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Date: Tue, 15 Aug 2023 18:45:57 +0900
To: cygwin@cygwin.com
Cc: =?ISO-2022-JP?B?GyRCJS0lYyVtJSYhISVeITwlLxsoQg==?= <github@callow.im>
Subject: Re: Pipes truncating data in cygwin from main and cygwin-3_4-branch
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From: Takashi Yano via Cygwin <cygwin@cygwin.com>
Reply-To: Takashi Yano <takashi.yano@nifty.ne.jp>
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On Tue, 15 Aug 2023 18:09:50 +0900
キャロウ　マーク wrote:
> > On Aug 15, 2023, at 15:42, Takashi Yano <takashi.yano@nifty.ne.jp> wrote:
> > 
> >> 
> >>> 
> >>> New pipe implementation since cygwin 3.4.x provides the pipes
> >>> more similar to pipe in command prompt for non-cygwin apps.
> >> 
> >> What are the differences between these pipes? What changed?
> > 
> > Many changes. But, the change which triggers this behaviour
> > is setting FILE_SYNCHRONOUS_IO_NONALERT create option.
> > 
> > With this option, seekg() of Microsoft library gets success
> > for pipes, despite it should not I suppose.
> 
> On what create is this option specified?

Pipe itself. We use NtCreateNamedPipeFile() to create a pipe.
https://learn.microsoft.com/en-us/windows/win32/devnotes/nt-create-named-pipe-file

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

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