Boost C++ Libraries: Ticket #11633: chrono IO V1 may throw bad_cast

attachment set

Wed, 09 Sep 2015 14:59:59 GMT

attachment → chrono_io_bad_cast.tgz

viboes — Thu, 10 Sep 2015 05:00:43 GMT

Hi,

I didn't through to multi-threading while developing this code :(

Could you try to comment the line? Could you also try version v2 by defining before including any boost/chrono/... file

#define BOOST_CHRONO_VERSION 2
#include <boost/chrono/chrono.hpp>
#include <boost/chrono/chrono_io.hpp>

viboes — Thu, 10 Sep 2015 05:20:12 GMT

The following avoids the race, but breaks other functionalities

template <class CharT, class Traits, class Rep, class Period>
std::basic_ostream<CharT, Traits>&
operator<<(std::basic_ostream<CharT, Traits>& os, const duration<Rep, Period>& d)
{
    typedef duration_punct<CharT> Facet;
    Facet f;
    return os << d.count() << ' ' << f.template name<Period>(d.count());
}

I tried with version 2 and I was not able to reproduce the issue. Please let me know.

viboes — Thu, 10 Sep 2015 05:41:22 GMT

For what I understand std::ios_base::imbue is not thread-safe.

Version 1 is bugged as it does an imbue if the facet is not present, raising possible undefined behavior.

Version 2 duration operator<< doesn't imbues the facet by itself. If not present, it uses duration_put.

status, component changed; owner set

viboes — Thu, 10 Sep 2015 05:42:32 GMT

owner set to viboes
status new → assigned
component None → chrono

Thu, 10 Sep 2015 08:08:31 GMT

Hi Vincente, thank you for answering so quickly.

I tried with version 2 and I was not able to reproduce the issue. Please let me know.

same here.

For what I understand std::ios_base::imbue is not thread-safe. Version 1 is bugged as it does an imbue if the facet is not present, raising possible undefined behavior. Version 2 duration operator<< doesn't imbues the facet by itself. If not present, it uses duration_put.

would it be possible to fix v1? Maybe with something like this (untested):

template <class CharT, class Traits, class Rep, class Period>
std::basic_ostream<CharT, Traits>&
operator<<(std::basic_ostream<CharT, Traits>& os, const duration<Rep, Period>& d)
{
    typedef duration_punct<CharT> Facet;
    os << d.count() << ' ';
    try {
        os << std::use_facet<Facet>(os.getloc()).template name<Period>(d.count());
    } catch (std::bad_cast) {
       // os locale does not have the facet
       os << Facet().template name<Period>(d.count());
    }
    return os;
}

viboes — Thu, 10 Sep 2015 17:53:06 GMT

Have you tried this? This is in some way what version 2 does.

Fri, 11 Sep 2015 13:51:31 GMT

Replying to viboes:

Have you tried this? This is in some way what version 2 does.

No (as the "untested" suggested), and sadly I'm by no way an iostream/locale expert.

viboes — Fri, 11 Sep 2015 17:01:30 GMT

Please, could you test it?

viboes — Wed, 23 Sep 2015 23:05:27 GMT

PING!!!

type changed

viboes — Sun, 25 Oct 2015 23:50:56 GMT

type Bugs → Support Requests

Moved to support until someone respond.

summary changed

viboes — Mon, 28 Aug 2017 05:19:54 GMT

summary chrono IO may throw bad_cast → chrono IO V1 may throw bad_cast