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Using unique_ptr in local_load to replace static variable. Also adding local_load_safety_guard.

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Ralf W. Grosse-Kunstleve 2021-01-23 22:01:00 -08:00
parent 631a288d69
commit 3d17f6f6a1
1 changed files with 27 additions and 11 deletions
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38
include/pybind11/detail/classh_type_casters.h
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@ -31,6 +31,9 @@ inline std::pair<bool, handle> find_existing_python_instance(void *src_void_ptr,
return std::make_pair(false, handle()); return std::make_pair(false, handle());
} }
// The modified_type_caster_generic_load_impl could replace type_caster_generic::load_impl but not
// vice versa. The main difference is that the original code only propagates a reference to the
// held value, while the modified implementation propagates value_and_holder.
// clang-format off // clang-format off
class modified_type_caster_generic_load_impl { class modified_type_caster_generic_load_impl {
public: public:
@ -84,12 +87,14 @@ public:
} }
PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) { PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) {
// Not thread safe. But the GIL needs to be held anyway in the context of this code. std::unique_ptr<modified_type_caster_generic_load_impl> loader(
static modified_type_caster_generic_load_impl caster; new modified_type_caster_generic_load_impl(ti));
caster = modified_type_caster_generic_load_impl(ti); if (loader->load(src, false)) {
if (caster.load(src, false)) {
// Trick to work with the existing pybind11 internals. // Trick to work with the existing pybind11 internals.
return &caster; // Any pointer except nullptr; // The void pointer is immediately captured in a new unique_ptr in
// try_load_foreign_module_local. If this assumption is violated sanitizers
// will most likely flag a leak (verified to be the case with ASAN).
return static_cast<void *>(loader.release());
} }
return nullptr; return nullptr;
} }
@ -108,15 +113,23 @@ public:
|| (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype))) || (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype)))
return false; return false;
void* void_ptr = foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo); void* foreign_loader_void_ptr =
if (void_ptr != nullptr) { foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo);
auto foreign_load_impl = static_cast<modified_type_caster_generic_load_impl *>(void_ptr); if (foreign_loader_void_ptr != nullptr) {
auto foreign_loader = std::unique_ptr<modified_type_caster_generic_load_impl>(
static_cast<modified_type_caster_generic_load_impl *>(foreign_loader_void_ptr));
// Magic number intentionally hard-coded for simplicity and maximum robustness.
if (foreign_loader->local_load_safety_guard != 37726257887406645) {
pybind11_fail(
"Unexpected local_load_safety_guard,"
" possibly due to py::class_ vs py::classh mixup.");
}
if (loaded_v_h_cpptype != nullptr) { if (loaded_v_h_cpptype != nullptr) {
pybind11_fail("classh_type_casters: try_load_foreign_module_local failure."); pybind11_fail("classh_type_casters: try_load_foreign_module_local failure.");
} }
loaded_v_h = foreign_load_impl->loaded_v_h; loaded_v_h = foreign_loader->loaded_v_h;
loaded_v_h_cpptype = foreign_load_impl->loaded_v_h_cpptype; loaded_v_h_cpptype = foreign_loader->loaded_v_h_cpptype;
implicit_cast = foreign_load_impl->implicit_cast; implicit_cast = foreign_loader->implicit_cast;
return true; return true;
} }
return false; return false;
@ -216,6 +229,9 @@ public:
void *(*implicit_cast)(void *) = nullptr; void *(*implicit_cast)(void *) = nullptr;
value_and_holder loaded_v_h; value_and_holder loaded_v_h;
bool reinterpret_cast_deemed_ok = false; bool reinterpret_cast_deemed_ok = false;
// Magic number intentionally hard-coded, to guard against class_ vs classh mixups.
// Ideally type_caster_generic would have a similar guard, but this requires a change there.
std::size_t local_load_safety_guard = 37726257887406645;
}; };
// clang-format on // clang-format on