services/core/java/com/android/server/graphics/fonts/FontManagerService.java

/*
 * Copyright (C) 2020 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.server.graphics.fonts;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.Context;
import android.graphics.Typeface;
import android.graphics.fonts.FontFamily;
import android.graphics.fonts.FontFileUtil;
import android.graphics.fonts.SystemFonts;
import android.os.SharedMemory;
import android.system.ErrnoException;
import android.text.FontConfig;
import android.util.Pair;
import android.util.Slog;

import com.android.internal.annotations.GuardedBy;
import com.android.server.LocalServices;
import com.android.server.SystemService;

import java.io.File;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.NioUtils;
import java.nio.channels.FileChannel;
import java.util.HashMap;
import java.util.Map;

/** A service for managing system fonts. */
// TODO(b/173619554): Add API to update fonts.
public final class FontManagerService {

    private static final String TAG = "FontManagerService";

    // TODO: make this a DeviceConfig flag.
    private static final boolean ENABLE_FONT_UPDATES = false;
    private static final String FONT_FILES_DIR = "/data/fonts/files";

    /** Class to manage FontManagerService's lifecycle. */
    public static final class Lifecycle extends SystemService {
        private final FontManagerService mService;

        public Lifecycle(@NonNull Context context) {
            super(context);
            mService = new FontManagerService();
        }

        @Override
        public void onStart() {
            LocalServices.addService(FontManagerInternal.class,
                    new FontManagerInternal() {
                        @Override
                        @Nullable
                        public SharedMemory getSerializedSystemFontMap() {
                            return mService.getSerializedSystemFontMap();
                        }
                    });
        }
    }

    private static class OtfFontFileParser implements UpdatableFontDir.FontFileParser {
        @Override
        public long getVersion(File file) throws IOException {
            ByteBuffer buffer = mmap(file);
            try {
                return FontFileUtil.getRevision(buffer, 0);
            } finally {
                NioUtils.freeDirectBuffer(buffer);
            }
        }

        private static ByteBuffer mmap(File file) throws IOException {
            try (FileInputStream in = new FileInputStream(file)) {
                FileChannel fileChannel = in.getChannel();
                return fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileChannel.size());
            }
        }
    }

    @Nullable
    private final UpdatableFontDir mUpdatableFontDir;

    @GuardedBy("FontManagerService.this")
    @Nullable
    private SharedMemory mSerializedSystemFontMap = null;

    private FontManagerService() {
        mUpdatableFontDir = ENABLE_FONT_UPDATES
                ? new UpdatableFontDir(new File(FONT_FILES_DIR), new OtfFontFileParser()) : null;
    }

    @Nullable
    private SharedMemory getSerializedSystemFontMap() {
        if (!Typeface.ENABLE_LAZY_TYPEFACE_INITIALIZATION) {
            return null;
        }
        synchronized (FontManagerService.this) {
            if (mSerializedSystemFontMap == null) {
                mSerializedSystemFontMap = createSerializedSystemFontMapLocked();
            }
            return mSerializedSystemFontMap;
        }
    }

    @Nullable
    private SharedMemory createSerializedSystemFontMapLocked() {
        if (mUpdatableFontDir != null) {
            HashMap<String, Typeface> systemFontMap = new HashMap<>();
            Map<String, File> fontFileMap = mUpdatableFontDir.getFontFileMap();
            Pair<FontConfig.Alias[], Map<String, FontFamily[]>> pair =
                    SystemFonts.initializeSystemFonts(fontFileMap);
            Typeface.initSystemDefaultTypefaces(systemFontMap, pair.second, pair.first);
            try {
                return Typeface.serializeFontMap(systemFontMap);
            } catch (IOException | ErrnoException e) {
                Slog.w(TAG, "Failed to serialize updatable font map. "
                        + "Retrying with system image fonts.", e);
            }
        }
        try {
            return Typeface.serializeFontMap(Typeface.getSystemFontMap());
        } catch (IOException | ErrnoException e) {
            Slog.e(TAG, "Failed to serialize SystemServer system font map", e);
        }
        return null;
    }

    private boolean installFontFile(String name, FileDescriptor fd) {
        if (mUpdatableFontDir == null) return false;
        synchronized (FontManagerService.this) {
            try {
                mUpdatableFontDir.installFontFile(name, fd);
            } catch (IOException e) {
                Slog.w(TAG, "Failed to install font file: " + name, e);
                return false;
            }
            // Create updated font map in the next getSerializedSystemFontMap() call.
            mSerializedSystemFontMap = null;
            return true;
        }
    }
}