WM_COPYDATA with and without quotes yields different results

Question

Using WM_COPYDATA to pass command line params to another app instance with Delphi XE as follows:

function DAppInstance.SendParamsToPrevInstance(AWindowHandle: THandle): Boolean;
var
  copyData: TCopyDataStruct;
  cmdParams : string;
  i : integer;
begin
  cmdParams := '';
  for i := 1 to ParamCount do
    cmdParams := cmdParams + ParamStr(i); //#1
  //cmdParams := cmdParams + '"' + ParamStr(i) + '" '; //#2
  //cmdParams := cmdParams + format('"%s" ', [ParamStr(i)]); //#3
  //cmdParams := cmdParams + format('%s;', [ParamStr(i)]); //#4

  copyData.lpData := pchar(cmdParams);
  copyData.cbData := 1 + (bytelength(cmdParams));
  copyData.dwData := WaterMark;  //ID for APP

  result := SendMessage(AWindowHandle, 
    WM_COPYDATA, 
    Application.Handle, 
    LPARAM(@copyData)) = 1;
end;

yields different results if the strings are quoted / appended to.

if #1 is used - the string comes in clean but is not usable if not quoted as filenames can have spaces and this:

C:\Users\MX4399\Research\delphi\instance\doc with spaces.doc

will be see as 3 paramaters in the end, while using #2 to quote the strings, or appending anything (#3, #4) causes

"C:\Users\MX4399\Research\delphi\instance\doc with spaces.doc"'#$FF00'궳獧

Answer 1

I think you meant copyData.cbdata := 1 * SizeOf(Char) + ... instead of just 1 + ....