environment: consolidate config values

The config values parsed in `git_default_config()` such as
`core.attributesFile` are loaded eagerly and stored in global variables.
Storing these values in global variables can lead to unexpected
behaviours when more than one Git repository run in the same Git process.

Move these values into a `struct config_values` which can be accessed per
repository. This centralization will be important in moving other
variables and this will prevent us from moving any code from
`git_default_config()`, ensuring the current behaviour remains the same
while also enabling the libification of Git.

Suggested-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Olamide Caleb Bello <belkid98@gmail.com>

Author: cloobTech

attr.c

@@ -881,10 +881,12 @@ 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 config_values *cfg = the_repository->cfg_values;
 
-	return git_attributes_file;
+	if (!cfg->attributes_file_path)
+		cfg->attributes_file_path = xdg_config_home("attributes");
+
+	return cfg->attributes_file_path;
 }
 
 int git_attr_system_is_enabled(void)

config.c

@@ -1761,6 +1761,11 @@ static int config_set_element_cmp(const void *cmp_data UNUSED,
 	return strcmp(e1->key, e2->key);
 }
 
+void config_values_clear(struct config_values *cfg)
+{
+	free(cfg->attributes_file_path);
+}
+
 void git_configset_init(struct config_set *set)
 {
 	hashmap_init(&set->config_hash, config_set_element_cmp, NULL, 0);

config.h

@@ -135,6 +135,12 @@ struct config_context {
 	/* Config source metadata for key and value. */
 	const struct key_value_info *kvi;
 };
+
+/* Holds default config values */
+struct config_values {
+	/* core config values */
+	char *attributes_file_path;
+};
 #define CONFIG_CONTEXT_INIT { 0 }
 
 /**
@@ -187,6 +193,7 @@ int git_config_from_blob_oid(config_fn_t fn, const char *name,
 void git_config_push_parameter(const char *text);
 void git_config_push_env(const char *spec);
 int git_config_from_parameters(config_fn_t fn, void *data);
+void config_values_clear(struct config_values *cfg);
 
 /*
  * Read config when the Git directory has not yet been set up. In case

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 config_values *cfg = the_repository->cfg_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_path);
+		return git_config_pathname(&cfg->attributes_file_path, var, value);
 	}
 
 	if (!strcmp(var, "core.bare")) {

environment.h

@@ -152,7 +152,6 @@ 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;

repository.c

@@ -55,6 +55,7 @@ void initialize_repository(struct repository *repo)
 	repo->remote_state = remote_state_new();
 	repo->parsed_objects = parsed_object_pool_new(repo);
 	ALLOC_ARRAY(repo->index, 1);
+	CALLOC_ARRAY(repo->cfg_values, 1);
 	index_state_init(repo->index, repo);
 	repo->check_deprecated_config = true;
 
@@ -403,6 +404,11 @@ void repo_clear(struct repository *repo)
 		FREE_AND_NULL(repo->remote_state);
 	}
 
+	if (repo->cfg_values) {
+		config_values_clear(repo->cfg_values);
+		FREE_AND_NULL(repo->cfg_values);
+	}
+
 	strmap_for_each_entry(&repo->submodule_ref_stores, &iter, e)
 		ref_store_release(e->value);
 	strmap_clear(&repo->submodule_ref_stores, 1);

repository.h

@@ -13,6 +13,7 @@ struct object_database;
 struct submodule_cache;
 struct promisor_remote_config;
 struct remote_state;
+struct config_values;
 
 enum ref_storage_format {
 	REF_STORAGE_FORMAT_UNKNOWN,
@@ -171,6 +172,9 @@ struct repository {
 
 	/* Should repo_config() check for deprecated settings */
 	bool check_deprecated_config;
+
+	/* Repository's default configuration values */
+	struct config_values *cfg_values;
 };
 
 #ifdef USE_THE_REPOSITORY_VARIABLE