539022 - HEAP_ALLOCA should be defined for Windows builds with RTC enabled

Status: VERIFIED FIXED

(Tamarin Graveyard :: Virtual Machine, defect)

Description

[Steven Johnson]

Attachment: Patch

MSVC has a debug facility that checks for overwrites of stack variables, including alloca usage. Unfortunately, this checking doesn't work properly with longjmp/setjmp and will get all crashy in some configurations, eg

void foo()
{
    jmp_buf jb;
	if (!setjmp(jb))
	{
	    long* aa = (long*)alloca(8);
	    longjmp(jb, 1);
	}
}

(note that this is the case whether you use msvc's normal longjmp, or our hacked no-unwind longjmp)

(note also that no such code construct appears to be in use in Tamarin itself, but embedders might be subject to it)

Fortunately, solution is simple: enable HEAP_ALLOCA for these builds.

Comment 1

[Steven Johnson]

Comment on attachment 421085 [details] [diff] [review]
Patch

Note that this patch also adds the missing-but-necessary define for Symbian, as well

Comment 2

[Steven Johnson]

http://hg.mozilla.org/tamarin-redux/rev/8098ac5d12ad