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Date:	Wed, 09 Mar 2011 13:41:12 -0500
From:	"Larry Hall (Cygwin)" <reply-to-list-only-lh AT cygwin DOT com>
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To:	cygwin AT cygwin DOT com
Cc:	wruck AT tweerlei DOT de
Subject:	Re: 1.7.8: write fails with EAGAIN
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On 3/9/2011 1:24 PM, Robert Wruck wrote:
> Hi,
>
>> Hang on, you are saying that a *blocking* write(2) to a pipe returns
>> with EAGAIN? Are you sure? It would be quite a surprise if git would
>> actually do that. EAGAIN is only an expected error for non-blocking
>> I/O, so applications which use blocking I/O usually only test for EINTR.
>
> I checked out the winsup sources and built a cygwin1.dll for debugging (btw:
>  Could you update the FAQ to state that gcc4 is required instead of gcc?).
>
> What I found out:
>
> In fhandler.cc, write_overlapped, there is the call to WriteFile:
>
> bool res = WriteFile (get_output_handle (), ptr, len, &nbytes, get_overlapped
> ());
>
> Surprisingly, this returns FALSE / nbytes = 0 / GetLastError =
> ERROR_INVALID_HANDLE on WinXP if the number of bytes exceeds some maximum and
>  the handle refers to a pipe. Since you don't know what kind of handle you're
> writing to in write_overlapped, it seems reasonable to do the write in
> chunks.

<http://cygwin.com/ml/cygwin/2011-03/msg00280.html>

-- 
Larry

_____________________________________________________________________

A: Yes.
> Q: Are you sure?
>> A: Because it reverses the logical flow of conversation.
>>> Q: Why is top posting annoying in email?

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