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From: Jeff King <peff@peff.net>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, jrnieder@gmail.com
Subject: Re: [PATCH 13/20] packed_object_info(): convert to new revindex API
Date: Tue, 12 Jan 2021 04:11:59 -0500	[thread overview]
Message-ID: <X/1n36/HtqAoKXrH@coredump.intra.peff.net> (raw)
In-Reply-To: <eab7ab1f35fa9703f56a99fa539839869fe4e54c.1610129796.git.me@ttaylorr.com>

On Fri, Jan 08, 2021 at 01:17:34PM -0500, Taylor Blau wrote:

> Convert another call of 'find_pack_revindex()' to its replacement
> 'pack_pos_to_offset()'. Likewise:
> 
>   - Avoid manipulating `struct packed_git`'s `revindex` pointer directly
>     by removing the pointer-as-array indexing.

Good.

>   - Add an additional guard to check that the offset 'obj_offset()'
>     points to a real object. This should be the case with well-behaved
>     callers to 'packed_object_info()', but isn't guarenteed.
>
>     Other blocks that fill in various other values from the 'struct
>     object_info' request handle bad inputs by setting the type to
>     'OBJ_BAD' and jumping to 'out'. Do the same when given a bad offset
>     here.

Also good. I wonder if we need to call error() here, too. The caller
will probably say something like "bad object" or whatever, but the user
will have no clue that it's related to the revindex.

That would match other parts of the function (e.g., calling into
unpack_entry() can generate lots of descriptive errors about exactly
what went wrong).

>     The previous code would have segfaulted when given a bad
>     'obj_offset' value, since 'find_pack_revindex()' would return
>     'NULL', and then the line that fills 'oi->disk_sizep' would try to
>     access 'NULL[1]' with a stride of 16 bytes (the width of 'struct
>     revindex_entry)'.

Yep. Again, I'm really happy to see these "should never happen" cases
converted to real errors or even BUG()s.

-Peff

  reply	other threads:[~2021-01-12  9:13 UTC|newest]

Thread overview: 121+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-08 18:16 [PATCH 00/20] pack-revindex: prepare for on-disk reverse index Taylor Blau
2021-01-08 18:16 ` [PATCH 01/20] pack-revindex: introduce a new API Taylor Blau
2021-01-12  8:41   ` Jeff King
2021-01-12  9:41     ` Jeff King
2021-01-12 16:27     ` Taylor Blau
2021-01-13  8:06   ` Junio C Hamano
2021-01-13  8:54     ` Junio C Hamano
2021-01-13 13:17     ` Jeff King
2021-01-13 16:23     ` Taylor Blau
2021-01-08 18:16 ` [PATCH 02/20] write_reuse_object(): convert to new revindex API Taylor Blau
2021-01-12  8:47   ` Jeff King
2021-01-12 16:31     ` Taylor Blau
2021-01-13 13:02       ` Jeff King
2021-01-08 18:16 ` [PATCH 03/20] write_reused_pack_one(): " Taylor Blau
2021-01-12  8:50   ` Jeff King
2021-01-12 16:34     ` Taylor Blau
2021-01-08 18:16 ` [PATCH 04/20] write_reused_pack_verbatim(): " Taylor Blau
2021-01-12  8:50   ` Jeff King
2021-01-08 18:17 ` [PATCH 05/20] check_object(): " Taylor Blau
2021-01-11 11:43   ` Derrick Stolee
2021-01-11 16:15     ` Taylor Blau
2021-01-12  8:54       ` Jeff King
2021-01-12  8:51   ` Jeff King
2021-01-08 18:17 ` [PATCH 06/20] bitmap_position_packfile(): " Taylor Blau
2021-01-08 18:17 ` [PATCH 07/20] show_objects_for_type(): " Taylor Blau
2021-01-12  8:57   ` Jeff King
2021-01-12 16:35     ` Taylor Blau
2021-01-08 18:17 ` [PATCH 08/20] get_size_by_pos(): " Taylor Blau
2021-01-08 18:17 ` [PATCH 09/20] try_partial_reuse(): " Taylor Blau
2021-01-12  9:06   ` Jeff King
2021-01-12 16:47     ` Taylor Blau
2021-01-08 18:17 ` [PATCH 10/20] rebuild_existing_bitmaps(): " Taylor Blau
2021-01-08 18:17 ` [PATCH 11/20] get_delta_base_oid(): " Taylor Blau
2021-01-08 18:17 ` [PATCH 12/20] retry_bad_packed_offset(): " Taylor Blau
2021-01-08 18:17 ` [PATCH 13/20] packed_object_info(): " Taylor Blau
2021-01-12  9:11   ` Jeff King [this message]
2021-01-12 16:51     ` Taylor Blau
2021-01-08 18:17 ` [PATCH 14/20] unpack_entry(): " Taylor Blau
2021-01-12  9:22   ` Jeff King
2021-01-12 16:56     ` Taylor Blau
2021-01-08 18:17 ` [PATCH 15/20] for_each_object_in_pack(): " Taylor Blau
2021-01-08 18:17 ` [PATCH 16/20] builtin/gc.c: guess the size of the revindex Taylor Blau
2021-01-11 11:52   ` Derrick Stolee
2021-01-11 16:23     ` Taylor Blau
2021-01-11 17:09       ` Derrick Stolee
2021-01-12  9:28         ` Jeff King
2021-01-08 18:17 ` [PATCH 17/20] pack-revindex: remove unused 'find_pack_revindex()' Taylor Blau
2021-01-08 18:17 ` [PATCH 18/20] pack-revindex: remove unused 'find_revindex_position()' Taylor Blau
2021-01-11 11:57   ` Derrick Stolee
2021-01-11 16:27     ` Taylor Blau
2021-01-11 17:11       ` Derrick Stolee
2021-01-12  9:32   ` Jeff King
2021-01-12 16:59     ` Taylor Blau
2021-01-13 13:05       ` Jeff King
2021-01-08 18:18 ` [PATCH 19/20] pack-revindex: hide the definition of 'revindex_entry' Taylor Blau
2021-01-11 11:57   ` Derrick Stolee
2021-01-12  9:34   ` Jeff King
2021-01-08 18:18 ` [PATCH 20/20] pack-revindex.c: avoid direct revindex access in 'offset_to_pack_pos()' Taylor Blau
2021-01-12  9:37   ` Jeff King
2021-01-12 17:02     ` Taylor Blau
2021-01-11 12:07 ` [PATCH 00/20] pack-revindex: prepare for on-disk reverse index Derrick Stolee
2021-01-11 16:30   ` Taylor Blau
2021-01-11 17:15     ` Derrick Stolee
2021-01-11 17:29       ` Taylor Blau
2021-01-11 18:40       ` Junio C Hamano
2021-01-12  9:45 ` Jeff King
2021-01-12 17:07   ` Taylor Blau
2021-01-13  0:23 ` Junio C Hamano
2021-01-13  0:52   ` Taylor Blau
2021-01-13  2:15     ` Junio C Hamano
2021-01-13  3:23       ` Taylor Blau
2021-01-13  8:21         ` Junio C Hamano
2021-01-13 13:13           ` Jeff King
2021-01-13 15:34             ` Taylor Blau
2021-01-13 20:06               ` Junio C Hamano
2021-01-13 20:13                 ` Taylor Blau
2021-01-13 20:22                 ` Jeff King
2021-01-13 22:23 ` [PATCH v2 " Taylor Blau
2021-01-13 22:23   ` [PATCH v2 01/20] pack-revindex: introduce a new API Taylor Blau
2021-01-14  6:46     ` Junio C Hamano
2021-01-14 12:00       ` Derrick Stolee
2021-01-14 17:06       ` Taylor Blau
2021-01-14 19:19         ` Jeff King
2021-01-14 20:47           ` Junio C Hamano
2021-01-13 22:23   ` [PATCH v2 02/20] write_reuse_object(): convert to new revindex API Taylor Blau
2021-01-13 22:23   ` [PATCH v2 03/20] write_reused_pack_one(): " Taylor Blau
2021-01-13 22:23   ` [PATCH v2 04/20] write_reused_pack_verbatim(): " Taylor Blau
2021-01-13 22:23   ` [PATCH v2 05/20] check_object(): " Taylor Blau
2021-01-13 22:23   ` [PATCH v2 06/20] bitmap_position_packfile(): " Taylor Blau
2021-01-13 22:23   ` [PATCH v2 07/20] show_objects_for_type(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 08/20] get_size_by_pos(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 09/20] try_partial_reuse(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 10/20] rebuild_existing_bitmaps(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 11/20] get_delta_base_oid(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 12/20] retry_bad_packed_offset(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 13/20] packed_object_info(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 14/20] unpack_entry(): " Taylor Blau
2021-01-13 22:24   ` [PATCH v2 15/20] for_each_object_in_pack(): " Taylor Blau
2021-01-14  6:43     ` Junio C Hamano
2021-01-14 17:00       ` Taylor Blau
2021-01-14 19:33       ` Jeff King
2021-01-14 20:11         ` Jeff King
2021-01-14 20:15           ` Taylor Blau
2021-01-15  2:22             ` Junio C Hamano
2021-01-15  2:29               ` Taylor Blau
2021-01-14 20:51         ` Junio C Hamano
2021-01-13 22:24   ` [PATCH v2 16/20] builtin/gc.c: guess the size of the revindex Taylor Blau
2021-01-14  6:33     ` Junio C Hamano
2021-01-14 16:53       ` Taylor Blau
2021-01-14 19:43         ` Jeff King
2021-01-13 22:24   ` [PATCH v2 17/20] pack-revindex: remove unused 'find_pack_revindex()' Taylor Blau
2021-01-13 22:25   ` [PATCH v2 18/20] pack-revindex: remove unused 'find_revindex_position()' Taylor Blau
2021-01-14  6:42     ` Junio C Hamano
2021-01-13 22:25   ` [PATCH v2 19/20] pack-revindex: hide the definition of 'revindex_entry' Taylor Blau
2021-01-13 22:25   ` [PATCH v2 20/20] pack-revindex.c: avoid direct revindex access in 'offset_to_pack_pos()' Taylor Blau
2021-01-14  6:42     ` Junio C Hamano
2021-01-14 16:56       ` Taylor Blau
2021-01-14 19:51   ` [PATCH v2 00/20] pack-revindex: prepare for on-disk reverse index Jeff King
2021-01-14 20:53     ` Junio C Hamano
2021-01-15  9:32       ` Jeff King
2021-01-15  9:33         ` Jeff King

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