1 #ifndef Py_EMSCRIPTEN_TRAMPOLINE_H 2 #define Py_EMSCRIPTEN_TRAMPOLINE_H 3 4 #include "pycore_runtime.h" // _PyRuntimeState 5 6 /** 7 * C function call trampolines to mitigate bad function pointer casts. 8 * 9 * Section 6.3.2.3, paragraph 8 reads: 10 * 11 * A pointer to a function of one type may be converted to a pointer to a 12 * function of another type and back again; the result shall compare equal to 13 * the original pointer. If a converted pointer is used to call a function 14 * whose type is not compatible with the pointed-to type, the behavior is 15 * undefined. 16 * 17 * Typical native ABIs ignore additional arguments or fill in missing values 18 * with 0/NULL in function pointer cast. Compilers do not show warnings when a 19 * function pointer is explicitly casted to an incompatible type. 20 * 21 * Bad fpcasts are an issue in WebAssembly. WASM's indirect_call has strict 22 * function signature checks. Argument count, types, and return type must match. 23 * 24 * Third party code unintentionally rely on problematic fpcasts. The call 25 * trampoline mitigates common occurrences of bad fpcasts on Emscripten. 26 */ 27 28 #if defined(__EMSCRIPTEN__) && defined(PY_CALL_TRAMPOLINE) 29 30 void _Py_EmscriptenTrampoline_Init(_PyRuntimeState *runtime); 31 32 PyObject* 33 _PyEM_TrampolineCall_JavaScript(PyCFunctionWithKeywords func, 34 PyObject* self, 35 PyObject* args, 36 PyObject* kw); 37 38 PyObject* 39 _PyEM_TrampolineCall_Reflection(PyCFunctionWithKeywords func, 40 PyObject* self, 41 PyObject* args, 42 PyObject* kw); 43 44 #define _PyEM_TrampolineCall(meth, self, args, kw) \ 45 ((_PyRuntime.wasm_type_reflection_available) ? \ 46 (_PyEM_TrampolineCall_Reflection((PyCFunctionWithKeywords)(meth), (self), (args), (kw))) : \ 47 (_PyEM_TrampolineCall_JavaScript((PyCFunctionWithKeywords)(meth), (self), (args), (kw)))) 48 49 #define _PyCFunction_TrampolineCall(meth, self, args) \ 50 _PyEM_TrampolineCall( \ 51 (*(PyCFunctionWithKeywords)(void(*)(void))(meth)), (self), (args), NULL) 52 53 #define _PyCFunctionWithKeywords_TrampolineCall(meth, self, args, kw) \ 54 _PyEM_TrampolineCall((meth), (self), (args), (kw)) 55 56 #define descr_set_trampoline_call(set, obj, value, closure) \ 57 ((int)_PyEM_TrampolineCall((PyCFunctionWithKeywords)(set), (obj), (value), (PyObject*)(closure))) 58 59 #define descr_get_trampoline_call(get, obj, closure) \ 60 _PyEM_TrampolineCall((PyCFunctionWithKeywords)(get), (obj), (PyObject*)(closure), NULL) 61 62 63 #else // defined(__EMSCRIPTEN__) && defined(PY_CALL_TRAMPOLINE) 64 65 #define _Py_EmscriptenTrampoline_Init(runtime) 66 67 #define _PyCFunction_TrampolineCall(meth, self, args) \ 68 (meth)((self), (args)) 69 70 #define _PyCFunctionWithKeywords_TrampolineCall(meth, self, args, kw) \ 71 (meth)((self), (args), (kw)) 72 73 #define descr_set_trampoline_call(set, obj, value, closure) \ 74 (set)((obj), (value), (closure)) 75 76 #define descr_get_trampoline_call(get, obj, closure) \ 77 (get)((obj), (closure)) 78 79 #endif // defined(__EMSCRIPTEN__) && defined(PY_CALL_TRAMPOLINE) 80 81 #endif // ndef Py_EMSCRIPTEN_SIGNAL_H 82