Subversion Repositories mkgmap

/*
 * Copyright (C) 2012.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 or
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
package uk.me.parabola.mkgmap.main;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import uk.me.parabola.imgfmt.ExitException;
import uk.me.parabola.mkgmap.CommandArgs;

/**
 * Ensure that the TYP file has the correct family and product id's as given by the
 * command line arguments.
 *
 * If they are correct, then returns the original name and nothing else is done.
 *
 * If they are not correct, then a new file is created which patches the id's
 * and its name is returned.
 */
class TypSaver implements MapProcessor {
        public String makeMap(CommandArgs args, String filename) {
                String outfilename = filename;

                // These are the family and product id's that are wanted.
                int familyId = args.get("family-id", CommandArgs.DEFAULT_FAMILYID);
                int productId = args.get("product-id", CommandArgs.DEFAULT_PRODUCTID);

                try (FileInputStream in = new FileInputStream(filename)) {
                        byte[] buf = new byte[256];
                        int n = in.read(buf);
                        if (n == -1)
                                throw new ExitException("TYP file is empty: " + filename);

                        ByteBuffer buffer = ByteBuffer.wrap(buf);
                        buffer.order(ByteOrder.LITTLE_ENDIAN);

                        // Get the product and family id's that are actually in the supplied TYP file.
                        int foundFamily = buffer.getChar(0x2f);
                        int foundProduct = buffer.getChar(0x31);

                        if (familyId != foundFamily || productId != foundProduct) {
                                buffer.putChar(0x2f, (char) familyId);
                                buffer.putChar(0x31, (char) productId);

                                outfilename = makeOutName(filename);
                                writeAlteredTyp(outfilename, in, buf, n);
                        }

                } catch (IOException e) {
                        throw new ExitException("TYP file cannot be opened or read: " + filename);
                }

                return outfilename;
        }

        /**
         * Write out the altered TYP file.
         *
         * @param outFilename The name to write to.
         * @param in The input file. This has already had the first block read from it.
         * @param buf The buffer holding the first block of the file. It is already modified, so just needs
         * to be written out.
         * @param n The number of characters in the first block. The minimum size of the TYP file is
         * less than the buffer size.
         */
        private static void writeAlteredTyp(String outFilename, FileInputStream in, byte[] buf, int n) {
                try (FileOutputStream out = new FileOutputStream(outFilename)) {
                        do {
                                out.write(buf, 0, n);
                        } while ((n = in.read(buf)) > 0);
                } catch (IOException e) {
                        throw new ExitException("Could not write temporary TYP file: " + outFilename);
                }
        }

        /**
         * Create a name for the patched file.
         *
         * We pre-pend a 'x' to the name part of the path.
         *
         * If the name is already 8+3 characters, then the name that appears inside the gmapsupp, will
         * not have the added character and so it is possible to have internal files with the same name.
         * I don't think this matters, since I don't think that the name is important, but I could be wrong.
         *
         * @param path The original name
         * @return The modified name.
         */
        private static String makeOutName(String path) {
                File f = new File(path);
                File dir = f.getParentFile();

                String name = f.getName();

                File out = new File(dir, "x" + name);
                return out.getPath();
        }
}