| /* |
| * Copyright (C) 2017 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 android.content.pm; |
| |
| import android.os.Parcel; |
| import android.util.Log; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| |
| /** |
| * Helper classes to read from and write to Parcel with pooled strings. |
| * |
| * @hide |
| */ |
| public class PackageParserCacheHelper { |
| private PackageParserCacheHelper() { |
| } |
| |
| private static final String TAG = "PackageParserCacheHelper"; |
| private static final boolean DEBUG = false; |
| |
| /** |
| * Parcel read helper with a string pool. |
| */ |
| public static class ReadHelper extends Parcel.ReadWriteHelper { |
| private final ArrayList<String> mStrings = new ArrayList<>(); |
| |
| private final Parcel mParcel; |
| |
| public ReadHelper(Parcel p) { |
| mParcel = p; |
| } |
| |
| /** |
| * Prepare to read from a parcel, and install itself as a read-write helper. |
| * |
| * (We don't do it in the constructor to avoid calling methods before the constructor |
| * finishes.) |
| */ |
| public void startAndInstall() { |
| mStrings.clear(); |
| |
| final int poolPosition = mParcel.readInt(); |
| final int startPosition = mParcel.dataPosition(); |
| |
| // The pool is at the end of the parcel. |
| mParcel.setDataPosition(poolPosition); |
| mParcel.readStringList(mStrings); |
| |
| // Then move back. |
| mParcel.setDataPosition(startPosition); |
| |
| if (DEBUG) { |
| Log.i(TAG, "Read " + mStrings.size() + " strings"); |
| for (int i = 0; i < mStrings.size(); i++) { |
| Log.i(TAG, " " + i + ": \"" + mStrings.get(i) + "\""); |
| } |
| } |
| |
| mParcel.setReadWriteHelper(this); |
| } |
| |
| /** |
| * Read an string index from a parcel, and returns the corresponding string from the pool. |
| */ |
| public String readString(Parcel p) { |
| return mStrings.get(p.readInt()); |
| } |
| |
| @Override |
| public String readString8(Parcel p) { |
| return readString(p); |
| } |
| |
| @Override |
| public String readString16(Parcel p) { |
| return readString(p); |
| } |
| } |
| |
| /** |
| * Parcel write helper with a string pool. |
| */ |
| public static class WriteHelper extends Parcel.ReadWriteHelper { |
| private final ArrayList<String> mStrings = new ArrayList<>(); |
| |
| private final HashMap<String, Integer> mIndexes = new HashMap<>(); |
| |
| private final Parcel mParcel; |
| private final int mStartPos; |
| |
| /** |
| * Constructor. Prepare a parcel, and install it self as a read-write helper. |
| */ |
| public WriteHelper(Parcel p) { |
| mParcel = p; |
| mStartPos = p.dataPosition(); |
| mParcel.writeInt(0); // We come back later here and write the pool position. |
| |
| mParcel.setReadWriteHelper(this); |
| } |
| |
| /** |
| * Instead of writing a string directly to a parcel, this method adds it to the pool, |
| * and write the index in the pool to the parcel. |
| */ |
| public void writeString(Parcel p, String s) { |
| final Integer cur = mIndexes.get(s); |
| if (cur != null) { |
| // String already in the pool. Just write the index. |
| p.writeInt(cur); // Already in the pool. |
| if (DEBUG) { |
| Log.i(TAG, "Duplicate '" + s + "' at " + cur); |
| } |
| } else { |
| // Not in the pool. Add to the pool, and write the index. |
| final int index = mStrings.size(); |
| mIndexes.put(s, index); |
| mStrings.add(s); |
| |
| if (DEBUG) { |
| Log.i(TAG, "New '" + s + "' at " + index); |
| } |
| |
| p.writeInt(index); |
| } |
| } |
| |
| @Override |
| public void writeString8(Parcel p, String s) { |
| writeString(p, s); |
| } |
| |
| @Override |
| public void writeString16(Parcel p, String s) { |
| writeString(p, s); |
| } |
| |
| /** |
| * Closes a parcel by appending the string pool at the end and updating the pool offset, |
| * which it assumes is at the first byte. It also uninstalls itself as a read-write helper. |
| */ |
| public void finishAndUninstall() { |
| // Uninstall first, so that writeStringList() uses the native writeString. |
| mParcel.setReadWriteHelper(null); |
| |
| final int poolPosition = mParcel.dataPosition(); |
| mParcel.writeStringList(mStrings); |
| |
| mParcel.setDataPosition(mStartPos); |
| mParcel.writeInt(poolPosition); |
| |
| // Move back to the end. |
| mParcel.setDataPosition(mParcel.dataSize()); |
| if (DEBUG) { |
| Log.i(TAG, "Wrote " + mStrings.size() + " strings"); |
| } |
| } |
| } |
| } |