[WIP]: async support

Cargo.toml

@@ -6,7 +6,7 @@ authors = [
     "Jesse Braham <jesse@beta7.io>",
 ]
 edition = "2021"
-rust-version = "1.59.0"
+rust-version = "1.71.0"
 description = "A cross-platform low-level serial port library."
 documentation = "https://docs.rs/serialport"
 repository = "https://github.com/serialport/serialport-rs"
@@ -15,7 +15,9 @@ keywords = ["serial", "hardware", "system", "RS232"]
 categories = ["hardware-support"]
 
 [target."cfg(unix)".dependencies]
+async-io = { version = "2.6.0", optional = true }
 bitflags = "2.4.0"
+blocking = { version = "1.6.2", optional = true }
 nix = { version = "0.26", default-features = false, features = ["fs", "ioctl", "poll", "signal", "term"] }
 
 [target.'cfg(all(target_os = "linux", not(target_env = "musl")))'.dependencies]
@@ -46,6 +48,7 @@ features = [
 
 [dependencies]
 cfg-if = "1.0.0"
+futures-io = { version = "0.3.31", optional = true }
 scopeguard = "1.1"
 serde = { version = "1.0", features = ["derive"], optional = true }
 
@@ -56,11 +59,7 @@ quote = ">=1, <=1.0.40"
 assert_hex = "0.4.1"
 clap = { version = "3.1.6", features = ["derive"] }
 envconfig = "0.10.0"
-# TODES Remove pinning this subdependency (of clap) when we are bumping our
-# MSRV (libc raised its MSRV with a patch release 0.2.167 from 1.19.0 to
-# 1.63.0). Trick the resolver into picking a compatible release of libc by
-# adding it as a direct dependency meanwhile.
-libc = ">=0.2.0, <=0.2.163"
+libc = "0.2"
 # TODO: Remove pinning this subdependency of clap when we are bumping our MSRV.
 # (There has been an incompatible change with the MSRV of os_str_bytes with
 # 6.6.0) Until then we are tricking the dependency resolver into using a
@@ -74,6 +73,7 @@ rustversion = "1.0.16"
 
 [features]
 default = ["libudev"]
+async = ["dep:futures-io", "dep:async-io", "dep:blocking"]
 hardware-tests = []
 # TODO: Make the feature unconditionally available with the next major release
 # (5.0) and remove this feature gate.

src/lib.rs

@@ -41,6 +41,8 @@ use std::time::Duration;
 
 #[cfg(unix)]
 mod posix;
+#[cfg(all(unix, feature = "async"))]
+pub use posix::AsyncSerialPort;
 #[cfg(unix)]
 pub use posix::{BreakDuration, TTYPort};
 
@@ -442,6 +444,12 @@ impl SerialPortBuilder {
     pub fn open_native(self) -> Result<COMPort> {
         windows::COMPort::open(&self)
     }
+
+    /// Open a runtime-agnostic asynchronous interface to the port with the specified settings.
+    #[cfg(all(unix, feature = "async"))]
+    pub fn open_async(self) -> Result<AsyncSerialPort> {
+        AsyncSerialPort::open(&self)
+    }
 }
 
 /// A trait for serial port devices