From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 17 Aug 2022 19:10:58 +0000 (-0400)
Subject: Fix: disable array/sequence compile-time type check in C
X-Git-Url: http://git.liburcu.org/?p=lttng-ust.git;a=commitdiff_plain;h=f04f60a5f613b5a850dbe0ee4e983f21803db1ed

Fix: disable array/sequence compile-time type check in C

Disable this compile-time check in C. Indeed, the C implementation of
lttng_ust_is_pointer_type does not support opaque pointer types, because
it relies on pointer arithmetic.

Therefore, remove this check to keep supporting opaque pointers as
array/sequence elements in probe providers.

The worse that could happen is that users providing an unsupported
type as array/sequence element will end up with a meaningless integer
field.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I0fa170f7af7fc016027685e48076ebaf0366cc5b
---

diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index 86098a98..81affd8c 100644
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -257,9 +257,16 @@ void lttng_ust__event_template_proto___##_provider##___##_name(LTTNG_UST__TP_ARG
 	};
 #include LTTNG_UST_TRACEPOINT_INCLUDE
 
+#if defined(__cplusplus)
+
 /*
  * Stage 0.9.1
- * Verifying array and sequence elements are of an integer type.
+ * Verifying array and sequence elements are of an integer or pointer
+ * type.
+ *
+ * This compile-time check is only enabled in C++, because the C
+ * implementation of lttng_ust_is_pointer_type does not support opaque
+ * pointer types.
  */
 
 /* Reset all macros within LTTNG_UST_TRACEPOINT_EVENT */
@@ -288,6 +295,8 @@ void lttng_ust__event_template_proto___##_provider##___##_name(LTTNG_UST__TP_ARG
 
 #include LTTNG_UST_TRACEPOINT_INCLUDE
 
+#endif
+
 /*
  * Stage 0.9.2 of tracepoint event generation.
  *
diff --git a/include/lttng/ust-utils.h b/include/lttng/ust-utils.h
index d815cf0c..e60cdbe3 100644
--- a/include/lttng/ust-utils.h
+++ b/include/lttng/ust-utils.h
@@ -62,6 +62,9 @@
  * lttng_ust_is_pointer_type - check if type is a pointer
  *
  * Returns true if the type of @type is a pointer.
+ *
+ * Note: The C implementation of lttng_ust_is_pointer_type uses pointer
+ * arithmetic, which does not work on opaque pointer types.
  */
 #if defined(__cplusplus)
 #define lttng_ust_is_pointer_type(type) (std::is_pointer<type>::value)