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Re: Bug: Synchronous signals broken on Cygwin 64




On 2018-04-26 12:45, Houder wrote:
On Thu, 26 Apr 2018 09:57:59, Thomas Zimmermann wrote:

Hello mailing list,

I noticed that synchronous signals (e.g., SIGSEGV, SIGFPE) appear to be broken on 64-bit Cygwin systems. I could not find additional information on the mailing list. If this is not already a known problem, you'll find
some analysis below.

I use Cygwin DLL 2.10 with all packages up-to-date. My test system runs
Windows 7.

The expected behavior is that an installed signal handler runs exactly
once for a signal and the OS terminates the program if the handler
returns. This works on 32-bit Cygwin. From my observation, Cygwin 64
differs in the follow ways:

.. uhm, unless SA_RESETHAND (sa_flags) has been specified, I expect the
handler to be invoked again and again ...

... and if SA_RESETHAND has been specified, the OS will terminate the program after the 1st invocation of the handler (yes, in case of this
    type of exception; in this case FPE)

And that is what I observe on Linux ...

1) Generating a synchronous signal on the main thread, makes the signal handler enter an endless loop. The attached test 'syncsig.c' illustrates
this.

2) Generating a synchronous signal on an additional POSIX thread ignores the installed signal handler entirely. The handler does not run and the
program gets terminated immediately. The attached test 'syncsig_mt.c'
illustrates this.

Yes, this behaviour is wrong ...

Henri

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