Fix T86983: `bl_description = None` crash on RNA class registration

1 files changed, 57 insertions, 46 deletions

diff --git a/source/blender/makesrna/intern/rna_wm.c b/source/blender/makesrna/intern/rna_wm.c
index d67d62d7af9..4a51db4e652 100644
--- a/source/blender/makesrna/intern/rna_wm.c
+++ b/source/blender/makesrna/intern/rna_wm.c
@@ -1781,41 +1781,40 @@ static void rna_Operator_bl_label_set(PointerRNA *ptr, const char *value)
   }
 }
 
-static void rna_Operator_bl_translation_context_set(PointerRNA *ptr, const char *value)
-{
-  wmOperator *data = (wmOperator *)(ptr->data);
-  char *str = (char *)data->type->translation_context;
-  if (!str[0]) {
-    BLI_strncpy(str, value, RNA_DYN_DESCR_MAX); /* utf8 already ensured */
-  }
-  else {
-    BLI_assert(!"setting the bl_translation_context on a non-builtin operator");
-  }
-}
-
-static void rna_Operator_bl_description_set(PointerRNA *ptr, const char *value)
-{
-  wmOperator *data = (wmOperator *)(ptr->data);
-  char *str = (char *)data->type->description;
-  if (!str[0]) {
-    BLI_strncpy(str, value, RNA_DYN_DESCR_MAX); /* utf8 already ensured */
-  }
-  else {
-    BLI_assert(!"setting the bl_description on a non-builtin operator");
-  }
-}
+/**
+ * Use callbacks that check for NULL instead of clearing #PROP_NEVER_NULL on the string property,
+ * so the internal value may be NULL, without allowing Python to assign `None` which doesn't
+ * make any sense in this case.
+ */
+#  define OPERATOR_STR_MAYBE_NULL_GETSET(attr, len) \
+    static void rna_Operator_bl_##attr##_set(PointerRNA *ptr, const char *value) \
+    { \
+      wmOperator *data = (wmOperator *)(ptr->data); \
+      char *str = (char *)data->type->attr; \
+      if (str && !str[0]) { \
+        BLI_strncpy(str, value, len); /* utf8 already ensured */ \
+      } \
+      else { \
+        BLI_assert( \
+            !"setting the bl_" STRINGIFY(translation_context) " on a non-builtin operator"); \
+      } \
+    } \
+    static void rna_Operator_bl_##attr##_get(PointerRNA *ptr, char *value) \
+    { \
+      const wmOperator *data = (wmOperator *)(ptr->data); \
+      const char *str = data->type->attr; \
+      BLI_strncpy(value, str ? str : "", len); \
+    } \
+    static int rna_Operator_bl_##attr##_length(PointerRNA *ptr) \
+    { \
+      const wmOperator *data = (wmOperator *)(ptr->data); \
+      const char *str = data->type->attr; \
+      return BLI_strnlen(str ? str : "", len); \
+    }
 
-static void rna_Operator_bl_undo_group_set(PointerRNA *ptr, const char *value)
-{
-  wmOperator *data = (wmOperator *)(ptr->data);
-  char *str = (char *)data->type->undo_group;
-  if (!str[0]) {
-    BLI_strncpy(str, value, OP_MAX_TYPENAME); /* utf8 already ensured */
-  }
-  else {
-    BLI_assert(!"setting the bl_undo_group on a non-builtin operator");
-  }
-}
+OPERATOR_STR_MAYBE_NULL_GETSET(translation_context, RNA_DYN_DESCR_MAX)
+OPERATOR_STR_MAYBE_NULL_GETSET(description, RNA_DYN_DESCR_MAX)
+OPERATOR_STR_MAYBE_NULL_GETSET(undo_group, OP_MAX_TYPENAME)
 
 static void rna_KeyMapItem_update(Main *UNUSED(bmain), Scene *UNUSED(scene), PointerRNA *ptr)
 {
@@ -1930,26 +1929,32 @@ static void rna_def_operator(BlenderRNA *brna)
   prop = RNA_def_property(srna, "bl_translation_context", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, NULL, "type->translation_context");
   RNA_def_property_string_maxlength(prop, RNA_DYN_DESCR_MAX); /* else it uses the pointer size! */
-  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_Operator_bl_translation_context_set");
+  RNA_def_property_string_funcs(prop,
+                                "rna_Operator_bl_translation_context_get",
+                                "rna_Operator_bl_translation_context_length",
+                                "rna_Operator_bl_translation_context_set");
   RNA_def_property_string_default(prop, BLT_I18NCONTEXT_OPERATOR_DEFAULT);
   RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
-  RNA_def_property_clear_flag(prop, PROP_NEVER_NULL); /* check for NULL */
 
   prop = RNA_def_property(srna, "bl_description", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, NULL, "type->description");
   RNA_def_property_string_maxlength(prop, RNA_DYN_DESCR_MAX); /* else it uses the pointer size! */
-  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_Operator_bl_description_set");
+  RNA_def_property_string_funcs(prop,
+                                "rna_Operator_bl_description_get",
+                                "rna_Operator_bl_description_length",
+                                "rna_Operator_bl_description_set");
   /* RNA_def_property_clear_flag(prop, PROP_EDITABLE); */
   RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
-  RNA_def_property_clear_flag(prop, PROP_NEVER_NULL); /* check for NULL */
 
   prop = RNA_def_property(srna, "bl_undo_group", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, NULL, "type->undo_group");
   RNA_def_property_string_maxlength(prop, OP_MAX_TYPENAME); /* else it uses the pointer size! */
-  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_Operator_bl_undo_group_set");
+  RNA_def_property_string_funcs(prop,
+                                "rna_Operator_bl_undo_group_get",
+                                "rna_Operator_bl_undo_group_length",
+                                "rna_Operator_bl_undo_group_set");
   /* RNA_def_property_clear_flag(prop, PROP_EDITABLE); */
   RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
-  RNA_def_property_clear_flag(prop, PROP_NEVER_NULL); /* check for NULL */
 
   prop = RNA_def_property(srna, "bl_options", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_sdna(prop, NULL, "type->flag");
@@ -2022,26 +2027,32 @@ static void rna_def_macro_operator(BlenderRNA *brna)
   prop = RNA_def_property(srna, "bl_translation_context", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, NULL, "type->translation_context");
   RNA_def_property_string_maxlength(prop, RNA_DYN_DESCR_MAX); /* else it uses the pointer size! */
-  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_Operator_bl_translation_context_set");
+  RNA_def_property_string_funcs(prop,
+                                "rna_Operator_bl_translation_context_get",
+                                "rna_Operator_bl_translation_context_length",
+                                "rna_Operator_bl_translation_context_set");
   RNA_def_property_string_default(prop, BLT_I18NCONTEXT_OPERATOR_DEFAULT);
   RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
-  RNA_def_property_clear_flag(prop, PROP_NEVER_NULL); /* check for NULL */
 
   prop = RNA_def_property(srna, "bl_description", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, NULL, "type->description");
   RNA_def_property_string_maxlength(prop, RNA_DYN_DESCR_MAX); /* else it uses the pointer size! */
-  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_Operator_bl_description_set");
+  RNA_def_property_string_funcs(prop,
+                                "rna_Operator_bl_description_get",
+                                "rna_Operator_bl_description_length",
+                                "rna_Operator_bl_description_set");
   /* RNA_def_property_clear_flag(prop, PROP_EDITABLE); */
   RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
-  RNA_def_property_clear_flag(prop, PROP_NEVER_NULL); /* check for NULL */
 
   prop = RNA_def_property(srna, "bl_undo_group", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, NULL, "type->undo_group");
   RNA_def_property_string_maxlength(prop, OP_MAX_TYPENAME); /* else it uses the pointer size! */
-  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_Operator_bl_undo_group_set");
+  RNA_def_property_string_funcs(prop,
+                                "rna_Operator_bl_undo_group_get",
+                                "rna_Operator_bl_undo_group_length",
+                                "rna_Operator_bl_undo_group_set");
   /* RNA_def_property_clear_flag(prop, PROP_EDITABLE); */
   RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
-  RNA_def_property_clear_flag(prop, PROP_NEVER_NULL); /* check for NULL */
 
   prop = RNA_def_property(srna, "bl_options", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_sdna(prop, NULL, "type->flag");