Subject: Re: [PATCH] Add an option not to use link(src, dest) && unlink(src) when that is unreliable

From: Johannes Sixt <[email-masked]>
Date: Thu, 23 Apr 2009 21:16:10 +0200

On Donnerstag, 23. April 2009, Johannes Schindelin wrote:
> It seems that accessing NTFS partitions with ufsd (at least on my EeePC)
> has an unnerving bug: if you link() a file and unlink() it right away,
> the target of the link() will have the correct size, but consist of NULs.
>
> It seems as if the calls are simply not serialized correctly, as
> single-stepping through the function move_temp_to_file() works flawlessly.
>
> As ufsd is "Commertial software", I cannot fix it, and have to work

"commercial software"

> around it in Git.
>
> At the same time, it seems that this fixes msysGit issues 222 and 229 to
> assume that Windows cannot handle link() && unlink().
>
> Signed-off-by: Johannes Schindelin <[email-masked]>
...
> @@ -2225,7 +2225,9 @@ int move_temp_to_file(const char *tmpfile, const char
> *filename) {
>  	int ret = 0;
>
> -	if (link(tmpfile, filename))
> +	if (unreliable_hardlinks)
> +		ret = ~EEXIST;

It took me a while to see why we need a tilde here, but it's ok. Perhaps this 
helps others:

+		ret = ~EEXIST;	/* anything but EEXIST */

Nevertheless:

Acked-by: Johannes Sixt <[email-masked]>

> +	else if (link(tmpfile, filename))
>  		ret = errno;

-- Hannes