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Date: Tue, 10 Aug 2004 09:31:00 -0000
From: "peturr02 at ru dot is" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20040810093113.16959.peturr02@ru.is>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug libstdc++/16959] New: [3.4/3.5 Regression] Segmentation fault in ios_base::sync_with_stdio
X-Bugzilla-Reason: CC
X-SW-Source: 2004-08/txt/msg00780.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

In src/ios_init.cc:

  bool 
  ios_base::sync_with_stdio(bool __sync)
  { 
    // _GLIBCXX_RESOLVE_LIB_DEFECTS
    // 49.  Underspecification of ios_base::sync_with_stdio
    bool __ret = ios_base::Init::_S_synced_with_stdio;

    // Turn off sync with C FILE* for cin, cout, cerr, clog iff
    // currently synchronized.
    if (!__sync && __ret)
      {
        ios_base::Init::_S_synced_with_stdio = __sync;

        // Explicitly call dtors to free any memory that is
        // dynamically allocated by filebuf ctor or member functions,
        // but don't deallocate all memory by calling operator delete.
        buf_cout_sync.~stdio_sync_filebuf<char>();
        buf_cin_sync.~stdio_sync_filebuf<char>();
        buf_cerr_sync.~stdio_sync_filebuf<char>();

This is fine, except that there is no guarantee that buf_cout_sync and friends
have been constructed before this gets run. If the objects haven't been
constructed, the program segfaults.

A simple fix would be to construct an ios_base::Init object at the beginning
of the block.

-- 
           Summary: [3.4/3.5 Regression] Segmentation fault in
                    ios_base::sync_with_stdio
           Product: gcc
           Version: 3.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: peturr02 at ru dot is
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16959