positioned-io-preview 0.3.3

Reading and writing at an offset


This crate allows you to specify an offset for reads and writes, without changing the current position in a file. This is similar to pread() and pwrite() in C.

The major advantages of this type of I/O are:

  • You don't need to seek before doing a random-access read or write, which is convenient.
  • Reads don't modify the file at all, so don't require mutability.

Build Status Windows build status Crates.io Documentation


Read the fifth 512-byte sector of a file:

use std::fs::File;
use positioned_io::ReadAt;

// note that file does not need to be mut
let file = File::open("tests/pi.txt")?;

// read up to 512 bytes
let mut buf = [0; 512];
let bytes_read = file.read_at(2048, &mut buf)?;

Note: If possible use the RandomAccessFile wrapper. On Windows ReadAt directly on File is very slow.



Preview release!

This is a preview release of positioned-io. Add it to your Cargo.toml like so:

positioned-io-preview = "0.3"

All examples assume you are using it as:

extern crate positioned_io_preview as positioned_io;


positioned-io is licensed under the MIT license.