186173 - attachment.cgi must LOCK groups

Status: RESOLVED INVALID

(Bugzilla :: Attachments & Requests, defect, P1)

Description

[Joel Peshkin]

Since attachment.cgi needs to check group permissions for users that may require
a rederive, it needs to LOCK groups at the same time it locks everything else.

In fixing this, watch for nested locks!!!

Comment 1

[Joel Peshkin]

OK... fundamental bbaetz question....

Functions that need to lock tables will be called from within other functions
that lock tables.

The simplest thing to do would be to have the enclosing LOCK include all the
locks needed for enclosed functions and then have a global lock_counter.  So, I
replace...

LOCK whatever

with 

if ($::lockcount == 0) {
   LOCK whatever
   $::lockcount = 1;
} else {
   $::lockcount++;
}


and replace
UNLOCK TABLES

with

if ($::lockcount == 1) {
    UNLOCK TABLES
    $::lockcount = 0;
} else {
    $::lockcount--;
}


Would this be the right approach?

Comment 2

[Joel Peshkin]

Doh!  This was caused by a site hack.

Comment 3

[Bradley Baetz (:bbaetz)]

> Functions that need to lock tables will be called from within other functions
> that lock tables.

Ideally, noone should be locking any table. SELECT FOR UPDATE + transactions
would do this for us.

So lets leave this problem until we do need to worry :)