[tor-bugs] #17808 [Tor]: Tor 0.2.7.6 doesn't produce a backtrace on gcc 4.9.3 on OS X 10.11.2

Tor Bug Tracker & Wiki blackhole at torproject.org
Wed Dec 16 18:48:12 UTC 2015


#17808: Tor 0.2.7.6 doesn't produce a backtrace on gcc 4.9.3 on OS X 10.11.2
--------------------+------------------------------------
 Reporter:  teor    |          Owner:
     Type:  defect  |         Status:  new
 Priority:  Medium  |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor     |        Version:  Tor: 0.2.7.6
 Severity:  Normal  |     Resolution:
 Keywords:          |  Actual Points:
Parent ID:          |         Points:
  Sponsor:          |
--------------------+------------------------------------

Comment (by cypherpunks):

 Only way to produce a backtrace reliably is to use platform with glibc-
 based `backtrace` function and to build code by GCC.

 In case of OS X,
 [https://opensource.apple.com/source/Libc/Libc-1081.1.3/gen/thread_stack_pcs.c
 syslib's backtrace] unwinds stack "manually", while GCC (with used -O2)
 guarantees to omit FP and to fail test.

 In case of FreeBSD, libexecinfo using similar technique to obtain
 backtrace, and shouldn't work too, at least for GCC with used -O2? But
 [https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=200778 seems]
 [https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203333 like working]
 for assert test and broken for crash test for lib's reasons only. (It
 really need to test and publish what output for GCC case and what output
 for clang case to sort stuff)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17808#comment:3>
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