Inno Setup Runtime error while accessing CurrentFileName when installing an empty folder

Question

I tried to access all files inside a folder through Pascal code. When I iterate through an empty folder I am getting the following error:

Exception: Internal error; An attempt was made to call the "CurrentFileName" function from outside a "Check", "BeforeInstall" or "AfterInstall" event function belonging to a "[Files]" entry

The code I used:

[Files]
Source: ".\3D_Dlls\*"; DestDir: {app}\3D_Dlls; \
    Flags: ignoreversion recursesubdirs createallsubdirs skipifsourcedoesntexist; \
    Check: FileBackup    

[Code]
function FileBackup(): Boolean; 
var FileName,Source,Target,TargetDir: String; 
begin 
  Result := True;
  Source := ExpandConstant(CurrentFileName);
end

Say for example my folder structure is like that:

3D_Dlls
-   Folder 1
-   Folder 2 // Empty folder and it invokes the problem
-   Folder 3

Answer 1

I believe this is a bug in Inno Setup triggered by the createallsubdirs flag.

When the flag is specified, Inno Setup collects a separate list of empty directories that need to be explicitly created during an installation. When "installing" the empty folder, the call to the CurrentFileName simply fails.

Workarounds:

• Remove the createallsubdirs flag, if possible.

  Instead, you can explicitly create empty directories using the [Dirs] section.

• Catch the exception:

  function FileBackup: Boolean; 
  begin 
    Result := True;
    try
      Source := ExpandConstant(CurrentFileName);
    except
      Log(GetExceptionMessage);
    end;
  end;
  

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I have reported this on Inno Setup newsgroup, but the newsgroup was reset since.