fcntl instead of flock

[rotis23]

Hi All,

I've got a problem with a script running on a Linux 2.4 kernel where 'flock' is apparently broken. Therefore I'm thinking of using the 'fcntl' wrapper.

Here's the existing flock call:

$retval = flock(QF, $LOCK_EX|$LOCK_NB)

So, I need to create an exclusive lock on an entire file (like flock does) and make it non-blocking. Can I do this with fcntl like this?

my $lock = struct_flock(F_WRLCK,SEEK_SET,0,0,0);
...
fcntl(QF, F_SETLK, $lock) or die "F_GETLK $$ @_: $!";
...

Are there any other modules/mthods I can use?

Thanks for any help on this.

rotis23

 

[TrojanWarBlade]

Have you tested "flock"?
"fcntl" is the only other obvious way I can see that you could do this.


Trojan.

 

[rotis23]

Thanks for your response Trojan. From the sendmail release notes for v8.13:

"The Linux kernel version 2.4 series has a broken flock() so change to using fcntl() locking until they can fix it. Be sure to update other sendmail related programs to match locking techniques"

This script scans large sendmail queues and move mails -we've seen problems.

Is my example of fcntl OK? Does anyone else use it for file locking (over flock)?

 

[TrojanWarBlade]

Dunno, never tried it.
Give it a go and see what happens.


Trojan.