Re: lldb unusable for regular user

On Tue, Sep 19, 2017, John Baldwin wrote:
> On Monday, September 18, 2017 02:41:06 PM Vladimir Zakharov wrote:
> > Hello!
> > 
> > lldb coredumps for regular user, but works for root.
> > > gdb `which lldb` lldb.core
> > ...
> > Reading symbols from /usr/bin/lldb...Reading symbols from /usr/lib/debug//usr/bin/lldb.debug...done.
> > done.
> > [New LWP 101610]
> > [New LWP 100968]
> > [New LWP 100126]
> > [New LWP 101631]
> > [New LWP 101637]
> > [New LWP 101662]
> > [New LWP 101672]
> > [New LWP 100337]
> > [New LWP 101593]
> > Core was generated by `lldb ./test'.
> > Program terminated with signal SIGSEGV, Segmentation fault.
> > #0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20, context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
> > 60      ./md-unwind-support.h: No such file or directory.
> > [Current thread is 1 (LWP 101610)]
> > (gdb) f
> > #0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20, context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
> > 60      in ./md-unwind-support.h
> > (gdb) bt
> > #0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20, context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
> > #1  uw_frame_state_for (context=context_at_entry=0x7fffddff6e20, fs=fs_at_entry=0x7fffddff6b70) at /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind-dw2.c:1249
> > #2  0x0000000804f6cffb in _Unwind_ForcedUnwind_Phase2 (exc=exc_at_entry=0x806b23230, context=context_at_entry=0x7fffddff6e20) at /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind.inc:155
> > #3  0x0000000804f6d334 in _Unwind_ForcedUnwind (exc=0x806b23230, stop=0x804631760 <thread_unwind_stop>, stop_argument=<optimized out>) at /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind.inc:207
> > #4  0x00000008046315c3 in _Unwind_ForcedUnwind (ex=<optimized out>, stop_func=0xe, stop_arg=0x806b23000) at /usr/src/lib/libthr/thread/thr_exit.c:106
> > #5  thread_unwind () at /usr/src/lib/libthr/thread/thr_exit.c:172
> > #6  _pthread_exit_mask (status=<optimized out>, mask=<optimized out>) at /usr/src/lib/libthr/thread/thr_exit.c:254
> > #7  0x00000008046313eb in _pthread_exit (status=0x806b23000) at /usr/src/lib/libthr/thread/thr_exit.c:206
> > #8  0x0000000804623c0d in thread_start (curthread=0x806b23000) at /usr/src/lib/libthr/thread/thr_create.c:289
> > #9  0x00007fffdddf7000 in ?? ()
> > Backtrace stopped: Cannot access memory at address 0x7fffddff7000
> 
> Your backtrace shows it crashed during thread exit inside of libthr, not in
> lldb itself.  Also, it seems you are using libgcc_s from external gcc rather
> than the base system libgcc_s which is built from
> contrib/llvm/projects/libunwind.  If lldb dlopen'd some object that depends
> on libgcc_s.so from ports gcc then that might explain this crash as it means
> you are mixing two different unwind libraries.  What does 'info sharedlibrary'
> from gdb show?

You're right, John. My environment had been polluted:
$ env | grep gcc
LIBRARY_PATH=/usr/local/lib/gcc6
LD_LIBRARY_PATH=/usr/local/lib/gcc6

I've deleted these variables, and lldb works now as expected.
Thanks a lot

-- 
Regards,                 | "In theory there is no difference between theory
  Vladimir Zakharov      | and practice. In practice there is."- Yogi Berra