Support empty resource table. (iBotPeaches#3230)

* test: assertions for empty arsc table

* fix: don't crash if no pkgs found

brut.apktool/apktool-lib/src/main/java/brut/androlib/res/decoder/ARSCDecoder.java

@@ -122,7 +122,7 @@ private ResPackage[] readResourceTable() throws IOException, AndrolibException {
             }
         }
 
-        if (mPkg.getResSpecCount() > 0) {
+        if (mPkg != null && mPkg.getResSpecCount() > 0) {
             addMissingResSpecs();
         }
 

brut.apktool/apktool-lib/src/test/java/brut/androlib/decode/EmptyArscTest.java

@@ -0,0 +1,65 @@
+/*
+ *  Copyright (C) 2010 Ryszard Wiśniewski <[email protected]>
+ *  Copyright (C) 2010 Connor Tumbleson <[email protected]>
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package brut.androlib.decode;
+
+import brut.androlib.ApkDecoder;
+import brut.androlib.BaseTest;
+import brut.androlib.TestUtils;
+import brut.common.BrutException;
+import brut.directory.ExtFile;
+import brut.util.OS;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+
+import static org.junit.Assert.assertTrue;
+
+public class EmptyArscTest extends BaseTest {
+
+    @BeforeClass
+    public static void beforeClass() throws Exception {
+        TestUtils.cleanFrameworkFile();
+        sTmpDir = new ExtFile(OS.createTempDirectory());
+        TestUtils.copyResourceDir(EmptyArscTest.class, "decode/issue2701/", sTmpDir);
+    }
+
+    @AfterClass
+    public static void afterClass() throws BrutException {
+        OS.rmdir(sTmpDir);
+    }
+
+    @Test
+    public void decodeWithEmptyArscFile() throws BrutException, IOException {
+        String apk = "test.apk";
+
+        // decode test.apk
+        ApkDecoder apkDecoder = new ApkDecoder(new File(sTmpDir + File.separator + apk));
+        sTestOrigDir = new ExtFile(sTmpDir + File.separator + apk + ".out");
+
+        File outDir = new File(sTmpDir + File.separator + apk + ".out");
+        apkDecoder.decode(outDir);
+
+        File publicXmlFile =  new File(sTestOrigDir,"res/values/public.xml");
+        assertTrue(publicXmlFile.isFile());
+
+        File androidManifestXmlFile =  new File(sTestOrigDir,"AndroidManifest.xml");
+        assertTrue(androidManifestXmlFile.isFile());
+    }
+}