py: Use a wrapper to explicitly check self argument of builtin methods.
Previous to this patch a call such as list.append(1, 2) would lead to a seg fault. This is because list.append is a builtin method and the first argument to such methods is always assumed to have the correct type. Now, when a builtin method is extracted like this it is wrapped in a checker object which checks the the type of the first argument before calling the builtin function. This feature is contrelled by MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG and is enabled by default. See issue #1216.
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@ -18,6 +18,7 @@
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#define MICROPY_ENABLE_SOURCE_LINE (0)
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#define MICROPY_ENABLE_DOC_STRING (0)
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#define MICROPY_ERROR_REPORTING (MICROPY_ERROR_REPORTING_TERSE)
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#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (0)
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#define MICROPY_PY_BUILTINS_BYTEARRAY (0)
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#define MICROPY_PY_BUILTINS_MEMORYVIEW (0)
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#define MICROPY_PY_BUILTINS_FROZENSET (0)
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@ -19,6 +19,7 @@
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#define MICROPY_ENABLE_SOURCE_LINE (0)
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#define MICROPY_ENABLE_DOC_STRING (0)
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#define MICROPY_ERROR_REPORTING (MICROPY_ERROR_REPORTING_TERSE)
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#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (0)
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#define MICROPY_PY_BUILTINS_BYTEARRAY (0)
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#define MICROPY_PY_BUILTINS_MEMORYVIEW (0)
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#define MICROPY_PY_BUILTINS_ENUMERATE (0)
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@ -393,6 +393,15 @@ typedef double mp_float_t;
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#define MICROPY_CAN_OVERRIDE_BUILTINS (0)
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#endif
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// Whether to check that the "self" argument of a builtin method has the
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// correct type. Such an explicit check is only needed if a builtin
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// method escapes to Python land without a first argument, eg
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// list.append([], 1). Without this check such calls will have undefined
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// behaviour (usually segfault) if the first argument is the wrong type.
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#ifndef MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
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#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (1)
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#endif
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/*****************************************************************************/
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/* Fine control over Python builtins, classes, modules, etc */
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60
py/runtime.c
60
py/runtime.c
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@ -887,6 +887,51 @@ mp_obj_t mp_load_attr(mp_obj_t base, qstr attr) {
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}
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}
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#if MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
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// The following "checked fun" type is local to the mp_convert_member_lookup
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// function, and serves to check that the first argument to a builtin function
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// has the correct type.
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typedef struct _mp_obj_checked_fun_t {
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mp_obj_base_t base;
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const mp_obj_type_t *type;
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mp_obj_t fun;
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} mp_obj_checked_fun_t;
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STATIC mp_obj_t checked_fun_call(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
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mp_obj_checked_fun_t *self = self_in;
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if (n_args > 0) {
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const mp_obj_type_t *arg0_type = mp_obj_get_type(args[0]);
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if (arg0_type != self->type) {
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if (MICROPY_ERROR_REPORTING != MICROPY_ERROR_REPORTING_DETAILED) {
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nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
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"argument has wrong type"));
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} else {
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nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
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"argument should be a '%q' not a '%q'", self->type->name, arg0_type->name));
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}
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}
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}
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return mp_call_function_n_kw(self->fun, n_args, n_kw, args);
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}
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STATIC const mp_obj_type_t mp_type_checked_fun = {
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{ &mp_type_type },
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.name = MP_QSTR_function,
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.call = checked_fun_call,
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};
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STATIC mp_obj_t mp_obj_new_checked_fun(const mp_obj_type_t *type, mp_obj_t fun) {
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mp_obj_checked_fun_t *o = m_new_obj(mp_obj_checked_fun_t);
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o->base.type = &mp_type_checked_fun;
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o->type = type;
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o->fun = fun;
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return o;
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}
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#endif // MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
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// Given a member that was extracted from an instance, convert it correctly
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// and put the result in the dest[] array for a possible method call.
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// Conversion means dealing with static/class methods, callables, and values.
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@ -903,9 +948,18 @@ void mp_convert_member_lookup(mp_obj_t self, const mp_obj_type_t *type, mp_obj_t
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// Don't try to bind types (even though they're callable)
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dest[0] = member;
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} else if (mp_obj_is_callable(member)) {
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// return a bound method, with self being this object
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dest[0] = member;
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dest[1] = self;
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#if MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
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if (self == MP_OBJ_NULL && mp_obj_get_type(member) == &mp_type_fun_builtin) {
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// we extracted a builtin method without a first argument, so we must
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// wrap this function in a type checker
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dest[0] = mp_obj_new_checked_fun(type, member);
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} else
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#endif
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{
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// return a bound method, with self being this object
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dest[0] = member;
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dest[1] = self;
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}
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} else {
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// class member is a value, so just return that value
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dest[0] = member;
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@ -0,0 +1,12 @@
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# check that we can use an instance of B in a method of A
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class A:
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def store(a, b):
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a.value = b
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class B:
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pass
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b = B()
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A.store(b, 1)
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print(b.value)
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@ -0,0 +1,31 @@
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# make sure type of first arg (self) to a builtin method is checked
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list.append
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try:
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list.append()
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except TypeError as e:
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print("TypeError")
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try:
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list.append(1)
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except TypeError as e:
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print("TypeError")
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try:
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list.append(1, 2)
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except TypeError as e:
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print("TypeError")
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l = []
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list.append(l, 2)
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print(l)
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try:
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getattr(list, "append")(1, 2)
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except TypeError as e:
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print("TypeError")
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l = []
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getattr(list, "append")(l, 2)
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print(l)
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@ -44,6 +44,7 @@
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#define MICROPY_OPT_COMPUTED_GOTO (0)
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#define MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE (0)
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#define MICROPY_CAN_OVERRIDE_BUILTINS (0)
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#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (0)
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#define MICROPY_CPYTHON_COMPAT (0)
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#define MICROPY_PY_BUILTINS_BYTEARRAY (0)
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#define MICROPY_PY_BUILTINS_MEMORYVIEW (0)
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