Reading from Resource Section Api Replacement

program Test;

// steve10120@ic0de.org

uses Windows, SysUtils;

{$R resource.Res} // resource.rc = EXE FILE "Hello.exe" //

type

  { Resource Dir String }

  PImageResourceDirString = ^TImageResourceDirString;

  TImageResourceDirString = packed record

    Length: Word;

    NameString: array[0..0] of WCHAR;

  end;

  { Data Entry }

  PImageResourceDataEntry = ^TImageResourceDataEntry;

  TImageResourceDataEntry = packed record

    OffsetToData: DWORD;

    Size: DWORD;

    CodePage: DWORD;

    Reserved: DWORD;

  end;

  { Dir Entry }

  PImageResourceDirectoryEntry = ^TImageResourceDirectoryEntry;

  TImageResourceDirectoryEntry = packed record

    Name: DWORD;

    OffsetToData: DWORD;

  end;

  { Directory }

  PImageResourceDirectory = ^TImageResourceDirectory;

  TImageResourceDirectory = packed record

    Characteristics: DWORD;

    TimeDateStamp: DWORD;

    MajorVersion: Word;

    MinorVersion: Word;

    NumberOfNamedEntries: Word;

    NumberOfIdEntries: Word;

  end;

const

  IMAGE_RESOURCE_DATA_IS_DIRECTORY: DWORD = $80000000;

  IMAGE_STRIP_HIGH_BIT:             DWORD = $7FFFFFFF;

function StripHighBit(dwValue:DWORD):DWORD;

begin

  Result := dwValue and IMAGE_STRIP_HIGH_BIT;

end;

function IsDirectory(dwValue:DWORD):Boolean;

begin

  Result := FALSE;

  if ((dwValue and IMAGE_RESOURCE_DATA_IS_DIRECTORY) <> 0) then

    Result := TRUE;

end;

function WideCharToMultiByteEx(var lp: PWideChar): string; // function from ErazerZ's UntPeFile

var

  len: Word;

begin

  len := Word(lp^);

  SetLength(Result, len);

  Inc(lp);

  WideCharToMultiByte(CP_ACP, 0, lp, Len, PChar(Result), Len +1, nil, nil);

  Inc(lp, len);

  Result := PChar(Result);

end;

function GetResource(szResourceType:string; szResourceName:string; var pResource:Pointer; var dwResourceSize:DWORD):Boolean;

var

  IDH:              PImageDosHeader;

  INH:              PImageNtHeaders;

  i:                DWORD;

  RootIRD:          PImageResourceDirectory;

  SubIRD:           PImageResourceDirectory;

  DataIRD:          PImageResourceDirectory;

  RootEntry:        PImageResourceDirectoryEntry;

  SubEntry:         PImageResourceDirectoryEntry;

  DataEntry:        PImageResourceDirectoryEntry;

  ResData:          PImageResourceDataEntry;

  ResType:          PImageResourceDirString;

  ResName:          PImageResourceDirString;

  hModule:          DWORD;

  szResType:        string;

  szResName:        string;

begin

  Result := FALSE;

  hModule := GetModuleHandle(nil);

  if (hModule <> 0) then

  begin

    IDH := Pointer(hModule);

    if (IDH^.e_magic = IMAGE_DOS_SIGNATURE) then

    begin

      INH := Pointer(hModule + IDH^._lfanew);

      if (INH^.Signature = IMAGE_NT_SIGNATURE) then

      begin

        if (INH^.OptionalHeader.DataDirectory[2].VirtualAddress > 0) then

        begin

          RootIRD := Pointer(hModule + INH^.OptionalHeader.DataDirectory[2].VirtualAddress);

          RootEntry := Pointer(DWORD(RootIRD) + SizeOf(TImageResourceDirectory));

          for i := 0 to (RootIRD^.NumberOfNamedEntries + RootIRD^.NumberOfIdEntries) - 1 do

          begin

            if (IsDirectory(RootEntry^.Name)) then

            begin

              ResType := Pointer(hModule + INH^.OptionalHeader.DataDirectory[2].VirtualAddress + StripHighBit(RootEntry^.Name));

              szResType := WideCharToMultiByteEx(PWideChar(DWORD(ResType)));

              if (szResType = szResourceType) then

              begin

                SubIRD := Pointer(DWORD(RootIRD) + StripHighBit(RootEntry^.OffsetToData));

                SubEntry := Pointer(DWORD(SubIRD) + SizeOf(TImageResourceDirectory));

                if (IsDirectory(SubEntry^.Name)) then

                begin

                  ResName := Pointer(DWORD(RootIRD) + StripHighBit(SubEntry^.Name));

                  szResName := WideCharToMultiByteEx(PWideChar(DWORD(ResName)));

                  if (szResName = szResourceName) then

                  begin

                    Result := TRUE;

                    DataIRD := Pointer(DWORD(RootIRD) + StripHighBit(SubEntry^.OffsetToData));

                    DataEntry := Pointer(DWORD(DataIRD) + SizeOf(TImageResourceDirectory));

                    ResData := Pointer(DWORD(RootIRD) + DataEntry^.OffsetToData);

                    pResource := Pointer(hModule + ResData^.OffsetToData);

                    dwResourceSize := ResData^.Size;

                    Exit;

                  end;

                end;

              end;

            end;                                

            Inc(RootEntry);

          end;

        end;

      end;                       

    end;

  end;

end;

var

  pRes:   Pointer;

  dwSize: DWORD;

  szMsg:  string;

begin

  if (GetResource('FILE', 'EXE', pRes, dwSize)) then

  begin

    szMsg := 'Address: ' + IntToHex(DWORD(pRes), 8) + #13#10 +

    'Size: ' + IntToHex(dwSize, 8) + #13#10 +

    'First byte: ' + IntToHex(PByte(pRes)^, 0);

    MessageBoxA(0, PChar(szMsg), 'RESOURCES', 0);

  end;

end.