FixedDtdInputStream.java

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/*
 * Gridarta MMORPG map editor for Crossfire, Daimonin and similar games.
 * Copyright (C) 2000-2023 The Gridarta Developers.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
package net.sf.gridarta.utils.xml;
 
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
 
public class FixedDtdInputStream extends InputStream {
 
    @NotNull
    private final InputStream inputStream;
 
    @NotNull
    private final String rootElement;
 
    @NotNull
    private final String systemId;
 
    private int state;
 
    @Nullable
    private InputStream inject;
 
    public FixedDtdInputStream(@NotNull final InputStream inputStream, @NotNull final String rootElement, @NotNull final String systemId) {
        this.inputStream = inputStream;
        this.rootElement = rootElement;
        this.systemId = systemId;
    }
 
    @Override
    public int read() throws IOException {
        if (inject != null) {
            final int ch = inject.read();
            if (ch != -1) {
                return ch;
            }
            inject = null;
        }
 
        final int ch = inputStream.read();
        if (ch == -1) {
            return -1;
        }
 
        switch (state) {
        case 0:
            if (ch == '<') {
                state = 1;
            }
            break;
 
        case 1:
            if (ch == '?') {
                state = 2;
            } else if (ch == '!') {
                state = 4;
            } else {
                final String doctypeDeclaration = "DOCTYPE " + rootElement + " SYSTEM \"" + systemId + "\"><" + (char) ch;
                inject = new ByteArrayInputStream(doctypeDeclaration.getBytes(StandardCharsets.US_ASCII));
                state = 12;
                return '!';
            }
            break;
 
        case 2:
            if (ch == '?') {
                state = 3;
            }
            break;
 
        case 3:
            if (ch == '>') {
                state = 0;
            } else if (ch != '?') {
                state = 2;
            }
            break;
 
        case 4:
            if (ch == 'D') {
                state = 5;
            } else {
                state = 11;
            }
            break;
 
        case 5:
            if (ch == 'O') {
                state = 6;
            } else {
                state = 11;
            }
            break;
 
        case 6:
            if (ch == 'C') {
                state = 7;
            } else {
                state = 11;
            }
            break;
 
        case 7:
            if (ch == 'T') {
                state = 8;
            } else {
                state = 11;
            }
            break;
 
        case 8:
            if (ch == 'Y') {
                state = 9;
            } else {
                state = 11;
            }
            break;
 
        case 9:
            if (ch == 'P') {
                state = 10;
            } else {
                state = 11;
            }
            break;
 
        case 10:
            if (ch == 'E') {
                state = 12;
            } else {
                state = 11;
            }
            break;
 
        case 11:
            if (ch == '>') {
                state = 0;
            }
            break;
 
        case 12:
            break;
        }
 
        return ch;
    }
 
}