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Delete the relocations from a PE file.

Post date: Mar 15, 2010 10:05:52 PM

This unit enables you to strip the table of the base relocations (Fix-Up Table) from EXE files and saves space, making them smaller. As a rule, there's no need for an EXE to have a base relocation table. This is because EXEs are the first thing loaded into an address space, and therefore are guaranteed to load at the preferred load address. It is recommend that you do not strip relocations from all EXEs you come across, because while this may save space, it may cause some executables not to work properly. If you take a look at Windows Notepad.exe the relocation table has been stripped.

{

Unit: uStripRelocs

Author: steve10120

Description: Delete the relocations from a PE file.

Website: http://hackhound.org

History: First try

}

unit uStripRelocs;

interface

uses Windows;

function StripRelocations(szFilePath:string; szDestFile:string):Boolean;

type

  TByteArray = array of Byte;

implementation

function FileToBytes(sPath:string; var bFile:TByteArray):Boolean;

var

hFile:    THandle;

dSize:    DWORD;

dRead:    DWORD;

begin

  Result := FALSE;

  hFile := CreateFile(PChar(sPath), GENERIC_READ, FILE_SHARE_READ, nil, OPEN_EXISTING, 0, 0);

  if hFile <> 0 then

  begin

    dSize := GetFileSize(hFile, nil);

    SetFilePointer(hFile, 0, nil, FILE_BEGIN);

    SetLength(bFile, dSize);

    if ReadFile(hFile, bFile[0], dSize, dRead, nil) then

      Result := TRUE;

    CloseHandle(hFile);

  end;

end;

procedure BytesToFile(bData:TByteArray; sPath:string);

var

hFile:    THandle;

dWritten: DWORD;

begin

  hFile := CreateFile(PChar(sPath), GENERIC_WRITE, FILE_SHARE_WRITE, nil, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);

  if hFile <> 0 then

  begin

    SetFilePointer(hFile, 0, nil, FILE_BEGIN);

    WriteFile(hFile, bData[0],Length(bData), dWritten, nil);

    CloseHandle(hFile);

  end;

end;

function StripRelocations(szFilePath:string; szDestFile:string):Boolean;

var

  bFile:      TByteArray;

  IDH:        TImageDosHeader;

  INH:        TImageNtHeaders;

  ISH:        TImageSectionHeader;

  szSecName:  array[0..7] of Char;

begin

  Result := FALSE;

  if FileToBytes(szFilePath, bFile) then

  begin

    CopyMemory(@IDH, @bFile[0], 64);

    if IDH.e_magic = IMAGE_DOS_SIGNATURE then

    begin

      CopyMemory(@INH, @bFile[IDH._lfanew], 248);

      if INH.Signature = IMAGE_NT_SIGNATURE then

      begin

        if (INH.OptionalHeader.DataDirectory[5].VirtualAddress > 0) and (INH.OptionalHeader.DataDirectory[5].Size > 0) then

        begin

          CopyMemory(@ISH, @bFile[IDH._lfanew + 248 + (INH.FileHeader.NumberOfSections - 1) * 40], 40);

          CopyMemory(@szSecName[0], @ISH.Name[0], 8);

          if szSecName = '.reloc' then

          begin

            SetLength(bFile, Length(bFile) - ISH.SizeOfRawData);

            INH.OptionalHeader.DataDirectory[5].VirtualAddress := 0;

            INH.OptionalHeader.DataDirectory[5].Size := 0;

            FillChar(ISH, 40, #0);

            CopyMemory(@bFile[IDH._lfanew + 248 + (INH.FileHeader.NumberOfSections - 1) * 40], @ISH, 40);

            Dec(INH.FileHeader.NumberOfSections);

            CopyMemory(@ISH, @bFile[IDH._lfanew + 248 + (INH.FileHeader.NumberOfSections - 1) * 40], 40);

            INH.OptionalHeader.SizeOfImage := ISH.VirtualAddress + ISH.Misc.VirtualSize;

            CopyMemory(@bFile[IDH._lfanew], @INH, 248);

            BytesToFile(bFile, szDestFile);

            Result := TRUE;

          end;

        end;

      end;

    end;

  end;

end;

end.

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