LOCK-files (.LCK)

(Appendix 31).

Added lock files when importing and exporting mail (same filename, extension added or replaced = "lck")

This means that while FBB is using MAIL.IN a file named MAIL.LCK exists.
In the same way, if a file named MAIL.LCK exists, FBB will delay MAIL.IN
This is to avoid conflicts between applications.


MAIL.LCK is not imported, it is only a (empty) temporary file which is used
as a flag.

When FBB imports MAIL.IN it does :

if MAIL.LCK exists
then begin
    do not import MAIL.IN
    if MAIL.LCK is older than one hour
    then begin
        delete (if possible) MAIL.LCK
    end
end
else begin
    create MAIL.LCK
    import MAIL.IN
    delete MAIL.LCK
end

this is checked every minute until MAIL.LCK no longer exist.

When FBB exports LA6CU.OUT, it does :

if LA6CU.LCK exists
then begin
    do not export LA6CU.OUT
    if LA6CU.LCK is older than one hour
    then begin
        delete (if possible) LA6CU.LCK
    end
end
else begin
    create LA6CU.LCK
    export LA6CU.OUT
    delete LA6CU.LCK
end

Another application should do the same to avoid conflicts.

Lock-files are deleted (if possible) after 1 hour.