[Boost-bugs] [Boost C++ Libraries] #4439: Possible infinite loop in boost:: filesystem::copy_file for unix

Subject: [Boost-bugs] [Boost C++ Libraries] #4439: Possible infinite loop in boost:: filesystem::copy_file for unix
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-07-15 12:54:51

#4439: Possible infinite loop in boost:: filesystem::copy_file for unix
--------------------------------------------------------------+-------------
 Reporter:  Roberto Carlos Toledano Gómez <rctg82@…>          |       Owner:  bemandawes
     Type:  Bugs                                              |      Status:  new       
Milestone:  Boost 1.44.0                                      |   Component:  filesystem
  Version:  Boost Development Trunk                           |    Severity:  Problem   
 Keywords:  copy, filesystem                                  |  
--------------------------------------------------------------+-------------
 In the write cycle:


       do
       {
         if ((sz = ::write(outfile, buf.get() + sz_write,
           sz_read - sz_write))< 0)
         {
           sz_read = sz; // cause read loop termination
           break;        //  and error to be thrown after closes
         }
         sz_write += sz;
       } while (sz_write < sz_read);




 Always try to write a number of bytes strictly greater than zero and the
 api ::write returns according to the official documentation :" On
 success,  the  number of bytes written is returned (Zero Indicates Nothing
 Was Written).  On error, -1 is returned, and errno is set appropriately".
 Now imagine that the ::write api for any error or side effect, always
 returns zero, then we are in an infinite loop.

 To fix it I think the appropriate condition should be:

   if ((sz =:: write (outfile, buf.get () + sz_write,
           sz_read - sz_write)) <= 0)

 that is, change the Boolean operation for less than or equal to (<=)

 If I'm wrong please let me know what to learn. In my opinion you are the
 best.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4439>
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