Fix --device argument to various backends (#938)

Fix `--device` argument to various backends

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [contrib] Hardened security of the systemd service units
 - [main] Verbose logging mode (`-v`, `--verbose`) now logs all parsed environment variables and command line arguments (credentials are redacted).
 - [playback] `Sink`: `write()` now receives ownership of the packet (breaking).
+- [playback] `pipe`: create file if it doesn't already exist
 
 ### Added
 - [cache] Add `disable-credential-cache` flag (breaking).

playback/src/audio_backend/pipe.rs

@@ -4,19 +4,27 @@ use crate::convert::Converter;
 use crate::decoder::AudioPacket;
 use std::fs::OpenOptions;
 use std::io::{self, Write};
+use std::process::exit;
 
 pub struct StdoutSink {
     output: Option<Box<dyn Write>>,
-    path: Option<String>,
+    file: Option<String>,
     format: AudioFormat,
 }
 
 impl Open for StdoutSink {
-    fn open(path: Option<String>, format: AudioFormat) -> Self {
+    fn open(file: Option<String>, format: AudioFormat) -> Self {
+        if let Some("?") = file.as_deref() {
+            info!("Usage:");
+            println!("  Output to stdout: --backend pipe");
+            println!("  Output to file:   --backend pipe --device {{filename}}");
+            exit(0);
+        }
+
         info!("Using pipe sink with format: {:?}", format);
         Self {
             output: None,
-            path,
+            file,
             format,
         }
     }
@@ -25,11 +33,12 @@ impl Open for StdoutSink {
 impl Sink for StdoutSink {
     fn start(&mut self) -> SinkResult<()> {
         if self.output.is_none() {
-            let output: Box<dyn Write> = match self.path.as_deref() {
-                Some(path) => {
+            let output: Box<dyn Write> = match self.file.as_deref() {
+                Some(file) => {
                     let open_op = OpenOptions::new()
                         .write(true)
-                        .open(path)
+                        .create(true)
+                        .open(file)
                         .map_err(|e| SinkError::ConnectionRefused(e.to_string()))?;
                     Box::new(open_op)
                 }

playback/src/audio_backend/rodio.rs

@@ -135,21 +135,18 @@ fn create_sink(
     host: &cpal::Host,
     device: Option<String>,
 ) -> Result<(rodio::Sink, rodio::OutputStream), RodioError> {
-    let rodio_device = match device {
-        Some(ask) if &ask == "?" => {
-            let exit_code = match list_outputs(host) {
-                Ok(()) => 0,
-                Err(e) => {
-                    error!("{}", e);
-                    1
-                }
-            };
-            exit(exit_code)
-        }
+    let rodio_device = match device.as_deref() {
+        Some("?") => match list_outputs(host) {
+            Ok(()) => exit(0),
+            Err(e) => {
+                error!("{}", e);
+                exit(1);
+            }
+        },
         Some(device_name) => {
             host.output_devices()?
                 .find(|d| d.name().ok().map_or(false, |name| name == device_name)) // Ignore devices for which getting name fails
-                .ok_or(RodioError::DeviceNotAvailable(device_name))?
+                .ok_or_else(|| RodioError::DeviceNotAvailable(device_name.to_string()))?
         }
         None => host
             .default_output_device()

playback/src/audio_backend/subprocess.rs

@@ -5,7 +5,7 @@ use crate::decoder::AudioPacket;
 use shell_words::split;
 
 use std::io::Write;
-use std::process::{Child, Command, Stdio};
+use std::process::{exit, Child, Command, Stdio};
 
 pub struct SubprocessSink {
     shell_command: String,
@@ -15,16 +15,24 @@ pub struct SubprocessSink {
 
 impl Open for SubprocessSink {
     fn open(shell_command: Option<String>, format: AudioFormat) -> Self {
+        let shell_command = match shell_command.as_deref() {
+            Some("?") => {
+                info!("Usage: --backend subprocess --device {{shell_command}}");
+                exit(0);
+            }
+            Some(cmd) => cmd.to_owned(),
+            None => {
+                error!("subprocess sink requires specifying a shell command");
+                exit(1);
+            }
+        };
+
         info!("Using subprocess sink with format: {:?}", format);
 
-        if let Some(shell_command) = shell_command {
-            SubprocessSink {
-                shell_command,
-                child: None,
-                format,
-            }
-        } else {
-            panic!("subprocess sink requires specifying a shell command");
+        Self {
+            shell_command,
+            child: None,
+            format,
         }
     }
 }

src/main.rs

@@ -748,18 +748,7 @@ fn get_setup() -> Setup {
         })
         .unwrap_or_default();
 
-    #[cfg(any(
-        feature = "alsa-backend",
-        feature = "rodio-backend",
-        feature = "portaudio-backend"
-    ))]
     let device = opt_str(DEVICE);
-
-    #[cfg(any(
-        feature = "alsa-backend",
-        feature = "rodio-backend",
-        feature = "portaudio-backend"
-    ))]
     if let Some(ref value) = device {
         if value == "?" {
             backend(device, format);
@@ -769,25 +758,6 @@ fn get_setup() -> Setup {
         }
     }
 
-    #[cfg(not(any(
-        feature = "alsa-backend",
-        feature = "rodio-backend",
-        feature = "portaudio-backend"
-    )))]
-    let device: Option<String> = None;
-
-    #[cfg(not(any(
-        feature = "alsa-backend",
-        feature = "rodio-backend",
-        feature = "portaudio-backend"
-    )))]
-    if opt_present(DEVICE) {
-        warn!(
-            "The `--{}` / `-{}` option is not supported by the included audio backend(s), and has no effect.",
-            DEVICE, DEVICE_SHORT,
-        );
-    }
-
     #[cfg(feature = "alsa-backend")]
     let mixer_type = opt_str(MIXER_TYPE);
     #[cfg(not(feature = "alsa-backend"))]