Bug 173720 – initializeThreading() [first] causes WTFCrash due to maxSingleAllocationSize not being initialized

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Vladimir Vukicevic]

This is probably an edge case, but -- in a JSC static build that gets linked into another DLL, and that DLL does some dumb stuff from static constructors, such as JSClassCreate, I get this crash because maxSingleAllocationSize is still 0 (it's set by Options::initialize() which hasn't been called yet by initializeThreading()) -- lambdas and other junk omitted from stack:

WTFCrash()
WTF::fastMalloc(unsigned __int64 n)
WTF::Lock::operator new(unsigned __int64 size)
std::make_unique<WTF::Lock>()
WTF::threadMap()
WTF::ThreadHolder::initializeOnce()
WTF::initializeThreading()
JSC::initializeThreading::__l2::<lambda>()
JSC::initializeThreading()
JSClassCreate(const JSClassDefinition * definition)
...

I don't know if this is valid (to do stuff like JSClassCreate from constructors without doing explicit engine initialization), but it worked on older versions of jscore.

[Vladimir Vukicevic]

Actually, now that I look closer.. I don't get how it's not initialized to size_t::max(), but is 0, other than static initializer order goop since it's initialized using 'std::numeric_limits<size_t>::max();' ?

[Vladimir Vukicevic]

Yep, changing the static initializer to a simple "= SIZE_MAX;" fixes this.

[Vladimir Vukicevic]

VS 2017 (cl 19.10.25019). max() is constexpr, so, I dunno why!

[Yusuke Suzuki]

(In reply to Vladimir Vukicevic from comment #3)
> VS 2017 (cl 19.10.25019). max() is constexpr, so, I dunno why!

Hmmmmm, yeah, that is strange. In the meantime, we just use SIZE_MAX.

[Yusuke Suzuki]

(In reply to Vladimir Vukicevic from comment #0)
> This is probably an edge case, but -- in a JSC static build that gets linked
> into another DLL, and that DLL does some dumb stuff from static
> constructors, such as JSClassCreate, I get this crash because
> maxSingleAllocationSize is still 0 (it's set by Options::initialize() which
> hasn't been called yet by initializeThreading()) -- lambdas and other junk
> omitted from stack:
> 
> WTFCrash()
> WTF::fastMalloc(unsigned __int64 n)
> WTF::Lock::operator new(unsigned __int64 size)
> std::make_unique<WTF::Lock>()
> WTF::threadMap()
> WTF::ThreadHolder::initializeOnce()
> WTF::initializeThreading()
> JSC::initializeThreading::__l2::<lambda>()
> JSC::initializeThreading()
> JSClassCreate(const JSClassDefinition * definition)
> ...
> 
> I don't know if this is valid (to do stuff like JSClassCreate from
> constructors without doing explicit engine initialization), but it worked on
> older versions of jscore.

Basically, we do not allow static constructors in WebKit.
If we use static constructors, mac build with clang will fail due to the option restricting static constructors.

[Yusuke Suzuki]

Created attachment 313700 [details]
Patch

[Mark Lam]

Comment on attachment 313700 [details]
Patch

r=me

[Yusuke Suzuki]

Comment on attachment 313700 [details]
Patch

Thanks!

[WebKit Commit Bot]

Comment on attachment 313700 [details]
Patch

Clearing flags on attachment: 313700

Committed r218800: <http://trac.webkit.org/changeset/218800>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.