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From: Jakub Narebski <jnareb@gmail.com>
To: Derrick Stolee <dstolee@microsoft.com>
Cc: "git\@vger.kernel.org" <git@vger.kernel.org>,
	"gitster\@pobox.com" <gitster@pobox.com>,
	"stolee\@gmail.com" <stolee@gmail.com>,
	"avarab\@gmail.com" <avarab@gmail.com>,
	"marten.agren\@gmail.com" <marten.agren@gmail.com>,
	"peff\@peff.net" <peff@peff.net>
Subject: Re: [PATCH v3 12/20] commit-graph: verify parent list
Date: Sat, 02 Jun 2018 01:21:14 +0200	[thread overview]
Message-ID: <86lgbyum8l.fsf@gmail.com> (raw)
In-Reply-To: <20180524162504.158394-13-dstolee@microsoft.com> (Derrick Stolee's message of "Thu, 24 May 2018 16:25:52 +0000")

Derrick Stolee <dstolee@microsoft.com> writes:

> The commit-graph file stores parents in a two-column portion of the
> commit data chunk. If there is only one parent, then the second column
> stores 0xFFFFFFFF to indicate no second parent.

All right, it is certainly nice to have this information, but isn't it
something that one caan find in Documentation/technical/commit-graph-format.txt?

>
> The 'verify' subcommand checks the parent list for the commit loaded
> from the commit-graph and the one parsed from the object database. Test
> these checks for corrupt parents, too many parents, and wrong parents.
>
> The octopus merge will be tested in a later commit.

Does this mean that after this commit but before the next one the
'verify' subcommand would have false negatives for octopus merges
(falsely indicating that commit-graph is invalid)?

>
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  commit-graph.c          | 25 +++++++++++++++++++++++++
>  t/t5318-commit-graph.sh | 18 ++++++++++++++++++
>  2 files changed, 43 insertions(+)
>
> diff --git a/commit-graph.c b/commit-graph.c
> index 19ea369fc6..fff22dc0c3 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -921,6 +921,7 @@ int verify_commit_graph(struct commit_graph *g)
>  
>  	for (i = 0; i < g->num_commits; i++) {
>  		struct commit *graph_commit, *odb_commit;
> +		struct commit_list *graph_parents, *odb_parents;
>  
>  		hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
>  
> @@ -938,6 +939,30 @@ int verify_commit_graph(struct commit_graph *g)
>  				     oid_to_hex(&cur_oid),
>  				     oid_to_hex(get_commit_tree_oid(graph_commit)),
>  				     oid_to_hex(get_commit_tree_oid(odb_commit)));
> +
> +		graph_parents = graph_commit->parents;
> +		odb_parents = odb_commit->parents;
> +
> +		while (graph_parents) {
> +			if (odb_parents == NULL) {
> +				graph_report("commit-graph parent list for commit %s is too long",
> +					     oid_to_hex(&cur_oid));
> +				break;
> +			}

All right, so this would catch the situation where there are more
parents for a commit in commit-graph than they are in the object
database version.

> +
> +			if (oidcmp(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
> +				graph_report("commit-graph parent for %s is %s != %s",
> +					     oid_to_hex(&cur_oid),
> +					     oid_to_hex(&graph_parents->item->object.oid),
> +					     oid_to_hex(&odb_parents->item->object.oid));

All right, so this would catch the situation where parents do not match
between commit-graph and the object database.

> +
> +			graph_parents = graph_parents->next;
> +			odb_parents = odb_parents->next;
> +		}
> +
> +		if (odb_parents != NULL)
> +			graph_report("commit-graph parent list for commit %s terminates early",
> +				     oid_to_hex(&cur_oid));

So this would catch the situation where there are more parents for a
commit in the object database than they are in the commit-graph.  Does
this handle octopus merges automatically, or is it left for the future
work/commit?

>  	}
>  
>  	return verify_commit_graph_error;
> diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
> index 21cc8e82f3..12f0d7f54d 100755
> --- a/t/t5318-commit-graph.sh
> +++ b/t/t5318-commit-graph.sh
> @@ -269,6 +269,9 @@ GRAPH_BYTE_OID_LOOKUP_ORDER=`expr $GRAPH_OID_LOOKUP_OFFSET + $HASH_LEN \* 8`
>  GRAPH_BYTE_OID_LOOKUP_MISSING=`expr $GRAPH_OID_LOOKUP_OFFSET + $HASH_LEN \* 4 + 10`
>  GRAPH_COMMIT_DATA_OFFSET=`expr $GRAPH_OID_LOOKUP_OFFSET + $HASH_LEN \* $NUM_COMMITS`
>  GRAPH_BYTE_COMMIT_TREE=$GRAPH_COMMIT_DATA_OFFSET
> +GRAPH_BYTE_COMMIT_PARENT=`expr $GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN`
> +GRAPH_BYTE_COMMIT_EXTRA_PARENT=`expr $GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 4`
> +GRAPH_BYTE_COMMIT_WRONG_PARENT=`expr $GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 3`
>  
>  # usage: corrupt_graph_and_verify <position> <data> <string>
>  # Manipulates the commit-graph file at the position
> @@ -348,4 +351,19 @@ test_expect_success 'detect incorrect tree OID' '
>  		"root tree OID for commit"
>  '
>  
> +test_expect_success 'detect incorrect parent int-id' '
> +	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_PARENT "\01" \
> +		"invalid parent"
> +'

So this would actually be caught by code introduced earlier, and not by
the one introduced in this commit -- but logically this test belongs
here, ian't it?

> +
> +test_expect_success 'detect extra parent int-id' '
> +	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_EXTRA_PARENT "\00" \
> +		"is too long"
> +'

O.K., so the commit has one parent and we have corrupted it to read as
if it had more than one (and commit-graph would then have more parents
than reality, that is the object database).

Sidenote: I think we can use regexp for checking if the error message
matches, isn't it?

> +
> +test_expect_success 'detect incorrect tree OID' '

Errr... what?  The name of this test seems very wrong...

> +	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_WRONG_PARENT "\01" \
> +		"commit-graph parent for"
> +'

So here you modify the prent list in commit graph so that the commit
number points fits within commit-graph; it would of course make the
commit-graph and the object database version of parents do not match.
Good.

> +
>  test_done

  reply	other threads:[~2018-06-01 23:21 UTC|newest]

Thread overview: 149+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17 18:10 [RFC PATCH 00/12] Integrate commit-graph into 'fsck' and 'gc' Derrick Stolee
2018-04-17 18:10 ` [RFC PATCH 01/12] fixup! commit-graph: always load commit-graph information Derrick Stolee
2018-04-17 18:10 ` [RFC PATCH 03/12] commit-graph: check file header information Derrick Stolee
2018-04-19 15:58   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 02/12] commit-graph: add 'check' subcommand Derrick Stolee
2018-04-19 13:24   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 04/12] commit-graph: parse commit from chosen graph Derrick Stolee
2018-04-19 17:21   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 05/12] commit-graph: check fanout and lookup table Derrick Stolee
2018-04-20  7:27   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 06/12] commit: force commit to parse from object database Derrick Stolee
2018-04-20 12:13   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 07/12] commit-graph: load a root tree from specific graph Derrick Stolee
2018-04-20 12:18   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 08/12] commit-graph: verify commit contents against odb Derrick Stolee
2018-04-20 16:47   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 10/12] commit-graph: add '--reachable' option Derrick Stolee
2018-04-20 17:17   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 09/12] fsck: check commit-graph Derrick Stolee
2018-04-20 16:59   ` Jakub Narebski
2018-04-17 18:10 ` [RFC PATCH 11/12] gc: automatically write commit-graph files Derrick Stolee
2018-04-20 17:34   ` Jakub Narebski
2018-04-20 18:33     ` Ævar Arnfjörð Bjarmason
2018-04-17 18:10 ` [RFC PATCH 12/12] commit-graph: update design document Derrick Stolee
2018-04-20 19:10   ` Jakub Narebski
2018-04-17 18:50 ` [RFC PATCH 00/12] Integrate commit-graph into 'fsck' and 'gc' Derrick Stolee
2018-05-10 17:34 ` [PATCH 00/12] Integrate commit-graph into fsck, gc, and fetch Derrick Stolee
2018-05-10 17:34   ` [PATCH 01/12] commit-graph: add 'verify' subcommand Derrick Stolee
2018-05-10 18:15     ` Martin Ågren
2018-05-10 17:34   ` [PATCH 02/12] commit-graph: verify file header information Derrick Stolee
2018-05-10 18:21     ` Martin Ågren
2018-05-10 17:34   ` [PATCH 03/12] commit-graph: parse commit from chosen graph Derrick Stolee
2018-05-10 17:34   ` [PATCH 04/12] commit-graph: verify fanout and lookup table Derrick Stolee
2018-05-10 18:29     ` Martin Ågren
2018-05-11 15:17       ` Derrick Stolee
2018-05-10 17:34   ` [PATCH 05/12] commit: force commit to parse from object database Derrick Stolee
2018-05-10 17:34   ` [PATCH 06/12] commit-graph: load a root tree from specific graph Derrick Stolee
2018-05-10 17:34   ` [PATCH 07/12] commit-graph: verify commit contents against odb Derrick Stolee
2018-05-10 17:34   ` [PATCH 08/12] fsck: verify commit-graph Derrick Stolee
2018-05-10 17:34   ` [PATCH 09/12] commit-graph: add '--reachable' option Derrick Stolee
2018-05-10 17:34   ` [PATCH 10/12] gc: automatically write commit-graph files Derrick Stolee
2018-05-10 17:34   ` [PATCH 11/12] fetch: compute commit-graph by default Derrick Stolee
2018-05-10 17:34   ` [PATCH 12/12] commit-graph: update design document Derrick Stolee
2018-05-10 19:05   ` [PATCH 00/12] Integrate commit-graph into fsck, gc, and fetch Martin Ågren
2018-05-10 19:22     ` Stefan Beller
2018-05-11 17:23       ` Derrick Stolee
2018-05-11 17:30         ` Martin Ågren
2018-05-10 19:17   ` Ævar Arnfjörð Bjarmason
2018-05-11 17:23     ` Derrick Stolee
2018-05-11 21:15   ` [PATCH v2 00/12] Integrate commit-graph into fsck and gc Derrick Stolee
2018-05-11 21:15     ` [PATCH v2 01/12] commit-graph: add 'verify' subcommand Derrick Stolee
2018-05-12 13:31       ` Martin Ågren
2018-05-14 13:27         ` Derrick Stolee
2018-05-20 12:10       ` Jakub Narebski
2018-05-11 21:15     ` [PATCH v2 02/12] commit-graph: verify file header information Derrick Stolee
2018-05-12 13:35       ` Martin Ågren
2018-05-14 13:31         ` Derrick Stolee
2018-05-20 20:00       ` Jakub Narebski
2018-05-11 21:15     ` [PATCH v2 03/12] commit-graph: test that 'verify' finds corruption Derrick Stolee
2018-05-12 13:43       ` Martin Ågren
2018-05-21 18:53       ` Jakub Narebski
2018-05-24 16:28         ` Derrick Stolee
2018-05-11 21:15     ` [PATCH v2 04/12] commit-graph: parse commit from chosen graph Derrick Stolee
2018-05-12 20:50       ` Martin Ågren
2018-05-11 21:15     ` [PATCH v2 05/12] commit-graph: verify fanout and lookup table Derrick Stolee
2018-05-11 21:15     ` [PATCH v2 06/12] commit: force commit to parse from object database Derrick Stolee
2018-05-12 20:54       ` Martin Ågren
2018-05-11 21:15     ` [PATCH v2 07/12] commit-graph: load a root tree from specific graph Derrick Stolee
2018-05-12 20:55       ` Martin Ågren
2018-05-11 21:15     ` [PATCH v2 08/12] commit-graph: verify commit contents against odb Derrick Stolee
2018-05-12 21:17       ` Martin Ågren
2018-05-14 13:44         ` Derrick Stolee
2018-05-15 21:12       ` Martin Ågren
2018-05-11 21:15     ` [PATCH v2 09/12] fsck: verify commit-graph Derrick Stolee
2018-05-17 18:13       ` Martin Ågren
2018-05-11 21:15     ` [PATCH v2 10/12] commit-graph: add '--reachable' option Derrick Stolee
2018-05-17 18:16       ` Martin Ågren
2018-05-11 21:15     ` [PATCH v2 11/12] gc: automatically write commit-graph files Derrick Stolee
2018-05-17 18:20       ` Martin Ågren
2018-05-11 21:15     ` [PATCH v2 12/12] commit-graph: update design document Derrick Stolee
2018-05-24 16:25     ` [PATCH v3 00/20] Integrate commit-graph into 'fsck' and 'gc' Derrick Stolee
2018-05-24 16:25       ` [PATCH v3 01/20] commit-graph: UNLEAK before die() Derrick Stolee
2018-05-24 22:47         ` Stefan Beller
2018-05-25  0:08           ` Derrick Stolee
2018-05-24 16:25       ` [PATCH v3 02/20] commit-graph: fix GRAPH_MIN_SIZE Derrick Stolee
2018-05-26 18:46         ` Jakub Narebski
2018-05-26 20:30           ` brian m. carlson
2018-06-02 19:43             ` Jakub Narebski
2018-05-24 16:25       ` [PATCH v3 03/20] commit-graph: parse commit from chosen graph Derrick Stolee
2018-05-27 10:23         ` Jakub Narebski
2018-05-29 12:31           ` Derrick Stolee
2018-05-24 16:25       ` [PATCH v3 04/20] commit: force commit to parse from object database Derrick Stolee
2018-05-27 18:04         ` Jakub Narebski
2018-05-24 16:25       ` [PATCH v3 05/20] commit-graph: load a root tree from specific graph Derrick Stolee
2018-05-27 19:12         ` Jakub Narebski
2018-05-24 16:25       ` [PATCH v3 06/20] commit-graph: add 'verify' subcommand Derrick Stolee
2018-05-27 22:55         ` Jakub Narebski
2018-05-30 16:07           ` Derrick Stolee
2018-06-02 21:19             ` Jakub Narebski
2018-06-04 11:30               ` Derrick Stolee
2018-05-24 16:25       ` [PATCH v3 07/20] commit-graph: verify catches corrupt signature Derrick Stolee
2018-05-28 14:05         ` Jakub Narebski
2018-05-29 12:43           ` Derrick Stolee
2018-06-02 22:30             ` Jakub Narebski
2018-05-24 16:25       ` [PATCH v3 08/20] commit-graph: verify required chunks are present Derrick Stolee
2018-05-28 17:11         ` Jakub Narebski
2018-05-24 16:25       ` [PATCH v3 09/20] commit-graph: verify corrupt OID fanout and lookup Derrick Stolee
2018-05-30 13:34         ` Jakub Narebski
2018-05-30 16:18           ` Derrick Stolee
2018-06-02  4:38         ` Duy Nguyen
2018-06-04 11:32           ` Derrick Stolee
2018-06-04 14:42             ` Duy Nguyen
2018-05-24 16:25       ` [PATCH v3 10/20] commit-graph: verify objects exist Derrick Stolee
2018-05-30 19:22         ` Jakub Narebski
2018-05-31 12:53           ` Derrick Stolee
2018-05-24 16:25       ` [PATCH v3 11/20] commit-graph: verify root tree OIDs Derrick Stolee
2018-05-30 22:24         ` Jakub Narebski
2018-05-31 13:16           ` Derrick Stolee
2018-06-02 22:50             ` Jakub Narebski
2018-05-24 16:25       ` [PATCH v3 12/20] commit-graph: verify parent list Derrick Stolee
2018-06-01 23:21         ` Jakub Narebski [this message]
2018-05-24 16:25       ` [PATCH v3 13/20] commit-graph: verify generation number Derrick Stolee
2018-06-02 12:23         ` Jakub Narebski
2018-06-04 11:47           ` Derrick Stolee
2018-05-24 16:25       ` [PATCH v3 14/20] commit-graph: verify commit date Derrick Stolee
2018-06-02 12:29         ` Jakub Narebski
2018-05-24 16:25       ` [PATCH v3 15/20] commit-graph: test for corrupted octopus edge Derrick Stolee
2018-06-02 12:39         ` Jakub Narebski
2018-06-04 13:08           ` Derrick Stolee
2018-05-24 16:26       ` [PATCH v3 16/20] commit-graph: verify contents match checksum Derrick Stolee
2018-05-30 12:35         ` SZEDER Gábor
2018-06-02 15:52         ` Jakub Narebski
2018-06-04 11:55           ` Derrick Stolee
2018-05-24 16:26       ` [PATCH v3 17/20] fsck: verify commit-graph Derrick Stolee
2018-06-02 16:17         ` Jakub Narebski
2018-06-04 11:59           ` Derrick Stolee
2018-05-24 16:26       ` [PATCH v3 18/20] commit-graph: add '--reachable' option Derrick Stolee
2018-06-02 17:34         ` Jakub Narebski
2018-06-04 12:44           ` Derrick Stolee
2018-05-24 16:26       ` [PATCH v3 19/20] gc: automatically write commit-graph files Derrick Stolee
2018-06-02 18:03         ` Jakub Narebski
2018-06-04 12:51           ` Derrick Stolee
2018-05-24 16:26       ` [PATCH v3 20/20] commit-graph: update design document Derrick Stolee
2018-06-02 18:27         ` Jakub Narebski
2018-05-24 21:15       ` [PATCH v3 00/20] Integrate commit-graph into 'fsck' and 'gc' Ævar Arnfjörð Bjarmason
2018-05-25  4:11       ` Junio C Hamano
2018-05-29  4:27       ` Junio C Hamano
2018-05-29 12:37         ` Derrick Stolee
2018-05-29 13:41           ` Junio C Hamano

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