Check if a file is open from another process

Question

How do I check if a file is already used by another process from Powerscript ?

Answer 1

You could try to open it and if it errors then it is probably already locked.

Answer 2

The best way that I found is to call the WinAPI CreateFile to open a given file in exclusive mode.

First, declare the following Local External Function (PB10)

FUNCTION Long CreateFile(ref string lpszName, long fdwAccess, long fdwShareMode, long lpsa, &
long fdwCreate, long fdwAttrsAndFlags, long hTemplateFile) LIBRARY "Kernel32.dll" &
ALIAS FOR "CreateFileA;Ansi"
FUNCTION boolean CloseHandle (long file_hand) LIBRARY "KERNEL32.DLL"

then from Powerscript :

CONSTANT ulong GENERIC_ACCESS = 268435456  //  &H10000000
CONSTANT ulong EXCLUSIVE_ACCESS = 0
CONSTANT ulong OPEN_EXISTING = 3

long ll_handle
String ls_file 

ls_file = "c:\temp\myfile.xls"

ll_handle = CreateFile ( ls_file, GENERIC_ACCESS, EXCLUSIVE_ACCESS,  0, OPEN_EXISTING, 0, 0) 
IF ll_handle < 1 THEN 
    MessageBox("", "Can't open, maybe missing or already opened ?!?")
ELSE
    MessageBox("","File can be opened")
END IF

CloseHandle(ll_handle)