[v2,2/3] replace-objects: create wrapper around setting

Commit Message

Derrick Stolee June 2, 2023, 2:29 p.m. UTC

From: Derrick Stolee <[e-mail]>

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 <[e-mail]>
---
 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(-)

Comments

René Scharfe June 3, 2023, 6:22 a.m. UTC | #1

Am 02.06.23 um 16:29 schrieb Derrick Stolee via GitGitGadget:
> 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;
> +

This breaks compilation:

   replace-object.c:88:12: error: static declaration of 'read_replace_refs' follows non-static declaration
   static int read_replace_refs = 1;
              ^
   ./replace-object.h:14:12: note: previous declaration is here
   extern int read_replace_refs;
              ^

And this variable is still referenced in two more places outside this
file, which won't work now that it has become static (file-scoped):

   $ git grep read_replace_refs
   builtin/commit-graph.c:extern int read_replace_refs;
   config.c:               read_replace_refs = git_config_bool(var, value);
   replace-object.c: * references, regardless of the value of read_replace_refs.
   replace-object.c:static int read_replace_refs = 1;
   replace-object.c:       read_replace_refs = 0;
   replace-object.c:       return read_replace_refs;
   replace-object.h:extern int read_replace_refs;

Perhaps postpone adding "static" to patch 3?

>  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);
> +
>  /*
>   * If object sha1 should be replaced, return the replacement object's
>   * name (replaced recursively, if necessary).  The return value is
> @@ -41,7 +54,7 @@ const struct object_id *do_lookup_replace_object(struct repository *r,
>  static inline const struct object_id *lookup_replace_object(struct repository *r,
>  							    const struct object_id *oid)
>  {
> -	if (!read_replace_refs ||
> +	if (!replace_refs_enabled(r) ||
>  	    (r->objects->replace_map_initialized &&
>  	     r->objects->replace_map->map.tablesize == 0))
>  		return oid;

Derrick Stolee June 5, 2023, 1:22 p.m. UTC | #2

On 6/3/2023 2:22 AM, René Scharfe wrote:
> Am 02.06.23 um 16:29 schrieb Derrick Stolee via GitGitGadget:
>> 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;
>> +
> 
> This breaks compilation:
> 
>    replace-object.c:88:12: error: static declaration of 'read_replace_refs' follows non-static declaration
>    static int read_replace_refs = 1;
>               ^
>    ./replace-object.h:14:12: note: previous declaration is here
>    extern int read_replace_refs;
>               ^

Thanks for finding this issue within the patch. The removal of the global
should have happened in this patch, but I missed it when adjusting things
for this version.

> And this variable is still referenced in two more places outside this
> file, which won't work now that it has become static (file-scoped):
> 
>    $ git grep read_replace_refs
>    builtin/commit-graph.c:extern int read_replace_refs;
>    config.c:               read_replace_refs = git_config_bool(var, value);
>    replace-object.c: * references, regardless of the value of read_replace_refs.
>    replace-object.c:static int read_replace_refs = 1;
>    replace-object.c:       read_replace_refs = 0;
>    replace-object.c:       return read_replace_refs;
>    replace-object.h:extern int read_replace_refs;
> 
> Perhaps postpone adding "static" to patch 3?

You're right that this won't work unless we fix the config-parsing code
already here, so I should move the introduction of the static global until
patch 3, as you suggest.

Thanks,
-Stolee

Patch

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;
diff --git a/environment.c b/environment.c
index 3b4d87c322f..e198b48081a 100644
--- a/environment.c
+++ b/environment.c
@@ -63,7 +63,6 @@  const char *editor_program;
 const char *askpass_program;
 const char *excludes_file;
 enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
-int read_replace_refs = 1;
 enum eol core_eol = EOL_UNSET;
 int global_conv_flags_eol = CONV_EOL_RNDTRP_WARN;
 char *check_roundtrip_encoding = "SHIFT-JIS";
diff --git a/log-tree.c b/log-tree.c
index 143b86fecf9..86212af3626 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -155,7 +155,7 @@  static int add_ref_decoration(const char *refname, const struct object_id *oid,
 
 	if (starts_with(refname, git_replace_ref_base)) {
 		struct object_id original_oid;
-		if (!read_replace_refs)
+		if (!replace_refs_enabled(the_repository))
 			return 0;
 		if (get_oid_hex(refname + strlen(git_replace_ref_base),
 				&original_oid)) {
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);
+
 /*
  * If object sha1 should be replaced, return the replacement object's
  * name (replaced recursively, if necessary).  The return value is
@@ -41,7 +54,7 @@  const struct object_id *do_lookup_replace_object(struct repository *r,
 static inline const struct object_id *lookup_replace_object(struct repository *r,
 							    const struct object_id *oid)
 {
-	if (!read_replace_refs ||
+	if (!replace_refs_enabled(r) ||
 	    (r->objects->replace_map_initialized &&
 	     r->objects->replace_map->map.tablesize == 0))
 		return oid;