Subject: [Outreachy PATCH v5 1/3] environment: stop storing `core.attributesFile` globally

From: Olamide Caleb Bello <[email-masked]>
Date: Sat, 24 Jan 2026 13:21:11 +0100

The `core.attributeFile` config value is parsed in
git_default_core_config(), loaded eagerly and stored in the global
variable `git_attributes_file`. Storing this value in a global variable
can lead to it being overwritten by another repository when more than one
Git repository run in the same Git process.

Create a new struct `repo_config_values` to hold this value and
other repository dependent values parsed by `git_default_config()`.
For now the value can be accessed via the_repository in
`git_default_config()`.
This will ensure the current behaviour remains the same while also
enabling the libification of Git.

It is important to note that `git_default_config()` is a wrapper to other
`git_default_*_config()` functions such as `git_default_core_config()`.
Therefore to access and modify this global variable,
the change has to be made `git_default_core_config()`.

Suggested-by: Phillip Wood <[email-masked]>
Mentored-by: Christian Couder <[email-masked]>
Mentored-by: Usman Akinyemi <[email-masked]>
Signed-off-by: Olamide Caleb Bello <[email-masked]>
---
 attr.c        |  7 ++++---
 environment.c | 12 +++++++++---
 environment.h |  8 +++++++-
 repository.c  |  1 +
 repository.h  |  4 ++++
 5 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/attr.c b/attr.c
index 4999b7e09d..b8b70e6dce 100644
--- a/attr.c
+++ b/attr.c
@@ -881,10 +881,11 @@ const char *git_attr_system_file(void)
 
 const char *git_attr_global_file(void)
 {
-	if (!git_attributes_file)
-		git_attributes_file = xdg_config_home("attributes");
+	struct repo_config_values *cfg = &the_repository->config_values;
+	if (!cfg->attributes_file)
+		cfg->attributes_file = xdg_config_home("attributes");
 
-	return git_attributes_file;
+	return cfg->attributes_file;
 }
 
 int git_attr_system_is_enabled(void)
diff --git a/environment.c b/environment.c
index a770b5921d..72735d9e4b 100644
--- a/environment.c
+++ b/environment.c
@@ -53,7 +53,6 @@ char *git_commit_encoding;
 char *git_log_output_encoding;
 char *apply_default_whitespace;
 char *apply_default_ignorewhitespace;
-char *git_attributes_file;
 int zlib_compression_level = Z_BEST_SPEED;
 int pack_compression_level = Z_DEFAULT_COMPRESSION;
 int fsync_object_files = -1;
@@ -327,6 +326,8 @@ static enum fsync_component parse_fsync_components(const char *var, const char *
 static int git_default_core_config(const char *var, const char *value,
 				   const struct config_context *ctx, void *cb)
 {
+	struct repo_config_values *cfg = &the_repository->config_values;
+
 	/* This needs a better name */
 	if (!strcmp(var, "core.filemode")) {
 		trust_executable_bit = git_config_bool(var, value);
@@ -364,8 +365,8 @@ static int git_default_core_config(const char *var, const char *value,
 	}
 
 	if (!strcmp(var, "core.attributesfile")) {
-		FREE_AND_NULL(git_attributes_file);
-		return git_config_pathname(&git_attributes_file, var, value);
+		FREE_AND_NULL(cfg->attributes_file);
+		return git_config_pathname(&cfg->attributes_file, var, value);
 	}
 
 	if (!strcmp(var, "core.bare")) {
@@ -756,3 +757,8 @@ int git_default_config(const char *var, const char *value,
 	/* Add other config variables here and to Documentation/config.adoc. */
 	return 0;
 }
+
+void repo_config_values_init(struct repo_config_values *cfg)
+{
+	cfg->attributes_file = NULL;
+}
diff --git a/environment.h b/environment.h
index 51898c99cd..0c0dcc6847 100644
--- a/environment.h
+++ b/environment.h
@@ -84,6 +84,11 @@ extern const char * const local_repo_env[];
 
 struct strvec;
 
+struct repo_config_values {
+	/* section "core" config values */
+	char *attributes_file;
+};
+
 /*
  * Wrapper of getenv() that returns a strdup value. This value is kept
  * in argv to be freed later.
@@ -107,6 +112,8 @@ const char *strip_namespace(const char *namespaced_ref);
 int git_default_config(const char *, const char *,
 		       const struct config_context *, void *);
 
+void repo_config_values_init(struct repo_config_values *cfg);
+
 /*
  * TODO: All the below state either explicitly or implicitly relies on
  * `the_repository`. We should eventually get rid of these and make the
@@ -152,7 +159,6 @@ extern int assume_unchanged;
 extern int warn_on_object_refname_ambiguity;
 extern char *apply_default_whitespace;
 extern char *apply_default_ignorewhitespace;
-extern char *git_attributes_file;
 extern int zlib_compression_level;
 extern int pack_compression_level;
 extern unsigned long pack_size_limit_cfg;
diff --git a/repository.c b/repository.c
index c7e75215ac..d308cd78bf 100644
--- a/repository.c
+++ b/repository.c
@@ -57,6 +57,7 @@ void initialize_repository(struct repository *repo)
 	ALLOC_ARRAY(repo->index, 1);
 	index_state_init(repo->index, repo);
 	repo->check_deprecated_config = true;
+	repo_config_values_init(&repo->config_values);
 
 	/*
 	 * When a command runs inside a repository, it learns what
diff --git a/repository.h b/repository.h
index 6063c4b846..638a142577 100644
--- a/repository.h
+++ b/repository.h
@@ -3,6 +3,7 @@
 
 #include "strmap.h"
 #include "repo-settings.h"
+#include "environment.h"
 
 struct config_set;
 struct git_hash_algo;
@@ -148,6 +149,9 @@ struct repository {
 	/* Repository's compatibility hash algorithm. */
 	const struct git_hash_algo *compat_hash_algo;
 
+	/* Repository's config values parsed by git_default_config() */
+	struct repo_config_values config_values;
+
 	/* Repository's reference storage format, as serialized on disk. */
 	enum ref_storage_format ref_storage_format;
 
-- 
2.34.1