Re: Bug report: Incorrect GIT_FLUSH behavior in 2.43.1 (regression and breaking)

[Phillip Wood <phillip.wood123@gmail.com>]

Hi Junio

On 13/02/2024 19:48, Junio C Hamano wrote:
> Junio C Hamano <gitster@pobox.com> writes:
> 
>> Unfortunately the minimum fix is already in 'next', so let me turn
>> what you wrote into an update relative to that.  I'll assume your
>> patch in the discussion is signed-off already?
> 
> Nah, my mistake.  The topic still is outside 'next', so I'll replace
> it with the attached while queuing.
 >
> Thanks.
> 
> ------- >8 ------------- >8 ------------- >8 -------
> Subject: [PATCH] write-or-die: fix the polarity of GIT_FLUSH environment variable
> 
> When GIT_FLUSH is set to 1, true, on, yes, then we should disable
> skip_stdout_flush, but the conversion somehow did the opposite.
> 
> With the understanding of the original motivation behind "skip" in
> 06f59e9f (Don't fflush(stdout) when it's not helpful, 2007-06-29),
> we can sympathize with the current naming (we wanted to avoid
> useless flushing of stdout by default, with an escape hatch to
> always flush), but it is still not a good excuse.
> 
> Retire the "skip_stdout_flush" variable and replace it with "flush_stdout"
> that tells if we do or do not want to run fflush().

I think the patch looks good and the commit message nicely explains why 
we want to change the name of the variable.

Best Wishes

Phillip

> Reported-by: Xiaoguang WANG <wxiaoguang@gmail.com>
> Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>   write-or-die.c | 16 ++++++++--------
>   1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/write-or-die.c b/write-or-die.c
> index 3942152865..01a9a51fa2 100644
> --- a/write-or-die.c
> +++ b/write-or-die.c
> @@ -18,20 +18,20 @@
>    */
>   void maybe_flush_or_die(FILE *f, const char *desc)
>   {
> -	static int skip_stdout_flush = -1;
> -
>   	if (f == stdout) {
> -		if (skip_stdout_flush < 0) {
> -			skip_stdout_flush = git_env_bool("GIT_FLUSH", -1);
> -			if (skip_stdout_flush < 0) {
> +		static int force_flush_stdout = -1;
> +
> +		if (force_flush_stdout < 0) {
> +			force_flush_stdout = git_env_bool("GIT_FLUSH", -1);
> +			if (force_flush_stdout < 0) {
>   				struct stat st;
>   				if (fstat(fileno(stdout), &st))
> -					skip_stdout_flush = 0;
> +					force_flush_stdout = 1;
>   				else
> -					skip_stdout_flush = S_ISREG(st.st_mode);
> +					force_flush_stdout = !S_ISREG(st.st_mode);
>   			}
>   		}
> -		if (skip_stdout_flush && !ferror(f))
> +		if (!force_flush_stdout && !ferror(f))
>   			return;
>   	}
>   	if (fflush(f)) {