#memory-mapping #mmap #generic #unix #fd #file

mapped-file

Construct a memory mapping over any file object

9 releases

0.0.8 Mar 10, 2023
0.0.8-r1 Jun 6, 2024
0.0.7 Feb 10, 2023
0.0.5 Nov 2, 2022
0.0.4 Oct 23, 2022

#110 in Memory management

Download history 8/week @ 2024-02-26 5/week @ 2024-03-11 54/week @ 2024-04-01 77/week @ 2024-06-03 3/week @ 2024-06-10

80 downloads per month

MIT license

77KB
2.5K SLoC

MemoryFile<T>: Wrap memory mappings over any file-like object

A safe and ergonomic mmap() wrapper for arbitrary file-descriptor handles.

NOTE: Working release, but still in development.

Usage

MemoryFile<T> can be used to consume any type T that implements AsRawFd, form a mapping over that file-descriptor, and then unmap the memory before the T itself is dropped (which can be a reference or value.) The MemoryFile<T> can also be consumed back into the T, unmapping (and optionally syncing) the memory in the process.

Examples

A function mapping file memory working on arbitrary file-descriptor holding objects.

pub fn files_equal<T: ?Sized, U: ?Sized>(file1: &T, file2: &U, size: usize) -> io::Result<bool>
	where T: AsRawFd,
		  U: AsRawFd
{
	let file1 = MappedFile::try_new(file1, size, Perm::Readonly, Flags::Private)?.with_advice(Advice::Sequential)?;
	let file2 = MappedFile::try_new(file2, size, Perm::Readonly, Flags::Private)?.with_advice(Advice::Sequential)?;
	Ok(&file1[..] == &file2[..])
}

Although, it is probably a better pattern to allow the caller to handle the mapping, and the callee to take any kind of mapping like so:

pub fn files_equal<T: ?Sized, U: ?Sized>(file1: &MappedFile<T>, file2: &MappedFile<U>) -> bool
	where T: AsRawFd,
		  U: AsRawFd
{
	&file1[..] == &file2[..]
}

However, MappedFile<T> also implements Borrow<[u8]>, so any &MappedFile<T> can be passed to any function as AsRef<[u8]> too.

License

MIT

Dependencies

~180–365KB