logger.c: Automatically add a newline to formats that don't have one

Scope tracing allows you to not specify a format string or variable,
in which case it just prints the indent, file, function, and line
number.  The trace output automatically adds a newline to the end
in this case.  If you also have debugging turned on for the module,
a debug message is also printed but the standard log functionality
which prints it doesn't add the newline so you have messages
that don't break correctly.

 * format_log_message_ap(), which is the common log
   message formatter for all channels, now adds a
   newline to the end of format strings that don't
   already have a newline.

ASTERISK-29209
Reported by: Alexander Traud

Change-Id: I994a7df27f88df343b7d19f3e81a4b562d9d41da

main/logger.c

@@ -1672,6 +1672,11 @@ static struct logmsg * __attribute__((format(printf, 7, 0))) format_log_message_
 		return NULL;
 	}
 
+	/* Automatically add a newline to format strings that don't have one */
+	if (!ast_ends_with(ast_str_buffer(buf), "\n")) {
+		ast_str_append(&buf, 0, "\n");
+	}
+
 	/* Create a new logging message */
 	if (!(logmsg = ast_calloc_with_stringfields(1, struct logmsg, res + 128))) {
 		return NULL;