[Boost-bugs] [Boost C++ Libraries] #6819: appending fixed-size array of length 1 is a no-op in path v3

Subject: [Boost-bugs] [Boost C++ Libraries] #6819: appending fixed-size array of length 1 is a no-op in path v3
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-04-21 20:17:22

#6819: appending fixed-size array of length 1 is a no-op in path v3
------------------------------+---------------------------------------------
 Reporter:  mejedi@…          |       Owner:  bemandawes
     Type:  Bugs              |      Status:  new       
Milestone:  To Be Determined  |   Component:  filesystem
  Version:  Boost 1.48.0      |    Severity:  Problem   
 Keywords:                    |  
------------------------------+---------------------------------------------
 Boost::filesystem::path recognizes appending a fixed-size array of length
 1 as a special case and does nothing. This looks pretty reasonable until
 you consider using boost::filesystem together with C libraries. In C a
 common trick is to allocate a structure AND a character buffer with a
 single call to a memory allocation routine. The structure is often
 declared and allocated as follows

 {{{#!C++
 struct c_struct
 {
     int foo;
     int bar;
     char flexible_buf[1];
 };

 c_struct *p = malloc(sizeof *p + EXTRA);
 }}}

 Consider a C library exposing a structure similar to c_struct and a piece
 of C++ code appending  flexible_buf to a path object. This will result in
 a hard to find bug since a programmer is probably assuming that appending
 a string to a path object will actually append a string.

 To make matters worse a casual user of a C library is not even aware that
 the library is playing the flexible buffer trick. Library docs may pretend
 that the structure has a character pointer field but the implementation
 declares a char![1] field instead.

 An example is fts(3) http://www.kernel.org/doc/man-

 pages/online/pages/man3/fts.3.html. Manual pretends that fts_name is a
 character pointer field in _ftsent struct but on Linux and MacOS X
 fts_name is char![1] instead.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6819>
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