[Boost-bugs] [Boost C++ Libraries] #3238: asio, kqueue_reactor, result of kevent() isn't checked for error

Subject: [Boost-bugs] [Boost C++ Libraries] #3238: asio, kqueue_reactor, result of kevent() isn't checked for error
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-07-02 18:02:09

#3238: asio, kqueue_reactor, result of kevent() isn't checked for error
-------------------------------+--------------------------------------------
 Reporter:  devel@…            |       Owner:  chris_kohlhoff
     Type:  Bugs               |      Status:  new           
Milestone:                     |   Component:  asio          
  Version:  Boost 1.38.0       |    Severity:  Problem       
 Keywords:  asio kqueue        |  
-------------------------------+--------------------------------------------
 No kevent() result checking.
 {{{
 asio/detail/kqueue_reactor.hpp:438
 ...
     wait_in_progress_ = true;
     lock.unlock();

     // Block on the kqueue descriptor.
     struct kevent events[128];
     int num_events = (block || need_kqueue_wait_)
       ? kevent(kqueue_fd_, 0, 0, events, 128, timeout)
       : 0;

     lock.lock();
     wait_in_progress_ = false;

     // Block signals while performing operations.
     boost::asio::detail::signal_blocker sb;

     // Dispatch the waiting events.
     for (int i = 0; i < num_events; ++i)
     {
             // processing events
 ...
 }}}
 Here is '''int num_events = kevent(kqueue_fd_, ...''', then '''for (int i
 = 0; i < num_events''' but '''num_events''' can be -1 here, and all this
 code makes no sense then.

 Suppose we have such code:
 {{{
 smtp_queue q("/var/spool/smtpq");
 asio::io_service io_service;
 smtp_server s(io_service, 25, q);
 smtp_client c(io_service, "target.host", "smtp", q);
 if(fork()) exit(0); // daemonize
 io_service.run();
 }}}
 Here we call '''fork()''' then '''io_service.run()'''.
 fork doesn't copy kqueue descriptor and subsequent kevent(fd,...) calls
 return -1 with errno = 9 (EBADFD, "Bad file descriptor").
 This case makes asio's kqueue reactor hangup.
 Probably, kevent() result should be checked for error and exception thrown
 if any.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3238>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.