[Bug 40285] Re: libgcc_s.so.1 must be installed for pthread_cancel to work

[Bartosz Brachaczek]

In the case of Kadu this was actually caused by Kadu being built with
hardened flags and one header declaring a function that was never
implemented or called. We deleted that declaration and it fixed the
problem. You can check for any possibly missing symbols by exporting an
LD_BIND_NOW=1 environment variable and the running the program. Though,
I really doubt all these apps problems are about missing symbols.

Also, if linking explicitly with -lgcc_s fixes the problem for you, you
can try running `LD_PRELOAD=/path/to/libgcc_s.so.1 your_app', maybe it
will work.

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https://bugs.launchpad.net/bugs/40285

Title:
  libgcc_s.so.1 must be installed for pthread_cancel to work

Status in “gcc-3.3” package in Ubuntu:
  Fix Released
Status in “gcc-4.4” package in Ubuntu:
  Confirmed
Status in “gcc-4.6” package in Ubuntu:
  New
Status in “pound” package in Ubuntu:
  Invalid

Bug description:
  the error:

   libgcc_s.so.1 must be installed for pthread_cancel to work

  is printed by applications using pthreads and calling:

  set the thread to check or cancel:
  thread_setcancelstate (PTHREAD_CANCEL_ENABLE, NULL);
          pthread_setcanceltype (PTHREAD_CANCEL_DEFERRED, NULL);

  and then in a tight loop try to lock a mutex and call test cancel like:
  while (pthread_mutex_trylock (&progress_lock) ==
                                 EBUSY)
                                  pthread_testcancel ();

  if the thread is exited because the parent thread sent a pthread_exit
  (NULL); for instance, you will see that error.

  gcc thinks that this file is in:
  $> gcc --print-file-name=libgcc_s.so.1
  /lib/../lib/libgcc_s.so.1

  and not /lib/libgcc_s.so.1. though the path should really point to the
  same file in the end.

  This error is fixed by adding /lib to /etc/ld.so.conf and running
  ldconfig

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