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Clear external pointer before calling finalizer #1038

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Merged
merged 3 commits into from
Dec 20, 2019
Merged

Clear external pointer before calling finalizer #1038

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497f7ba
Clear external pointer before calling finalizer
krlmlr Dec 17, 2019
8fb0bb1
Define "interesting"
krlmlr Dec 19, 2019
0142938
additional check and small cleanup
eddelbuettel Dec 19, 2019
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23 changes: 15 additions & 8 deletions inst/include/Rcpp/XPtr.h
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Original file line number Diff line number Diff line change
Expand Up @@ -33,11 +33,19 @@ void standard_delete_finalizer(T* obj) {

template <typename T, void Finalizer(T*) >
void finalizer_wrapper(SEXP p) {
if (TYPEOF(p) == EXTPTRSXP) {
T* ptr = (T*) R_ExternalPtrAddr(p);
RCPP_DEBUG_3("finalizer_wrapper<%s>(SEXP p = <%p>). ptr = %p", DEMANGLE(T), p, ptr)
Finalizer(ptr);
}
if (TYPEOF(p) != EXTPTRSXP)
return;

T* ptr = (T*) R_ExternalPtrAddr(p);
RCPP_DEBUG_3("finalizer_wrapper<%s>(SEXP p = <%p>). ptr = %p", DEMANGLE(T), p, ptr)

if (ptr == NULL)
return;

// Clear before finalizing to avoid behavior like access of freed memory
R_ClearExternalPtr(p);

Finalizer(ptr);
}

template <
Expand Down Expand Up @@ -174,10 +182,9 @@ class XPtr :
// Call the finalizer -- note that this implies that finalizers
// need to be ready for a NULL external pointer value (our
// default C++ finalizer is since delete NULL is a no-op).
// This clears the external pointer just before calling the finalizer,
// to avoid interesting behavior with co-dependent finalizers.
finalizer_wrapper<T,Finalizer>(Storage::get__());

// Clear the external pointer
R_ClearExternalPtr(Storage::get__());
}
}

Expand Down