Buffering/caching

[paulyoung]

fatfs recommends using fscommon::BufStream

Note: it is recommended to wrap the underlying file struct in a buffering/caching object like BufStream from
fscommon crate. For example:

 let buf_stream = BufStream::new(img_file);
 let fs = fatfs::FileSystem::new(buf_stream, fatfs::FsOptions::new())?;

dfinity/cdk-rs#245 and dfinity/cdk-rs#247 appear to be doing something similar that won’t work out of the box here.

[paulyoung]

See also: BufRead, BufReader, and BufWriter: https://github.com/rust-lang/rust/blob/3d237ab52920924694f6fc3e47ee8588514bfa70/library/std/src/io/mod.rs#L38-L120