[Boost-bugs] [Boost C++ Libraries] #4979: shared_memory_object open_only ctor resets permissions to default

Subject: [Boost-bugs] [Boost C++ Libraries] #4979: shared_memory_object open_only ctor resets permissions to default
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-12-13 18:17:01

#4979: shared_memory_object open_only ctor resets permissions to default
------------------------------------------------+---------------------------
 Reporter:  Bob Dempsey <rdempsey@…>            |       Owner:  igaztanaga  
     Type:  Bugs                                |      Status:  new         
Milestone:  To Be Determined                    |   Component:  interprocess
  Version:  Boost 1.45.0                        |    Severity:  Problem     
 Keywords:                                      |  
------------------------------------------------+---------------------------
 Because of a call to ::fchmod() in
 shared_memory_object::priv_open_or_create, if you use attempt to open a
 shm segment using the open_only tag, you will always reset the existing
 perms to the default. These 3 lines are the problem:

 {{{
    if(m_handle >= 0){
       ::fchmod(m_handle, perm.get_permissions());
    }
 }}}

 If you delete these lines (on Linux, anyway) things looks right. I don't
 know why those lines are there, but if they are needed for portability,
 perhaps something like

 {{{
    if(m_handle >= 0 && type != detail::DoOpen){
       ::fchmod(m_handle, perm.get_permissions());
    }
 }}}

 might work better.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4979>
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