Add support for custom library (#33)

Author: MinnDevelopment

README.md

@@ -53,6 +53,11 @@ dependencies {
 }
 ```
 
+> [!NOTE]
+> ### Alternative: Custom Native Library
+> 
+> You can bring your own `libdave` binary by using `-Djdave.library.path=/path/to/libdave.so` as a JVM argument or setting it using `System.setProperty(NativeLibraryLoader.LIBRARY_PATH_PROPERTY, path)` before loading the `LibDave` class.
+
 ## Example: JDA
 
 To use this library with [JDA](https://github.com/discord-jda/JDA), you can use the [JDaveSessionFactory](api/src/main/java/club/minnced/discord/jdave/interop/JDaveSessionFactory.java) to configure the audio module:

api/src/main/java/club/minnced/discord/jdave/utils/NativeLibraryLoader.java

@@ -11,8 +11,27 @@
 import java.util.StringJoiner;
 import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class NativeLibraryLoader {
+    public static final String LIBRARY_PATH_PROPERTY = "jdave.library.path";
+
+    private static final Logger log = LoggerFactory.getLogger(NativeLibraryLoader.class);
+
+    /**
+     * Returns the path to a local libdave binary, if set.
+     *
+     * <p>Uses {@link #LIBRARY_PATH_PROPERTY} to determine the path from system properties.
+     * If the property is not set, this method returns null.
+     *
+     * @return The path to a local libdave binary, or null if not set.
+     */
+    @Nullable
+    public static String getLibraryPath() {
+        return System.getProperty(LIBRARY_PATH_PROPERTY);
+    }
+
     @NonNull
     public static NativeLibrary getNativeLibrary() {
         return resolveLibrary("dave");
@@ -46,6 +65,11 @@ public static Path createTemporaryFile() {
 
     @NonNull
     public static SymbolLookup getSymbolLookup() {
+        String customLibraryPath = getLibraryPath();
+        if (customLibraryPath != null) {
+            return getSymbolLookupFromPath(customLibraryPath);
+        }
+
         Path tempFile = createTemporaryFile();
         return SymbolLookup.libraryLookup(tempFile, Arena.global());
     }
@@ -68,6 +92,23 @@ public static NativeLibrary resolveLibrary(
         return new NativeLibrary(os, arch, baseName);
     }
 
+    @NonNull
+    private static SymbolLookup getSymbolLookupFromPath(@NonNull String customLibraryPath) {
+        Path path = Path.of(customLibraryPath).toAbsolutePath();
+        log.debug("Loading library from custom path: {}", path);
+        if (!Files.exists(path)) {
+            throw new IllegalStateException("Could not find library at path: " + path);
+        }
+        if (!Files.isRegularFile(path)) {
+            throw new IllegalStateException("Path is not a regular file: " + path);
+        }
+        if (!Files.isReadable(path)) {
+            throw new IllegalStateException("Path is not readable: " + path);
+        }
+
+        return SymbolLookup.libraryLookup(path, Arena.global());
+    }
+
     @NonNull
     private static OperatingSystem getOperatingSystem(@NonNull String osName) {
         osName = osName.toLowerCase();