On Jul 25 01:36, Daniel Colascione wrote:
> On 7/25/2013 12:11 AM, Daniel Colascione wrote:
> > On 7/24/2013 11:55 PM, Daniel Colascione wrote:
> >> Does that help at all? I only started seeing this problem after I
> >> recompiled
> >> _wp.dll using gcc 4.7.3.
> >
> > Actually, this problem looks a lot like
> > http://www.mail-archive.com/gcc@gcc.gnu.org/msg68316.html: neither Python
> > nor
> > _wp links dynamically to libgcc, but cygsqlite3-0.dll does.
> >
>
> And this is a very nasty bug; Eli's analysis is correct. Say we have modules
> Foo
> and Bar. Foo links against shared libgcc, but Bar does not. Now, if we load
> Foo,
> load Bar, unload Foo, then unload Bar, then Foo's initialization code finds
> libgcc and registers itself with it, but Foo's deinitializaton code doesn't
> find
> libgcc, tries to instead unregister with Foo's internal data structures, finds
> them uninitialized, and aborts. No wonder changing Python module order around
> makes the problem go away for a little while.
>
> The right fix for libgcc looks something like this:
Good catch! Any chance you could send this upstream?
JonY, do you have any spare cycles to create new 32 and 64 bit gcc
packages with this fix?
Thanks,
Corinna
> --- config/i386/cygming-crtbegin.c.orig 2013-07-25 00:07:35.000000000 -0800
> +++ config/i386/cygming-crtbegin.c 2013-07-25 00:33:11.000000000 -0800
> @@ -82,6 +82,8 @@
> extern void __gcc_register_frame (void);
> extern void __gcc_deregister_frame (void);
>
> +static HANDLE libgcc_dll;
> +
> void
> __gcc_register_frame (void)
> {
> @@ -94,8 +96,11 @@
> void (*register_frame_fn) (const void *, struct object *);
> HANDLE h = GetModuleHandle (LIBGCC_SONAME);
> if (h)
> - register_frame_fn = (void (*) (const void *, struct object *))
> - GetProcAddress (h, "__register_frame_info");
> + {
> + libgcc_dll = LoadLibrary (LIBGCC_SONAME); /* Hold reference */
> + register_frame_fn = (void (*) (const void *, struct object *))
> + GetProcAddress (h, "__register_frame_info");
> + }
> else
> register_frame_fn = __register_frame_info;
> if (register_frame_fn)
> @@ -124,13 +129,16 @@
> {
> #if DWARF2_UNWIND_INFO
> void * (*deregister_frame_fn) (const void *);
> - HANDLE h = GetModuleHandle (LIBGCC_SONAME);
> - if (h)
> + if (libgcc_dll)
> deregister_frame_fn = (void* (*) (const void *))
> - GetProcAddress (libgcc_dl,
> "__deregister_frame_info");
> + GetProcAddress (libgcc_dll, "__deregister_frame_info");
> else
> deregister_frame_fn = __deregister_frame_info;
> if (deregister_frame_fn)
> deregister_frame_fn (__EH_FRAME_BEGIN__);
> +
> + if (libgcc_dll)
> + FreeLibrary (libgcc_dll);
> +
> #endif
>
> The problem is that this code is baked into every module compiled with the
> buggy
> libgcc. You have to recompile the world to fix it for good --- except if
> shared
> libgcc is pinned in memory.
>
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
--
Problem reports: http://cygwin.com/problems.html
FAQ: http://cygwin.com/faq/
Documentation: http://cygwin.com/docs.html
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
