96514 - Getting a nonexistent pref should not stuff bogus value into result

Status: VERIFIED FIXED

(Core :: Preferences: Backend, defect)

Description

[Conrad Carlen (not reading bugmail)]

This is a problem is where somebody uses code like this (very common):

        PRBool paintFrameCounts       = PR_FALSE;
        prefs->GetBoolPref("layout.reflow.showframecounts", &paintFrameCounts);

without checking the result code. It assumes that, if the pref does not exist,
the PRBool param it passed will be untouched. That's why it initialized it
beforehand. Reasonable. That's what I'd expect. Unfortunately, if the pref in
question has had its user value reset, which happens in profile switching, a
bogus value will be returned.

Comment 1

[Conrad Carlen (not reading bugmail)]

Attachment: patch so we don't stuff bogus value on error

Comment 2

[Conrad Carlen (not reading bugmail)]

This blocks bug 86021. If I can get it reviewed an in today... It's extremely
low risk. Chris, can you sr=?

Comment 3

[Brian Nesse (gone)]

Looks like what we discussed. r=bnesse.

Comment 4

[Conrad Carlen (not reading bugmail)]

While this is a serious problem and should be checked in ASAP anyway, it appears
to no longer be blocking bug 86021. On testing that patch without this one over
the past 2 days, the problem this bug causes has mysteriously disappeared.
Removing blockage.

Comment 5

[Simon Fraser [no longer active]]

sr=sfraser

Comment 6

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

a=dbaron (on behalf of drivers)

Comment 7

[Brian Nesse (gone)]

Checked in.

Comment 8

[sairuh (rarely reading bugmail)]

rubberstamp.