164294 - NTBUCKETS returns 1 for an empty hash table

Status: RESOLVED INVALID

(Core :: XPCOM, defect)

Description

[Mike Kaply [:mkaply]]

See

http://lxr.mozilla.org/seamonkey/source/nsprpub/lib/ds/plhash.c#425

If you call an enumerate function on an empty hash table, it crashes.

It shouldn't. The problem is that the NTBUCKETS macro is returning 1 even though
the hash table is empty.

Comment 1

[Wan-Teh Chang]

Attachment: A test program that enumerates an empty hash table

Michael,

I don't understand this bug.  As this test program
demonstrates, I can enumerate an empty hash table
without crashing.  The PL_HashTableEnumerateEntries
correctly returns 0.

Comment 2

[Mike Kaply [:mkaply]]

Interesting. Maybe the problem is only with a hash table created with
nsHashTable (XPCOM)

I create an nsHashTable hashtable;

and if I try to enumerate on it, I crash.

I'll move this to XPCOM.

Comment 3

[Doug Turner (:dougt)]

Mike, do you have a test case which demonstrates this crash you are seeing?

Comment 4

[Mike Kaply [:mkaply]]

Not exactly. I'll create one.

We found it when creating a hashtable for our font code.

We put an nsHashTable in a class (not a pointer)

then we added code at shutdown that enumerated the hashtable and freed the entries.

What we found is that if we had not added anything, the ::enumerate still called
into NSPR.

Comment 5

[Mike Kaply [:mkaply]]

My bad.

A static initializer wasn't getting called because we wrote our own DLL init
function.

This was masquerading as this problem.

nsHashTables always have 16 by default - it's in the default constructor.