setup: split off $GIT_DIR-set case from setup_git_directory_gently

If $GIT_DIR is set, setup_git_directory_gently does not have
to do any repository discovery at all.  Split off a function
for the validation it still does do, in the hope that this will
make setup_git_directory_gently proper less daunting to read.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 37 insertions, 32 deletions

diff --git a/setup.c b/setup.c
index 2769160527..16bee6d485 100644
--- a/setup.c
+++ b/setup.c
@@ -313,6 +313,41 @@ const char *read_gitfile_gently(const char *path)
 	return path;
 }
 
+static const char *setup_explicit_git_dir(const char *gitdirenv,
+				const char *work_tree_env, int *nongit_ok)
+{
+	static char buffer[1024 + 1];
+	const char *retval;
+
+	if (PATH_MAX - 40 < strlen(gitdirenv))
+		die("'$%s' too big", GIT_DIR_ENVIRONMENT);
+	if (!is_git_directory(gitdirenv)) {
+		if (nongit_ok) {
+			*nongit_ok = 1;
+			return NULL;
+		}
+		die("Not a git repository: '%s'", gitdirenv);
+	}
+	if (!work_tree_env) {
+		retval = set_work_tree(gitdirenv);
+		/* config may override worktree */
+		if (check_repository_format_gently(nongit_ok))
+			return NULL;
+		return retval;
+	}
+	if (check_repository_format_gently(nongit_ok))
+		return NULL;
+	retval = get_relative_cwd(buffer, sizeof(buffer) - 1,
+			get_git_work_tree());
+	if (!retval || !*retval)
+		return NULL;
+	set_git_dir(make_absolute_path(gitdirenv));
+	if (chdir(work_tree_env) < 0)
+		die_errno ("Could not chdir to '%s'", work_tree_env);
+	strcat(buffer, "/");
+	return retval;
+}
+
 /*
  * We cannot decide in this function whether we are in the work tree or
  * not, since the config can only be read _after_ this function was called.
@@ -343,38 +378,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	 * validation.
 	 */
 	gitdirenv = getenv(GIT_DIR_ENVIRONMENT);
-	if (gitdirenv) {
-		if (PATH_MAX - 40 < strlen(gitdirenv))
-			die("'$%s' too big", GIT_DIR_ENVIRONMENT);
-		if (is_git_directory(gitdirenv)) {
-			static char buffer[1024 + 1];
-			const char *retval;
-
-			if (!work_tree_env) {
-				retval = set_work_tree(gitdirenv);
-				/* config may override worktree */
-				if (check_repository_format_gently(nongit_ok))
-					return NULL;
-				return retval;
-			}
-			if (check_repository_format_gently(nongit_ok))
-				return NULL;
-			retval = get_relative_cwd(buffer, sizeof(buffer) - 1,
-					get_git_work_tree());
-			if (!retval || !*retval)
-				return NULL;
-			set_git_dir(make_absolute_path(gitdirenv));
-			if (chdir(work_tree_env) < 0)
-				die_errno ("Could not chdir to '%s'", work_tree_env);
-			strcat(buffer, "/");
-			return retval;
-		}
-		if (nongit_ok) {
-			*nongit_ok = 1;
-			return NULL;
-		}
-		die("Not a git repository: '%s'", gitdirenv);
-	}
+	if (gitdirenv)
+		return setup_explicit_git_dir(gitdirenv, work_tree_env, nongit_ok);
 
 	if (!getcwd(cwd, sizeof(cwd)-1))
 		die_errno("Unable to read current working directory");