Subject: Re: [PATCH] mergetools/p4merge: Handle "/dev/null"

From: Jeremy Morton <[email-masked]>
Date: Sat, 27 Oct 2012 09:47:05 +0100

Sorry to be replying to this so late; I hadn't noticed the post until now!

I've tried putting that code in my p4merge script and yes it does indeed 
work fine.  However, it puts a temporary file in the working directory 
which I'm not sure is a good idea?  If we look at this patch which 
actually solved pretty much the same problem, but when merging and, 
during a merge conflict, a file was created in both branches:
https://github.com/git/git/commit/ec245ba

... it is creating a temp file in a proper temp dir, rather than in the 
working dir.  I think that would be the proper solution here.  However, 
I really want to get this fixed so I'd be happy for this band-aid fix of 
the p4merge script to be checked in until we could get a patch more like 
the aforementioned one, at a later date, to create empty files in a 
proper temp dir and pass them as $LOCAL and $REMOTE.  :-)

-- 
Best regards,
Jeremy Morton (Jez)

On 11/10/2012 04:22, David Aguilar wrote:
> p4merge does not properly handle the case where "/dev/null"
> is passed as a filename.
>
> Workaround it by creating a temporary file for this purpose.
>
> Reported-by: Jeremy Morton<[email-masked]>
> Signed-off-by: David Aguilar<[email-masked]>
> ---
> Jeremy, can you test this?
>
>   mergetools/p4merge | 25 +++++++++++++++++++++++++
>   1 file changed, 25 insertions(+)
>
> diff --git a/mergetools/p4merge b/mergetools/p4merge
> index 1a45c1b..295361a 100644
> --- a/mergetools/p4merge
> +++ b/mergetools/p4merge
> @@ -1,5 +1,30 @@
>   diff_cmd () {
> +	# p4merge does not like /dev/null
> +	rm_local=
> +	rm_remote=
> +	if test "/dev/null" = "$LOCAL"
> +	then
> +		LOCAL="./p4merge-dev-null.LOCAL.$$"
> +		>"$LOCAL"
> +		rm_local=true
> +	fi
> +	if test "/dev/null" = "$REMOTE"
> +	then
> +		REMOTE="./p4merge-dev-null.REMOTE.$$"
> +		>"$REMOTE"
> +		rm_remote=true
> +	fi
> +
>   	"$merge_tool_path" "$LOCAL" "$REMOTE"
> +
> +	if test -n "$rm_local"
> +	then
> +		rm -f "$LOCAL"
> +	fi
> +	if test -n "$rm_remote"
> +	then
> +		rm -f "$REMOTE"
> +	fi
>   }
>
>   merge_cmd () {