Modifying a string in resource of an exe

Question

How do I modify buffer in following code then save the changes in resource of the executable? I'm looking for something like SetString(handle,index,buffer,size).

var
  hExe : Cardinal;
  buffer : array [0..4097] of ansichar;
begin
  hExe:=LoadLibraryEx(PAnsiChar(Edit2.Text),0,LOAD_LIBRARY_AS_DATAFILE);
  LoadString(hExe,65300,buffer,SizeOf(buffer));
  ShowMessage(buffer);
  //need to modify buffer here then I'll unload the resources..
end;

Update: Here's my attempt on UpdateResource

var
  hEXE: DWORD;
  pData: PAnsiChar;
begin
  pData := PAnsiChar(Edit1.Text);
  hEXE := BeginUpdateResource(pchar(edit2.text), FALSE);
  if hEXE <> 0 then
  begin
    UpdateResource(hEXE, RT_string, MAKEINTRESOURCE(4082), LANG_NEUTRAL,
      @pData, Length(pData)); //if i change 4082 to 65300 it creates another key like 4082
    EndUpdateResource(hEXE, FALSE);
  end;

This code messes up the whole 4082 content. The problem is item named 4082 in RT_STRING is group of strings. When I open the exe in a resource editor, click string table then 4082 the result is:

STRINGTABLE
LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
{
65296,  "Unicode"
65297,  "Big Endian Unicode"
65298,  "UTF-8"
65299,  "UTF-7"
65300,  "ABCDE12345"
}

So I either need to parse the string group or I need an API to set modify string with the index 65300 in the group. Any ideas?

Answer 1

I've found the answer using Google. (English translation from Chinese) Thanks anyways everyone!

procedure UpdateResString(AFileName, ANewString: string; AStringIdent: Integer);
  procedure WriteToArray(AArray: TByteDynArray; AData: Word; var APos: Integer);
  begin
    AArray[APos] := Lo(AData);
    AArray[APos + 1] := Hi(AData);
    Inc(APos, 2);
  end;

  function ReadFromArray(AArray: TByteDynArray; APos: Integer): Word;
  begin
    Result := AArray[APos] + AArray[APos + 1] * 16;
  end;

var
  hModule, hResInfo, hUpdate: THandle;
  ResData, TempData: TByteDynArray;
  wsNewString: WideString;
  iSection, iIndexInSection: Integer;
  i, iLen, iSkip, iPos: Integer;
begin
  hModule := LoadLibrary(PChar(AFileName));
  if hModule = 0 then
    raise Exception.CreateFmt('file %s failed to load.', [AFileName]);

  // Calculate the resource string area and the string index in that area
  iSection := AStringIdent div 16 + 1;
  iIndexInSection := AStringIdent mod 16;

  // If the resource already exists, then read it out of the original data
  hResInfo := FindResource(hModule, MakeIntResource(iSection), RT_STRING);
  if hResInfo <> 0 then
  begin
    iLen := SizeOfResource(hModule, hResInfo);
    SetLength(ResData, iLen);
    CopyMemory(ResData, LockResource(LoadResource(hModule, hResInfo)), iLen);
  end;
  // Should first close the file, and then update
  FreeLibrary(hModule);
  // Calculate the new data is written to location
  wsNewString := WideString(ANewString);
  iLen := Length(wsNewString);
  iPos := 0;
  for i := 0 to iIndexInSection do
  begin
    if iPos > High(ResData) then
      SetLength(ResData, iPos + 2);
    if i <> iIndexInSection then
    begin
      iSkip := (ReadFromArray(ResData, iPos) + 1) * 2;
      Inc(iPos, iSkip);
    end;
  end;

  // Delete the original data and the data behind the temporary
  // storage of data to be added
  iSkip := (ReadFromArray(ResData, iPos) + 1) * 2;
  TempData := Copy(ResData, iPos + iSkip, Length(ResData) - iSkip);
  SetLength(ResData, iPos);
  SetLength(ResData, iPos + (iLen + 1) * 2 + Length(TempData));

  // Write new data
  WriteToArray(ResData, iLen, iPos);
  for i := 1 to iLen do
    WriteToArray(ResData, Ord(wsNewString[i]), iPos);
  // Write back to the original data
  for i := 0 to High(TempData) do
    ResData[iPos + i] := TempData[i];

  // Write the data back to file
  hUpdate := BeginUpdateResource(PChar(AFileName), False);
  if hUpdate = 0 then
    raise Exception.CreateFmt(
      'cannot write file %s. Please check whether it is open or set read-only.',
      [AFileName]);

  UpdateResource(hUpdate, RT_STRING, MakeIntResource(iSection), LANG_NEUTRAL,
    ResData, Length(ResData));
  EndUpdateResource(hUpdate, False);
end;