use quick_error::quick_error;use std::path::{Path, PathBuf}; quick_error! {    #[derive(Debug)]    pub enum Error {        FindHeadRef(err: git_ref::file::find::existing::Error) {            display("Could not find a valid HEAD reference")            from()            source(err)        }        MisplacedHead(name: crate::object::bstr::BString) {            display("Expected HEAD at '.git/HEAD', got '.git/{}'", name)        }        MissingObjectsDirectory(missing: PathBuf) {            display("Expected an objects directory at '{}'", missing.display())        }        MissingRefsDirectory(missing: PathBuf) {            display("Expected a refs directory at '{}'", missing.display())        }    }} /// Returns true if the given `git_dir` seems to be a bare repository.////// Please note that repositories without any file in their working tree will also appear bare.pub fn is_bare(git_dir: impl AsRef<Path>) -> bool {    !git_dir.as_ref().join("index").exists()} /// What constitutes a valid git repository, and what's yet to be implemented.////// * [x] a valid head/// * [ ] git common directory///   * [ ] respect GIT_COMMON_DIR/// * [x] an objects directory///   * [x] respect GIT_OBJECT_DIRECTORY/// * [x] a refs directorypub fn is_git(git_dir: impl AsRef<Path>) -> Result<crate::Kind, Error> {    let dot_git = git_dir.as_ref();     {        let refs = git_ref::file::Store::at(&dot_git, Default::default());        let head = refs.loose_find_existing("HEAD")?;        if head.name.as_bstr() != "HEAD" {            return Err(Error::MisplacedHead(head.name.into_inner()));        }    }     {        let objects_path = std::env::var("GIT_OBJECT_DIRECTORY")            .map(PathBuf::from)            .unwrap_or_else(|_| dot_git.join("objects"));        if !objects_path.is_dir() {            return Err(Error::MissingObjectsDirectory(objects_path));        }    }    {        let refs_path = dot_git.join("refs");        if !refs_path.is_dir() {            return Err(Error::MissingRefsDirectory(refs_path));        }    }     Ok(if is_bare(git_dir) {        crate::Kind::Bare    } else {        crate::Kind::WorkingTree    })}