Passing a commandline parameter containing quotes to installer - inno-setup

Question

I'm trying to pass a custom commandline parameter to an installer created with Inno Setup. The parameter value actually consists of several parameters that will be used to launch the installed program when installation is complete, so the value contains spaces as well as quotes to group together parameters.
For example, when -arg "C:\path with spaces" -moreargs should be used as Parameters in a [Run] section entry, I would like to launch the installer like this:
setup.exe /abc="-arg "C:\path with spaces" -moreargs"
Outputting the parameters that the installer receives in a [Code] section via ParamStr() shows them (of course) split up: /abc=-arg C:\path, with, spaces -moreargs
How do I escape the quotes to retain them?
I tried doubling the inner quotes:
setup.exe /abc="-arg ""C:\path with spaces"" -moreargs"
This correctly keeps the parameter together (/abc=-arg C:\path with spaces -moreargs), however it seems that ParamStr() removes all quotes.
Is there a way to retain quotes within a parameter retrieved with ParamStr() or a param constant {param:abc|DefaultValue}?
Alternatives seem to be to either do my own parameter parsing from GetCmdTail (which contains the original parameter string) or use another character instead of the inner quotes that are retained in ParamStr() and then replace them with quotes afterwards. But I would prefer not doing that if there is a way to use the built-in functions.

Answer 1

It seems both {param} and ParamStr() strip out double quotes, but as you pointed out (thanks!) the GetCmdTail function returns the original.
So here's a function to get the original parameters with quotes:
function ParamStrWithQuotes(ParamName: String) : string;
var
fullCmd : String;
currentParamName : string;
i : Integer;
startPos : Integer;
endPos : Integer;
begin
fullCmd := GetCmdTail
// default to end of string, in case the option is the last item
endPos := Length(fullCmd);
for i := 0 to ParamCount-1 do
begin
// extract parameter name (eg, "/Option=")
currentParamName := Copy(ParamStr(i), 0, pos('=',ParamStr(i)));
// once found, we want the following item
if (startPos > 0) then
begin
endPos := pos(currentParamName,fullCmd)-2; // -1 to move back to actual end position, -1 for space
break; // exit loop
end;
if (CompareText(currentParamName, '/'+ParamName+'=') = 0) then // case-insensitive compare
begin
// found target item, so save its string position
StartPos := pos(currentParamName,fullCmd)+2+Length(ParamName);
end;
end;
if ((fullCmd[StartPos] = fullCmd[EndPos])
and ((fullCmd[StartPos] = '"') or (fullCmd[StartPos] = ''''))) then
begin
// exclude surrounding quotes
Result := Copy(fullCmd, StartPos+1, EndPos-StartPos-1);
end
else
begin
// return as-is
Result := Copy(fullCmd, StartPos, EndPos-StartPos+1);
end;
end;
You can access this with {code:ParamStrWithQuotes|abc}
When invoking the setup.exe, you do have to escape the quotes, so one of the following works for that:
setup.exe /abc="-arg ""C:\path with spaces"" -moreargs"
or
setup.exe /abc='-arg "C:\path with spaces" -moreargs'