pub struct MmapRaw { /* private fields */ }
Expand description

A handle to a raw memory mapped buffer.

This struct never hands out references to its interior, only raw pointers. This can be helpful when creating shared memory maps between untrusted processes.

Implementations

Creates a writeable memory map backed by a file.

This is equivalent to calling MmapOptions::new().map_raw(file).

Errors

This method returns an error when the underlying system call fails, which can happen for a variety of reasons, such as when the file is not open with read and write permissions.

Returns a raw pointer to the memory mapped file.

Before dereferencing this pointer, you have to make sure that the file has not been truncated since the memory map was created. Avoiding this will not introduce memory safety issues in Rust terms, but will cause SIGBUS (or equivalent) signal.

Returns an unsafe mutable pointer to the memory mapped file.

Before dereferencing this pointer, you have to make sure that the file has not been truncated since the memory map was created. Avoiding this will not introduce memory safety issues in Rust terms, but will cause SIGBUS (or equivalent) signal.

Returns the length in bytes of the memory map.

Note that truncating the file can cause the length to change (and render this value unusable).

Flushes outstanding memory map modifications to disk.

When this method returns with a non-error result, all outstanding changes to a file-backed memory map are guaranteed to be durably stored. The file’s metadata (including last modification timestamp) may not be updated.

Example
use std::fs::OpenOptions;
use std::io::Write;
use std::path::PathBuf;
use std::slice;

use memmap2::MmapRaw;

let tempdir = tempfile::tempdir()?;
let path: PathBuf = /* path to file */
let file = OpenOptions::new().read(true).write(true).create(true).open(&path)?;
file.set_len(128)?;

let mut mmap = unsafe { MmapRaw::map_raw(&file)? };

let mut memory = unsafe { slice::from_raw_parts_mut(mmap.as_mut_ptr(), 128) };
memory.write_all(b"Hello, world!")?;
mmap.flush()?;

Asynchronously flushes outstanding memory map modifications to disk.

This method initiates flushing modified pages to durable storage, but it will not wait for the operation to complete before returning. The file’s metadata (including last modification timestamp) may not be updated.

Flushes outstanding memory map modifications in the range to disk.

The offset and length must be in the bounds of the memory map.

When this method returns with a non-error result, all outstanding changes to a file-backed memory in the range are guaranteed to be durable stored. The file’s metadata (including last modification timestamp) may not be updated. It is not guaranteed the only the changes in the specified range are flushed; other outstanding changes to the memory map may be flushed as well.

Asynchronously flushes outstanding memory map modifications in the range to disk.

The offset and length must be in the bounds of the memory map.

This method initiates flushing modified pages to durable storage, but it will not wait for the operation to complete before returning. The file’s metadata (including last modification timestamp) may not be updated. It is not guaranteed that the only changes flushed are those in the specified range; other outstanding changes to the memory map may be flushed as well.

Advise OS how this memory map will be accessed. Only supported on Unix.

See madvise() map page.

Advise OS how this range of memory map will be accessed.

The offset and length must be in the bounds of the memory map.

Only supported on Unix.

See madvise() map page.

Lock the whole memory map into RAM. Only supported on Unix.

See mlock() map page.

Unlock the whole memory map. Only supported on Unix.

See munlock() map page.

Trait Implementations

Formats the value using the given formatter. Read more
Converts to this type from the input type.
Converts to this type from the input type.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.