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GDScript: Properly validate return type

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When the type cannot be validated at compile time, the runtime must do a
check to ensure type safety is kept, as the code might be assuming the
return type is correct in another place, leading to crashes if the
contract is broken.
This commit is contained in:
George Marques
2021-04-02 10:34:44 -03:00
parent 655a913e22
commit 35682d3079
4 changed files with 304 additions and 6 deletions
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81
modules/gdscript/gdscript_byte_codegen.cpp
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@@ -1286,8 +1286,85 @@ void GDScriptByteCodeGenerator::write_newline(int p_line) {
}
void GDScriptByteCodeGenerator::write_return(const Address &p_return_value) {
append(GDScriptFunction::OPCODE_RETURN, 1);
append(p_return_value);
if (!function->return_type.has_type || p_return_value.type.has_type) {
// Either the function is untyped or the return value is also typed.
// If this is a typed function, then we need to check for potential conversions.
if (function->return_type.has_type) {
if (function->return_type.kind == GDScriptDataType::BUILTIN && function->return_type.builtin_type == Variant::ARRAY && function->return_type.has_container_element_type()) {
// Typed array.
const GDScriptDataType &element_type = function->return_type.get_container_element_type();
Variant script = function->return_type.script_type;
int script_idx = get_constant_pos(script);
script_idx |= (GDScriptFunction::ADDR_TYPE_LOCAL_CONSTANT << GDScriptFunction::ADDR_BITS);
append(GDScriptFunction::OPCODE_RETURN_TYPED_ARRAY, 2);
append(p_return_value);
append(script_idx);
append(element_type.kind == GDScriptDataType::BUILTIN ? element_type.builtin_type : Variant::OBJECT);
append(element_type.native_type);
} else if (function->return_type.kind == GDScriptDataType::BUILTIN && p_return_value.type.kind == GDScriptDataType::BUILTIN && function->return_type.builtin_type != p_return_value.type.builtin_type) {
// Add conversion.
append(GDScriptFunction::OPCODE_RETURN_TYPED_BUILTIN, 1);
append(p_return_value);
append(function->return_type.builtin_type);
} else {
// Just assign.
append(GDScriptFunction::OPCODE_RETURN, 1);
append(p_return_value);
}
} else {
append(GDScriptFunction::OPCODE_RETURN, 1);
append(p_return_value);
}
} else {
switch (function->return_type.kind) {
case GDScriptDataType::BUILTIN: {
if (function->return_type.builtin_type == Variant::ARRAY && function->return_type.has_container_element_type()) {
const GDScriptDataType &element_type = function->return_type.get_container_element_type();
Variant script = function->return_type.script_type;
int script_idx = get_constant_pos(script);
script_idx |= (GDScriptFunction::ADDR_TYPE_LOCAL_CONSTANT << GDScriptFunction::ADDR_BITS);
append(GDScriptFunction::OPCODE_RETURN_TYPED_ARRAY, 2);
append(p_return_value);
append(script_idx);
append(element_type.kind == GDScriptDataType::BUILTIN ? element_type.builtin_type : Variant::OBJECT);
append(element_type.native_type);
} else {
append(GDScriptFunction::OPCODE_RETURN_TYPED_BUILTIN, 1);
append(p_return_value);
append(function->return_type.builtin_type);
}
} break;
case GDScriptDataType::NATIVE: {
append(GDScriptFunction::OPCODE_RETURN_TYPED_NATIVE, 2);
append(p_return_value);
int class_idx = GDScriptLanguage::get_singleton()->get_global_map()[function->return_type.native_type];
class_idx |= (GDScriptFunction::ADDR_TYPE_GLOBAL << GDScriptFunction::ADDR_BITS);
append(class_idx);
} break;
case GDScriptDataType::GDSCRIPT:
case GDScriptDataType::SCRIPT: {
Variant script = function->return_type.script_type;
int script_idx = get_constant_pos(script);
script_idx |= (GDScriptFunction::ADDR_TYPE_LOCAL_CONSTANT << GDScriptFunction::ADDR_BITS);
append(GDScriptFunction::OPCODE_RETURN_TYPED_SCRIPT, 2);
append(p_return_value);
append(script_idx);
} break;
default: {
ERR_PRINT("Compiler bug: unresolved return.");
// Shouldn't get here, but fail-safe to a regular return;
append(GDScriptFunction::OPCODE_RETURN, 1);
append(p_return_value);
} break;
}
}
}
void GDScriptByteCodeGenerator::write_assert(const Address &p_test, const Address &p_message) {