Re: [PATCH 2/2] bugfix: git diff --quiet -w never returns with exit status 1

[Junio C Hamano <gitster@pobox.com>]

Larry D'Anna <larry@elder-gods.org> writes:

> Rationale: diff_flush_patch expects to write its output to options->file.
> Adding a "silence" flag to diff_flush_patch and everything it calls would be
> more invasive.

I would agree that the logic to redirect the output to nowhere may be the
easiest way out, but because the reason anybody sane would want to give -q
is to say "I don't care what the actual changes are, but I want to know if
there is any real quick" (otherwise the call would be "diff -w >/dev/null"),
shouldn't we at least be exiting the loop early when we see any difference?

> Signed-off-by: Larry D'Anna <larry@elder-gods.org>
> ---
>  diff.c |   20 ++++++++++++++++++++
>  1 files changed, 20 insertions(+), 0 deletions(-)
>
> diff --git a/diff.c b/diff.c
> index 68def6c..ff00816 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -3522,6 +3522,26 @@ void diff_flush(struct diff_options *options)
>  		separator++;
>  	}
>  
> +	if (output_format & DIFF_FORMAT_NO_OUTPUT &&
> +	    DIFF_OPT_TST(options, EXIT_WITH_STATUS) &&
> +	    DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
> +		/* run diff_flush_patch for the exit status */
> +		/* setting options->file to /dev/null should be safe, becaue we
> +		   aren't supposed to produce any output anyways */

Style?

> +		static FILE *devnull = NULL;

Would this cause one file descriptor to leak?  Do we care?

> +		if(!devnull) {

Style?	if (!devnull)

> +			devnull = fopen("/dev/null", "w");
> +			if (!devnull)
> +				die_errno("Could not open /dev/null");
> +		}
> +		options->file = devnull;

Would this cause the original "options->file" leak?  Do we care?

> +		for (i = 0; i < q->nr; i++) {
> +			struct diff_filepair *p = q->queue[i];
> +			if (check_pair_status(p))
> +				diff_flush_patch(p, options);
> +		}
> +	}
> +
>  	if (output_format & DIFF_FORMAT_PATCH) {
>  		if (separator) {
>  			putc(options->line_termination, options->file);
> -- 
> 1.7.0.rc2.40.g7d8aa