From 75527deec8016b4aa77ce67b7988b905da68c37c Mon Sep 17 00:00:00 2001
From: Sven Lechner <SirWindfield@users.noreply.github.com>
Date: Mon, 17 Aug 2020 20:10:58 +0200
Subject: [PATCH] feat: add name resolving library open function

The newly added method does resolve the library name passed to it by
adhering to platform-specific naming schemes using Rust provided
constants.

Closes #62
---
 src/lib.rs | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 139 insertions(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index 4b522f0..6d6476d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -46,9 +46,11 @@
 #![cfg_attr(docsrs, feature(doc_cfg))]
 
 
+use std::borrow::Cow;
+use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
 use std::ffi::OsStr;
 use std::fmt;
-use std::ops;
+use std::ops::{self, Deref};
 use std::marker;
 
 #[cfg(unix)]
@@ -128,6 +130,35 @@ impl Library {
         imp::Library::new(filename).map(From::from)
     }
 
+    fn resolve_name<'a>(name: &'a str) -> Cow<'a, str> {
+        match (name.starts_with(DLL_PREFIX), name.ends_with(DLL_SUFFIX)) {
+            (true, true) => Cow::Borrowed(name),
+            (true, false) => Cow::Owned(format!("{}{}", name, DLL_SUFFIX)),
+            (false, true) => Cow::Owned(format!("{}{}", DLL_PREFIX, name)),
+            (false, false) => Cow::Owned(format!("{}{}{}", DLL_PREFIX, name, DLL_SUFFIX)),
+        }
+    }
+
+    /// Loads a library and does resolve it's name to match platform-specific
+    /// naming schemes.
+    ///
+    /// For a given library called `engine`, this method will resolve the name
+    /// to the following:
+    /// - `Linux`: `libengine.so`
+    /// - `macOS`: `libengine.dylib`
+    /// - `Windows`: `engine.dll`
+    ///
+    /// # Note
+    ///
+    /// This function does only work with library names and does not work when
+    /// supplying a path to a library. The function assumes that the library is
+    /// already present inside a path that is detectable and searchable by the
+    /// OS during runtime.
+    pub fn with_name_resolve<T: AsRef<str>>(libname: T) -> Result<Library, Error> {
+        let resolved_name = Self::resolve_name(libname.as_ref());
+        Self::new(resolved_name.deref())
+    }
+
     /// Get a pointer to function or static variable by symbol name.
     ///
     /// The `symbol` may not contain any null bytes, with an exception of last byte. A null
@@ -337,3 +368,110 @@ impl<'lib, T> fmt::Debug for Symbol<'lib, T> {
 
 unsafe impl<'lib, T: Send> Send for Symbol<'lib, T> {}
 unsafe impl<'lib, T: Sync> Sync for Symbol<'lib, T> {}
+
+#[cfg(test)]
+mod tests {
+    use super::Library;
+
+    #[cfg(target_os = "windows")]
+    #[test]
+    fn test_resolve_name_none() {
+        let name = "audioengine";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "audioengine.dll");
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    fn test_resolve_name_none() {
+        let name = "audioengine";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.so");
+    }
+
+    #[cfg(target_os = "macos")]
+    #[test]
+    fn test_resolve_name_none() {
+        let name = "audioengine";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.dylib");
+    }
+
+    // prefix only
+
+    #[cfg(target_os = "windows")]
+    #[test]
+    fn test_resolve_name_prefix() {
+        let name = "audioengine";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "audioengine.dll");
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    fn test_resolve_name_prefix() {
+        let name = "libaudioengine";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.so");
+    }
+
+    #[cfg(target_os = "macos")]
+    #[test]
+    fn test_resolve_name_prefix() {
+        let name = "libaudioengine";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.dylib");
+    }
+
+    // suffix only
+
+    #[cfg(target_os = "windows")]
+    #[test]
+    fn test_resolve_name_suffix() {
+        let name = "audioengine.dll";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "audioengine.dll");
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    fn test_resolve_name_suffix() {
+        let name = "audioengine.so";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.so");
+    }
+
+    #[cfg(target_os = "macos")]
+    #[test]
+    fn test_resolve_name_suffix() {
+        let name = "audioengine.dylib";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.dylib");
+    }
+
+    // both
+
+    #[cfg(target_os = "windows")]
+    #[test]
+    fn test_resolve_name_prefix_and_suffix() {
+        let name = "audioengine.dll";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "audioengine.dll");
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    fn test_resolve_name_prefix_and_suffix() {
+        let name = "libaudioengine.so";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.so");
+    }
+
+    #[cfg(target_os = "macos")]
+    #[test]
+    fn test_resolve_name_prefix_and_suffix() {
+        let name = "libaudioengine.dylib";
+        let resolved = Library::resolve_name(name);
+        assert_eq!(&resolved, "libaudioengine.dylib");
+    }
+}