Re: [PATCH] config.mak.uname: Cygwin: Use renames for creation

[Johannes Schindelin <johannes.schindelin@gmx.de>]

Hi Adam,

On 2015-08-09 19:05, Adam Dinwoodie wrote:
> On 09/08/2015 10:01, Johannes Schindelin wrote:
>> On 2015-08-09 04:01, Adam Dinwoodie wrote:
>>> 
>>>> We've gotten a lot of users on the list who ask why their Git
>>>> directories on shared drives aren't working (or are broken in some way).
>>>> Since I don't use Windows, let me ask: does the Cygwin DLL handle
>>>> link(2) properly on shared drives, and if not, would this patch help it
>>>> do so?  I can imagine that perhaps SMB doesn't support the necessary
>>>> operations to make a POSIX link(2) work properly.
>>>
>>> I'd need to go back to the Cygwin list to get a definite answer, but as
>>> I understand it, yes, this is is exactly the problem -- quoting Corinna,
>>> one of the Cygwin project leads, "The MS NFS is not very reliable in
>>> keeping up with changes to metadata."
>>>
>>> We have verified that setting `core.createobject rename` resolves the
>>> problem for people who are seeing it, which very strongly implies that
>>> this build option would solve the problem similarly, but would fix it
>>> for all users, not just those who spend enough time investigating the
>>> problem to find that setting.
>>
>>  From my experience, it appears that providing Corinna Vinschen (or better put: the Cygwin developers in general) with a sound patch gets things fixed pretty timely.
>>
>> And since `core.createObject = rename` seems to work around the problem, it should be possible to patch the Cygwin runtime accordingly. Sure, it will take a little investigation *what* code should be changed, and how, but the obvious benefit to *all* Cygwin applications should make that effort worth your while.
> 
> Hmm. I'm not sure what a Cygwin fix would look like here. As I
> understand it, using link(2) will fail if the target exists, while
> using rename(2) will just clobber a target file.

Thanks to you and Junio for explaining why my idea was bad. Sorry!

Ciao,
Johannes