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From: Victoria Dye <vdye@github.com>
To: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Cc: me@ttaylorr.com, newren@gmail.com, gitster@pobox.com,
	Derrick Stolee <derrickstolee@github.com>
Subject: Re: [PATCH 2/3] replace-objects: create wrapper around setting
Date: Thu, 1 Jun 2023 09:35:40 -0700	[thread overview]
Message-ID: <49ea603b-ebbd-4a14-e0dd-07078e56de0a@github.com> (raw)
In-Reply-To: <5fc2f923d9e6aa13781d7d6567c9bd38a9dd1f0e.1685126618.git.gitgitgadget@gmail.com>

Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <derrickstolee@github.com>
> 
> The 'read_replace_objects' constant is initialized by git_default_config
> (if core.useReplaceRefs is disabled) and within setup_git_env (if
> GIT_NO_REPLACE_OBJECTS) is set. To ensure that this variable cannot be
> set accidentally in other places, wrap it in a replace_refs_enabled()
> method.
> 
> This allows us to remove the global from being recognized outside of
> replace-objects.c.
> 
> Further, a future change will help prevent the variable from being read
> before it is initialized. Centralizing its access is an important first
> step.
> 
> Signed-off-by: Derrick Stolee <derrickstolee@github.com>
> ---
>  commit-graph.c   |  4 +---
>  environment.c    |  1 -
>  log-tree.c       |  2 +-
>  replace-object.c |  7 +++++++
>  replace-object.h | 15 ++++++++++++++-
>  5 files changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/commit-graph.c b/commit-graph.c
> index 43558b4d9b0..95873317bf7 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -203,14 +203,12 @@ static struct commit_graph *alloc_commit_graph(void)
>  	return g;
>  }
>  
> -extern int read_replace_refs;
> -
>  static int commit_graph_compatible(struct repository *r)
>  {
>  	if (!r->gitdir)
>  		return 0;
>  
> -	if (read_replace_refs) {
> +	if (replace_refs_enabled(r)) {
>  		prepare_replace_object(r);
>  		if (hashmap_get_size(&r->objects->replace_map->map))
>  			return 0;

This and the other 'read_replace_refs' -> 'replace_refs_enabled()'
replacements all look good. Although we're not using the 'struct repository'
argument yet, I see that it'll be used in patch 3 - adding the (unused) arg
here helps avoid the extra churn there.

> diff --git a/replace-object.c b/replace-object.c
> index ceec81c940c..cf91c3ba456 100644
> --- a/replace-object.c
> +++ b/replace-object.c
> @@ -85,7 +85,14 @@ const struct object_id *do_lookup_replace_object(struct repository *r,
>  	die(_("replace depth too high for object %s"), oid_to_hex(oid));
>  }
>  
> +static int read_replace_refs = 1;
> +
>  void disable_replace_refs(void)
>  {
>  	read_replace_refs = 0;
>  }
> +
> +int replace_refs_enabled(struct repository *r)
> +{
> +	return read_replace_refs;
> +}
> diff --git a/replace-object.h b/replace-object.h
> index 7786d4152b0..b141075023e 100644
> --- a/replace-object.h
> +++ b/replace-object.h
> @@ -27,6 +27,19 @@ void prepare_replace_object(struct repository *r);
>  const struct object_id *do_lookup_replace_object(struct repository *r,
>  						 const struct object_id *oid);
>  
> +
> +/*
> + * Some commands disable replace-refs unconditionally, and otherwise each
> + * repository could alter the core.useReplaceRefs config value.
> + *
> + * Return 1 if and only if all of the following are true:
> + *
> + *  a. disable_replace_refs() has not been called.
> + *  b. GIT_NO_REPLACE_OBJECTS is unset or zero.
> + *  c. the given repository does not have core.useReplaceRefs=false.
> + */
> +int replace_refs_enabled(struct repository *r);

Since the purpose of this function is to access global state, would
'environment.[c|h]' be a more appropriate place for it (and
'disable_replace_refs()', for that matter)? There's also some precedent;
'set_shared_repository()' and 'get_shared_repository()' have a very similar
design to what you've added here.


  reply	other threads:[~2023-06-01 16:35 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-26 18:43 [PATCH 0/3] Create stronger guard rails on replace refs Derrick Stolee via GitGitGadget
2023-05-26 18:43 ` [PATCH 1/3] repository: create disable_replace_refs() Derrick Stolee via GitGitGadget
2023-05-31  4:41   ` Elijah Newren
2023-05-31 13:37     ` Derrick Stolee
2023-06-01 17:47       ` Jeff King
2023-06-03  0:28         ` Junio C Hamano
2023-06-04  6:32           ` Jeff King
2023-06-01  5:23   ` Junio C Hamano
2023-06-01 16:35   ` Victoria Dye
2023-05-26 18:43 ` [PATCH 2/3] replace-objects: create wrapper around setting Derrick Stolee via GitGitGadget
2023-06-01 16:35   ` Victoria Dye [this message]
2023-06-01 19:50     ` Derrick Stolee
2023-06-03  1:47       ` Elijah Newren
2023-06-05 15:44         ` Derrick Stolee
2023-05-26 18:43 ` [PATCH 3/3] repository: create read_replace_refs setting Derrick Stolee via GitGitGadget
2023-06-01 16:36   ` Victoria Dye
2023-06-01 19:52     ` Derrick Stolee
2023-05-31  5:11 ` [PATCH 0/3] Create stronger guard rails on replace refs Elijah Newren
2023-06-02 14:29 ` [PATCH v2 " Derrick Stolee via GitGitGadget
2023-06-02 14:29   ` [PATCH v2 1/3] repository: create disable_replace_refs() Derrick Stolee via GitGitGadget
2023-06-02 14:29   ` [PATCH v2 2/3] replace-objects: create wrapper around setting Derrick Stolee via GitGitGadget
2023-06-03  6:22     ` René Scharfe
2023-06-05 13:22       ` Derrick Stolee
2023-06-02 14:29   ` [PATCH v2 3/3] repository: create read_replace_refs setting Derrick Stolee via GitGitGadget
2023-06-05 19:32     ` Victoria Dye
2023-06-03  1:52   ` [PATCH v2 0/3] Create stronger guard rails on replace refs Elijah Newren
2023-06-06 13:24   ` [PATCH v3 " Derrick Stolee via GitGitGadget
2023-06-06 13:24     ` [PATCH v3 1/3] repository: create disable_replace_refs() Derrick Stolee via GitGitGadget
2023-06-06 13:24     ` [PATCH v3 2/3] replace-objects: create wrapper around setting Derrick Stolee via GitGitGadget
2023-06-06 13:24     ` [PATCH v3 3/3] repository: create read_replace_refs setting Derrick Stolee via GitGitGadget
2023-06-06 16:15     ` [PATCH v3 0/3] Create stronger guard rails on replace refs Victoria Dye
2023-06-12 20:45     ` Junio C Hamano

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