prevent copying of NULL (bug #4307)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@5708 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/funcs/func_logic.c b/funcs/func_logic.c
index d20b771..8df1732 100755 (executable)
--- a/funcs/func_logic.c
+++ b/funcs/func_logic.c
@@ -52,12 +52,14 @@ static char *builtin_function_if(struct ast_channel *chan, char *cmd, char *data
                                *iffalse = '\0';
                                iffalse++;
                        }
-               } else 
-                       iffalse = "";
+               } 
+
                if (expr && iftrue) {
                        ret = ast_true(expr) ? iftrue : iffalse;
-                       strncpy(buf, ret, len);
-                       ret = buf;
+                       if (ret) {
+                               ast_copy_string(buf, ret, len);
+                               ret = buf;
+                       }
                } else {
                        ast_log(LOG_WARNING, "Syntax $(if <expr>?[<truecond>][:<falsecond>])\n");
                        ret = NULL;