Handling other signals

Apart from handling interrupts, sig_on() provides more general signal handling. For example, it handles alarm() time-outs by raising an AlarmInterrupt (inherited from KeyboardInterrupt) exception.

If the code inside sig_on() would generate a segmentation fault or call the C function abort() (or more generally, raise any of SIGSEGV, SIGILL, SIGABRT, SIGFPE, SIGBUS), this is caught by the interrupt framework and an exception is raised (RuntimeError for SIGABRT, FloatingPointError for SIGFPE and the custom exception SignalError, based on BaseException, otherwise):

from libc.stdlib cimport abort
from cysignals.signals cimport sig_on, sig_off

def abort_example():
    sig_on()
    abort()
    sig_off()

>>> abort_example()
Traceback (most recent call last):
...
RuntimeError: Aborted

This exception can be handled by a try/except block as explained above. A segmentation fault or abort() unguarded by sig_on() would simply terminate the Python Interpreter. This applies only to sig_on(), the function sig_check() only deals with interrupts and alarms.

Instead of sig_on(), there is also a function sig_str(s), which takes a C string s as argument. It behaves the same as sig_on(), except that the string s will be used as a string for the exception. sig_str(s) should still be closed by sig_off(). Example Cython code:

from libc.stdlib cimport abort
from cysignals.signals cimport sig_str, sig_off

def abort_example_with_sig_str():
    sig_str("custom error message")
    abort()
    sig_off()

Executing this gives:

>>> abort_example_with_sig_str()
Traceback (most recent call last):
...
RuntimeError: custom error message

With regard to ordinary interrupts (i.e. SIGINT), sig_str(s) behaves the same as sig_on(): a simple KeyboardInterrupt is raised.