diff options
Diffstat (limited to 'Objects/codeobject.c')
| -rw-r--r-- | Objects/codeobject.c | 170 |
1 files changed, 153 insertions, 17 deletions
diff --git a/Objects/codeobject.c b/Objects/codeobject.c index 92eaf5e00bc..ee869d991d9 100644 --- a/Objects/codeobject.c +++ b/Objects/codeobject.c @@ -1955,12 +1955,130 @@ finally: } +int +_PyCode_CheckNoInternalState(PyCodeObject *co, const char **p_errmsg) +{ + const char *errmsg = NULL; + // We don't worry about co_executors, co_instrumentation, + // or co_monitoring. They are essentially ephemeral. + if (co->co_extra != NULL) { + errmsg = "only basic code objects are supported"; + } + + if (errmsg != NULL) { + if (p_errmsg != NULL) { + *p_errmsg = errmsg; + } + return 0; + } + return 1; +} + +int +_PyCode_CheckNoExternalState(PyCodeObject *co, _PyCode_var_counts_t *counts, + const char **p_errmsg) +{ + const char *errmsg = NULL; + assert(counts->locals.hidden.total == 0); + if (counts->numfree > 0) { // It's a closure. + errmsg = "closures not supported"; + } + else if (counts->unbound.globals.numglobal > 0) { + errmsg = "globals not supported"; + } + else if (counts->unbound.globals.numbuiltin > 0 + && counts->unbound.globals.numunknown > 0) + { + errmsg = "globals not supported"; + } + // Otherwise we don't check counts.unbound.globals.numunknown since we can't + // distinguish beween globals and builtins here. + + if (errmsg != NULL) { + if (p_errmsg != NULL) { + *p_errmsg = errmsg; + } + return 0; + } + return 1; +} + +int +_PyCode_VerifyStateless(PyThreadState *tstate, + PyCodeObject *co, PyObject *globalnames, + PyObject *globalsns, PyObject *builtinsns) +{ + const char *errmsg; + _PyCode_var_counts_t counts = {0}; + _PyCode_GetVarCounts(co, &counts); + if (_PyCode_SetUnboundVarCounts( + tstate, co, &counts, globalnames, NULL, + globalsns, builtinsns) < 0) + { + return -1; + } + // We may consider relaxing the internal state constraints + // if it becomes a problem. + if (!_PyCode_CheckNoInternalState(co, &errmsg)) { + _PyErr_SetString(tstate, PyExc_ValueError, errmsg); + return -1; + } + if (builtinsns != NULL) { + // Make sure the next check will fail for globals, + // even if there aren't any builtins. + counts.unbound.globals.numbuiltin += 1; + } + if (!_PyCode_CheckNoExternalState(co, &counts, &errmsg)) { + _PyErr_SetString(tstate, PyExc_ValueError, errmsg); + return -1; + } + // Note that we don't check co->co_flags & CO_NESTED for anything here. + return 0; +} + + +int +_PyCode_CheckPureFunction(PyCodeObject *co, const char **p_errmsg) +{ + const char *errmsg = NULL; + if (co->co_flags & CO_GENERATOR) { + errmsg = "generators not supported"; + } + else if (co->co_flags & CO_COROUTINE) { + errmsg = "coroutines not supported"; + } + else if (co->co_flags & CO_ITERABLE_COROUTINE) { + errmsg = "coroutines not supported"; + } + else if (co->co_flags & CO_ASYNC_GENERATOR) { + errmsg = "generators not supported"; + } + + if (errmsg != NULL) { + if (p_errmsg != NULL) { + *p_errmsg = errmsg; + } + return 0; + } + return 1; +} + /* Here "value" means a non-None value, since a bare return is identical * to returning None explicitly. Likewise a missing return statement * at the end of the function is turned into "return None". */ static int code_returns_only_none(PyCodeObject *co) { + if (!_PyCode_CheckPureFunction(co, NULL)) { + return 0; + } + int len = (int)Py_SIZE(co); + assert(len > 0); + + // The last instruction either returns or raises. We can take advantage + // of that for a quick exit. + _Py_CODEUNIT final = _Py_GetBaseCodeUnit(co, len-1); + // Look up None in co_consts. Py_ssize_t nconsts = PyTuple_Size(co->co_consts); int none_index = 0; @@ -1971,26 +2089,42 @@ code_returns_only_none(PyCodeObject *co) } if (none_index == nconsts) { // None wasn't there, which means there was no implicit return, - // "return", or "return None". That means there must be - // an explicit return (non-None). - return 0; - } + // "return", or "return None". - // Walk the bytecode, looking for RETURN_VALUE. - Py_ssize_t len = Py_SIZE(co); - for (int i = 0; i < len; i += _PyInstruction_GetLength(co, i)) { - _Py_CODEUNIT inst = _Py_GetBaseCodeUnit(co, i); - if (IS_RETURN_OPCODE(inst.op.code)) { - assert(i != 0); - // Ignore it if it returns None. - _Py_CODEUNIT prev = _Py_GetBaseCodeUnit(co, i-1); - if (prev.op.code == LOAD_CONST) { - // We don't worry about EXTENDED_ARG for now. - if (prev.op.arg == none_index) { - continue; + // That means there must be + // an explicit return (non-None), or it only raises. + if (IS_RETURN_OPCODE(final.op.code)) { + // It was an explicit return (non-None). + return 0; + } + // It must end with a raise then. We still have to walk the + // bytecode to see if there's any explicit return (non-None). + assert(IS_RAISE_OPCODE(final.op.code)); + for (int i = 0; i < len; i += _PyInstruction_GetLength(co, i)) { + _Py_CODEUNIT inst = _Py_GetBaseCodeUnit(co, i); + if (IS_RETURN_OPCODE(inst.op.code)) { + // We alraedy know it isn't returning None. + return 0; + } + } + // It must only raise. + } + else { + // Walk the bytecode, looking for RETURN_VALUE. + for (int i = 0; i < len; i += _PyInstruction_GetLength(co, i)) { + _Py_CODEUNIT inst = _Py_GetBaseCodeUnit(co, i); + if (IS_RETURN_OPCODE(inst.op.code)) { + assert(i != 0); + // Ignore it if it returns None. + _Py_CODEUNIT prev = _Py_GetBaseCodeUnit(co, i-1); + if (prev.op.code == LOAD_CONST) { + // We don't worry about EXTENDED_ARG for now. + if (prev.op.arg == none_index) { + continue; + } } + return 0; } - return 0; } } return 1; @@ -2230,6 +2364,8 @@ free_monitoring_data(_PyCoMonitoringData *data) static void code_dealloc(PyObject *self) { + PyThreadState *tstate = PyThreadState_GET(); + _Py_atomic_add_uint64(&tstate->interp->_code_object_generation, 1); PyCodeObject *co = _PyCodeObject_CAST(self); _PyObject_ResurrectStart(self); notify_code_watchers(PY_CODE_EVENT_DESTROY, co); |