[vala/staging: 3/3] codegen: Check vfunc of abstract/virtual properties for NULL before using it

[Rico Tzschichholz <ricotz src gnome org>]

commit 5abec1cfc532e525a4adbfa330133cdbb7132ad6
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Wed Apr 15 16:24:10 2020 +0200

    codegen: Check vfunc of abstract/virtual properties for NULL before using it
    
    Fixes https://gitlab.gnome.org/GNOME/vala/issues/153

 codegen/valaccodebasemodule.vala | 35 +++++++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)
---
diff --git a/codegen/valaccodebasemodule.vala b/codegen/valaccodebasemodule.vala
index 470305c6d..fb3c70154 100644
--- a/codegen/valaccodebasemodule.vala
+++ b/codegen/valaccodebasemodule.vala
@@ -1757,6 +1757,12 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
 
                        push_function (function);
 
+                       if (acc.value_type.is_non_null_simple_type () && default_value_for_type 
(acc.value_type, false) == null) {
+                               var vardecl = new CCodeVariableDeclarator ("result", default_value_for_type 
(acc.value_type, true));
+                               vardecl.init0 = true;
+                               ccode.add_declaration (get_ccode_name (acc.value_type), vardecl);
+                       }
+
                        if (prop.binding == MemberBinding.INSTANCE) {
                                if (!acc.readable || returns_real_struct) {
                                        create_property_type_check_statement (prop, false, t, true, "self");
@@ -1769,13 +1775,19 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
                        if (prop.parent_symbol is Interface) {
                                var iface = (Interface) prop.parent_symbol;
 
-                               vcast = new CCodeFunctionCall (new CCodeIdentifier 
(get_ccode_interface_get_function (iface)));
-                               ((CCodeFunctionCall) vcast).add_argument (new CCodeIdentifier ("self"));
+                               vcast = new CCodeIdentifier ("_iface_");
+                               var vcastcall = new CCodeFunctionCall (new CCodeIdentifier 
(get_ccode_interface_get_function (iface)));
+                               ((CCodeFunctionCall) vcastcall).add_argument (new CCodeIdentifier ("self"));
+                               ccode.add_declaration ("%s*".printf (get_ccode_type_name (iface)), new 
CCodeVariableDeclarator ("_iface_"));
+                               ccode.add_assignment (vcast, vcastcall);
                        } else {
                                var cl = (Class) prop.parent_symbol;
                                if (!cl.is_compact) {
-                                       vcast = new CCodeFunctionCall (new CCodeIdentifier 
(get_ccode_class_get_function (cl)));
-                                       ((CCodeFunctionCall) vcast).add_argument (new CCodeIdentifier 
("self"));
+                                       vcast = new CCodeIdentifier ("_klass_");
+                                       var vcastcall = new CCodeFunctionCall (new CCodeIdentifier 
(get_ccode_class_get_function (cl)));
+                                       ((CCodeFunctionCall) vcastcall).add_argument (new CCodeIdentifier 
("self"));
+                                       ccode.add_declaration ("%sClass*".printf (get_ccode_name (cl)), new 
CCodeVariableDeclarator ("_klass_"));
+                                       ccode.add_assignment (vcast, vcastcall);
                                } else {
                                        vcast = new CCodeIdentifier ("self");
                                }
@@ -1784,6 +1796,10 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
                        if (acc.readable) {
                                var vcall = new CCodeFunctionCall (new CCodeMemberAccess.pointer (vcast, 
"get_%s".printf (prop.name)));
                                vcall.add_argument (new CCodeIdentifier ("self"));
+
+                               // check if vfunc pointer is properly set
+                               ccode.open_if (vcall.call);
+
                                if (returns_real_struct) {
                                        vcall.add_argument (new CCodeIdentifier ("result"));
                                        ccode.add_expression (vcall);
@@ -1801,11 +1817,21 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
 
                                        ccode.add_return (vcall);
                                }
+                               ccode.close ();
+
+                               if (acc.value_type.is_non_null_simple_type () && default_value_for_type 
(acc.value_type, false) == null) {
+                                       ccode.add_return (new CCodeIdentifier ("result"));
+                               } else if (!(acc.value_type is VoidType)) {
+                                       ccode.add_return (default_value_for_type (acc.value_type, false, 
true));
+                               }
                        } else {
                                var vcall = new CCodeFunctionCall (new CCodeMemberAccess.pointer (vcast, 
"set_%s".printf (prop.name)));
                                vcall.add_argument (new CCodeIdentifier ("self"));
                                vcall.add_argument (new CCodeIdentifier ("value"));
 
+                               // check if vfunc pointer is properly set
+                               ccode.open_if (vcall.call);
+
                                if (acc.value_type is ArrayType && get_ccode_array_length (prop)) {
                                        var array_type = (ArrayType) acc.value_type;
 
@@ -1821,6 +1847,7 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
                                }
 
                                ccode.add_expression (vcall);
+                               ccode.close ();
                        }
 
                        pop_function ();