Subject: Any ideas? (Was: Signal handling)
From: [email-masked] (Sergey Okhapkin)

4 Apr 1997 03:20:26 -0800
Approved: [email-masked]
Distribution: cygnus
Message-ID: <[email-masked]>
Original-To: "'Gnu-Win32'" <[email-masked]>
Encoding: 28 TEXT
Original-Sender: [email-masked]

Hi!

In brief, signal handling in cygwin.dll does the following:

signal arrived (in separate signal processing thread);
if(signal masked or ignored)
  return;
if(signal handler == SIG_DFL)
  exit process;
suspend main thread;
save IP of main thread;
set main thread IP to signal handler address;
resume main thread;
exit signal thread;
when signal handler exits, restore original IP;

This scheme has one misfeature - signal handler will not start immediately 
if main thread is in a blocking Win32 syscall (WaitForMultipleObjects(), 
ReadConsoleInput() etc), but when this syscall terminates. This misfeature 
brokes signal semantic. We can't start signal handler in a context of 
signal processing thread, because this handler may never return (longjmp() 
from within signal handler is allowed). Any ideas are welcome...

--
Sergey Okhapkin
Moscow, Russia
Looking for a job.

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