gcc4: throwing exception from signal handler
Don Ward
don2387ward@sprynet.com
Thu Jul 8 14:10:00 GMT 2010
Václav Haismam wrote:
> On Thu, 8 Jul 2010 09:01:41 -0400, "Don Ward" wrote:
>> I would like to be able to catch certain signals (SIGSEGV and SIGSYS)
> and
>> throw a C++ exception (to be caught in a try/catch construct). As a
>> simple
>> example:
>>[...]
>> Am I misunderstanding how this should work or doing something wrong? Or
>> is
>> this a problem with Cygwin or gcc?
> I do not think that handling SIGSEGV with an exception is a good idea.
I agree, in general.
> Unless you get SIGSEGV as a result of some well thought through memory
> management games
But that is what I am doing. I also want to catch SIGSYS to determine
whether shmat() is available when we don't know in advance whether cygserver
is running. In either case, if the signal is generated I want to catch it
and try something else. In these contexts I want to treat SIGSEGV and
SIGSYS as non-fatal error returns.
. . .
> I am not sure but I do not think that throwing exceptions from signal
> handlers is generally supported.
It appears that is what the -fnon-call-exceptions is for. From the
gcc-4.3.5 manual:
"-fnon-call-exceptions: Generate code that allows trapping instructions to
throw exceptions. Note that this requires platform-specific runtime support
that does not exist everywhere."
I guess one question is whether the runtime support exists in Cygwin 1.7
with gcc 4.3.4.
-- Don W.
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