Add config module with two functions in it

Fixes: #128

src/config.rs

@@ -0,0 +1,15 @@
+//! Configuration file API
+//!
+//! For now, just contains two functions regarding the global configuration
+//! stored as a cache inside alsa-lib. Calling `update_free_global` might help
+//! against valgrind reporting memory leaks.
+use crate::{alsa};
+use super::error::*;
+
+pub fn update() -> Result<()> {
+	acheck!(snd_config_update()).map(|_| ())
+}
+
+pub fn update_free_global() -> Result<()> {
+	acheck!(snd_config_update_free_global()).map(|_| ())
+}

src/lib.rs

@@ -110,6 +110,8 @@ pub use crate::hctl::HCtl as HCtl;
 pub mod pcm;
 pub use crate::pcm::PCM as PCM;
 
+pub mod config;
+
 pub mod rawmidi;
 pub use crate::rawmidi::Rawmidi as Rawmidi;
 

src/pcm.rs

@@ -239,9 +239,9 @@ impl PCM {
         self.verify_format(S::FORMAT).map(|_| IO::new(self))
     }
 
-    /// Creates IO without checking [`S`] is valid type.
+    /// Creates IO without checking `S` is valid type.
     ///
-    /// SAFETY: Caller must guarantee [`S`] is valid type for this PCM stream
+    /// SAFETY: Caller must guarantee `S` is valid type for this PCM stream
     /// and that no other IO objects exist at the same time for the same stream
     /// (or in some other way guarantee mmap safety)
     pub unsafe fn io_unchecked<S: IoFormat>(&self) -> IO<S> {