The orignal AtomicReader would only read blocks upto 2GB. This is because the underlying posix read() function is limited to INT_MAX (+2147483647) as documented here https://www.ibm.com/docs/en/zos/2.1.0?topic=functions-read-read-from-file-socket

The update checks the size of the slice we are requesting if it is greater than MAX_BUFFER_SIZE_USIZE, then it limits the slice size to MAX_BUFFER_SIZE_USIZE. The remainder of the buffer will be requested on the next call to AtomicReader::read as intended.

   Compiling sv v0.2.1 (/mnt/dbox/Dropbox/dev/rust/libera/bisevi/_info/crates/rust-sv)
error[E0283]: type annotations needed
   --> src/messages/message.rs:366:83
    |
366 |             Message::Other(s) => Err(io::Error::new(io::ErrorKind::InvalidData, s.as_ref())),
    |                                                                                 --^^^^^^--
    |                                                                                 | |
    |                                                                                 | cannot infer type for type parameter `T` declared on the trait `AsRef`
    |                                                                                 this method call resolves to `&T`
    |
    = note: cannot satisfy `String: AsRef<_>`
help: use the fully qualified path for the potential candidates
    |
366 |             Message::Other(s) => Err(io::Error::new(io::ErrorKind::InvalidData, <String as AsRef<OsStr>>::as_ref(s))),
    |                                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
366 |             Message::Other(s) => Err(io::Error::new(io::ErrorKind::InvalidData, <String as AsRef<Path>>::as_ref(s))),
    |                                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
366 |             Message::Other(s) => Err(io::Error::new(io::ErrorKind::InvalidData, <String as AsRef<[u8]>>::as_ref(s))),
    |                                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
366 |             Message::Other(s) => Err(io::Error::new(io::ErrorKind::InvalidData, <String as AsRef<str>>::as_ref(s))),
    |                                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0283`.
error: could not compile `sv