Add NativeBuildsJvmLoader.overrideLoader for customized JNI lib loading logic

Author: wkornewald

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.9.0
+
+* Added `NativeBuildsJvmLoader.overrideLoader` to allow fully customizing the JNI lib loading logic.
+
 ## 0.8.4
 
 * Fixed Android JNI loading.

nativebuilds-loader/src/main/kotlin/com/ensody/nativebuilds/loader/NativeBuildsJvmLoader.kt

@@ -3,6 +3,11 @@ package com.ensody.nativebuilds.loader
 import java.io.File
 import kotlin.uuid.Uuid
 
+/**
+ * JNI native .so (shared library) loading mechanism for JVM and Android.
+ *
+ * This works with the NativeBuilds project out of the box and can also be customized via [overrideLoader].
+ */
 public object NativeBuildsJvmLoader {
     private val loadedLibs = mutableSetOf<NativeBuildsJvmLib>()
     private val tempDir by lazy {
@@ -13,46 +18,73 @@ public object NativeBuildsJvmLoader {
         }
     }
 
+    /**
+     * Allows customizing the loading mechanism.
+     *
+     * The default value is the default loading mechanism. To delegate to the default loading mechanism you can save
+     * the old value before overriding:
+     *
+     * ```kotlin
+     * val original = NativeBuildsJvmLoader.overrideLoader
+     * NativeBuildsJvmLoader.overrideLoader = {
+     *     if (...) {
+     *         original(it)
+     *     } else {
+     *         // custom logic
+     *     }
+     * }
+     * ```
+     */
+    public var overrideLoader: (lib: NativeBuildsJvmLib) -> Unit = ::realLoad
+
+    /**
+     * Loads the given [lib] for use with JNI code.
+     */
     public fun load(lib: NativeBuildsJvmLib) {
         synchronized(lib) {
             if (lib !in loadedLibs) {
-                val vendor = System.getProperty("java.vendor")
-                if (vendor == "The Android Project") {
-                    System.loadLibrary(lib.libName.removePrefix("lib"))
-                    loadedLibs.add(lib)
-                    return
-                }
-                val osName = System.getProperty("os.name")!!.lowercase()
-                val osArch = when (val osArch = System.getProperty("os.arch")!!.lowercase()) {
-                    "x86_64", "amd64" -> "X64"
-                    "aarch64", "arm64" -> "Arm64"
-                    else -> error("Unsupported arch: $osArch (os=$osName)")
-                }
-                val platform = when {
-                    "windows" in osName -> "mingw$osArch"
-                    "linux" in osName -> "linux$osArch"
-                    "mac" in osName || "darwin" in osName -> "macos$osArch"
-                    else -> error("Unsupported OS: $osName (arch=$osArch)")
-                }
-                val libFileName = lib.platformFileName[platform]
-                    ?: error("Could not find library ${lib.libName} for platform $platform")
-                val path = "/jni/$platform/$libFileName"
-                val tempFile = File(tempDir, libFileName).apply {
-                    deleteOnExit()
-                }
+                overrideLoader(lib)
+                loadedLibs.add(lib)
+            }
+        }
+    }
 
-                val resource = checkNotNull(lib::class.java.getResourceAsStream(path)) {
-                    "Could not find shared library: $path"
-                }
-                resource.use { inputStream ->
-                    tempFile.outputStream().use {
-                        inputStream.copyTo(it)
-                    }
-                }
+    @Suppress("UnsafeDynamicallyLoadedCode")
+    private fun realLoad(lib: NativeBuildsJvmLib) {
+        val vendor = System.getProperty("java.vendor")
+        if (vendor == "The Android Project") {
+            System.loadLibrary(lib.libName.removePrefix("lib"))
+            loadedLibs.add(lib)
+            return
+        }
+        val osName = System.getProperty("os.name")!!.lowercase()
+        val osArch = when (val osArch = System.getProperty("os.arch")!!.lowercase()) {
+            "x86_64", "amd64" -> "X64"
+            "aarch64", "arm64" -> "Arm64"
+            else -> error("Unsupported arch: $osArch (os=$osName)")
+        }
+        val platform = when {
+            "windows" in osName -> "mingw$osArch"
+            "linux" in osName -> "linux$osArch"
+            "mac" in osName || "darwin" in osName -> "macos$osArch"
+            else -> error("Unsupported OS: $osName (arch=$osArch)")
+        }
+        val libFileName = lib.platformFileName[platform]
+            ?: error("Could not find library ${lib.libName} for platform $platform")
+        val path = "/jni/$platform/$libFileName"
+        val tempFile = File(tempDir, libFileName).apply {
+            deleteOnExit()
+        }
 
-                System.load(tempFile.absolutePath)
-                loadedLibs.add(lib)
+        val resource = checkNotNull(lib::class.java.getResourceAsStream(path)) {
+            "Could not find shared library: $path"
+        }
+        resource.use { inputStream ->
+            tempFile.outputStream().use {
+                inputStream.copyTo(it)
             }
         }
+
+        System.load(tempFile.absolutePath)
     }
 }