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//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
/*
* Copyright (c) 2002 Sergey Chaban <serge@wildwestsoftware.com>
*/
// see http://cvs.winehq.com/cvsweb/wine/dlls/imagehlp/modify.c
// starting from Revision 1.8
using System;
using System.IO;
namespace Mono.PEToolkit {
public sealed class CheckSum {
private CheckSum()
{
// Never instantiated.
}
public static uint Calc(string peFile)
{
uint res = 0;
FileInfo pe = new FileInfo(peFile);
if (!pe.Exists) {
throw new Exception("CheckSum : Invalid file path.");
}
using (BinaryReader reader = new BinaryReader(pe.OpenRead())) {
if (!reader.BaseStream.CanSeek) {
throw new Exception("Can't seek.");
}
DOSHeader dosHdr = new DOSHeader();
COFFHeader coffHdr = new COFFHeader();
PEHeader peHdr = new PEHeader();
dosHdr.Read (reader);
reader.BaseStream.Position = dosHdr.Lfanew;
ExeSignature peSig = (ExeSignature) reader.ReadUInt16();
if (peSig != ExeSignature.NT) {
throw new BadImageException("Checksum : Invalid image format, cannot find PE signature.");
}
peSig = (ExeSignature) reader.ReadUInt16();
if (peSig != ExeSignature.NT2) {
throw new BadImageException("Checksum : Invalid image format, cannot find PE signature.");
}
coffHdr.Read(reader);
peHdr.Read(reader);
uint oldSum = peHdr.CheckSum;
reader.BaseStream.Position = 0;
long len = pe.Length;
long whole = len >> 1;
uint sum = 0;
uint hi, lo;
for (long i = whole; --i >= 0;) {
sum += reader.ReadUInt16();
hi = sum >> 16;
if (hi != 0) {
sum = hi + (sum & 0xFFFF);
}
}
if ((len & 1L) != 0) {
sum += (uint) reader.ReadByte();
hi = sum >> 16;
if (hi != 0) {
sum = hi + (sum & 0xFFFF);
}
}
// fix low word of checksum
lo = oldSum & 0xFFFF;
if ((sum & 0xFFFF) >= lo) {
sum -= lo;
} else {
sum = (((sum & 0xFFFF) - lo) & 0xFFFF) - 1;
}
// fix high word of checksum
hi = oldSum >> 16;
if ((sum & 0xFFFF) >= hi) {
sum -= hi;
} else {
sum = (((sum & 0xFFFF) - hi) & 0xFFFF) - 1;
}
}
return res;
}
}
}
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