io_safety feature is incomplete

[betelgeuse]

The io_safety feature introduced in #134 is incomplete. The API still allows usage of raw file descriptors.

$ cargo add io_uring --features io_safety
warning: translating `io_uring` to `io-uring`
    Updating crates.io index
      Adding io-uring v0.7.11 to dependencies
             Features:
             + io_safety
             - bindgen
             - direct-syscall
             - overwrite
             - sc

use io_uring::*;

fn main() {
    let entry = opcode::Splice::new(types::Fd(666), -1, types::Fd(666), -1, 100).build();
}

root@14c0e8d412b1:/app# cargo build
   Compiling libc v0.2.178
   Compiling io-uring v0.7.11
   Compiling io_uring_safe_example v0.1.0 (/app)
warning: unused variable: `entry`
 --> src/main.rs:4:9
  |
4 |     let entry = opcode::Splice::new(types::Fd(666), -1, types::Fd(666), -1, 100).build();
  |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_entry`
  |
  = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default

warning: `io_uring_safe_example` (bin "io_uring_safe_example") generated 1 warning (run `cargo fix --bin "io_uring_safe_example" -p io_uring_safe_example` to apply 1 suggestion)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.22s

A proper IO safe API would not allow taking integers as parameters.

https://rust-lang.github.io/rfcs/3128-io-safety.html

[quininer]

You may have misunderstood the mean of #134. It does not attempt to abstract the opcode into io-safety, it only uses this abstraction for IoUring.

Tracking fd lifetimes in opcode is not design purpose of this crate, which is the same as use raw pointer in opcode.

[betelgeuse]

You may have misunderstood the mean of #134. It does not attempt to abstract the opcode into io-safety, it only uses this abstraction for IoUring.

Given that io safety has been in stable rust for a while already, how about removing the feature flag by using the features always (in a version appropriate for semver)?

[quininer]

PR is welcome. :D