+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;
+}
+