Allow unset tags on variant field types

This allows the creation of a variant while not specifying the variant's
tag's name and type which is needed to support untagged variants.

This will allow the support of constructs such as:
variant name {
    field_type sel1;
    field_type sel2;
    field_type sel3;
    /* ... */
};

struct {
    enum : integer_type { sel1, sel2, sel3, /* ... */ } tag_field;
    /* ... */
    variant name <tag_field> v;
}

The validation of variant fields thus becomes optional and will
be implemented as part of the freeze() of variants in a later commit.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/formats/ctf/ir/event-types.c b/formats/ctf/ir/event-types.c
index ad569c6ce12c20cae71220df09b0570d40bc1033..e7263d5cc55d802c2ae90eac8041a9f2c4849d84 100644 (file)
--- a/formats/ctf/ir/event-types.c
+++ b/formats/ctf/ir/event-types.c
@@ -1210,8 +1210,7 @@ struct bt_ctf_field_type *bt_ctf_field_type_variant_create(
 {
        struct bt_ctf_field_type_variant *variant = NULL;
 
-       if (!enum_tag || bt_ctf_validate_identifier(tag_name) ||
-               (enum_tag->declaration->id != CTF_TYPE_ENUM)) {
+       if (tag_name && bt_ctf_validate_identifier(tag_name)) {
                goto error;
        }
 
@@ -1226,9 +1225,12 @@ struct bt_ctf_field_type *bt_ctf_field_type_variant_create(
        variant->field_name_to_index = g_hash_table_new(NULL, NULL);
        variant->fields = g_ptr_array_new_with_free_func(
                (GDestroyNotify)destroy_structure_field);
-       bt_ctf_field_type_get(enum_tag);
-       variant->tag = container_of(enum_tag,
-               struct bt_ctf_field_type_enumeration, parent);
+       if (enum_tag) {
+               bt_ctf_field_type_get(enum_tag);
+               variant->tag = container_of(enum_tag,
+                       struct bt_ctf_field_type_enumeration, parent);
+       }
+
        bt_ctf_field_type_init(&variant->parent);
        return &variant->parent;
 error:
@@ -1246,6 +1248,10 @@ struct bt_ctf_field_type *bt_ctf_field_type_variant_get_tag_type(
        }
 
        variant = container_of(type, struct bt_ctf_field_type_variant, parent);
+       if (!variant->tag) {
+               goto end;
+       }
+
        tag_type = &variant->tag->parent;
        bt_ctf_field_type_get(tag_type);
 end:
@@ -1263,6 +1269,10 @@ const char *bt_ctf_field_type_variant_get_tag_name(
        }
 
        variant = container_of(type, struct bt_ctf_field_type_variant, parent);
+       if (variant->tag_name->len == 0) {
+               goto end;
+       }
+
        tag_name = variant->tag_name->str;
 end:
        return tag_name;
@@ -1274,7 +1284,6 @@ int bt_ctf_field_type_variant_add_field(struct bt_ctf_field_type *type,
 {
        size_t i;
        int ret = 0;
-       int name_found = 0;
        struct bt_ctf_field_type_variant *variant;
        GQuark field_name_quark = g_quark_from_string(field_name);
 
@@ -1287,19 +1296,31 @@ int bt_ctf_field_type_variant_add_field(struct bt_ctf_field_type *type,
        }
 
        variant = container_of(type, struct bt_ctf_field_type_variant, parent);
-       /* Make sure this name is present in the enum tag */
-       for (i = 0; i < variant->tag->entries->len; i++) {
-               struct enumeration_mapping *mapping =
-                       g_ptr_array_index(variant->tag->entries, i);
 
-               if (mapping->string == field_name_quark) {
-                       name_found = 1;
-                       break;
+       /* The user has explicitly provided a tag; validate against it. */
+       if (variant->tag) {
+               int name_found = 0;
+
+               /* Make sure this name is present in the enum tag */
+               for (i = 0; i < variant->tag->entries->len; i++) {
+                       struct enumeration_mapping *mapping =
+                               g_ptr_array_index(variant->tag->entries, i);
+
+                       if (mapping->string == field_name_quark) {
+                               name_found = 1;
+                               break;
+                       }
+               }
+
+               if (!name_found) {
+                       /* Validation failed */
+                       ret = -1;
+                       goto end;
                }
        }
 
-       if (!name_found || add_structure_field(variant->fields,
-               variant->field_name_to_index, field_type, field_name)) {
+       if (add_structure_field(variant->fields, variant->field_name_to_index,
+               field_type, field_name)) {
                ret = -1;
                goto end;
        }
@@ -2305,8 +2326,13 @@ int bt_ctf_field_type_variant_serialize(struct bt_ctf_field_type *type,
        GString *variant_field_name = context->field_name;
 
        context->field_name = g_string_new("");
-       g_string_append_printf(context->string,
-               "variant <%s> {\n", variant->tag_name->str);
+       if (variant->tag_name->len > 0) {
+               g_string_append_printf(context->string,
+                       "variant <%s> {\n", variant->tag_name->str);
+       } else {
+               g_string_append(context->string, "variant {\n");
+       }
+
        context->current_indentation_level++;
        for (i = 0; i < variant->fields->len; i++) {
                struct structure_field *field = variant->fields->pdata[i];

diff --git a/include/babeltrace/ctf-ir/event-types.h b/include/babeltrace/ctf-ir/event-types.h
index 774a88ed651d402c3fb20b82a3d6694463ae6518..9562318172103ba14e1ad961af80a02b80f8b0b7 100644 (file)
--- a/include/babeltrace/ctf-ir/event-types.h
+++ b/include/babeltrace/ctf-ir/event-types.h
@@ -486,7 +486,7 @@ extern struct bt_ctf_field_type *bt_ctf_field_type_variant_create(
  *
  * @param variant Variant type.
  *
- * Returns a field type instance on success, NULL on error.
+ * Returns a field type instance on success, NULL if unset.
  */
 extern struct bt_ctf_field_type *bt_ctf_field_type_variant_get_tag_type(
                struct bt_ctf_field_type *variant);
@@ -496,7 +496,7 @@ extern struct bt_ctf_field_type *bt_ctf_field_type_variant_get_tag_type(
  *
  * @param variant Variant type.
  *
- * Returns the tag field's name, NULL on error.
+ * Returns the tag field's name, NULL if unset.
  */
 extern const char *bt_ctf_field_type_variant_get_tag_name(
                struct bt_ctf_field_type *variant);