Refine locating ld.config.txt

mobile/src/main/java/be/mygod/librootkotlinx/RootServer.kt

@@ -171,13 +171,10 @@ class RootServer @JvmOverloads constructor(private val warnLogger: (String) -> U
             // unfortunately native ld.config.txt only recognizes /data,/system,/system_ext as system directories;
             // to link correctly, we need to add our path to the linker config too
             val ldConfig = "$apexPath/etc/ld.config.txt"
-            val masterLdConfig = if (Build.VERSION.SDK_INT == 29) {
-                "/system/etc/ld.config.29.txt"
-            } else "/linkerconfig/ld.config.txt"
             writer.writeBytes("[ -f $ldConfig ] || " +
                     "mkdir -p $apexPath/etc && " +
                     "echo dir.system = $apexPath >$ldConfig && " +
-                    "cat $masterLdConfig >>$ldConfig || exit 1\n")
+                    "cat $genericLdConfigFilePath >>$ldConfig || exit 1\n")
             "$apexPath/bin" to "$apexPath/bin/app_process"
         }
         writer.writeBytes("[ -f $relocated ] || " +

mobile/src/main/java/be/mygod/librootkotlinx/Utils.kt

@@ -4,13 +4,37 @@ package be.mygod.librootkotlinx
 
 import android.annotation.SuppressLint
 import android.content.Context
+import android.os.Build
 import android.os.Parcel
 import android.os.Parcelable
 import android.util.*
+import androidx.annotation.RequiresApi
 import kotlinx.android.parcel.Parcelize
+import java.io.File
 
 class NoShellException(cause: Throwable) : Exception("Root missing", cause)
 
+/**
+ * Based on: https://android.googlesource.com/platform/bionic/+/aff9a34/linker/linker.cpp#3397
+ */
+@get:RequiresApi(29)
+val genericLdConfigFilePath: String get() {
+    "/system/etc/ld.config.${Build.VERSION.SDK_INT}.txt".let { if (File(it).isFile) return it }
+    if (Build.VERSION.SDK_INT >= 30) "/linkerconfig/ld.config.txt".let {
+        check(File(it).isFile) { "failed to find generated linker configuration from \"$it\"" }
+        return it
+    }
+    val prop = Class.forName("android.os.SystemProperties")
+    if (prop.getDeclaredMethod("getBoolean", String::class.java, Boolean::class.java).invoke(null,
+                    "ro.vndk.lite", false) as Boolean) return "/system/etc/ld.config.vndk_lite.txt"
+    when (val version = prop.getDeclaredMethod("get", String::class.java, String::class.java).invoke(null,
+            "ro.vndk.version", "") as String) {
+        "", "current" -> { }
+        else -> "/system/etc/ld.config.$version.txt".let { if (File(it).isFile) return it }
+    }
+    return "/system/etc/ld.config.txt"
+}
+
 val systemContext by lazy {
     val classActivityThread = Class.forName("android.app.ActivityThread")
     val activityThread = classActivityThread.getMethod("systemMain").invoke(null)