run-command: refactor subprocess env preparation

submodule.c has functionality that prepares the environment for running
a subprocess in a new repo. The lazy-fetching code (used in partial
clones) will need this in a subsequent commit, so move it to a more
central location.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: jonathantanmy

run-command.c

@@ -1892,3 +1892,15 @@ int run_auto_maintenance(int quiet)
 
 	return run_command(&maint);
 }
+
+void prepare_other_repo_env(struct strvec *env_array, const char *new_git_dir)
+{
+	const char * const *var;
+
+	for (var = local_repo_env; *var; var++) {
+		if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
+		    strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
+			strvec_push(env_array, *var);
+	}
+	strvec_pushf(env_array, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
+}

run-command.h

@@ -483,4 +483,14 @@ int run_processes_parallel_tr2(int n, get_next_task_fn, start_failure_fn,
 			       task_finished_fn, void *pp_cb,
 			       const char *tr2_category, const char *tr2_label);
 
+/**
+ * Convenience function which prepares env_array for a command to be run in a
+ * new repo. This adds all GIT_* environment variables to env_array with the
+ * exception of GIT_CONFIG_PARAMETERS and GIT_CONFIG_COUNT (which cause the
+ * corresponding environment variables to be unset in the subprocess) and adds
+ * an environment variable pointing to new_git_dir. See local_repo_env in
+ * cache.h for more information.
+ */
+void prepare_other_repo_env(struct strvec *env_array, const char *new_git_dir);
+
 #endif

submodule.c

@@ -484,28 +484,14 @@ static void print_submodule_diff_summary(struct repository *r, struct rev_info *
 	strbuf_release(&sb);
 }
 
-static void prepare_submodule_repo_env_no_git_dir(struct strvec *out)
-{
-	const char * const *var;
-
-	for (var = local_repo_env; *var; var++) {
-		if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
-		    strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
-			strvec_push(out, *var);
-	}
-}
-
 void prepare_submodule_repo_env(struct strvec *out)
 {
-	prepare_submodule_repo_env_no_git_dir(out);
-	strvec_pushf(out, "%s=%s", GIT_DIR_ENVIRONMENT,
-		     DEFAULT_GIT_DIR_ENVIRONMENT);
+	prepare_other_repo_env(out, DEFAULT_GIT_DIR_ENVIRONMENT);
 }
 
 static void prepare_submodule_repo_env_in_gitdir(struct strvec *out)
 {
-	prepare_submodule_repo_env_no_git_dir(out);
-	strvec_pushf(out, "%s=.", GIT_DIR_ENVIRONMENT);
+	prepare_other_repo_env(out, ".");
 }
 
 /*