Re: signals on windows

Hi,
This MS documentation looks like it's slightly retro. I've been trying
to decypher this stuff myself for a decade, so I might offer some points:.

>Andrew Dunstan wrote:
>
>
>> *   Note   SIGINT is not supported for any Win32 application, including
>>*   Windows 98/Me and Windows NT/2000/XP.When a CTRL+C interrupt occurs,
>> *   Win32 operating systems generate a new thread to specifically handle
>> *   that interrupt. This can cause a single-thread application such as
>>UNIX,
>> *   to become multithreaded, resulting in unexpected behavior.
>>
Odd. First they say it's not supported, then they go on to define how it
works. Probably what they mean is that Win32 _GUI_ applications have no
way to have receive SIGINT from Ctrl+C, because that's handled as just
another keystroke by the GUI system (sometimes you'll see the older
documentation use Win32 as a term implying GUI).  Win32 console apps
appear to respond to Ctrl+C much like unices do.

Since Win32 will create a new thread for you, if you prepare your app
for that, I don't see a reason you can't make pure Win32 system calls
from that thread. You mainly want to be careful to not confuse a
single-threaded C runtime. Note that the doc
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_CRT_signal.asp
says not to "use any function that generates a system call (e.g.,
*_getcwd*, *time*)", it doesn't say not to make system calls themselves.
It doesn't look like a "signal" is not a kernel primitive on NT, it's a
feature of the CRT implemented in userspace with lower-level OS primitives.

>> * I have no idea how to handle this. (Strange they call UNIX an
>>application!)
>> * So this will need some testing on Windows.
>> * One alternative might be to set a flag that we periodically check for.
>>
A kernel Event
(http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/createevent.asp)
is a common tool for this sort of thing.

- Marsh