X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Foptional.h;h=0d99fe3224f4e419679d22627a0f4899f0c2a9d2;hp=1da5fda5da21ac0e8d9acd9c4b7f9f3821b950a9;hb=3da864a94ccc39239fea82c4803b58b6b56a1003;hpb=2c5ff4e47394f9588ac1a0ab50e8fbdf36727cbe

diff --git a/src/common/optional.h b/src/common/optional.h
index 1da5fda5d..0d99fe322 100644
--- a/src/common/optional.h
+++ b/src/common/optional.h
@@ -1,18 +1,8 @@
 /*
- * Copyright (C) 2019 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2 only,
- * as published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #ifndef LTTNG_OPTIONAL_H
@@ -32,9 +22,6 @@
  * 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 +44,16 @@
 		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 +63,19 @@
  */
 #define LTTNG_OPTIONAL_GET(optional)			\
         ({						\
-		assert(optional.is_set);		\
-		optional.value;				\
+		assert((optional).is_set);		\
+		(optional).value;			\
+	})
+
+/*
+ * This macro is available as a 'convenience' to allow sites that assume
+ * an optional value is set to assert() that it is set when fecthing the
+ * underlying value's address.
+ */
+#define LTTNG_OPTIONAL_GET_PTR(optional)			\
+	({						\
+		assert((optional).is_set);		\
+		&(optional).value;			\
 	})
 
 /*
@@ -79,12 +87,16 @@
 #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 */