingError>

Tries to read a type T from offset.

pub fn fill_at( &self, offset: usize, val: u8, len: usize, ) -> Result<(), SparseMappingError>

Tries to fill a region of the sparse mapping with val.

pub fn atomic_slice(&self, start: usize, len: usize) -> &[AtomicU8]

Gets a slice for accessing the mapped data directly.

This is safe from a Rust memory model perspective, since the underlying VA is either mapped and is owned in a shared state by this object (in which case &AtomicU8 access from multiple threads is fine), or the VA is not mapped but is reserved and so will not be mapped by another Rust object.

In the latter case, actually accessing the data may cause a fault, which will likely lead to a process crash, so care must nonetheless be taken when using this method.

Trait Implementations

impl Debug for SparseMapping

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

Formats the value using the given formatter.

impl Drop for SparseMapping

fn drop(&mut self)

Executes the destructor for this type.

impl Send for SparseMapping

impl Sync for SparseMapping