From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Tue, 29 Nov 2016 17:10:57 +0000 (-0500)
Subject: lttng-ust(3): document `lttng_ust_loaded` symbol
X-Git-Tag: v2.9.0~1
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=273554e4e1c9747afc2b0911fd0d124708720cea;p=lttng-ust.git

lttng-ust(3): document `lttng_ust_loaded` symbol

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/doc/man/lttng-ust.3.txt b/doc/man/lttng-ust.3.txt
index 65fb4d35..9fd3e8b8 100644
--- a/doc/man/lttng-ust.3.txt
+++ b/doc/man/lttng-ust.3.txt
@@ -991,6 +991,33 @@ Fields:
 |===
 
 
+Detect if LTTng-UST is loaded
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+To detect if `liblttng-ust` is loaded from an application:
+
+. Define the `lttng_ust_loaded` weak symbol globally:
++
+------------------------------------------------------------------------
+int lttng_ust_loaded __attribute__((weak));
+------------------------------------------------------------------------
++
+This weak symbol is set by the constructor of `liblttng-ust`.
+
+. Test `lttng_ust_loaded` where needed:
++
+------------------------------------------------------------------------
+/* ... */
+
+if (lttng_ust_loaded) {
+    /* LTTng-UST is loaded */
+} else {
+    /* LTTng-UST is NOT loaded */
+}
+
+/* ... */
+------------------------------------------------------------------------
+
+
 [[example]]
 EXAMPLE
 -------