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Date:	Tue, 18 Apr 2023 18:21:48 +0200
To:	Bruno Haible <bruno AT clisp DOT org>
Subject:	Re: renameat2 works differently than on Linux
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From:	Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
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Cc:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>, cygwin AT cygwin DOT com
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Hi Bruno,

On Apr 18 14:47, Bruno Haible via Cygwin wrote:
> Hi,
> 
> The renameat2 function is "Linux-specific", says the man page [1]; however,
> Cygwin implements it as well.
> 
> In Cygwin 3.4.6, in a specific case, it operates differently than the
> Linux function. Namely, if the old* arguments and the new* arguments
> are the same and the flag RENAME_NOREPLACE is specified.
> [...]
> Output on Linux (glibc, musl libc):
> ret=-1, errno=17=EEXIST
> 
> Output on Cygwin 3.4.6:
> ret=0
> 
> Note that there is some ambiguity about this case in [1]: One one hand,
> there is the general statement about rename():
>   "If oldpath and newpath are existing hard links referring to the
>    same file, then rename() does nothing, and returns a success status."
> On the other hand, the text regarding RENAME_NOREPLACE says:
>   "Return an error if newpath already exists."

Thanks for the testcase.  I guess the ambiguity doesn't matter, given
it's a Linux function anyway.  It makes sense to behave the same, if
possible.

I pushed a patch.  The next test release cygwin-3.5.0-0.284.gd30a5917a9c4
will contain the patch for testing.


Thanks,
Corinna

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