(tye)Re: Selecting on STDIN in Win32

Yes, Win32's select only works on TCP sockets. Worse, I haven't found a reasonable way to poll STDIN under Windows whether STDIN is a "console" or not (that is, no way to see if characters are pending from STDIN, set a timeout on a read from STDIN, or just make STDIN nonblocking). Someone please prove me wrong!

One alternative is to rework the script to use a TCP socket connected to localhost so you can use select(), though the odds of that working for your problem seem small.

- tye (but my friends call me "Tye")

Comment on (tye)Re: Selecting on STDIN in Win32

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Re: (tye)Re: Selecting on STDIN in Win32 by John M. Dlugosz (Monsignor) on Jul 16, 2001 at 23:04 UTC
I haven't found a reasonable way to poll STDIN under Windows whether STDIN is a "console" or not (that is, no way to see if characters are pending from STDIN, set a timeout on a read from STDIN, or just make STDIN nonblocking). Someone please prove me wrong! If STDIN is indeed the input stream for a console (not redirected), then `WaitForSingleObject` et.al. with a timeout of zero will do just that—check the state without blocking. On the `CONIN$` device, a handle is signaled when input is waiting to be read. Other file handles don't do that. In a more general case, the way to emulate it is with a helper thread that does a blocking read, buffers what it did read, and signals the main program that it got something. Or, more nativly, issue an asyncronous read and get signaled when that particular request is fulfilled. In that last case, in general, instead of using select to watch for input and then read it, you issue async read requests for all the inputs, then wait for (any) to complete. —John	[reply] [d/l] [select]

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Re: (tye)Re: Selecting on STDIN in Win32
by John M. Dlugosz (Monsignor) on Jul 16, 2001 at 23:04 UTC

I haven't found a reasonable way to poll STDIN under Windows whether STDIN is a "console" or not (that is, no way to see if characters are pending from STDIN, set a timeout on a read from STDIN, or just make STDIN nonblocking). Someone please prove me wrong!

WaitForSingleObject

On the CONIN$ device, a handle is signaled when input is waiting to be read. Other file handles don't do that.

In a more general case, the way to emulate it is with a helper thread that does a blocking read, buffers what it did read, and signals the main program that it got something. Or, more nativly, issue an asyncronous read and get signaled when that particular request is fulfilled.

In that last case, in general, instead of using select to watch for input and then read it, you issue async read requests for all the inputs, then wait for (any) to complete.

—John

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