Re: [PATCH 4/8] diff: support reading a file from stdin via "-"

From: Junio C Hamano <junkio@cox.net>
Date: Feb 25, 2007, 22:57 UTC
Message-ID: <7vvehprgl7.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <Pine.LNX.4.63.0702252335410.22628@wbgn013.biozentrum.uni-wuerzburg.de>

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

Show 13 quoted lines

> This allows you to say
>
> 	echo Hello World | git diff x -
>
> to compare the contents of file "x" with the line "Hello World".
> This automatically switches to --no-index mode.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>
> 	Since the revision machinery checks for the presence of files,
> 	diff_populate_filespec() will only change behaviour when there
> 	is a file "-"... I have yet to think of an elegant fix for that.

Another thing is that at some point diff_populate_filespec() needs to have a way to discard what was cached if memory pressure gets tight, and we would want to keep this data read from the standard input.

One solution would be to add a "const char *stdin_data" to diffopts and read the data from stdin when you parse the options, and have populate_filespec point at that with s->data (setting should_free and should_munmap both to 0).