Logger crashes in fclose()

[Jakub Jermář]

As of mainline,1685, logger crashes in the following code path:

fclose() [stream is NULL]
log_release()
unregister_logs()
logger_connection_handler_writer()

[Vojtech Horky]

Fixed in mainline,1686.

For the record: the bug can be reproduced by running /app/tester on any test except the logger ones (e.g. tester softfloat1).

The cause of the fault was that logger opens the log file (e. g. /log/tester) only when it is really needed – i. e. on first write to that file. Thus, if some application initializes logging but logs nothing (such as the softfloat1 test), on application exit the logger was closing NULL file stream.