embedded-exfat

An exFAT Library in rust mainly focusing on no_std embedded system with async support

alloc is mandatory for this crate, although memory allocation is minimized, 256B for upcase table and 12B plus name size for each file or directory, and 12B for root directory.

For async scenario, enable async-std feature if std library available otherwide enable async feature

For no_std scenario, be aware that thread safety is provided by spin crate, which potenitally leads to dead lock.

Using this crate

use std::io::Write;
use exfat::error::Error;
use exfat::io::std::FileIO;
use exfat::ExFAT;
use exfat::FileOrDirectory;

let io = FileIO::open(device).map_err(|e| Error::IO(e)).unwrap();
let mut exfat = ExFAT::new(io).unwrap();
exfat.validate_checksum().unwrap();
let mut root = exfat.root_directory().unwrap();
root.validate_upcase_table_checksum().unwrap();
let mut file = match root.open().unwrap().open("test.txt").unwrap() {
    FileOrDirectory::File(f) => f,
    FileOrDirectory::Directory(_) => panic!("Not a file"),
};
let mut stdout = std::io::stdout();
let mut buf = [0u8; 512];
loop {
    let size = file.read(&mut buf).unwrap();
    stdout.write_all(&buf[..size]).unwrap();
    if size < buf.len() {
        break;
    }
}

Features

• async

  Enable async support

• async-std

  Enable async support with std library

• std (enable by default)

  Use std library

• extern-datetime-now

  Link an external exfat_datetime_now function to get current datetime, If not enabled, a default datetime will be used.

• log-max-level-off

  Disable logging at compile time

• max-filename-size-30

  Limit filename size to 30 bytes to reduce stack cost, any file or directory name longer than this size will be ignored, creating file with name size exceeds will return error.

• precise-allocation-counter (enable by default)

  Count exact cluster allocation size to maintain precise disk usage, needs to scan whole allocation bitmap and slows down initiation. If not enabled, disk usage calculation pretends to be more than actual.