/*
* Copyright (C) 2011 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.sugree.inputmethod.latin;
import android.content.ContentResolver;
import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.database.Cursor;
import android.net.Uri;
import android.text.TextUtils;
import android.util.Log;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
/**
* Group class for static methods to help with creation and getting of the binary dictionary
* file from the dictionary provider
*/
public class BinaryDictionaryFileDumper {
private static final String TAG = BinaryDictionaryFileDumper.class.getSimpleName();
private static final boolean DEBUG = false;
/**
* The size of the temporary buffer to copy files.
*/
private static final int FILE_READ_BUFFER_SIZE = 1024;
// TODO: make the following data common with the native code
private static final byte[] MAGIC_NUMBER = new byte[] { 0x78, (byte)0xB1 };
private static final String DICTIONARY_PROJECTION[] = { "id" };
// Prevents this class to be accidentally instantiated.
private BinaryDictionaryFileDumper() {
}
/**
* Return for a given locale or dictionary id the provider URI to get the dictionary.
*/
private static Uri getProviderUri(String path) {
return new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT)
.authority(BinaryDictionary.DICTIONARY_PACK_AUTHORITY).appendPath(
path).build();
}
/**
* Queries a content provider for the list of word lists for a specific locale
* available to copy into Latin IME.
*/
private static List<WordListInfo> getWordListWordListInfos(final Locale locale,
final Context context) {
final ContentResolver resolver = context.getContentResolver();
final Uri dictionaryPackUri = getProviderUri(locale.toString());
final Cursor c = resolver.query(dictionaryPackUri, DICTIONARY_PROJECTION, null, null, null);
if (null == c) return Collections.<WordListInfo>emptyList();
if (c.getCount() <= 0 || !c.moveToFirst()) {
c.close();
return Collections.<WordListInfo>emptyList();
}
try {
final List<WordListInfo> list = new ArrayList<WordListInfo>();
do {
final String wordListId = c.getString(0);
final String wordListLocale = c.getString(1);
if (TextUtils.isEmpty(wordListId)) continue;
list.add(new WordListInfo(wordListId, wordListLocale));
} while (c.moveToNext());
c.close();
return list;
} catch (Exception e) {
// Just in case we hit a problem in communication with the dictionary pack.
// We don't want to die.
Log.e(TAG, "Exception communicating with the dictionary pack : " + e);
return Collections.<WordListInfo>emptyList();
}
}
/**
* Helper method to encapsulate exception handling.
*/
private static AssetFileDescriptor openAssetFileDescriptor(final ContentResolver resolver,
final Uri uri) {
try {
return resolver.openAssetFileDescriptor(uri, "r");
} catch (FileNotFoundException e) {
// I don't want to log the word list URI here for security concerns
Log.e(TAG, "Could not find a word list from the dictionary provider.");
return null;
}
}
/**
* Caches a word list the id of which is passed as an argument. This will write the file
* to the cache file name designated by its id and locale, overwriting it if already present
* and creating it (and its containing directory) if necessary.
*/
private static AssetFileAddress cacheWordList(final String id, final String locale,
final ContentResolver resolver, final Context context) {
final int COMPRESSED_CRYPTED_COMPRESSED = 0;
final int CRYPTED_COMPRESSED = 1;
final int COMPRESSED_CRYPTED = 2;
final int COMPRESSED_ONLY = 3;
final int CRYPTED_ONLY = 4;
final int NONE = 5;
final int MODE_MIN = COMPRESSED_CRYPTED_COMPRESSED;
final int MODE_MAX = NONE;
final Uri wordListUri = getProviderUri(id);
final String outputFileName = BinaryDictionaryGetter.getCacheFileName(id, locale, context);
for (int mode = MODE_MIN; mode <= MODE_MAX; ++mode) {
InputStream originalSourceStream = null;
InputStream inputStream = null;
File outputFile = null;
FileOutputStream outputStream = null;
AssetFileDescriptor afd = null;
try {
// Open input.
afd = openAssetFileDescriptor(resolver, wordListUri);
// If we can't open it at all, don't even try a number of times.
if (null == afd) return null;
originalSourceStream = afd.createInputStream();
// Open output.
outputFile = new File(outputFileName);
outputStream = new FileOutputStream(outputFile);
// Get the appropriate decryption method for this try
switch (mode) {
case COMPRESSED_CRYPTED_COMPRESSED:
inputStream = FileTransforms.getUncompressedStream(
FileTransforms.getDecryptedStream(
FileTransforms.getUncompressedStream(
originalSourceStream)));
break;
case CRYPTED_COMPRESSED:
inputStream = FileTransforms.getUncompressedStream(
FileTransforms.getDecryptedStream(originalSourceStream));
break;
case COMPRESSED_CRYPTED:
inputStream = FileTransforms.getDecryptedStream(
FileTransforms.getUncompressedStream(originalSourceStream));
break;
case COMPRESSED_ONLY:
inputStream = FileTransforms.getUncompressedStream(originalSourceStream);
break;
case CRYPTED_ONLY:
inputStream = FileTransforms.getDecryptedStream(originalSourceStream);
break;
case NONE:
inputStream = originalSourceStream;
break;
}
checkMagicAndCopyFileTo(new BufferedInputStream(inputStream), outputStream);
if (0 >= resolver.delete(wordListUri, null, null)) {
Log.e(TAG, "Could not have the dictionary pack delete a word list");
}
// Success! Close files (through the finally{} clause) and return.
return AssetFileAddress.makeFromFileName(outputFileName);
} catch (Exception e) {
if (DEBUG) {
Log.i(TAG, "Can't open word list in mode " + mode + " : " + e);
}
if (null != outputFile) {
// This may or may not fail. The file may not have been created if the
// exception was thrown before it could be. Hence, both failure and
// success are expected outcomes, so we don't check the return value.
outputFile.delete();
}
// Try the next method.
} finally {
// Ignore exceptions while closing files.
try {
// afd.close() will close inputStream, we should not call inputStream.close().
if (null != afd) afd.close();
} catch (Exception e) {
Log.e(TAG, "Exception while closing a cross-process file descriptor : " + e);
}
try {
if (null != outputStream) outputStream.close();
} catch (Exception e) {
Log.e(TAG, "Exception while closing a file : " + e);
}
}
}
// We could not copy the file at all. This is very unexpected.
// I'd rather not print the word list ID to the log out of security concerns
Log.e(TAG, "Could not copy a word list. Will not be able to use it.");
// If we can't copy it we should probably delete it to avoid trying to copy it over
// and over each time we open LatinIME.
if (0 >= resolver.delete(wordListUri, null, null)) {
Log.e(TAG, "In addition, we were unable to delete it.");
}
return null;
}
/**
* Queries a content provider for word list data for some locale and cache the returned files
*
* This will query a content provider for word list data for a given locale, and copy the
* files locally so that they can be mmap'ed. This may overwrite previously cached word lists
* with newer versions if a newer version is made available by the content provider.
* @returns the addresses of the word list files, or null if no data could be obtained.
* @throw FileNotFoundException if the provider returns non-existent data.
* @throw IOException if the provider-returned data could not be read.
*/
public static List<AssetFileAddress> cacheWordListsFromContentProvider(final Locale locale,
final Context context) {
final ContentResolver resolver = context.getContentResolver();
final List<WordListInfo> idList = getWordListWordListInfos(locale, context);
final List<AssetFileAddress> fileAddressList = new ArrayList<AssetFileAddress>();
for (WordListInfo id : idList) {
final AssetFileAddress afd = cacheWordList(id.mId, id.mLocale, resolver, context);
if (null != afd) {
fileAddressList.add(afd);
}
}
return fileAddressList;
}
/**
* Copies the data in an input stream to a target file if the magic number matches.
*
* If the magic number does not match the expected value, this method throws an
* IOException. Other usual conditions for IOException or FileNotFoundException
* also apply.
*
* @param input the stream to be copied.
* @param outputFile an outputstream to copy the data to.
*/
private static void checkMagicAndCopyFileTo(final BufferedInputStream input,
final FileOutputStream output) throws FileNotFoundException, IOException {
// Check the magic number
final byte[] magicNumberBuffer = new byte[MAGIC_NUMBER.length];
final int readMagicNumberSize = input.read(magicNumberBuffer, 0, MAGIC_NUMBER.length);
if (readMagicNumberSize < MAGIC_NUMBER.length) {
throw new IOException("Less bytes to read than the magic number length");
}
if (!Arrays.equals(MAGIC_NUMBER, magicNumberBuffer)) {
throw new IOException("Wrong magic number for downloaded file");
}
output.write(MAGIC_NUMBER);
// Actually copy the file
final byte[] buffer = new byte[FILE_READ_BUFFER_SIZE];
for (int readBytes = input.read(buffer); readBytes >= 0; readBytes = input.read(buffer))
output.write(buffer, 0, readBytes);
input.close();
}
}