NSIS Check if an empty directory exists

Question

I need to check if an USB dongle has been inserted. I use the following code to do so:

!macro HAS_USB_DONGLE
  IfFileExists "E:\*.*" hasDongle 0
  MessageBox MB_OK "USB Dongle is not inserted. Please insert the USB dongle and re-run this installer."
Abort

  hasDongle:
!macroend

This however only works if there are any files (or directories) on E:. How can I check if an empty directory exists?

Answer 1

Do you mean a specific folder?

IfFileExists can be used with a file, a wildcard, or a directory .

!macro HAS_USB_DONGLE
  IfFileExists "E:\ThisIsTheFolderYouAreLookingFor" hasDongle 0
  MessageBox MB_OK "USB Dongle is not inserted. Please insert the USB dongle and re-run this installer."
Abort

  hasDongle:
!macroend

Answer 2

Here is a code to perform it

!macro uni_isEmptyDir un
Function ${un}isEmptyDir
    # Stack ->                    # Stack: <directory>
    Exch $0                       # Stack: $0
    Push $1                       # Stack: $1, $0
    FindFirst $0 $1 "$0\*.*"
    strcmp $1 "." 0 _notempty
    FindNext $0 $1
    strcmp $1 ".." 0 _notempty
    ClearErrors
    FindNext $0 $1
    IfErrors 0 _notempty
    FindClose $0
    Pop $1                  # Stack: $0
    StrCpy $0 1
    Exch $0                 # Stack: 1 (true)
    goto _end
    _notempty:
        FindClose $0
    ClearErrors
    Pop $1                   # Stack: $0
    StrCpy $0 0
    Exch $0                  # Stack: 0 (false)
    _end:
FunctionEnd
!macroend

; make isEmptyDir function available both for installer and uninstaller
!insertmacro uni_isEmptyDir ""
!insertmacro uni_isEmptyDir "un."

Usage from the installer section:

Push "Path to check"
Call isEmptyDir
Pop $0

Usage from the uninstall section:

Push "Path to check"
Call un.isEmptyDir
Pop $0

Hope this helps.

Answer 3

Seeing as this has become a popular question, I thought I'd post my own solution. The answers which I tried above were not reliable for me. I have not tested the solution provided by khayk, that may be the best one. In the end I solved the problem by creating a dummy file, checking if directory exists and then delete the dummy file. Hacky, but works well for my use.

!macro HAS_USB_DONGLE
  FileOpen $0 "$USB_DIR\dummy" w
  FileClose $0
  ClearErrors

  IfFileExists "$USB_DIR*" hasDongle 0
  MessageBox MB_OK "USB Dongle is not inserted. Please insert the USB dongle and re-run this installer."
  Abort

  hasDongle:
  Delete "$USB_DIR\dummy"
  ClearErrors
!macroend

Answer 4

Take a look at this function .

Also note, that your macro would not work. Macros are repeated code and you can't use the same label multiple times (within the same section/function).