Re: FYI: Linker & Verifier fixes

[Andrew Haley <aph at redhat dot com>]

Bryce McKinlay writes:
 > Hi Robert,
 > 
 > I believe there is still a bug here with the String being passed to 
 > ffi_prep_closure:
 > 
 > +          // Initializes the cif and the closure. If that worked the 
 > closure is
 > +          // stored as a function pointer in the atable.
 > +          if ( ffi_prep_cif(cif, FFI_DEFAULT_ABI, 1,
 > +                            &ffi_type_void, arg_types) == FFI_OK
 > +               && (ffi_prep_closure
 > +                   (closure, cif,
 > +                   _Jv_ThrowNoClassDefFoundErrorTrampoline,
 > +                   (void *) _Jv_NewStringUtf8Const(sym.class_name))
 > +                   == FFI_OK))
 > 
 > The String returned by _Jv_NewStringUtf8Const(sym.class_name) is 
 > allocated by the GC, but there is no pointer to this string that is 
 > visible to the GC, so it is at risk of being prematurely collected. (The 
 > closure data itself will not be visible to the GC as it will not scan 
 > malloc()'ed memory).
 > 
 > A simple solution would be to add the Strings as keys in a HashMap each 
 > time a closure is created.

Easier, surely, to:

               (ffi_prep_closure
                (closure, cif,
                _Jv_ThrowNoClassDefFoundErrorTrampoline,
                sym.class_name)
                == FFI_OK))

and do _Jv_NewStringUtf8Const() in the trampoline.

Andrew.