From: Taylor Blau <me@ttaylorr.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, dstolee@microsoft.com, jrnieder@gmail.com,
peff@peff.net
Subject: Re: [PATCH v2 1/8] packfile: prepare for the existence of '*.rev' files
Date: Thu, 14 Jan 2021 13:28:47 -0500 [thread overview]
Message-ID: <YACNX+ExF1yAn4g3@nand.local> (raw)
In-Reply-To: <xmqqwnwgx9rm.fsf@gitster.c.googlers.com>
On Wed, Jan 13, 2021 at 11:22:53PM -0800, Junio C Hamano wrote:
> Taylor Blau <me@ttaylorr.com> writes:
>
> > +== pack-*.rev files have the format:
> > +
> > + - A 4-byte magic number '0x52494458' ('RIDX').
> > +
> > + - A 4-byte version identifier (= 1)
> > +
> > + - A 4-byte hash function identifier (= 1 for SHA-1, 2 for SHA-256)
>
> These two are presumably 4-byte-wide network byte order integers.
> We should spell it out.
Yep, all entries are network order. I added a sentence at the bottom of
this sub-section to say as much.
> We've seen hardcoded constant "12" twice so far in this patch.
>
> We need a C proprocessor macro "#define RIDX_FILE_HEADER_SIZE 12" or
> something, perhaps?
Good idea, thanks.
> > - return p->revindex[pos].nr;
> > +
> > + if (p->revindex)
> > + return p->revindex[pos].nr;
> > + else
> > + return get_be32((char *)p->revindex_data + (pos * sizeof(uint32_t)));
>
> Good. We are using 32-bit uint in network byte order. We should
> document it as such.
>
> Let's not strip const away while casting, though. get_be32()
> ensures that it only reads and never writes thru the pointer, and
> p->revindex_data is a "const void *".
Agreed, and thanks for the suggestion. I take it that what you mean is:
- return get_be32((char *)p->revindex_data + (pos * sizeof(uint32_t)));
+ return get_be32((const char *)p->revindex_data + (pos * sizeof(uint32_t)));
...yes?
> > diff --git a/pack-revindex.h b/pack-revindex.h
> > index 6e0320b08b..01622cf21a 100644
> > --- a/pack-revindex.h
> > +++ b/pack-revindex.h
> > @@ -21,6 +21,9 @@ struct packed_git;
> > /*
> > * load_pack_revindex populates the revindex's internal data-structures for the
> > * given pack, returning zero on success and a negative value otherwise.
> > + *
> > + * If a '.rev' file is present, it is checked for consistency, mmap'd, and
> > + * pointers are assigned into it (instead of using the in-memory variant).
>
> Hmph, I missed where it got checked for consistency, though. If the
> file is corrupt and has say duplicated entries, we'd happily grab
> the data via get_be32(), for example.
It doesn't, I'm mistaken. I removed that incorrect detail from this
comment. Thanks for catching it.
Thanks,
Taylor
next prev parent reply other threads:[~2021-01-14 18:33 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-08 18:19 [PATCH 0/8] pack-revindex: introduce on-disk '.rev' format Taylor Blau
2021-01-08 18:19 ` [PATCH 1/8] packfile: prepare for the existence of '*.rev' files Taylor Blau
2021-01-08 18:20 ` [PATCH 2/8] pack-write.c: prepare to write 'pack-*.rev' files Taylor Blau
2021-01-08 18:20 ` [PATCH 3/8] builtin/index-pack.c: write reverse indexes Taylor Blau
2021-01-08 18:20 ` [PATCH 4/8] builtin/pack-objects.c: respect 'pack.writeReverseIndex' Taylor Blau
2021-01-08 18:20 ` [PATCH 5/8] Documentation/config/pack.txt: advertise 'pack.writeReverseIndex' Taylor Blau
2021-01-08 18:20 ` [PATCH 6/8] t: prepare for GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-12 17:11 ` Ævar Arnfjörð Bjarmason
2021-01-12 18:40 ` Taylor Blau
2021-01-08 18:20 ` [PATCH 7/8] t: support GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-12 16:49 ` Derrick Stolee
2021-01-12 17:34 ` Taylor Blau
2021-01-12 17:18 ` Ævar Arnfjörð Bjarmason
2021-01-12 17:39 ` Derrick Stolee
2021-01-12 18:17 ` Taylor Blau
2021-01-08 18:20 ` [PATCH 8/8] pack-revindex: ensure that on-disk reverse indexes are given precedence Taylor Blau
2021-01-13 22:28 ` [PATCH v2 0/8] pack-revindex: introduce on-disk '.rev' format Taylor Blau
2021-01-13 22:28 ` [PATCH v2 1/8] packfile: prepare for the existence of '*.rev' files Taylor Blau
2021-01-14 7:22 ` Junio C Hamano
2021-01-14 12:07 ` Derrick Stolee
2021-01-14 19:57 ` Jeff King
2021-01-14 18:28 ` Taylor Blau [this message]
2021-01-14 7:26 ` Junio C Hamano
2021-01-14 18:13 ` Taylor Blau
2021-01-14 20:57 ` Junio C Hamano
2021-01-22 22:54 ` Jeff King
2021-01-25 17:44 ` Taylor Blau
2021-01-25 18:27 ` Jeff King
2021-01-25 19:04 ` Junio C Hamano
2021-01-25 19:23 ` Taylor Blau
2021-01-13 22:28 ` [PATCH v2 2/8] pack-write.c: prepare to write 'pack-*.rev' files Taylor Blau
2021-01-22 23:24 ` Jeff King
2021-01-25 19:15 ` Taylor Blau
2021-01-26 21:43 ` Jeff King
2021-01-13 22:28 ` [PATCH v2 3/8] builtin/index-pack.c: write reverse indexes Taylor Blau
2021-01-22 23:53 ` Jeff King
2021-01-25 20:03 ` Taylor Blau
2021-01-13 22:28 ` [PATCH v2 4/8] builtin/pack-objects.c: respect 'pack.writeReverseIndex' Taylor Blau
2021-01-22 23:57 ` Jeff King
2021-01-23 0:08 ` Jeff King
2021-01-25 20:21 ` Taylor Blau
2021-01-25 20:50 ` Jeff King
2021-01-13 22:28 ` [PATCH v2 5/8] Documentation/config/pack.txt: advertise 'pack.writeReverseIndex' Taylor Blau
2021-01-13 22:28 ` [PATCH v2 6/8] t: prepare for GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-13 22:28 ` [PATCH v2 7/8] t: support GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-13 22:28 ` [PATCH v2 8/8] pack-revindex: ensure that on-disk reverse indexes are given precedence Taylor Blau
2021-01-25 23:37 ` [PATCH v3 00/10] pack-revindex: introduce on-disk '.rev' format Taylor Blau
2021-01-25 23:37 ` [PATCH v3 01/10] packfile: prepare for the existence of '*.rev' files Taylor Blau
2021-01-29 0:27 ` Jeff King
2021-01-29 1:14 ` Taylor Blau
2021-01-30 8:39 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 02/10] pack-write.c: prepare to write 'pack-*.rev' files Taylor Blau
2021-01-25 23:37 ` [PATCH v3 03/10] builtin/index-pack.c: allow stripping arbitrary extensions Taylor Blau
2021-01-29 0:28 ` Jeff King
2021-01-29 1:15 ` Taylor Blau
2021-01-25 23:37 ` [PATCH v3 04/10] builtin/index-pack.c: write reverse indexes Taylor Blau
2021-01-25 23:37 ` [PATCH v3 05/10] builtin/pack-objects.c: respect 'pack.writeReverseIndex' Taylor Blau
2021-01-25 23:37 ` [PATCH v3 06/10] Documentation/config/pack.txt: advertise 'pack.writeReverseIndex' Taylor Blau
2021-01-29 0:30 ` Jeff King
2021-01-29 1:17 ` Taylor Blau
2021-01-30 8:41 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 07/10] t: prepare for GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-29 0:45 ` Jeff King
2021-01-29 1:09 ` Eric Sunshine
2021-01-29 1:21 ` Taylor Blau
2021-01-30 8:43 ` Jeff King
2021-01-29 2:42 ` Junio C Hamano
2021-01-25 23:37 ` [PATCH v3 08/10] t: support GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-29 0:47 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 09/10] pack-revindex: ensure that on-disk reverse indexes are given precedence Taylor Blau
2021-01-29 0:53 ` Jeff King
2021-01-29 1:25 ` Taylor Blau
2021-01-30 8:46 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 10/10] t5325: check both on-disk and in-memory reverse index Taylor Blau
2021-01-29 1:04 ` Jeff King
2021-01-29 1:05 ` Jeff King
2021-01-29 1:32 ` Taylor Blau
2021-01-30 8:47 ` Jeff King
2021-01-26 2:36 ` [PATCH v3 00/10] pack-revindex: introduce on-disk '.rev' format Junio C Hamano
2021-01-26 2:49 ` Taylor Blau
2021-01-29 1:06 ` Jeff King
2021-01-29 1:34 ` Taylor Blau
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