[Playerstage-developers] Shared Object Loading Bug & Fix

[Kratochvil, B. E. <kra...@ir...>]

Hello all,

If you've installed Player v1.5 and are using player-mod (or some
derivation thereof) to use shared objects for your driver files, you
will most likely run the following error when you try to load your
library:

** Player v1.5 ** Opening shared object ./exampledriver.so...
  ./exampledriver.so: undefined symbol:
_ZN11DriverTable9AddDriverEPccPFP7CDeviceS0_P10ConfigFileiE

This is because when the library is loaded using dlopen:

       External  references in the library are resolved using the
       libraries in that library's dependency list and any  other
       libraries previously opened with the RTLD_GLOBAL flag.  If
       the executable was linked with the flag "-rdynamic",  then
       the  global symbols in the executable will also be used to
       resolve references in a dynamically loaded library.
       http://www.rt.com/man/dlopen.3.html

I looked through the old makefiles of Player 1.4 and it seems that
RTK_LDADD was including the -rdynamic flag in the linking stage, and now
it isn't.

To fix this, you will need to add -rdynamic to the player_LDADD in the
Makefile in the server directory.  I figured I'd post this in the
developers list, so that hopefully it will be fixed and included in the
standard 1.5 release.  Please let me know if you have any questions.

Best regards,

Brad