system-interface adds extensions to the Rust standard library, seeking to stay within the style of std, while exposing additional functionality:

• fs::FileIoExt - Extra support for working with files, including all the features of std::io::Read, std::io::Write, std::io::Seek, and std::os::unix::fs::FileExt, but with both POSIX-ish and Windows support, and with additional features, including read and write with all combinations of _vectored, _at, and _exact/_all. If you've ever wanted something like read_exact_vectored_at, write_all_vectored_at, or any other combination, or even read_to_end_at or read_to_string_at, they're all here, and they work on Windows too!
• io::IsTerminal - Test whether a given I/O handle refers to a terminal (aka a tty).
• io::ReadReady - Query the number of bytes ready to be read immediately from an I/O handle.
• io::Peek - Read from an I/O handle without consuming the data.

Everything in this crate is portable across popular POSIX-ish platforms and Windows.

Many of system-interface's features correspond to features in WASI, and are designed to work with cap-std, however it's not specific to WASI and can be used with regular std too. To separate concerns, all sandboxing and capability-oriented APIs are left to cap-std, so this crate's features are usable independently.

Support for async-std and socket2 is temporarily disabled until those crates contain the needed implementations of the I/O safety traits.