[Bug c++/12159] New: static C++ objects inside global functions (within a shared library) cause crash on program exit on Linux

[Bug c++/12159] New: static C++ objects inside global functions (within a shared library) cause crash on program exit on Linux

[tim dot crook at adobe dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12159

           Summary: static C++ objects inside global functions (within a
                    shared library) cause crash on program exit on Linux
           Product: gcc
           Version: 3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tim dot crook at adobe dot com
                CC: gcc-bugs at gcc dot gnu dot org

If you have a function like:

ComplexClass
foo ()
{
   static ComplexClass blah;
   return blah;
}

in a shared library and call it at least once (to initialize it with the 
constructor), when the shared library is unloaded before main terminates, your 
program will have a segment fault.

Under the covers, the code being generated for destruction of "blah" is done 
using the C function atexit. A function "__tcf_0" was generated by the compiler 
to do the cleanup - I turned off inlining.

By the definition in the Linux man page, the functions registered with atexit 
are called on program termination. As the code segment for the shared library 
has been deleted, this causes a memory fault.

On Solaris, the man page defines atexit functions as being called when EITHER 
objects are unloaded OR program termination occurs. As a result, this problem 
never happens on Solaris.

The solution to this problem may be to hook __tcf_0 into the function _fini, 
which is called when a shared library is unloaded. It appears that for each 
module compiled with at least one global static inside a global function, a 
__tcf_0 is generated.

[Bug c++/12159] static C++ objects inside global functions (within a shared library) cause crash on program exit on Linux

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12159


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-09-07 03:07 -------
This is not a GCC bug but rather a glibc bug (report it to them) as we have no control over 
when functions are called when dealing with shared libraries.

[Bug c++/12159] static C++ objects inside global functions (within a shared library) cause crash on program exit on Linux

[tim dot crook at adobe dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12159



------- Additional Comments From tim dot crook at adobe dot com  2003-09-09 14:41 -------
Subject: RE:  static C++ objects inside global functions (w
	ithin a shared library) cause crash on program exit on Linux

I think this bug can be dropped. I found out that configuring gcc with
--enable-__cxa_atexit eliminates the problem. Using -fuse-cxa-atexit didn't
seem sufficient - strange.

-----Original Message-----
From: pinskia at gcc dot gnu dot org [mailto:gcc-bugzilla@gcc.gnu.org]
Sent: Saturday, September 06, 2003 11:08 PM
To: tim.crook@adobe.com
Subject: [Bug c++/12159] static C++ objects inside global functions
(within a shared library) cause crash on program exit on Linux


PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12159


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-09-07
03:07 -------
This is not a GCC bug but rather a glibc bug (report it to them) as we have
no control over 
when functions are called when dealing with shared libraries.



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