Merged revisions 328717 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.10

................
  r328717 | twilson | 2011-07-18 20:55:32 -0500 (Mon, 18 Jul 2011) | 14 lines
  
  Merged revisions 328716 via svnmerge from 
  https://origsvn.digium.com/svn/asterisk/branches/1.8
  
  ........
    r328716 | twilson | 2011-07-18 20:35:53 -0500 (Mon, 18 Jul 2011) | 7 lines
    
    Make AST_LIST_REMOVE safer
    
    AST_LIST_REMOVE shouldn't modify the element passed in if it isn't found. This
    commit also adds linked list unit tests.
    
    Review: https://reviewboard.asterisk.org/r/1321/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@328718 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/linkedlists.h

@@ -838,7 +838,10 @@ struct {								\
  */
 #define AST_LIST_REMOVE(head, elm, field) ({			        \
 	__typeof(elm) __res = NULL; \
-	if ((head)->first == (elm)) {					\
+	__typeof(elm) __tmp = elm; \
+	if (!__tmp) { \
+		__res = NULL; \
+	} else if ((head)->first == (elm)) {					\
 		__res = (head)->first;                      \
 		(head)->first = (elm)->field.next;			\
 		if ((head)->last == (elm))			\
@@ -854,7 +857,9 @@ struct {								\
 				(head)->last = curelm;				\
 		} \
 	}								\
-	(elm)->field.next = NULL;                                       \
+	if (__res) { \
+		(__res)->field.next = NULL; \
+	} \
 	(__res); \
 })