Re: Segments

Michael S <already5chosen@yahoo.com> writes:

=46rom cppreference: https://en.cppreference.com/w/c/program/signal
"If the user defined function returns when handling SIGFPE, SIGILL or
SIGSEGV, the behavior is undefined."

As is almost everything else occurring in production code.  So such
references are not particularly relevant for production code; what
actual (in this case) operating system kernels and libraries do is
relevant.

And my experience from three decades across a wide variety of Unix
systems on a wide variety of hardware is that what we do in our
SIGSEGV handler works.  But our signal handlers don't return, they
longjmp() (in the cases that do not terminate the process).

AFAIK returning would usually try to reexecute the segfaulting
instruction, which would be the right thing if we had eliminated the
cause for the SIGSEGV in the signal handler, but we don't do that in
Gforth.  Continuing with the next instruction would not be very useful
for us, either.

- anton
--
'Anyone trying for "industrial quality" ISA should avoid undefined behavior.'
  Mitch Alsup, <c17fcd89-f024-40e7-a594-88a85ac10d20o@googlegroups.com>