From: Russell Bryant <russell@russellbryant.com>
Date: Fri, 28 Mar 2008 22:50:46 +0000 (+0000)
Subject: Make some notes about common usage of pbx_builtin_getvar_helper() that is not
X-Git-Tag: 1.6.2.0-beta1~2587
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=afd878357717fc46e8edc3369216aa6e5de2e80c;p=thirdparty%2Fasterisk.git

Make some notes about common usage of pbx_builtin_getvar_helper() that is not
thread-safe.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@111909 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---

diff --git a/doc/janitor-projects.txt b/doc/janitor-projects.txt
index 9d89ef18ca..b111204f05 100644
--- a/doc/janitor-projects.txt
+++ b/doc/janitor-projects.txt
@@ -1,3 +1,15 @@
+ -- There a bunch of places where the result of pbx_builtin_getvar_helper()
+    gets stored and used.  This is not threadsafe.  This code should be replaced
+	with the following thread-safe version:
+
+	const char *var;
+
+	ast_channel_lock(chan);
+	if ((var = pbx_builtin_getvar_helper(chan, "MYVAR"))) {
+		var = ast_strdupa(var);
+	}
+	ast_channel_unlock(chan);
+
  -- Convert all existing uses of astobj.h to astobj2.h
     -- (chan_sip already in progress in a branch)
 
diff --git a/include/asterisk/pbx.h b/include/asterisk/pbx.h
index 1761a9bd7f..56bd83fa56 100644
--- a/include/asterisk/pbx.h
+++ b/include/asterisk/pbx.h
@@ -800,6 +800,20 @@ int pbx_builtin_serialize_variables(struct ast_channel *chan, struct ast_str **b
 
 /*!
  * \note Will lock the channel.
+ *
+ * \note This function will return a pointer to the buffer inside the channel
+ * variable.  This value should only be accessed with the channel locked.  If
+ * the value needs to be kept around, it should be done by using the following
+ * thread-safe code:
+ * \code
+ *		const char *var;
+ *
+ *		ast_channel_lock(chan);
+ *		if ((var = pbx_builtin_getvar_helper(chan, "MYVAR"))) {
+ *			var = ast_strdupa(var);
+ *		}
+ *		ast_channel_unlock(chan);
+ * \endcode
  */
 const char *pbx_builtin_getvar_helper(struct ast_channel *chan, const char *name);