From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>
Cc: git@vger.kernel.org, "René Scharfe" <l.s.r@web.de>,
"Duy Nguyen" <pclouds@gmail.com>
Subject: Re: [PATCH 28/31] dir: make untracked cache extension hash size independent
Date: Tue, 12 Feb 2019 12:08:01 +0100 [thread overview]
Message-ID: <87y36ljmcu.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <20190212012256.1005924-29-sandals@crustytoothpaste.net>
On Tue, Feb 12 2019, brian m. carlson wrote:
> Instead of using a struct with a flex array member to read and write the
> untracked cache extension, use a shorter, fixed-length struct and add
> the name and hash data explicitly.
> [...]
> struct stat_data info_exclude_stat;
> struct stat_data excludes_file_stat;
> uint32_t dir_flags;
> - unsigned char info_exclude_sha1[20];
> - unsigned char excludes_file_sha1[20];
> - char exclude_per_dir[FLEX_ARRAY];
> };
Both this & the follow-up 29/31 look scary since this is an on-disk
structure and this patch & the next one rather than implementing some
transition, just changes the structs & code we use to read & write to
use the current hash size.
So what are we going to do when the "current" size is SHA-256 and our
on-disk cache is SHA-1? It seems like with this we'd at best (I haven't
tested) throw away the SHA-1 UC data, and at worst introduce some silent
persistent read failure.
In any case that seems like something we should have tests for with an
on-disk format, i.e. write in one hash, see what happens when we read in
another, and perhaps instead of not understanding SHA-1 hashes in
SHA-256 mode we'd read the SHA-1 and consult the SHA-1<->SHA-256 lookup
table we're going to be eventually maintaining on the side?
next prev parent reply other threads:[~2019-02-12 11:08 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 1:22 [PATCH 00/31] Hash function transition part 16 brian m. carlson
2019-02-12 1:22 ` [PATCH 01/31] t/lib-submodule-update: use appropriate length constant brian m. carlson
2019-02-12 1:22 ` [PATCH 02/31] pack-bitmap: make bitmap header handling hash agnostic brian m. carlson
2019-02-12 1:22 ` [PATCH 03/31] pack-bitmap: convert struct stored_bitmap to object_id brian m. carlson
2019-02-12 1:22 ` [PATCH 04/31] pack-bitmap: replace sha1_to_hex brian m. carlson
2019-02-12 6:37 ` Jeff King
2019-02-13 0:00 ` brian m. carlson
2019-02-14 4:41 ` Jeff King
2019-02-12 1:22 ` [PATCH 05/31] pack-bitmap: switch hard-coded constants to the_hash_algo brian m. carlson
2019-02-12 11:13 ` Ævar Arnfjörð Bjarmason
2019-02-12 1:22 ` [PATCH 06/31] submodule: avoid hard-coded constants brian m. carlson
2019-02-12 1:22 ` [PATCH 07/31] notes-merge: switch to use the_hash_algo brian m. carlson
2019-02-12 1:22 ` [PATCH 08/31] notes: make hash size independent brian m. carlson
2019-02-12 1:37 ` Eric Sunshine
2019-02-12 1:42 ` brian m. carlson
2019-02-12 1:22 ` [PATCH 09/31] notes: replace sha1_to_hex brian m. carlson
2019-02-12 1:22 ` [PATCH 10/31] object-store: rename and expand packed_git's sha1 member brian m. carlson
2019-02-12 3:32 ` Eric Sunshine
2019-02-14 3:33 ` brian m. carlson
2019-02-12 1:22 ` [PATCH 11/31] builtin/name-rev: make hash-size independent brian m. carlson
2019-02-12 1:22 ` [PATCH 12/31] fast-import: " brian m. carlson
2019-02-12 3:44 ` Eric Sunshine
2019-02-12 23:36 ` brian m. carlson
2019-02-12 1:22 ` [PATCH 13/31] fast-import: replace sha1_to_hex brian m. carlson
2019-02-12 1:22 ` [PATCH 14/31] builtin/am: make hash size independent brian m. carlson
2019-02-12 1:22 ` [PATCH 15/31] builtin/pull: make hash-size independent brian m. carlson
2019-02-12 3:47 ` Eric Sunshine
2019-02-12 1:22 ` [PATCH 16/31] http-push: convert to use the_hash_algo brian m. carlson
2019-02-12 1:22 ` [PATCH 17/31] http-backend: allow 64-character hex names brian m. carlson
2019-02-12 1:22 ` [PATCH 18/31] http-push: remove remaining uses of sha1_to_hex brian m. carlson
2019-02-12 1:22 ` [PATCH 19/31] http-walker: replace sha1_to_hex brian m. carlson
2019-02-12 3:51 ` Eric Sunshine
2019-02-12 1:22 ` [PATCH 20/31] http: replace hard-coded constant with the_hash_algo brian m. carlson
2019-02-12 1:22 ` [PATCH 21/31] http: compute hash of downloaded objects using the_hash_algo brian m. carlson
2019-02-12 1:22 ` [PATCH 22/31] http: replace sha1_to_hex brian m. carlson
2019-02-12 1:22 ` [PATCH 23/31] remote-curl: make hash size independent brian m. carlson
2019-02-12 11:11 ` Ævar Arnfjörð Bjarmason
2019-02-12 1:22 ` [PATCH 24/31] archive-tar: " brian m. carlson
2019-02-12 7:20 ` René Scharfe
2019-02-12 17:33 ` René Scharfe
2019-02-13 0:11 ` brian m. carlson
2019-02-12 1:22 ` [PATCH 25/31] archive: convert struct archiver_args to object_id brian m. carlson
2019-02-12 1:22 ` [PATCH 26/31] refspec: make hash size independent brian m. carlson
2019-02-12 1:22 ` [PATCH 27/31] builtin/difftool: use parse_oid_hex brian m. carlson
2019-02-12 8:27 ` Eric Sunshine
2019-02-12 1:22 ` [PATCH 28/31] dir: make untracked cache extension hash size independent brian m. carlson
2019-02-12 11:08 ` Ævar Arnfjörð Bjarmason [this message]
2019-02-13 0:30 ` brian m. carlson
2019-02-12 1:22 ` [PATCH 29/31] read-cache: read data in a hash-independent way brian m. carlson
2019-02-12 1:22 ` [PATCH 30/31] Git.pm: make hash size independent brian m. carlson
2019-02-12 10:59 ` Ævar Arnfjörð Bjarmason
2019-02-18 19:09 ` brian m. carlson
2019-02-18 21:00 ` Ævar Arnfjörð Bjarmason
2019-02-12 1:22 ` [PATCH 31/31] gitweb: " brian m. carlson
2019-02-12 10:57 ` Ævar Arnfjörð Bjarmason
2019-02-12 11:15 ` [PATCH 00/31] Hash function transition part 16 Ævar Arnfjörð Bjarmason
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