Fix: optional.h macro missing parentheses and guards

[lttng-tools.git] / src / common / optional.h

diff --git a/src/common/optional.h b/src/common/optional.h
index 1da5fda5da21ac0e8d9acd9c4b7f9f3821b950a9..53215b0315e299695e03ec67dc49890176707cd4 100644 (file)
--- a/src/common/optional.h
+++ b/src/common/optional.h
@@ -32,9 +32,6 @@
  * Prefer using this macro where "special" values would be used, e.g.
  * -1ULL for uint64_t types.
  *
- * LTTNG_OPTIONAL should be combined with the LTTNG_PACKED macro when
- * used for IPC / network communication.
- *
  * Declaration example:
  * struct my_struct {
  *     int a;
@@ -57,6 +54,16 @@
                type value;  \
        }
 
+/*
+ * Alias used for communication structures. If the layout of an LTTNG_OPTIONAL
+ * is changed, the original layout should still be used for communication
+ * purposes.
+ *
+ * LTTNG_OPTIONAL_COMM should be combined with the LTTNG_PACKED macro when
+ * used for IPC / network communication.
+ */
+#define LTTNG_OPTIONAL_COMM LTTNG_OPTIONAL
+
 /*
  * This macro is available as a 'convenience' to allow sites that assume
  * an optional value is set to assert() that it is set when accessing it.
@@ -66,8 +73,8 @@
  */
 #define LTTNG_OPTIONAL_GET(optional)                   \
         ({                                             \
-               assert(optional.is_set);                \
-               optional.value;                         \
+               assert((optional).is_set);              \
+               (optional).value;                       \
        })
 
 /*
@@ -79,12 +86,16 @@
 #define LTTNG_OPTIONAL_INIT { .is_set = 0 }
 
 /* Set the value of an optional field. */
-#define LTTNG_OPTIONAL_SET(field_ptr, val) \
-       (field_ptr)->value = val;          \
-       (field_ptr)->is_set = 1;
+#define LTTNG_OPTIONAL_SET(field_ptr, val)     \
+       do {                                    \
+               (field_ptr)->value = (val);     \
+               (field_ptr)->is_set = 1;        \
+       } while (0)
 
 /* Put an optional field in the "unset" (NULL-ed) state. */
-#define LTTNG_OPTIONAL_UNSET(field_ptr)    \
-       (field_ptr)->is_set = 0;
+#define LTTNG_OPTIONAL_UNSET(field_ptr)                \
+       do {                                    \
+               (field_ptr)->is_set = 0;        \
+       } while (0)
 
 #endif /* LTTNG_OPTIONAL_H */