[Boost-bugs] [Boost C++ Libraries] #7795: Bug creating structures in files mapped with small sizes

Subject: [Boost-bugs] [Boost C++ Libraries] #7795: Bug creating structures in files mapped with small sizes
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-12-14 00:05:31

#7795: Bug creating structures in files mapped with small sizes
----------------------------------+-----------------------------------------
 Reporter:  lodos@…               |       Owner:  igaztanaga  
     Type:  Bugs                  |      Status:  new         
Milestone:  To Be Determined      |   Component:  interprocess
  Version:  Boost 1.52.0          |    Severity:  Problem     
 Keywords:  mapped file size      |  
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 To reproduce the bug one could use doc_managed_mapped_file.cpp in the
 example folder. Set the FileSize variable to small values (less than 100
 for instance) and the construct method will cause a crash. An exception is
 expected instead.

 For completeness I include below our exchange in the boost developer list.
 Thank you.

 > > > When the size to map is too small, take 1 or 2 bytes for
 > > > instance, the library fails in a non elegant way. This is a corner
 > > > case, but I could not find this documented. Is this a bug?
 > >
 > > You need a minimum size to construct managed memory's internal
 > > structures. Maybe the behaviour should be documented. What do you
 > mean
 > > with "non-elegant", your application crashses? Nevertheless, mapping
 > 1
 > > or 2 bytes you waste resources, as the OS will map at least one page
 > > (4K on most 32 bit systems and 64 K on Windows).

 > Yes, the application crashes. I am mapping large complex containers
 > with different sizes, the crashes took place when I was developing
 > tests. I would expect an exception when the size of the mapping is not
 > enough.
 > It is time consuming to develop a structure that would need more than
 > 4Kb for its initial mapping. if I create a ticket with a sample using a
 > few bytes just to demonstrate the problem, would you consider it? I
 > understand this is not a show stopper :-) Thank you for your answers
 > and again for boost::interprocess.

 This seems a bug, please fill another ticket with your example.

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/7795>
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