Re: [PATCH] refs: print errno for read_raw_ref if GIT_TRACE_REFS is set

From: Junio C Hamano <gitster@pobox.com>
To: "Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Han-Wen Nienhuys <hanwenn@gmail.com>,
	Han-Wen Nienhuys <hanwen@google.com>
Subject: Re: [PATCH] refs: print errno for read_raw_ref if GIT_TRACE_REFS is set
Date: Mon, 12 Apr 2021 14:45:47 -0700	[thread overview]
Message-ID: <xmqq4kgbb2ic.fsf@gitster.g> (raw)
In-Reply-To: <pull.1002.git.git.1618255954484.gitgitgadget@gmail.com> (Han-Wen Nienhuys via GitGitGadget's message of "Mon, 12 Apr 2021 19:32:34 +0000")

"Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com> writes:

> diff --git a/refs/debug.c b/refs/debug.c
> index 922e64fa6ad9..576bf98e74ae 100644
> --- a/refs/debug.c
> +++ b/refs/debug.c
> @@ -244,6 +244,7 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
>  	int res = 0;
>  
>  	oidcpy(oid, &null_oid);
> +	errno = 0;
>  	res = drefs->refs->be->read_raw_ref(drefs->refs, refname, oid, referent,
>  					    type);
>  
> @@ -251,7 +252,9 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
>  		trace_printf_key(&trace_refs, "read_raw_ref: %s: %s (=> %s) type %x: %d\n",
>  			refname, oid_to_hex(oid), referent->buf, *type, res);
>  	} else {
> -		trace_printf_key(&trace_refs, "read_raw_ref: %s: %d\n", refname, res);
> +		trace_printf_key(&trace_refs,
> +				 "read_raw_ref: %s: %d (errno %d)\n", refname,
> +				 res, errno);
>  	}

OK.  Between trace_printf_key() and the return of the call to
read_raw_ref() method of the ref backend is only an "if (res == 0)"
condition and I do not see anything that might clobber errno.

I do wonder if we want strerror(errno) instead of the number, but I
can go either way (it's just a trace output).

Thanks, will queue.