[Boost-bugs] [Boost C++ Libraries] #4782: ioctl constants are sign extended on 64 bit builds

Subject: [Boost-bugs] [Boost C++ Libraries] #4782: ioctl constants are sign extended on 64 bit builds
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-10-24 22:47:32

#4782: ioctl constants are sign extended on 64 bit builds
-----------------------------+----------------------------------------------
 Reporter:  arvid@…          |       Owner:  chris_kohlhoff
     Type:  Bugs             |      Status:  new           
Milestone:  Boost-1.45.0     |   Component:  None          
  Version:  Boost 1.44.0     |    Severity:  Regression    
 Keywords:                   |  
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 Sometime between boost 1.40 and 1.44 asio started to keep track of whether
 or not the user had set the FIONBIO ioctl (non blocking I/O). On a 64 bit
 build this test fails, and asio believes that the socket is still in
 blocking mode. The reason why it fails is because the constants defined
 are unsigned ints, in asio's io control wrapper template, the "name" is
 returned as an int. This is later cast to a long and then compared to the
 system constants.

 The problem is that the system constants, although they fit in a 32 bit
 value, have the most significant bit set, so the cast from int -> long
 causes sign extension, and the comparison to the FIONBIO constant always
 fails.

 The fix for this is quite simple; in the file
 boost/asio/detail/io_control.hpp, just change the return value of
 non_blocking_io::name() to be a long instead of an int.

 asio seems to be using longs in the socket_ops.hpp for its ioctl()
 wrapper, so this seems like the most appropriate solution. This goes for
 all classes implementing the IoControlCommand concept.

 I marked this as a regression, but it might make sense to consider it a
 show-stopper, because it means any application that relies on non-blocking
 operations will freeze. On Mac OS X, 64 bit builds are defaults, so all
 mac applications are affected.

 I tried to post this to the mailing list with a few more details a few
 weeks ago, but I don't think it made it through.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4782>
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