1.15.19 dlopen() dies with no dlerror()

[Larry Hall (Cygwin)]

Jim Kleckner wrote:
> Jim Kleckner wrote:
>> Michael McKerns wrote:
>>> Yes, yes...  I've not given you enough information...
>>> ...
>>> See:
>>> http://cygwin.com/cygwin-ug-net/dll.html
>>> http://cygwin.com/faq.html#faq.programming.dll-relocatable
>>>   
>> I'm seeing a similar problem with python and 1.5.19 and also tried the 
>> snapshot of 22-May.
>>
>> CYGWIN_NT-5.1 kleckner2 1.5.20s(0.155/4/2) 20060522 00:51:23 i686 Cygwin
>>
>> A simple test case doesn't fail in dlopen().
>>
>> My code is not simple but has been working prior to the most recent 
>> update (which also updated python and other packages).
>> A downrev of python does not make the problem go away.  If I downrev 
>> cygwin, I get complaints about missing entry points.
>>
>> What do you recommend as the best way to isolate this?
> 
> I tried using "prev" with setup.exe but that didn't make the problem go 
> away.
> 
> A simple test case with python access to a trivial function works fine 
> (can supply if anyone wants).
> The complex dll that used to work simply doesn't return from dlopen.
> 
> I downloaded the 20060522 snapshot with debug symbols to get a backtrace 
> with GDB.
> GDB says there is a seg fault and somehow this is preventing any 
> information from reaching dlerror().
> Without the dlerror() info, it is hard to figure out what needs to 
> change with the dll.
> It appears that some constructors are having trouble.
> 
> Let me know if there is some single stepping that could be helpful.
> 
> ==================== Trivial program to use dlopen on a non-trivial dll
> 
> #include <stdio.h>
> #include <dlfcn.h>
> 
> int main( int argc, char **argv)
> {
>    fprintf( stderr, "Error: %s\n", dlerror());
>    void *dlp = dlopen("_pycode.dll", RTLD_NOW);
>    fprintf( stderr, "Error: %s\n", dlerror());
>    return 0;
> }
> 
> ==================== GDB Traceback
> 
> $ gdb a.exe
> GNU gdb 6.3.50_2004-12-28-cvs (cygwin-special)
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you 
> are
> welcome to change it and/or distribute copies of it under certain 
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "i686-pc-cygwin"...
> (gdb) run
> Starting program: .../Programs/a.exe
> Error: (null)
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x610b1ff8 in pthread_key_create () from /usr/bin/cygwin1.dll
> (gdb) add-symbol-file /bin/cygwin1-20060522.dbg
> add symbol table from file "/bin/cygwin1-20060522.dbg" at
> (y or n) y
> Reading symbols from /bin/cygwin1-20060522.dbg...warning: no loadable 
> sections found in added symbol-file /bin/cygwin1-20060522.dbg
> done.
> Current language:  auto; currently c++
> (gdb) bt
> #0  0x610b1ff8 in pthread_key_create (key=0x6622f8, destructor=0) at 
                     ^^^^^^^^^^^^^^^^^^^
Known issue already fixed in the Cygwin snapshot and in GDB's CVS.  This
is not fatal.  Just continue until you stop seeing this complaint.


-- 
Larry Hall                              http://www.rfk.com
RFK Partners, Inc.                      (508) 893-9779 - RFK Office
838 Washington Street                   (508) 893-9889 - FAX
Holliston, MA 01746

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