128 lines
3.7 KiB
Java
128 lines
3.7 KiB
Java
package com.webcodepro.shrinkit;
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import java.io.IOException;
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import java.util.Date;
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import com.webcodepro.shrinkit.io.LittleEndianByteInputStream;
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/**
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* The Master Header Block contains information about the entire
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* ShrinkIt archive.
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* <p>
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* Note that we need to support multiple versions of the NuFX
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* archive format. Some details may be invalid, depending on
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* version, and those are documented in the getter methods.
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*
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* @author robgreene@users.sourceforge.net
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* @see http://www.nulib.com/library/FTN.e08002.htm
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*/
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public class MasterHeaderBlock {
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private static final int MASTER_HEADER_LENGTH = 48;
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private int masterCrc;
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private boolean validCrc;
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private long totalRecords;
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private Date archiveCreateWhen;
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private Date archiveModWhen;
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private int masterVersion;
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private long masterEof;
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private byte[] nuFileId = {0,0,0,0,0,0};
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/**
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* Create the Master Header Block, based on the LittleEndianByteInputStream.
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*/
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public MasterHeaderBlock(LittleEndianByteInputStream bs) throws IOException {
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int headerOffset = 0; // Binary II wrappers will need to bump out the normal header size
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nuFileId = bs.readBytes(6);
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if (checkId(nuFileId,BXY_ID)) {
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// Binary II wrapper present...
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bs.readBytes(127 - NUFILE_ID.length);
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headerOffset = 128;
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int count = bs.read();
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if (count != 0)
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throw new IOException("This is actually a Binary II archive with multiple files in it.");
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nuFileId = bs.readBytes(6);
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}
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if (!checkId(nuFileId,NUFILE_ID)) {
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throw new IOException("Unable to decode this archive.");
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}
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masterCrc = bs.readWord();
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bs.resetCrc(); // CRC is computed from this point to the end of the header
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totalRecords = bs.readLong();
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archiveCreateWhen = bs.readDate();
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archiveModWhen = bs.readDate();
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masterVersion = bs.readWord();
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if (masterVersion > 0) {
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bs.readBytes(8); // documented to be null, but we don't care
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masterEof = bs.readLong();
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} else {
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masterEof = -1;
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}
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// Read whatever remains of the fixed size header
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while (bs.getTotalBytesRead() < MASTER_HEADER_LENGTH + headerOffset) {
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bs.readByte();
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}
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validCrc = (masterCrc == bs.getCrcValue());
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}
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// GENERATED CODE
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public int getMasterCrc() {
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return masterCrc;
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}
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public void setMasterCrc(int masterCrc) {
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this.masterCrc = masterCrc;
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}
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public long getTotalRecords() {
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return totalRecords;
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}
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public void setTotalRecords(long totalRecords) {
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this.totalRecords = totalRecords;
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}
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public Date getArchiveCreateWhen() {
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return archiveCreateWhen;
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}
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public void setArchiveCreateWhen(Date archiveCreateWhen) {
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this.archiveCreateWhen = archiveCreateWhen;
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}
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public Date getArchiveModWhen() {
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return archiveModWhen;
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}
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public void setArchiveModWhen(Date archiveModWhen) {
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this.archiveModWhen = archiveModWhen;
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}
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public int getMasterVersion() {
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return masterVersion;
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}
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public void setMasterVersion(int masterVersion) {
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this.masterVersion = masterVersion;
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}
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public long getMasterEof() {
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return masterEof;
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}
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public void setMasterEof(long masterEof) {
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this.masterEof = masterEof;
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}
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public boolean isValidCrc() {
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return validCrc;
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}
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/**
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* Test that the requested constant is present.
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*/
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private boolean checkId(byte[] data, byte[] constant) {
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for (int i = 0; i < constant.length; i++){
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if (data[i] != constant[i])
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return false;
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}
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return true;
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}
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/** Master Header Block identifier "magic" bytes. */
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public static final byte[] NUFILE_ID = { 0x4e, (byte)0xf5, 0x46, (byte)0xe9, 0x6c, (byte)0xe5 };
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/** Header Block identifier "magic" bytes. */
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public static final byte[] NUFX_ID = { 0x4e, (byte)0xf5, 0x46, (byte)0xd8 };
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/** Binay II identifier "magic" bytes. */
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public static final byte[] BXY_ID = { 0x0a, 0x47, 0x4c };
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}
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