Re: [Boost-bugs] [Boost C++ Libraries] #1578: bug in readdir_r_simulator() in a multi-threaded environment

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #1578: bug in readdir_r_simulator() in a multi-threaded environment
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-02-14 21:10:47

#1578: bug in readdir_r_simulator() in a multi-threaded environment
-----------------------------+----------------------------------------------
  Reporter:  raulh39_at_[hidden]  |       Owner:  bemandawes
      Type:  Bugs            |      Status:  assigned  
 Milestone:  Boost 1.35.0    |   Component:  filesystem
   Version:  Boost 1.34.1    |    Severity:  Problem   
Resolution:                  |    Keywords:            
-----------------------------+----------------------------------------------
Comment (by raulh39):

 Ok.
 I've been studying the problem, and I have come to the conclusion that
 it's a bug in Solaris.

 The function readdir_r (despite what is indicated here:
 http://tinyurl.com/35aek7) with
   int r = readdir_r(dirp,entry,result);
 returns r==-1, do NOT set *result to NULL, and leaves errno with its
 previous value when it reaches an end-of-directory.

 This way it "cheats" dir_itr_increment (lines 1269 and 1270 of
 operations.cpp in boost 1.34.1) to believe that an error has ocurred
 (because of the -1), but returns errno, whose value is 0, which means OK!

 So basic_directory_iterator<Path>::increment() understands (lines 940 to
 944 of operations.hpp) that everything is OK, and because *result has not
 been set to NULL, m_imp->m_handle is not NULL, so (line 950) it is not
 understand as an end-of-directory.

 I have change readdir_r_simulator (lines 1247-1248) from this:
 {{{
           if ( ::sysconf( _SC_THREAD_SAFE_FUNCTIONS ) >= 0 )
             { return ::readdir_r( dirp, entry, result ); }
 }}}
 to this:
 {{{
           if ( ::sysconf( _SC_THREAD_SAFE_FUNCTIONS ) >= 0 )
             {
                 int r = ::readdir_r( dirp, entry, result );
                 #ifdef __sun__
                 if(r==-1 && errno==0)
                 {
                     r=0;
                     *result=0;
                 }
                 #endif
                 return r;
             }
 }}}
 and now it works as expected.

 Please consider whether this changes might be made in any branch of Boost.
 Thank you.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1578#comment:4>
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