From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: Eric Sunshine <sunshine@sunshineco.com>
Cc: "Git List" <git@vger.kernel.org>, "René Scharfe" <l.s.r@web.de>,
"Duy Nguyen" <pclouds@gmail.com>
Subject: Re: [PATCH 12/31] fast-import: make hash-size independent
Date: Tue, 12 Feb 2019 23:36:48 +0000 [thread overview]
Message-ID: <20190212233648.GF684736@genre.crustytoothpaste.net> (raw)
In-Reply-To: <CAPig+cQivuPjDztK30QO0xKx1Tx+nYDPzTvgXvi9WVyRX5-aRQ@mail.gmail.com>
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On Mon, Feb 11, 2019 at 10:44:12PM -0500, Eric Sunshine wrote:
> On Mon, Feb 11, 2019 at 8:23 PM brian m. carlson
> <sandals@crustytoothpaste.net> wrote:
> > Replace several uses of GIT_SHA1_HEXSZ and 40-based constants with
> > references to the_hash_algo. Update the note handling code here to
> > compute path sizes based on GIT_MAX_RAWSZ as well.
> >
> > Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> > ---
> > diff --git a/fast-import.c b/fast-import.c
> > @@ -2047,7 +2047,8 @@ static uintmax_t do_change_note_fanout(
> > - char realpath[60];
> > + char realpath[GIT_MAX_RAWSZ * 3];
>
> I wonder if the fixed multiplier deserves a comment explaining that
> this is reserving enough space for a hex representation with '/'
> between each digit pair plus NUL. Which leads to the next question: Is
> there is GIT_MAX_HEXSZ constant? If so, this might be more clearly
> represented (or not) by taking advantage of that value.
There is such a constant. I'll add a comment and see if I can write it
in a way that makes it more intuitive what we're computing.
> Also, there are a number of hardcoded 60's in the code earlier in this
> file, such as:
>
> if ((max_packsize && (pack_size + 60 + len) > max_packsize)
> || (pack_size + 60 + len) < pack_size)
> cycle_packfile();
>
> Is that just a coincidence or is it related to the 60 characters
> allocated for 'realpath'?
That's an interesting question. It looks like these are indeed related
to the hash size, but they're not related to the realpath call above.
I'll convert them as well.
> > @@ -2405,7 +2406,7 @@ static void note_change_n(const char *p, struct branch *b, unsigned char *old_fa
> > char *buf = read_object_with_reference(&commit_oid,
> > commit_type, &size,
> > &commit_oid);
> > - if (!buf || size < 46)
> > + if (!buf || size < the_hash_algo->hexsz)
>
> What exactly did the 46 represent and how does it relate to 'hexsz'?
> Stated differently, why didn't this become:
>
> the_hash_algo->hexsz + 6'
>
> ?
Good catch. I believe that 46 is the number of bytes in "tree %s\n",
which is the smallest possible commit (a root commit without an author
or committer).
I'll fix this misconversion.
--
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204
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next prev parent reply other threads:[~2019-02-12 23:36 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 [this message]
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
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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