From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 18 Jun 2012 17:23:55 GMT
Subject: Re: [PATCH 1/2] sha1_name: don't trigger detailed diagnosis for file arguments
Message-ID: <7vehpc4jpw.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1339958341-22186-1-git-send-email-Matthieu.Moy@imag.fr>

Matthieu Moy <Matthieu.Moy@imag.fr> writes:

> diagnose_invalid_sha1_path is normally meant to be called to diagnose
> <treeish>:<pathname> when <pathname> does not exist in <treeish>.
> However, the current code may call it if <treeish>:<pathname> is invalid
> (which triggers another call with only_to_die == 1), but for another
> reason. This happens when calling e.g.
>
>   git log existing-file HEAD:existing-file
>
> (because existing-file is a file and not a revision, the next arguments
> are assumed to be files too), leading to incorrect message like
> "existing-file does not exist in HEAD".
>
> Check that the search for <pathname> in <treeish> fails before triggering
> the diagnosis.
>
> Bug report and code fix by: Junio C Hamano <gitster@pobox.com>
> Test by: Matthieu Moy <Matthieu.Moy@imag.fr>
>
> Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
> ---
>
> This patch is very simple and should be rather uncontroversial.

I am not so sure about that.  The "only-to-die" caller is not even
expecting that the call to this codepath would successfully return.

Or at least, it shouldn't.

So it might not be a bad idea to actually catch this as a
programming error and do

	if (only_to_die) {
        	if (!ret)
                	die("BUG");
		diagnose_invalid_sha1_path(...);
	}

instead, especially since we will have a more fundamental fix with
your 2/2 patch as a longer-term fix.

>  sha1_name.c                    |  2 +-
>  t/t1506-rev-parse-diagnosis.sh | 11 +++++++++++
>  2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/sha1_name.c b/sha1_name.c
> index c633113..5d81ea0 100644
> --- a/sha1_name.c
> +++ b/sha1_name.c
> @@ -1127,7 +1127,7 @@ int get_sha1_with_context_1(const char *name, unsigned char *sha1,
>  			if (new_filename)
>  				filename = new_filename;
>  			ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
> -			if (only_to_die) {
> +			if (ret && only_to_die) {
>  				diagnose_invalid_sha1_path(prefix, filename,
>  							   tree_sha1, object_name);
>  				free(object_name);
> diff --git a/t/t1506-rev-parse-diagnosis.sh b/t/t1506-rev-parse-diagnosis.sh
> index 0843a1c..4a39ac5 100755
> --- a/t/t1506-rev-parse-diagnosis.sh
> +++ b/t/t1506-rev-parse-diagnosis.sh
> @@ -171,4 +171,15 @@ test_expect_success 'relative path when startup_info is NULL' '
>  	grep "BUG: startup_info struct is not initialized." error
>  '
>  
> +test_expect_success '<commit>:file correctly diagnosed after a pathname' '
> +	test_must_fail git rev-parse file.txt HEAD:file.txt 1>actual 2>error &&
> +	test_i18ngrep ! "exists on disk" error &&
> +	test_i18ngrep "unknown revision or path not in the working tree" error &&
> +	cat >expect <<EOF &&
> +file.txt
> +HEAD:file.txt
> +EOF
> +	test_cmp expect actual
> +'
> +
>  test_done