sound: move CLI arg types to lib submodule

Currently, the main CLI struct type is defined in src/main.rs thus
inaccessible when using the crate as a library. Move it to its own
module under src/args.rs

This will be useful for followup commits that will use src/args.rs
directly to generate manual pages using clap_mangen

Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>

vhost-device-sound/src/args.rs

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+//! An arguments type for the binary interface of this library.
+
+use std::path::PathBuf;
+
+use clap::{Parser, ValueEnum};
+
+#[derive(Parser, Debug)]
+#[clap(version, about, long_about = None)]
+pub struct SoundArgs {
+    /// vhost-user Unix domain socket path.
+    #[clap(long)]
+    pub socket: PathBuf,
+    /// audio backend to be used
+    #[clap(long)]
+    #[clap(value_enum)]
+    pub backend: BackendType,
+}
+
+#[derive(ValueEnum, Clone, Copy, Default, Debug, Eq, PartialEq)]
+pub enum BackendType {
+    #[default]
+    Null,
+    #[cfg(all(feature = "pw-backend", target_env = "gnu"))]
+    Pipewire,
+    #[cfg(all(feature = "alsa-backend", target_env = "gnu"))]
+    Alsa,
+}

vhost-device-sound/src/lib.rs

@@ -37,6 +37,7 @@ pub fn init_logger() {
     let _ = env_logger::builder().is_test(true).try_init();
 }
 
+pub mod args;
 pub mod audio_backends;
 pub mod device;
 pub mod stream;
@@ -50,7 +51,7 @@ use std::{
     sync::Arc,
 };
 
-use clap::ValueEnum;
+pub use args::BackendType;
 pub use stream::Stream;
 use thiserror::Error as ThisError;
 use vhost_user_backend::{VhostUserDaemon, VringRwLock, VringT};
@@ -191,16 +192,6 @@ impl From<stream::Error> for Error {
     }
 }
 
-#[derive(ValueEnum, Clone, Copy, Default, Debug, Eq, PartialEq)]
-pub enum BackendType {
-    #[default]
-    Null,
-    #[cfg(all(feature = "pw-backend", target_env = "gnu"))]
-    Pipewire,
-    #[cfg(all(feature = "alsa-backend", target_env = "gnu"))]
-    Alsa,
-}
-
 #[derive(Debug, PartialEq, Eq)]
 pub struct InvalidControlMessage(u32);
 
@@ -263,6 +254,14 @@ pub struct SoundConfig {
     audio_backend: BackendType,
 }
 
+impl From<args::SoundArgs> for SoundConfig {
+    fn from(cmd_args: args::SoundArgs) -> Self {
+        let args::SoundArgs { socket, backend } = cmd_args;
+
+        Self::new(socket, false, backend)
+    }
+}
+
 impl SoundConfig {
     /// Create a new instance of the SoundConfig struct, containing the
     /// parameters to be fed into the sound-backend server.

vhost-device-sound/src/main.rs

@@ -1,35 +1,14 @@
 // Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
 // Stefano Garzarella <sgarzare@redhat.com>
 // SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
-use std::{convert::TryFrom, path::PathBuf};
 
 use clap::Parser;
-use vhost_device_sound::{start_backend_server, BackendType, Error, Result, SoundConfig};
-
-#[derive(Parser, Debug)]
-#[clap(version, about, long_about = None)]
-struct SoundArgs {
-    /// vhost-user Unix domain socket path.
-    #[clap(long)]
-    socket: PathBuf,
-    /// audio backend to be used
-    #[clap(long)]
-    #[clap(value_enum)]
-    backend: BackendType,
-}
-
-impl TryFrom<SoundArgs> for SoundConfig {
-    type Error = Error;
-
-    fn try_from(cmd_args: SoundArgs) -> Result<Self> {
-        Ok(SoundConfig::new(cmd_args.socket, false, cmd_args.backend))
-    }
-}
+use vhost_device_sound::{args::SoundArgs, start_backend_server, SoundConfig};
 
 fn main() {
     env_logger::init();
 
-    let config = SoundConfig::try_from(SoundArgs::parse()).unwrap();
+    let config = SoundConfig::from(SoundArgs::parse());
 
     loop {
         start_backend_server(config.clone());
@@ -38,19 +17,14 @@ fn main() {
 
 #[cfg(test)]
 mod tests {
+    use std::path::{Path, PathBuf};
+
+    use clap::Parser;
     use rstest::*;
+    use vhost_device_sound::BackendType;
 
     use super::*;
 
-    impl SoundArgs {
-        fn from_args(socket: PathBuf) -> Self {
-            SoundArgs {
-                socket,
-                backend: BackendType::default(),
-            }
-        }
-    }
-
     fn init_logger() {
         std::env::set_var("RUST_LOG", "trace");
         let _ = env_logger::builder().is_test(true).try_init();
@@ -59,15 +33,15 @@ mod tests {
     #[test]
     fn test_sound_config_setup() {
         init_logger();
-        let args = SoundArgs::from_args(PathBuf::from("/tmp/vhost-sound.socket"));
+        let args = SoundArgs {
+            socket: PathBuf::from("/tmp/vhost-sound.socket"),
+            backend: BackendType::default(),
+        };
+        let config = SoundConfig::from(args);
 
-        let config = SoundConfig::try_from(args);
-        assert!(config.is_ok());
-
-        let config = config.unwrap();
         assert_eq!(
             config.get_socket_path(),
-            PathBuf::from("/tmp/vhost-sound.socket")
+            Path::new("/tmp/vhost-sound.socket")
         );
     }
 
@@ -90,10 +64,7 @@ mod tests {
             backend_name,
         ]);
 
-        let config = SoundConfig::try_from(args);
-        assert!(config.is_ok());
-
-        let config = config.unwrap();
+        let config = SoundConfig::from(args);
         assert_eq!(config.get_audio_backend(), backend);
     }
 }