Merge "Check the magic number of a decoded file"

import android.text.TextUtils;

import android.util.Log;

import java.io.BufferedInputStream;

import java.io.File;

import java.io.FileInputStream;

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;

    /**

     * The size of the temporary buffer to copy files.

     */

    static final int FILE_READ_BUFFER_SIZE = 1024;

    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" };

        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 {

                if (null == afd) return null;

                originalSourceStream = afd.createInputStream();

                // Open output.

                outputStream = new FileOutputStream(outputFileName);

                outputFile = new File(outputFileName);

                outputStream = new FileOutputStream(outputFile);

                // Get the appropriate decryption method for this try

                switch (mode) {

                    case COMPRESSED_CRYPTED_COMPRESSED:

                        inputStream = originalSourceStream;

                        break;

                    }

                copyFileTo(inputStream, outputStream);

                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");

                }

                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.

    }

    /**

     * Copies the data in an input stream to a target file.

     * 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 copyFileTo(final InputStream input, final FileOutputStream output)

            throws FileNotFoundException, IOException {

    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);