Subject: Re: Pipes truncating data in cygwin from main and cygwin-3_4-branch
From: Takashi Yano via Cygwin <[email-masked]>
To: [email-masked]
Cc: キャロウ マーク <[email-masked]>
Date: Tue, 15 Aug 2023 18:45:57 +0900
List-Id: General Cygwin discussions and problem reports <cygwin.cygwin.com>

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 <[email-masked]> 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 <[email-masked]>

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