Add automatic decryption capabilities. (A3)

Bug: 7388852
Change-Id: Ie952b1ad6cfad2f83793bd968e159d3cfbf20a47

tools/dicttool/src/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtils.java

@@ -24,8 +24,6 @@ import java.io.BufferedOutputStream;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.io.BufferedInputStream;
-import java.io.BufferedOutputStream;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.util.ArrayList;
@@ -42,6 +40,7 @@ public final class BinaryDictOffdeviceUtils {
     private final static String SUFFIX = ".tmp";
 
     public final static String COMPRESSION = "compression";
+    public final static String ENCRYPTION = "encryption";
 
     public static class DecoderChainSpec {
         ArrayList<String> mDecoderSpec = new ArrayList<String>();
@@ -88,6 +87,14 @@ public final class BinaryDictOffdeviceUtils {
             if (null == newSpec) return null;
             return newSpec.addStep(COMPRESSION);
         }
+        // It's not a compressed either - try to see if it's crypted.
+        final File decryptedFile = tryGetDecryptedFile(src);
+        if (null != decryptedFile) {
+            final DecoderChainSpec newSpec =
+                    getRawBinaryDictionaryOrNullInternal(spec, decryptedFile);
+            if (null == newSpec) return null;
+            return newSpec.addStep(ENCRYPTION);
+        }
         return null;
     }
 
@@ -108,4 +115,22 @@ public final class BinaryDictOffdeviceUtils {
             return null;
         }
     }
+
+    /* Try to decrypt the file passed as an argument.
+     *
+     * If the file can be decrypted, the decrypted version is returned. Otherwise, null
+     * is returned.
+     */
+    private static File tryGetDecryptedFile(final File src) {
+        try {
+            final File dst = File.createTempFile(PREFIX, SUFFIX);
+            final FileOutputStream dstStream = new FileOutputStream(dst);
+            copy(Crypt.getDecryptedStream(new BufferedInputStream(new FileInputStream(src))),
+                    dstStream); // #copy() closes the streams
+            return dst;
+        } catch (IOException e) {
+            // Could not uncompress the file: presumably the file is simply not a compressed file
+            return null;
+        }
+    }
 }

tools/dicttool/src/com/android/inputmethod/latin/dicttool/Crypt.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * 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
+ *
+ * http://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 com.android.inputmethod.latin.dicttool;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class Crypt {
+    public static OutputStream getCryptedStream(final OutputStream out) {
+        // Encryption is not supported
+        return out;
+    }
+
+    public static InputStream getDecryptedStream(final InputStream in) {
+        // Decryption is not supported
+        return in;
+    }
+}