14820 - Fixing up the relationship between nsCodeBasePrincipal and nsJSPrincipals

Status: VERIFIED FIXED

(Core :: Security: CAPS, defect, P3)

Description

[Scott MacGregor]

This came out of an IRC discussion with brendan about Bug #14815 about how to
properly fix the relationship between nsCodeBasePrincipal and nsJSPrincipals.

Rather than re-summarize the discussion, I'm going to save my wrists and just
dump part of the irc session:

<brendan2> the idea is this: JSPrincipals (part of a C api) has a ref_count
member, non-XPCOM refcounting
<brendan2> so instead of NS_IMPL_ISUPPORTS in impls that embed a struct member
JSPrincipals
<brendan2> write custom addref/release that use the embedded JSPrincipals
struct's ref_count member
<brendan2> if this is more than you wanted to know, i'll just update the bug
<mscott> hang on i'm looking back at the code
<brendan2> see, that weak ref must be weak because nsJSPrincipals is a struct
that must be embedded
<mscott> JSPrincipals has the ref cnt variable it just doesn't appear to be
used?
<brendan2> it'd be better if there were only one ref_count for any ns*Principal
impl that embedded JSPrincipals
<mscott> i'm with you
<mscott> so the codebase principal needs to addref the struct's refcnt variable
instead of using the XPCOM versions?
<brendan2> the ns*Principal (note singular, not Principals) impls could all have
custom AddRef methods that call JSPRINCIPALS_HOLD, and Release methods that call
 JSPRINCIPALS_DROP
<brendan2> could share these (one AddRef/Release pair among all ns*Principal
Impls)
<brendan2> JSPrincipals.destroy knows how to downcast JSPrincipals* to
nsJSPrincipals*, then gets weak ref to ns*Principal and deletes the impl
<brendan2> one goal here is to fuse allocations, avoid yet another malloc
<brendan2> another is to fuse refcounts
<brendan2> arielb met first goal, not second, left bugs

Comment 1

[Norris Boyd]

QA: code change: no verification needed.

We now have a common refcount.

Comment 2

[leger]

Moving all CAPS bugs to Security: CAPS component.  CAPS component will be 
deleted.

Comment 3

[John Unruh]

Verified.