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Subject:	Re: /dev/clipboard sometimes fails to set CF_UNICODETEXT data.
To:	cygwin AT cygwin DOT com
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From:	Mark Geisert <mark AT maxrnd DOT com>
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Date:	Tue, 5 Jul 2022 00:42:50 -0700
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Hi Takashi,

Takashi Yano wrote:
> Hello,
> 
> In one of my PCs,
> dd if=/dev/urandom count=10 | xxd > /dev/clipboard
> sometimes fails to set CF_UNICODETEXT data.
> As a result, pasting clipboard to notepad does not work.
> 
> Even in the case, cygnativeformat data is set correctly.
> So, "cat /dev/clipboard" works.
> 
> This problem depends on machine very much.
> 
> My one PC with Xeon E3-1281 v3 CPU has a high probability of failure,
> however, another machine with Core i7-6700K CPU does not.
> 
> I looked into this problem, and found OpenClipboard() for
> CF_UNICODETEXT fails. It seems that OpenClipboard() just
> after CloseClipboard() has high probability of failure.
> 
> You can see the following test case immediately stops with error.
> Even with Core i7-6700K CPU machine above, the test case fails.
> 
> #include <windows.h>
> #include <stdio.h>
> 
> int main()
> {
> 	for (;;) {
> 		if (!OpenClipboard(0)) {
> 			printf("Open error.\n");
> 			break;
> 		}
> 		if (!EmptyClipboard()) {
> 			printf("Empty error.\n");
> 			break;
> 		}
> 		if (!CloseClipboard()) {
> 			printf("Cloes error.\n");
> 			break;
> 		}
> 	}
> 	return 0;
> }
> 
> I also found the patch attached solves the issue.
> 
> I would appreciate any suggestion.

Would be neet if this patch wasn't needed, but, oh well.  My only comment on the 
patch would be to possibly call the new wrapper function MyOpenClipboard, or 
CygOpenClipboard, to help keep the name paired with CloseClipboard.

I suppose it might happen in the future that a faster processor will require the 
loop count to be made larger.  Once again, oh well.
My 2c (adjusted for inflation),

..mark

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