Refactoring: struct lttng_enum_desc and lttng_enum_entry

[lttng-ust.git] / include / lttng / ust-events.h

diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index acea99105a86492646723732f930cc8fe250ab85..164c82c4c8288617702a56edc5eec30ba341b6aa 100644 (file)
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -83,16 +83,26 @@ enum lttng_enum_entry_options {
        LTTNG_ENUM_ENTRY_OPTION_IS_AUTO = 1U << 0,
 };
 
-#define LTTNG_UST_ENUM_ENTRY_PADDING   16
-struct lttng_enum_entry {
+/*
+ * Enumeration entry description
+ *
+ * IMPORTANT: this structure is part of the ABI between the probe and
+ * UST. Fields need to be only added at the end, never reordered, never
+ * removed.
+ *
+ * The field @struct_size should be used to determine the size of the
+ * structure. It should be queried before using additional fields added
+ * at the end of the structure.
+ */
+
+struct lttng_ust_enum_entry {
+       uint32_t struct_size;
+
        struct lttng_enum_value start, end; /* start and end are inclusive */
        const char *string;
-       union {
-               struct {
-                       unsigned int options;
-               } LTTNG_PACKED extra;
-               char padding[LTTNG_UST_ENUM_ENTRY_PADDING];
-       } u;
+       unsigned int options;
+
+       /* End of base ABI. Fields below should be used after checking struct_size. */
 };
 
 #define __type_integer(_type, _byte_order, _base, _encoding)   \
@@ -168,7 +178,7 @@ struct lttng_type {
                        enum lttng_string_encodings encoding;
                } string;
                struct {
-                       const struct lttng_enum_desc *desc;     /* Enumeration mapping */
+                       const struct lttng_ust_enum_desc *desc; /* Enumeration mapping */
                        struct lttng_type *container_type;
                } enum_nestable;
                struct {
@@ -191,12 +201,26 @@ struct lttng_type {
        } u;
 };
 
-#define LTTNG_UST_ENUM_TYPE_PADDING    24
-struct lttng_enum_desc {
+/*
+ * Enumeration description
+ *
+ * IMPORTANT: this structure is part of the ABI between the probe and
+ * UST. Fields need to be only added at the end, never reordered, never
+ * removed.
+ *
+ * The field @struct_size should be used to determine the size of the
+ * structure. It should be queried before using additional fields added
+ * at the end of the structure.
+ */
+
+struct lttng_ust_enum_desc {
+       uint32_t struct_size;
+
        const char *name;
-       const struct lttng_enum_entry *entries;
+       const struct lttng_ust_enum_entry **entries;
        unsigned int nr_entries;
-       char padding[LTTNG_UST_ENUM_TYPE_PADDING];
+
+       /* End of base ABI. Fields below should be used after checking struct_size. */
 };
 
 /*
@@ -460,7 +484,7 @@ struct lttng_ust_event_notifier {
 };
 
 struct lttng_enum {
-       const struct lttng_enum_desc *desc;
+       const struct lttng_ust_enum_desc *desc;
        struct lttng_session *session;
        struct cds_list_head node;      /* Enum list in session */
        struct cds_hlist_node hlist;    /* Session ht of enums */