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82 lines
2.8 KiB
C#
82 lines
2.8 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Runtime.InteropServices;
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using System.Text;
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using System.Threading.Tasks;
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namespace SCJMapper_V2.p4kFile
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{
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/// Represents an Z64EndOfCentralDirLocator entry in the p4k file
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/// The file seems to be based on a Zip64 file structure
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internal class p4kZ64EndOfCentralDirLocator
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{
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/// <summary>
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/// ctor: Create class from data returned by the Reader
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/// </summary>
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/// <param name="reader">A binary data reader for this type of data already positioned</param>
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public p4kZ64EndOfCentralDirLocator( p4kRecReader reader )
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{
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// sanity check only
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System.Diagnostics.Trace.Assert( Marshal.SizeOf( typeof( MyRecord ) ) == RecordLength,
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"Record size does not match!(" + Marshal.SizeOf( typeof( MyRecord ) ).ToString( ) + ")" );
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if ( reader.IsOpen( ) ) {
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try {
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long cPos = p4kSignatures.FindSignatureInPageBackwards( reader, p4kSignatures.Z64EndOfCentralDirLocator );
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if ( cPos >= 0 ) {
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m_recordOffset = cPos;
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reader.Seek( cPos );
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m_item = p4kRecReader.ByteToType<MyRecord>( reader.TheReader );
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m_itemValid = true;
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}
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}
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catch {
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m_itemValid = false;
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m_recordOffset = -1;
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}
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finally {
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if ( !m_itemValid ) {
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throw new OperationCanceledException( string.Format( "EOF - cannot find Z64EndOfCentralDirLocator" ) );
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}
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}
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}
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}
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public bool IsValid { get => m_itemValid; }
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public long RecordOffset { get => m_recordOffset; }
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public long Z64EndOfCentralDir
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{
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get {
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if ( m_itemValid )
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return (long)m_item.OffsetOfz64EofCDir;
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else
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return -1;
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}
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}
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private MyRecord m_item;
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private bool m_itemValid = false;
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private long m_recordOffset = -1; // offset from start (current position)
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//4.3.15 Zip64 end of central directory locator
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private const int RecordLength = 20;
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[StructLayout( LayoutKind.Sequential, Pack = 1 )] // , Size = RecordLength
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private struct MyRecord
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{
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[MarshalAs( UnmanagedType.ByValArray, SizeConst = 4 )]
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public byte[] ID; // zip64 end of central dir locator signature 4 bytes(0x07064b50)
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[MarshalAs( UnmanagedType.U4 )]
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public UInt32 DiskNumber; // number of the disk with the start of the zip64 end of central directory 4 bytes
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[MarshalAs( UnmanagedType.U8 )]
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public UInt64 OffsetOfz64EofCDir; // relative offset of the zip64 end of central directory record 8 bytes (pts to Z64CentralDirRecEnd)
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[MarshalAs( UnmanagedType.U4 )]
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public UInt32 TotalNumEntries; // total number of disks 4 bytes
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}
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}
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}
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