missing sig_on/off in symbolic arithmetics

[rws]

Throwing exceptions from Pynac when Python raises some will crash Sage in a Pynac prototype because signal guards are missing in exception.pyx.

[rws]

New commits:

​aa71b3d

23199: missing sig_on/off in symbolic arithmetics

[jdemeyer]

You can simplify

try:
    [...]
    X
except (...):
    X
    raise

to

try:
    [...]
finally:
    X

---

New commits:

​fa449e4

23199: missing sig_on/off in symbolic arithmetics

[rws]

New commits:

​7f69a64

23199: missing sig_on/off in symbolic arithmetics

[jdemeyer]

This is wrong:

try:
    sig_on()
    [...]
finally:
    sig_off()

It should be

sig_on()
try:
    [...]
finally:
    sig_off()

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​af5ef8b

23199: fix previous commit

[tscrim]

LGTM.

[jdemeyer]

+1

[thansen]

With sage 8.0.beta11 building against Debian packages we still get this segfault after the docbuild. We are already using pynac 0.7.8.

Done building the documentation!
------------------------------------------------------------------------
/usr/lib/python2.7/dist-packages/cysignals/signals.x86_64-linux-gnu.so(+0x4e77)[0x7fb1c8788e77]
/usr/lib/python2.7/dist-packages/cysignals/signals.x86_64-linux-gnu.so(+0x5a05)[0x7fb1c8789a05]
/usr/lib/python2.7/dist-packages/cysignals/signals.x86_64-linux-gnu.so(+0x8057)[0x7fb1c878c057]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x110c0)[0x7fb1cdf3e0c0]
python(PyErr_Fetch+0xa)[0x55fbc80988da]
/home/thansen/src/sage/sagemath/sagemath/debian/build/usr/lib/python2.7/dist-packages/sage/rings/number_field/number_field_element_quadratic.so(+0x8a0f)[0x7fb0b5a36a0f]
/usr/lib/x86_64-linux-gnu/libpynac.so.13(+0x169451)[0x7fb09bb3f451]
/lib/x86_64-linux-gnu/libc.so.6(+0x35910)[0x7fb1cd29e910]
/lib/x86_64-linux-gnu/libc.so.6(+0x3596a)[0x7fb1cd29e96a]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf8)[0x7fb1cd2892b8]
python(_start+0x2a)[0x55fbc806031a]
------------------------------------------------------------------------
Attaching gdb to process id 6055.

Saved trace to /home/thansen/src/sage/sagemath/sagemath/debian/test/crash_logs/crash_tq1JYo.log
------------------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred.
This probably occurred because a *compiled* module has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Python will now terminate.

The crash log file is empty.

[rws]

Moved to #23264

[jdemeyer]

I have some doubts about this ticket now. The problem is that Pynac is executing Python code and executing Python code during sig_on() is not supported. This is especially problematic in case that garbage collection is done during sig_on(). See #27060

[jdemeyer]

Ralf, do you remember exactly which problem this ticket was supposed to address? When removing those sig_on() statements again in #27060, I don't see any problems appearing. So either the problem here is fixed in a different way or we are missing tests for it.