> Doesn't exist any way of copying into a file with exclusive access a
> Blob/memo and to execute it with a DO command; a small interval time
> exists where the file is free;
> a good hacker can
> - capture the API FCLOSE event
> - to put to sleep VFP,
> - to modify it ;
> to wake up again VFP that performs confident a different thing.

I don't know that there is a good way around this problem. The Blob/Memo is going to be stored in a file too.

Maybe you could store a check sum in your script table and compare the check sum before you execute the script. You could also check the file size.

You can open the object file read-only to lock it and the script will still execute. I just tried this and it worked:

** create a binary script
STRTOFILE("MESSAGEBOX('Hello World')","temp.prg")
COMPILE temp.prg
cBlob = FILETOSTR("temp.fxp")
DELETE FILE temp.prg
DELETE FILE temp.fxp


** test our function
SECURESCRIPT(cBlob)

***********************************
FUNCTION SECURESCRIPT(cBlob)

cTempFile = ADDBS(SYS(2023))+SYS(2015)+".fxp"
** copy script to temp file
nLen = STRTOFILE(cBlob, cTempFile)
** open file readonly to lock it
hnd = FOPEN(cTempFile)
** check the file size to make sure it is OK
IF FSEEK(hnd,0,2) = nLen
   ** execute it
   DO (cTempFile)
ENDIF
** cleanup
FCLOSE(hnd)
DELETE FILE (cTempFile)