Andrei Alexandrescu wrote:
Jeremie Pelletier wrote:
Is this Linux specific? what about other *nix systems, like BSD and
solaris?
Signal handler are standard to most *nix platforms since they're part
of the posix C standard libraries, maybe some platforms will require a
special handling but nothing impossible to do.
Let me write a message on behalf of Sean Kelly. He wrote that to Walter
and myself this morning, then I suggested him to post it but probably he
is off email for a short while. Hopefully the community will find a
solution to the issue he's raising. Let me post this:
===================
Sean Kelly wrote:
There's one minor problem with his code. It's not safe to throw an
exception from a signal handler. Here's a quote from the POSIX spec at
opengroup.org:
"In order to prevent errors arising from interrupting non-reentrant
function calls, applications should protect calls to these functions
either by blocking the appropriate signals or through the use of some
programmatic semaphore (see semget() , sem_init() , sem_open() , and so
on). Note in particular that even the "safe" functions may modify errno;
the signal-catching function, if not executing as an independent thread,
may want to save and restore its value. Naturally, the same principles
apply to the reentrancy of application routines and asynchronous data
access. Note thatlongjmp() and siglongjmp() are not in the list of
reentrant functions. This is because the code executing after longjmp()
and siglongjmp() can call any unsafe functions with the same danger as
calling those unsafe functions directly from the signal handler.
Applications that use longjmp() andsiglongjmp() from within signal
handlers require rigorous protection in order to be portable."
If this were an acceptable approach it would have been in druntime ages
ago :-)
===================
Andrei
Yes but the segfault signal handler is not made to design code that can
live with these exceptions, its just a feature to allow segfaults to be
sent to the crash handler to get a backtrace dump. Even on windows while
you can recover from access violations, its generally a bad idea to
allow for bugs to be turned into features.
Jeremie
