SharedLibraryLoader: introduce to work around Samsung PackageManager bugs

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/backend/GoBackend.java

@@ -19,6 +19,7 @@ import com.wireguard.android.model.Tunnel;
 import com.wireguard.android.model.Tunnel.State;
 import com.wireguard.android.model.Tunnel.Statistics;
 import com.wireguard.android.util.ExceptionLoggers;
+import com.wireguard.android.util.SharedLibraryLoader;
 import com.wireguard.config.Config;
 import com.wireguard.config.IPCidr;
 import com.wireguard.config.Interface;
@@ -38,15 +39,12 @@ public final class GoBackend implements Backend {
     private static final String TAG = "WireGuard/" + GoBackend.class.getSimpleName();
     private static CompletableFuture<VpnService> vpnService = new CompletableFuture<>();
 
-    static {
-        System.loadLibrary("wg-go");
-    }
-
     private final Context context;
     private Tunnel currentTunnel;
     private int currentTunnelHandle = -1;
 
     public GoBackend(final Context context) {
+        SharedLibraryLoader.loadSharedLibrary(context, "wg-go");
         this.context = context;
     }
 

app/src/main/java/com/wireguard/android/util/SharedLibraryLoader.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright © 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+package com.wireguard.android.util;
+
+import android.content.Context;
+import android.os.Build;
+import android.util.Log;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.ZipFile;
+import java.util.zip.ZipEntry;
+
+public final class SharedLibraryLoader {
+    private static final String TAG = "WireGuard/" + SharedLibraryLoader.class.getSimpleName();
+
+    private SharedLibraryLoader() {
+    }
+
+    public static final void loadSharedLibrary(final Context context, final String libName) {
+        Throwable noAbiException;
+        try {
+            System.loadLibrary(libName);
+            return;
+        } catch (UnsatisfiedLinkError e) {
+            Log.d(TAG, "Failed to load library normally, so attempting to extract from apk", e);
+            noAbiException = e;
+        }
+
+        final ZipFile zipFile;
+        try {
+            zipFile = new ZipFile(new File(context.getApplicationInfo().sourceDir), ZipFile.OPEN_READ);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        final String mappedLibName = System.mapLibraryName(libName);
+        byte buffer[] = new byte[1024 * 32];
+        for (final String abi : Build.SUPPORTED_ABIS) {
+            final String libZipPath = "lib" + File.separatorChar + abi + File.separatorChar + mappedLibName;
+            final ZipEntry zipEntry = zipFile.getEntry(libZipPath);
+            if (zipEntry == null)
+                continue;
+            File f = null;
+            try {
+                f = File.createTempFile("lib", ".so", context.getCacheDir());
+                Log.d(TAG, "Extracting apk:/" + libZipPath + " to " + f.getAbsolutePath() + " and loading");
+                FileOutputStream out = new FileOutputStream(f);
+                InputStream in = zipFile.getInputStream(zipEntry);
+                int len;
+                while ((len = in.read(buffer)) != -1) {
+                    out.write(buffer, 0, len);
+                }
+                out.close();
+                System.load(f.getAbsolutePath());
+                return;
+            } catch (Exception e) {
+                Log.d(TAG, "Failed to load library apk:/" + libZipPath, e);
+                noAbiException = e;
+            } finally {
+                if (f != null)
+                    f.delete();
+            }
+        }
+        if (noAbiException instanceof RuntimeException)
+            throw (RuntimeException) noAbiException;
+        throw new RuntimeException(noAbiException);
+    }
+}