FreeTDS Development Group

[Chris <ccortner AT cvol.net>]

Maybe this helps

[root@Fear-Linux bin]# ldd /www/libexec/libphp4.so
        /lib/libtsocks.so => /lib/libtsocks.so (0x4017b000)
        libodbc.so.1 => /usr/local/lib/libodbc.so.1 (0x40184000)
        libsybdb.so.2 => /usr/local/freetds/lib/libsybdb.so.2
(0x401dc000)
        libmysqlclient.so.10 => /usr/lib/mysql/libmysqlclient.so.10
(0x40208000)
        ......

On Sat, 2002-11-16 at 17:22, Chris wrote:
> Hello Again :) I followed your directions here to get a backtrace. I
> made sure that all the libraries involved were not stripped even httpd
> and all its dependent libraries. PHP, FreeTDS and Apache are all
> compiled with the -g flag. When I do a backtrace I get this, which Im
> pretty sure is not going to be useful for you; no function names.  
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x402076fb in ?? ()
> (gdb) bt 9
> #0  0x402076fb in ?? ()
> #1  0x40213df7 in ?? ()
> #2  0x4020fa7c in ?? ()
> #3  0x402152d7 in ?? ()
> #4  0x401f0a04 in ?? ()
> #5  0x402255a2 in ?? ()
> #6  0x40225f65 in ?? ()
> #7  0x402260fa in ?? ()
> #8  0x400446f0 in __ieee754_scalbf () from /lib/i686/libm.so.6
> (More stack frames follow...)
> (gdb)
> 
> Am I missing something? Someone in a c programming channel on IRC
> suggested I may have stack corruption. If this is what you want I'll
> send the entire script file. I apologize in advance if this whole
> segfault thing ends up being my fault. But I've checked and double
> checked my environment and don't see what I could be missing.
> 
> Also in another post freddy 77 wrote:
> 
> > Two thing. This problem can be due to increase of numeric precision in
> > libtds. You should recompile PHP (or PHP module) and retry.
> 
> I did do this again.. no luck.
> 
> Thanks
> Chris - ccortner AT cvol.net
> 
> On Thu, 2002-11-14 at 22:28, James K. Lowden wrote:
> > On 14 Nov 2002 16:18:55 -0600, Chris <ccortner AT cvol.net> wrote:
> > > I only have a little bit of experience with gdb none with using it to
> > > debug libraries. If you tell me what I need to do I'll do it, if
> > > anything for the educational value. Otherwise I'm going home for the
> > > night and I'll have to send you a backtrace sometime tommorow.
> > 
> > Hey, tomorrow's another day, right?  Didn't Scarlett say so?  
> > 
> > I hope I don't lead you on a wild goose chase; it's just that I can't
> > think of a more definitive answer than a bt.  I really should write this
> > up in the docs, because you're not the first fellow needing guidance.  I
> > have to warn you, though, I'm not an Apache or PHP guy.  I write C++ and
> > SQL for a living.  That means I can't really give you detailed
> > instructions.  
> > 
> > The good news is that if we determine it's not a FreeTDS problem (which I
> > fear it may be), you won't have to repeat this effort.  You can send the
> > same bt to the PHP boys.  
> > 
> > First I should refer you to 
> >     http://www.freetds.org/userguide/x2099.htm
> > 
> > which contains the earlier cautionary note that there is normally some
> > environmental difference.  I'll remind others following along that the
> > assertion here is that the environments are in fact identical, but that
> > the script runs fine from the command line and bombs under apache.  
> > 
> > Before starting with gdb, you should make sure the symbols haven't been
> > stripped (cf. strip(1)) from the executable.  Otherwise, we'll be looking
> > at a machine eye view of the code, and, well, I won't be able to help you.
> >  Use ldd(1) to check the executable's linkage, and file(1) to make sure it
> > and the relevant libraries are not stripped.  For instance:
> > 
> > $ file *syb*so*
> > libsybdb.so.1.0: NetBSD/i386 demand paged shared library not stripped
> > libsybdb.so.2.0: NetBSD/i386 demand paged shared library not stripped
> > 
> > If the segfault left a .core file around and the executable isn't
> > stripped, it might be possible to do a bt on it (gdb --core=httpd.core). 
> > I haven't had much luck with that; I think it's because it doesn't work
> > with shared libraries.  Maybe a real expert could explain why.  
> > 
> > What we want to do is start apache within gdb, and we don't want it to go
> > into daemon mode or spawn children.  My apache docs say that's the -X
> > switch.  
> > 
> > I think easiest is to make yourself a little .gdbinit file containing
> > macros for gdb to execute when it starts.  That file would be in the
> > current directory (wherever you launch gdb from) and would have:
> > 
> >     set args -X
> >     directory /path/to/PHP/stuff
> >     directory /path/to/FreeTDS/stuff
> > 
> > Then:
> > 
> > $ script bt
> > $ gdb httpd
> > (gdb) run
> > [go to your test script and execute it against this server]
> > segfault yada yada.....
> > (gdb) bt 9
> > [nine levels of unwraithlike call stack information]
> > (gdb) quit
> > $ ^D # closes script file "bt"
> > 
> > and send us the file that script(1) logged for you.  
> > 
> > Or something along those lines.  
> > 
> > > Thanks for all the help so far.
> > 
> > Surely.  Thanks for your patience.  One way or another, one of us will
> > learn something.  
> > 
> > --jkl
> > 
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