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From: Patrick Steinhardt <ps@pks.im>
To: "Eric W. Biederman" <ebiederm@gmail.com>
Cc: Junio C Hamano <gitster@pobox.com>,
	git@vger.kernel.org,
	"brian m. carlson" <sandals@crustytoothpaste.net>,
	Eric Sunshine <sunshine@sunshineco.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH v2 04/30] repository: add a compatibility hash algorithm
Date: Thu, 15 Feb 2024 12:22:00 +0100	[thread overview]
Message-ID: <Zc3z2F7r2oMSlOW-@tanuki> (raw)
In-Reply-To: <20231002024034.2611-4-ebiederm@gmail.com>

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On Sun, Oct 01, 2023 at 09:40:08PM -0500, Eric W. Biederman wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
> 
> We currently have support for using a full stage 4 SHA-256
> implementation.

What is a "full stage 4 SHA-256 implementation"? I was assuming that you
referred to "Documentation/technical/hash-function-transition.txt", but
it does not mention stages either.

> However, we'd like to support interoperability with
> SHA-1 repositories as well.  The transition plan anticipates a
> compatibility hash algorithm configuration option that we can use to
> implement support for this.  Let's add an element to the repository
> structure that indicates the compatibility hash algorithm so we can use
> it when we need to consider interoperability between algorithms.
> 
> Add a helper function repo_set_compat_hash_algo that takes a
> compatibility hash algorithm and sets "repo->compat_hash_algo".  If
> GIT_HASH_UNKNOWN is passed as the compatibility hash algorithm
> "repo->compat_hash_algo" is set to NULL.
> 
> For now, the code results in "repo->compat_hash_algo" always being set
> to NULL, but that will change once a configuration option is added.
> 
> Inspired-by: brian m. carlson <sandals@crustytoothpaste.net>
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
> ---
>  repository.c | 8 ++++++++
>  repository.h | 4 ++++
>  setup.c      | 3 +++
>  3 files changed, 15 insertions(+)
> 
> diff --git a/repository.c b/repository.c
> index a7679ceeaa45..80252b79e93e 100644
> --- a/repository.c
> +++ b/repository.c
> @@ -104,6 +104,13 @@ void repo_set_hash_algo(struct repository *repo, int hash_algo)
>  	repo->hash_algo = &hash_algos[hash_algo];
>  }
>  
> +void repo_set_compat_hash_algo(struct repository *repo, int algo)
> +{
> +	if (hash_algo_by_ptr(repo->hash_algo) == algo)
> +		BUG("hash_algo and compat_hash_algo match");
> +	repo->compat_hash_algo = algo ? &hash_algos[algo] : NULL;
> +}
> +
>  /*
>   * Attempt to resolve and set the provided 'gitdir' for repository 'repo'.
>   * Return 0 upon success and a non-zero value upon failure.
> @@ -184,6 +191,7 @@ int repo_init(struct repository *repo,
>  		goto error;
>  
>  	repo_set_hash_algo(repo, format.hash_algo);
> +	repo_set_compat_hash_algo(repo, GIT_HASH_UNKNOWN);
>  	repo->repository_format_worktree_config = format.worktree_config;
>  
>  	/* take ownership of format.partial_clone */
> diff --git a/repository.h b/repository.h
> index 5f18486f6465..bf3fc601cc53 100644
> --- a/repository.h
> +++ b/repository.h
> @@ -160,6 +160,9 @@ struct repository {
>  	/* Repository's current hash algorithm, as serialized on disk. */
>  	const struct git_hash_algo *hash_algo;
>  
> +	/* Repository's compatibility hash algorithm. */
> +	const struct git_hash_algo *compat_hash_algo;
> +
>  	/* A unique-id for tracing purposes. */
>  	int trace2_repo_id;
>  
> @@ -199,6 +202,7 @@ void repo_set_gitdir(struct repository *repo, const char *root,
>  		     const struct set_gitdir_args *extra_args);
>  void repo_set_worktree(struct repository *repo, const char *path);
>  void repo_set_hash_algo(struct repository *repo, int algo);
> +void repo_set_compat_hash_algo(struct repository *repo, int compat_algo);
>  void initialize_the_repository(void);
>  RESULT_MUST_BE_USED
>  int repo_init(struct repository *r, const char *gitdir, const char *worktree);
> diff --git a/setup.c b/setup.c
> index 18927a847b86..aa8bf5da5226 100644
> --- a/setup.c
> +++ b/setup.c
> @@ -1564,6 +1564,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
>  		}
>  		if (startup_info->have_repository) {
>  			repo_set_hash_algo(the_repository, repo_fmt.hash_algo);
> +			repo_set_compat_hash_algo(the_repository,
> +						  GIT_HASH_UNKNOWN);
>  			the_repository->repository_format_worktree_config =
>  				repo_fmt.worktree_config;
>  			/* take ownership of repo_fmt.partial_clone */
> @@ -1657,6 +1659,7 @@ void check_repository_format(struct repository_format *fmt)
>  	check_repository_format_gently(get_git_dir(), fmt, NULL);
>  	startup_info->have_repository = 1;
>  	repo_set_hash_algo(the_repository, fmt->hash_algo);
> +	repo_set_compat_hash_algo(the_repository, GIT_HASH_UNKNOWN);
>  	the_repository->repository_format_worktree_config =
>  		fmt->worktree_config;
>  	the_repository->repository_format_partial_clone =

There's also `init_db()`, where we call `repo_set_hash_algo()`. Would we
have to call `repo_set_compat_hash_algo()` there, too? There are some
other locations when handling remotes or clones, but I don't think those
are relevant right now.

Patrick

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  parent reply	other threads:[~2024-02-15 11:22 UTC|newest]

Thread overview: 104+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-27 19:49 [PATCH 00/30] Initial support for multiple hash functions Eric W. Biederman
2023-09-27 19:55 ` [PATCH 01/30] object-file-convert: Stubs for converting from one object format to another Eric W. Biederman
2023-09-27 20:42   ` Eric Sunshine
2023-10-02  1:22     ` Eric W. Biederman
2023-10-02  2:27       ` Eric Sunshine
2023-09-27 19:55 ` [PATCH 02/30] oid-array: Teach oid-array to handle multiple kinds of oids Eric W. Biederman
2023-09-27 23:20   ` Eric Sunshine
2023-09-27 19:55 ` [PATCH 03/30] object-names: Support input of oids in any supported hash Eric W. Biederman
2023-09-27 23:29   ` Eric Sunshine
2023-10-02  1:54     ` Eric W. Biederman
2023-09-27 19:55 ` [PATCH 04/30] repository: add a compatibility hash algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 05/30] loose: add a mapping between SHA-1 and SHA-256 for loose objects Eric W. Biederman
2023-09-28  7:14   ` Eric Sunshine
2023-10-02  2:11     ` Eric W. Biederman
2023-10-02  2:36       ` Eric Sunshine
2023-09-27 19:55 ` [PATCH 06/30] loose: Compatibilty short name support Eric W. Biederman
2023-09-27 19:55 ` [PATCH 07/30] object-file: Update the loose object map when writing loose objects Eric W. Biederman
2023-09-27 19:55 ` [PATCH 08/30] object-file: Add a compat_oid_in parameter to write_object_file_flags Eric W. Biederman
2023-09-27 19:55 ` [PATCH 09/30] commit: write commits for both hashes Eric W. Biederman
2023-09-27 19:55 ` [PATCH 10/30] commit: Convert mergetag before computing the signature of a commit Eric W. Biederman
2023-09-27 19:55 ` [PATCH 11/30] commit: Export add_header_signature to support handling signatures on tags Eric W. Biederman
2023-09-27 19:55 ` [PATCH 12/30] tag: sign both hashes Eric W. Biederman
2023-09-27 19:55 ` [PATCH 13/30] cache: add a function to read an OID of a specific algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 14/30] object: Factor out parse_mode out of fast-import and tree-walk into in object.h Eric W. Biederman
2023-09-27 19:55 ` [PATCH 15/30] object-file-convert: add a function to convert trees between algorithms Eric W. Biederman
2023-09-27 19:55 ` [PATCH 16/30] object-file-convert: convert tag objects when writing Eric W. Biederman
2023-09-27 19:55 ` [PATCH 17/30] object-file-convert: Don't leak when converting tag objects Eric W. Biederman
2023-09-27 19:55 ` [PATCH 18/30] object-file-convert: convert commit objects when writing Eric W. Biederman
2023-09-27 19:55 ` [PATCH 19/30] object-file-convert: Convert commits that embed signed tags Eric W. Biederman
2023-09-27 19:55 ` [PATCH 20/30] object-file: Update object_info_extended to reencode objects Eric W. Biederman
2023-09-27 19:55 ` [PATCH 21/30] repository: Implement extensions.compatObjectFormat Eric W. Biederman
2023-09-27 21:39   ` Junio C Hamano
2023-09-28 20:18     ` Junio C Hamano
2023-09-29  0:50       ` Eric Biederman
2023-09-29 16:59       ` Eric W. Biederman
2023-09-29 18:48         ` Junio C Hamano
2023-10-02  0:48           ` Eric W. Biederman
2023-10-02  1:31     ` Eric W. Biederman
2023-09-27 19:55 ` [PATCH 22/30] rev-parse: Add an --output-object-format parameter Eric W. Biederman
2023-09-27 19:55 ` [PATCH 23/30] builtin/cat-file: Let the oid determine the output algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 24/30] tree-walk: init_tree_desc take an oid to get the hash algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 25/30] object-file: Handle compat objects in check_object_signature Eric W. Biederman
2023-09-27 19:55 ` [PATCH 26/30] builtin/ls-tree: Let the oid determine the output algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 27/30] test-lib: Compute the compatibility hash so tests may use it Eric W. Biederman
2023-09-27 19:55 ` [PATCH 28/30] t1006: Rename sha1 to oid Eric W. Biederman
2023-09-27 19:55 ` [PATCH 29/30] t1006: Test oid compatibility with cat-file Eric W. Biederman
2023-09-27 19:55 ` [PATCH 30/30] t1016-compatObjectFormat: Add tests to verify the conversion between objects Eric W. Biederman
2023-09-27 21:31 ` [PATCH 00/30] Initial support for multiple hash functions Junio C Hamano
2023-10-02  2:39 ` [PATCH v2 00/30] initial " Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 01/30] object-file-convert: stubs for converting from one object format to another Eric W. Biederman
2024-02-08  8:23     ` Linus Arver
2024-02-15 11:21     ` Patrick Steinhardt
2023-10-02  2:40   ` [PATCH v2 02/30] oid-array: teach oid-array to handle multiple kinds of oids Eric W. Biederman
2024-02-13  8:16     ` Linus Arver
2024-02-15  6:22       ` Eric W. Biederman
2024-02-16  0:16         ` Linus Arver
2024-02-16  4:48           ` Eric W. Biederman
2024-02-17  1:59             ` Linus Arver
2024-02-13  8:31     ` Kristoffer Haugsbakk
2024-02-15  6:24       ` Eric W. Biederman
2024-02-15 11:21     ` Patrick Steinhardt
2023-10-02  2:40   ` [PATCH v2 03/30] object-names: support input of oids in any supported hash Eric W. Biederman
2024-02-13  9:33     ` Linus Arver
2024-02-15 11:21     ` Patrick Steinhardt
2023-10-02  2:40   ` [PATCH v2 04/30] repository: add a compatibility hash algorithm Eric W. Biederman
2024-02-13 10:02     ` Linus Arver
2024-02-15 11:22     ` Patrick Steinhardt [this message]
2023-10-02  2:40   ` [PATCH v2 05/30] loose: add a mapping between SHA-1 and SHA-256 for loose objects Eric W. Biederman
2024-02-14  7:20     ` Linus Arver
2024-02-15  5:33       ` Eric W. Biederman
2024-02-15 11:22     ` Patrick Steinhardt
2023-10-02  2:40   ` [PATCH v2 06/30] loose: compatibilty short name support Eric W. Biederman
2024-02-15 11:22     ` Patrick Steinhardt
2023-10-02  2:40   ` [PATCH v2 07/30] object-file: update the loose object map when writing loose objects Eric W. Biederman
2024-02-15 11:22     ` Patrick Steinhardt
2023-10-02  2:40   ` [PATCH v2 08/30] object-file: add a compat_oid_in parameter to write_object_file_flags Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 09/30] commit: write commits for both hashes Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 10/30] commit: convert mergetag before computing the signature of a commit Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 11/30] commit: export add_header_signature to support handling signatures on tags Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 12/30] tag: sign both hashes Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 13/30] cache: add a function to read an OID of a specific algorithm Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 14/30] object: factor out parse_mode out of fast-import and tree-walk into in object.h Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 15/30] object-file-convert: add a function to convert trees between algorithms Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 16/30] object-file-convert: convert tag objects when writing Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 17/30] object-file-convert: don't leak when converting tag objects Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 18/30] object-file-convert: convert commit objects when writing Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 19/30] object-file-convert: convert commits that embed signed tags Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 20/30] object-file: update object_info_extended to reencode objects Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 21/30] repository: implement extensions.compatObjectFormat Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 22/30] rev-parse: add an --output-object-format parameter Eric W. Biederman
2024-02-08 16:25     ` Jean-Noël Avila
2023-10-02  2:40   ` [PATCH v2 23/30] builtin/cat-file: let the oid determine the output algorithm Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 24/30] tree-walk: init_tree_desc take an oid to get the hash algorithm Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 25/30] object-file: handle compat objects in check_object_signature Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 26/30] builtin/ls-tree: let the oid determine the output algorithm Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 27/30] test-lib: compute the compatibility hash so tests may use it Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 28/30] t1006: rename sha1 to oid Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 29/30] t1006: test oid compatibility with cat-file Eric W. Biederman
2023-10-02  2:40   ` [PATCH v2 30/30] t1016-compatObjectFormat: add tests to verify the conversion between objects Eric W. Biederman
2024-02-07 22:18   ` [PATCH v2 00/30] initial support for multiple hash functions Junio C Hamano
2024-02-08  0:24     ` Linus Arver
2024-02-08  6:11       ` Patrick Steinhardt
2024-02-14  7:36       ` Linus Arver
2024-02-15 11:27   ` Patrick Steinhardt

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