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From: Duy Nguyen <pclouds@gmail.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Eric Sunshine <sunshine@sunshineco.com>
Subject: Re: [PATCH 08/41] packfile: abstract away hash constant values
Date: Tue, 1 May 2018 12:22:43 +0200	[thread overview]
Message-ID: <20180501102243.GE15820@duynguyen.home> (raw)
In-Reply-To: <20180423233951.276447-9-sandals@crustytoothpaste.net>

On Mon, Apr 23, 2018 at 11:39:18PM +0000, brian m. carlson wrote:
> There are several instances of the constant 20 and 20-based values in
> the packfile code.  Abstract away dependence on SHA-1 by using the
> values from the_hash_algo instead.

While we're abstracting away 20. There's the only 20 left in
sha1_file.c that should also be gone. But I guess you could do that
later since you need to rename fill_sha1_path to
fill_loose_object_path or something.


> @@ -507,15 +509,15 @@ static int open_packed_git_1(struct packed_git *p)
>  			     " while index indicates %"PRIu32" objects",
>  			     p->pack_name, ntohl(hdr.hdr_entries),
>  			     p->num_objects);
> -	if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
> +	if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)
>  		return error("end of packfile %s is unavailable", p->pack_name);
> -	read_result = read_in_full(p->pack_fd, sha1, sizeof(sha1));
> +	read_result = read_in_full(p->pack_fd, hash, hashsz);
>  	if (read_result < 0)
>  		return error_errno("error reading from %s", p->pack_name);
> -	if (read_result != sizeof(sha1))
> +	if (read_result != hashsz)
>  		return error("packfile %s signature is unavailable", p->pack_name);
> -	idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
> -	if (hashcmp(sha1, idx_sha1))
> +	idx_hash = ((unsigned char *)p->index_data) + p->index_size - hashsz * 2;
> +	if (hashcmp(hash, idx_hash))

Since the hash size is abstracted away, shouldn't this hashcmp become
oidcmp? (which still does not do the right thing, but at least it's
one less place to worry about)

Same comment for other hashcmp in this patch.

> @@ -675,7 +677,8 @@ struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
>  	p->pack_size = st.st_size;
>  	p->pack_local = local;
>  	p->mtime = st.st_mtime;
> -	if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
> +	if (path_len < the_hash_algo->hexsz ||
> +	    get_sha1_hex(path + path_len - the_hash_algo->hexsz, p->sha1))

get_sha1_hex looks out of place when we start going with
the_hash_algo. Maybe change to get_oid_hex() too.

> @@ -1678,10 +1683,10 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
>  
>  	index_lookup = index_fanout + 4 * 256;
>  	if (p->index_version == 1) {
> -		index_lookup_width = 24;
> +		index_lookup_width = hashsz + 4;

You did good research to spot this 24 constant ;-)

--
Duy

  reply	other threads:[~2018-05-01 10:22 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-23 23:39 [PATCH 00/41] object_id part 13 brian m. carlson
2018-04-23 23:39 ` [PATCH 01/41] cache: add a function to read an object ID from a buffer brian m. carlson
2018-04-24  9:39   ` Martin Ågren
2018-05-01  9:36   ` Duy Nguyen
2018-05-01 23:58     ` brian m. carlson
2018-04-23 23:39 ` [PATCH 02/41] server-info: remove unused members from struct pack_info brian m. carlson
2018-04-24  9:41   ` Martin Ågren
2018-05-01  9:39   ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 03/41] Remove unused member in struct object_context brian m. carlson
2018-05-01  9:50   ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 04/41] packfile: remove unused member from struct pack_entry brian m. carlson
2018-05-01 10:01   ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 05/41] packfile: convert has_sha1_pack to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 06/41] sha1_file: convert freshen functions " brian m. carlson
2018-04-23 23:39 ` [PATCH 07/41] packfile: convert find_pack_entry " brian m. carlson
2018-04-23 23:39 ` [PATCH 08/41] packfile: abstract away hash constant values brian m. carlson
2018-05-01 10:22   ` Duy Nguyen [this message]
2018-05-02  0:11     ` brian m. carlson
2018-05-02 15:26       ` Duy Nguyen
2018-05-02 23:05         ` brian m. carlson
2018-04-23 23:39 ` [PATCH 09/41] pack-objects: abstract away hash algorithm brian m. carlson
2018-05-01 10:26   ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 10/41] pack-redundant: " brian m. carlson
2018-04-23 23:39 ` [PATCH 11/41] tree-walk: avoid hard-coded 20 constant brian m. carlson
2018-04-23 23:39 ` [PATCH 12/41] tree-walk: convert get_tree_entry_follow_symlinks to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 13/41] fsck: convert static functions to struct object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 14/41] submodule-config: convert structures to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 15/41] split-index: convert struct split_index " brian m. carlson
2018-04-23 23:39 ` [PATCH 16/41] Update struct index_state to use struct object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 17/41] pack-redundant: convert linked lists " brian m. carlson
2018-04-23 23:39 ` [PATCH 18/41] index-pack: abstract away hash function constant brian m. carlson
2018-04-24  9:50   ` Martin Ågren
2018-04-24 23:51     ` brian m. carlson
2018-04-25 18:49       ` Martin Ågren
2018-04-26 15:46         ` Duy Nguyen
2018-04-27 21:08           ` brian m. carlson
2018-04-28  5:41             ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 19/41] commit: convert uses of get_sha1_hex to get_oid_hex brian m. carlson
2018-04-23 23:39 ` [PATCH 20/41] dir: convert struct untracked_cache_dir to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 21/41] http: eliminate hard-coded constants brian m. carlson
2018-04-24  9:53   ` Martin Ågren
2018-04-24 23:44     ` Junio C Hamano
2018-04-25  1:29       ` brian m. carlson
2018-04-23 23:39 ` [PATCH 22/41] revision: replace use of " brian m. carlson
2018-04-23 23:39 ` [PATCH 23/41] upload-pack: replace use of several " brian m. carlson
2018-04-24  7:53   ` Simon Ruderich
2018-04-23 23:39 ` [PATCH 24/41] diff: specify abbreviation size in terms of the_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 25/41] builtin/receive-pack: avoid hard-coded constants for push certs brian m. carlson
2018-04-24  9:58   ` Martin Ågren
2018-04-25  2:00     ` brian m. carlson
2018-04-25  5:06       ` Martin Ågren
2018-04-23 23:39 ` [PATCH 26/41] builtin/am: convert uses of EMPTY_TREE_SHA1_BIN to the_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 27/41] builtin/merge: switch tree functions to use object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 28/41] merge: convert empty tree constant to the_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 29/41] sequencer: convert one use of EMPTY_TREE_SHA1_HEX brian m. carlson
2018-04-23 23:39 ` [PATCH 30/41] submodule: convert several uses " brian m. carlson
2018-04-23 23:39 ` [PATCH 31/41] wt-status: convert two " brian m. carlson
2018-04-24 10:03   ` Martin Ågren
2018-05-01  2:29     ` brian m. carlson
2018-04-23 23:39 ` [PATCH 32/41] builtin/receive-pack: convert one use " brian m. carlson
2018-04-23 23:39 ` [PATCH 33/41] builtin/reset: convert use of EMPTY_TREE_SHA1_BIN brian m. carlson
2018-04-23 23:39 ` [PATCH 34/41] sha1_file: convert cached object code to struct object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 35/41] cache-tree: use is_empty_tree_oid brian m. carlson
2018-04-23 23:39 ` [PATCH 36/41] sequencer: use the_hash_algo for empty tree object ID brian m. carlson
2018-04-23 23:39 ` [PATCH 37/41] dir: use the_hash_algo for empty blob " brian m. carlson
2018-04-23 23:39 ` [PATCH 38/41] sha1_file: only expose empty object constants through git_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 39/41] Update shell scripts to compute empty tree object ID brian m. carlson
2018-05-01 10:42   ` Duy Nguyen
2018-05-04  1:29     ` brian m. carlson
2018-04-23 23:39 ` [PATCH 40/41] add--interactive: compute the empty tree value brian m. carlson
2018-04-23 23:39 ` [PATCH 41/41] merge-one-file: compute empty blob object ID brian m. carlson
2018-04-24  1:00   ` SZEDER Gábor
2018-04-24  1:03     ` brian m. carlson
2018-04-30 18:03 ` [PATCH 00/41] object_id part 13 Duy Nguyen
2018-04-30 23:59   ` brian m. carlson
2018-05-01 10:51     ` Duy Nguyen

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