#9583: Unhandled SIGSEGV with 4.5.2.alpha0 on t2
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Reporter: mpatel | Owner: drkirkby
Type: defect | Status: new
Priority: blocker | Milestone: sage-4.5.2
Component: solaris | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by SimonKing):
Hi!
Replying to [comment:3 mpatel]:
> Bisection indicates that #1396 is the source of the problem:
Then I think I should explain what portion of that patch I think might be
related, and my reasons for writing it.
As David find out using {{{sage -gdb}}}, the segfault occurs in
{{{sage.libs.singular.option.LibSingularOptions_abstract.load}}}, and the
C-code in the traceback suggests that it is exactly in line 286 of the
Cython file,
{{{
Kstd1_mu = value[2]
}}}
What happens at startup?
In line 666 of option.pyx, some {{{LibSingularOptions}}} object is
created, and in line 667, the method {{{reset_default()}}} is called.
There, we have
{{{
from sage.libs.singular.singular import _saved_options
self.load(_saved_options)
}}}
Where does _saved_options come from?
_saved_options is defined in line 51 of sage/libs/singular/singular.pyx.
It is immediately initialised with some value, which I explicitly did in
order to ''prevent'' a segfault caused by accessing an uninitialised
C-variable. But the true initialisation (with the actual value used by
libsingular) is then done at line 675.
In particular, {{{value[2]}}} in the segfaulting line should be
initialised to the value 0. So, I don't see why it should be a problem to
assign this to the int variable {{{Kstd1_mu}}}.
I am not familiar with t2, and I don't know whether I would be able to
build sage on it (I don't even know if I have an account). So, could you
please test (by adding print commands in the appropriate places or so):
1. Is _save_value indeed initialised in line 51 of
sage/libs/singular/singular.pyx?
2. Is the true initialisation in line 675 of
sage/libs/singular/singular.pyx executed?
3. What is the argument of the {{{load}}} function right before it
segfaults? It should be a list of three int, the last two being zero.
4. Could it be that I simply forgot to say {{{global _saved_options}}}
before line 51 of sage/libs/singular/singular.pyx?
Cheers,
Simon
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9583#comment:13>
Sage <http://www.sagemath.org>
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