We've been having problems with this since php 4.0.3.  Here is a
full backtrace of a running (not for long) httpd child that dies as
soon as sybase_connect is called.  You'll notice the segfault
complains at mail.c.  Since sybase has nothing to do with this
file, I'm guessing there's a crosslink somewhere in the PHP
code, or a pointer that is getting lost somewhere.

---------------------------------------------------------------
Attaching to program: /usr/sbin/httpd, Pid 4719
Reading symbols from /lib/libpam.so.0...done.
Reading symbols from /lib/libdl.so.2...done.
Reading symbols from /home/sybase/lib/libinsck.so...done.
Reading symbols from /home/sybase/lib/libsybtcl.so...done.
Reading symbols from /home/sybase/lib/libintl.so...done.
Reading symbols from /home/sybase/lib/libcomn.so...done.
Reading symbols from /home/sybase/lib/libct.so...done.
Reading symbols from /home/sybase/lib/libcs.so...done.
Reading symbols from /usr/lib/libpq.so...done.
Reading symbols from /usr/lib/libmcrypt.so.4...done.
Reading symbols from /usr/lib/libltdl.so.0...done.
Reading symbols from /usr/lib/libttf.so.2...done.
Reading symbols from /usr/lib/libpng.so.2...done.
Reading symbols from /usr/lib/libz.so.1...done.
Reading symbols from /usr/lib/libgd.so.1...done.
Reading symbols from /lib/libresolv.so.2...done.
Reading symbols from /lib/libm.so.6...done.
Reading symbols from /lib/libcrypt.so.1...done.
Reading symbols from /lib/libnsl.so.1...done.
Reading symbols from /lib/libdb.so.3...done.
Reading symbols from /lib/libc.so.6...done.
Reading symbols from /lib/ld-linux.so.2...done.
Reading symbols from /usr/X11R6/lib/libXpm.so.4...done.
Reading symbols from /usr/X11R6/lib/libX11.so.6...done.
Reading symbols from /lib/libnss_files.so.2...done.
Reading symbols from /lib/libnss_nisplus.so.2...done.
Reading symbols from /lib/libnss_nis.so.2...done.
0x402dfa02 in __libc_accept () from /lib/libc.so.6
(gdb) c
Continuing.

Program received signal SIGSEGV, Segmentation fault.
0x819dcaf in net_close (stream=0x82d1b90) at mail.c:4857
4857    mail.c: No such file or directory.
(gdb) bt
#0  0x819dcaf in net_close (stream=0x82d1b90) at mail.c:4857
#1  0x40093557 in np_io_close () from /home/sybase/lib/libct.so
#2  0x4009c327 in ct__tds_closeconn () from /home/sybase/lib/libct.so
#3  0x40063a3d in com__async_runstack () from /home/sybase/lib/libcomn.so
#4  0x40063939 in com__async_poll_state () from /home/sybase/lib/libcomn.so
#5  0x4006377f in com__async_do_poll () from /home/sybase/lib/libcomn.so
#6  0x400631eb in com_async_poll () from /home/sybase/lib/libcomn.so
#7  0x400a3ac1 in ct__api_async () from /home/sybase/lib/libct.so
#8  0x400a62c2 in ct__api_close () from /home/sybase/lib/libct.so
#9  0x400a63d1 in ct_close () from /home/sybase/lib/libct.so
#10 0x8114034 in _close_sybase_link (rsrc=0x832aea4) at php_sybase_ct.c:158
#11 0x812dd6a in list_entry_destructor (ptr=0x832aea4) at zend_list.c:258
#12 0x812cc3e in zend_hash_del_key_or_index (ht=0x82ab1c8, arKey=0x0,
    nKeyLength=0, h=1, flag=1) at zend_hash.c:535
#13 0x812daaf in zend_list_delete (id=1) at zend_list.c:59
#14 0x8129457 in _zval_dtor (zvalue=0x832840c) at zend_variables.c:80
#15 0x81238c2 in _zval_ptr_dtor (zval_ptr=0x82cb5c8)
    at zend_execute_API.c:261
#16 0x812ccd9 in zend_hash_destroy (ht=0x82ab0ac) at zend_hash.c:564
#17 0x8123752 in shutdown_executor () at zend_execute_API.c:165
#18 0x8129e07 in zend_deactivate () at zend.c:525
#19 0x80a7422 in php_request_shutdown (dummy=0x0) at main.c:688
#20 0x80a55ba in php_apache_request_shutdown ()
#21 0x8155c6e in run_cleanups ()
#22 0x815449d in ap_clear_pool ()
#23 0x8154511 in ap_destroy_pool ()
#24 0x816c1e2 in ap_destroy_sub_req ()
#25 0x807ffc8 in handle_include ()
#26 0x8082fc5 in send_parsed_content ()
#27 0x808359d in send_parsed_file ()
#28 0x8158f53 in ap_invoke_handler ()
#29 0x816ca99 in process_request_internal ()
#30 0x816cafc in ap_process_request ()
#31 0x81640ce in child_main ()
#32 0x816430c in make_child ()
#33 0x8164686 in perform_idle_server_maintenance ()
#34 0x8164bc5 in standalone_main ()
#35 0x8165183 in main ()
#36 0x402459cb in __libc_start_main (main=0x8164e3c <main>, argc=3,
    argv=0xbffff954, init=0x8070c34 <_init>, fini=0x81e4c8c <_fini>,
    rtld_fini=0x4000ae60 <_dl_fini>, stack_end=0xbffff94c)
    at ../sysdeps/generic/libc-start.c:92