Dec2017-Script-Dump/ICSharpCode.SharpZipLib/GZip/GZipInputStream.cs

using System;
using System.IO;
using ICSharpCode.SharpZipLib.Checksums;
using ICSharpCode.SharpZipLib.Zip.Compression;
using ICSharpCode.SharpZipLib.Zip.Compression.Streams;

namespace ICSharpCode.SharpZipLib.GZip
{
	// Token: 0x0200002A RID: 42
	public class GZipInputStream : InflaterInputStream
	{
		// Token: 0x0600012B RID: 299 RVA: 0x00008661 File Offset: 0x00007661
		public GZipInputStream(Stream baseInputStream)
			: this(baseInputStream, 4096)
		{
		}

		// Token: 0x0600012C RID: 300 RVA: 0x0000866F File Offset: 0x0000766F
		public GZipInputStream(Stream baseInputStream, int size)
			: base(baseInputStream, new Inflater(true), size)
		{
		}

		// Token: 0x0600012D RID: 301 RVA: 0x00008680 File Offset: 0x00007680
		public override int Read(byte[] buffer, int offset, int count)
		{
			while (this.readGZIPHeader || this.ReadHeader())
			{
				int num = base.Read(buffer, offset, count);
				if (num > 0)
				{
					this.crc.Update(buffer, offset, num);
				}
				if (this.inf.IsFinished)
				{
					this.ReadFooter();
				}
				if (num > 0)
				{
					return num;
				}
			}
			return 0;
		}

		// Token: 0x0600012E RID: 302 RVA: 0x000086D4 File Offset: 0x000076D4
		private bool ReadHeader()
		{
			this.crc = new Crc32();
			if (this.inputBuffer.Available <= 0)
			{
				this.inputBuffer.Fill();
				if (this.inputBuffer.Available <= 0)
				{
					return false;
				}
			}
			Crc32 crc = new Crc32();
			int num = this.inputBuffer.ReadLeByte();
			if (num < 0)
			{
				throw new EndOfStreamException("EOS reading GZIP header");
			}
			crc.Update(num);
			if (num != 31)
			{
				throw new GZipException("Error GZIP header, first magic byte doesn't match");
			}
			num = this.inputBuffer.ReadLeByte();
			if (num < 0)
			{
				throw new EndOfStreamException("EOS reading GZIP header");
			}
			if (num != 139)
			{
				throw new GZipException("Error GZIP header,  second magic byte doesn't match");
			}
			crc.Update(num);
			int num2 = this.inputBuffer.ReadLeByte();
			if (num2 < 0)
			{
				throw new EndOfStreamException("EOS reading GZIP header");
			}
			if (num2 != 8)
			{
				throw new GZipException("Error GZIP header, data not in deflate format");
			}
			crc.Update(num2);
			int num3 = this.inputBuffer.ReadLeByte();
			if (num3 < 0)
			{
				throw new EndOfStreamException("EOS reading GZIP header");
			}
			crc.Update(num3);
			if ((num3 & 224) != 0)
			{
				throw new GZipException("Reserved flag bits in GZIP header != 0");
			}
			for (int i = 0; i < 6; i++)
			{
				int num4 = this.inputBuffer.ReadLeByte();
				if (num4 < 0)
				{
					throw new EndOfStreamException("EOS reading GZIP header");
				}
				crc.Update(num4);
			}
			if ((num3 & 4) != 0)
			{
				for (int j = 0; j < 2; j++)
				{
					int num5 = this.inputBuffer.ReadLeByte();
					if (num5 < 0)
					{
						throw new EndOfStreamException("EOS reading GZIP header");
					}
					crc.Update(num5);
				}
				if (this.inputBuffer.ReadLeByte() < 0 || this.inputBuffer.ReadLeByte() < 0)
				{
					throw new EndOfStreamException("EOS reading GZIP header");
				}
				int num6 = this.inputBuffer.ReadLeByte();
				int num7 = this.inputBuffer.ReadLeByte();
				if (num6 < 0 || num7 < 0)
				{
					throw new EndOfStreamException("EOS reading GZIP header");
				}
				crc.Update(num6);
				crc.Update(num7);
				int num8 = (num6 << 8) | num7;
				for (int k = 0; k < num8; k++)
				{
					int num9 = this.inputBuffer.ReadLeByte();
					if (num9 < 0)
					{
						throw new EndOfStreamException("EOS reading GZIP header");
					}
					crc.Update(num9);
				}
			}
			if ((num3 & 8) != 0)
			{
				int num10;
				while ((num10 = this.inputBuffer.ReadLeByte()) > 0)
				{
					crc.Update(num10);
				}
				if (num10 < 0)
				{
					throw new EndOfStreamException("EOS reading GZIP header");
				}
				crc.Update(num10);
			}
			if ((num3 & 16) != 0)
			{
				int num11;
				while ((num11 = this.inputBuffer.ReadLeByte()) > 0)
				{
					crc.Update(num11);
				}
				if (num11 < 0)
				{
					throw new EndOfStreamException("EOS reading GZIP header");
				}
				crc.Update(num11);
			}
			if ((num3 & 2) != 0)
			{
				int num12 = this.inputBuffer.ReadLeByte();
				if (num12 < 0)
				{
					throw new EndOfStreamException("EOS reading GZIP header");
				}
				int num13 = this.inputBuffer.ReadLeByte();
				if (num13 < 0)
				{
					throw new EndOfStreamException("EOS reading GZIP header");
				}
				num12 = (num12 << 8) | num13;
				if (num12 != ((int)crc.Value & 65535))
				{
					throw new GZipException("Header CRC value mismatch");
				}
			}
			this.readGZIPHeader = true;
			return true;
		}

		// Token: 0x0600012F RID: 303 RVA: 0x000089E0 File Offset: 0x000079E0
		private void ReadFooter()
		{
			byte[] array = new byte[8];
			long num = this.inf.TotalOut & (long)((ulong)(-1));
			this.inputBuffer.Available += this.inf.RemainingInput;
			this.inf.Reset();
			int num2;
			for (int i = 8; i > 0; i -= num2)
			{
				num2 = this.inputBuffer.ReadClearTextBuffer(array, 8 - i, i);
				if (num2 <= 0)
				{
					throw new EndOfStreamException("EOS reading GZIP footer");
				}
			}
			int num3 = (int)(array[0] & byte.MaxValue) | ((int)(array[1] & byte.MaxValue) << 8) | ((int)(array[2] & byte.MaxValue) << 16) | ((int)array[3] << 24);
			if (num3 != (int)this.crc.Value)
			{
				throw new GZipException(string.Concat(new object[]
				{
					"GZIP crc sum mismatch, theirs \"",
					num3,
					"\" and ours \"",
					(int)this.crc.Value
				}));
			}
			uint num4 = (uint)((int)(array[4] & byte.MaxValue) | ((int)(array[5] & byte.MaxValue) << 8) | ((int)(array[6] & byte.MaxValue) << 16) | ((int)array[7] << 24));
			if (num != (long)((ulong)num4))
			{
				throw new GZipException("Number of bytes mismatch in footer");
			}
			this.readGZIPHeader = false;
		}

		// Token: 0x040000AB RID: 171
		protected Crc32 crc;

		// Token: 0x040000AC RID: 172
		private bool readGZIPHeader;
	}
}