// Shared.cs
//
// Copyright (c) 2006, 2007 Microsoft Corporation. All rights reserved.
//
// Part of an implementation of a zipfile class library.
// See the file ZipFile.cs for further information.
//
// Tue, 27 Mar 2007 15:30
using System;
namespace newtelligence.DasBlog.Util.Zip{
class Shared
{
protected internal static string StringFromBuffer(byte[] buf, int start, int maxlength)
{
int i;
char[] c = new char[maxlength];
for (i = 0; (i < maxlength) && (i < buf.Length) && (buf[i] != 0); i++)
{
c[i] = (char)buf[i]; // System.BitConverter.ToChar(buf, start+i*2);
}
string s = new System.String(c, 0, i);
return s;
}
protected internal static int ReadSignature(System.IO.Stream s)
{
int n = 0;
byte[] sig = new byte[4];
n = s.Read(sig, 0, sig.Length);
if (n != sig.Length) throw new Exception("Could not read signature - no data!");
int signature = (((sig[3] * 256 + sig[2]) * 256) + sig[1]) * 256 + sig[0];
return signature;
}
protected internal static long FindSignature(System.IO.Stream s, int SignatureToFind)
{
long startingPosition = s.Position;
int BATCH_SIZE = 1024;
byte[] targetBytes = new byte[4];
targetBytes[0] = (byte) (SignatureToFind >> 24);
targetBytes[1] = (byte) ((SignatureToFind & 0x00FF0000) >> 16);
targetBytes[2] = (byte) ((SignatureToFind & 0x0000FF00) >> 8);
targetBytes[3] = (byte) (SignatureToFind & 0x000000FF);
byte[] batch = new byte[BATCH_SIZE];
int n = 0;
bool success = false;
do
{
n = s.Read(batch, 0, batch.Length);
if (n != 0)
{
for (int i = 0; i < n; i++)
{
if (batch[i] == targetBytes[3])
{
s.Seek(i - n, System.IO.SeekOrigin.Current);
int sig = ReadSignature(s);
success = (sig == SignatureToFind);
if (!success) s.Seek(-3, System.IO.SeekOrigin.Current);
break; // out of for loop
}
}
}
else break;
if (success) break;
} while (true);
if (!success)
{
s.Seek(startingPosition, System.IO.SeekOrigin.Begin);
return -1; // or throw?
}
// subtract 4 for the signature.
long bytesRead = (s.Position - startingPosition) - 4 ;
// number of bytes read, should be the same as compressed size of file
return bytesRead;
}
protected internal static DateTime PackedToDateTime(Int32 packedDateTime)
{
Int16 packedTime = (Int16)(packedDateTime & 0x0000ffff);
Int16 packedDate = (Int16)((packedDateTime & 0xffff0000) >> 16);
int year = 1980 + ((packedDate & 0xFE00) >> 9);
int month = (packedDate & 0x01E0) >> 5;
int day = packedDate & 0x001F;
int hour = (packedTime & 0xF800) >> 11;
int minute = (packedTime & 0x07E0) >> 5;
int second = packedTime & 0x001F;
DateTime d = System.DateTime.Now;
try { d = new System.DateTime(year, month, day, hour, minute, second, 0); }
catch
{
Console.Write("\nInvalid date/time?:\nyear: {0} ", year);
Console.Write("month: {0} ", month);
Console.WriteLine("day: {0} ", day);
Console.WriteLine("HH:MM:SS= {0}:{1}:{2}", hour, minute, second);
}
return d;
}
protected internal static Int32 DateTimeToPacked(DateTime time)
{
UInt16 packedDate = (UInt16)((time.Day & 0x0000001F) | ((time.Month << 5) & 0x000001E0) | (((time.Year - 1980) << 9) & 0x0000FE00));
UInt16 packedTime = (UInt16)((time.Second & 0x0000001F) | ((time.Minute << 5) & 0x000007E0) | ((time.Hour << 11) & 0x0000F800));
return (Int32)(((UInt32)(packedDate << 16)) | packedTime);
}
}
}
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