1 files changed, 145 insertions, 0 deletions
diff --git a/storage/filesystem/internal/gitdir/gitdir.go b/storage/filesystem/internal/gitdir/gitdir.go
new file mode 100644
index 0000000..b5497b8
--- /dev/null
+++ b/storage/filesystem/internal/gitdir/gitdir.go
@@ -0,0 +1,145 @@
+package gitdir
+
+import (
+	"errors"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"gopkg.in/src-d/go-git.v4/clients/common"
+	"gopkg.in/src-d/go-git.v4/core"
+	"gopkg.in/src-d/go-git.v4/utils/fs"
+)
+
+const (
+	suffix         = ".git"
+	packedRefsPath = "packed-refs"
+)
+
+var (
+	// ErrNotFound is returned by New when the path is not found.
+	ErrNotFound = errors.New("path not found")
+	// ErrIdxNotFound is returned by Idxfile when the idx file is not found on the
+	// repository.
+	ErrIdxNotFound = errors.New("idx file not found")
+	// ErrPackfileNotFound is returned by Packfile when the packfile is not found
+	// on the repository.
+	ErrPackfileNotFound = errors.New("packfile not found")
+)
+
+// The GitDir type represents a local git repository on disk. This
+// type is not zero-value-safe, use the New function to initialize it.
+type GitDir struct {
+	fs      fs.FS
+	path    string
+	refs    map[string]core.Hash
+	packDir string
+}
+
+// New returns a GitDir value ready to be used. The path argument must
+// be the absolute path of a git repository directory (e.g.
+// "/foo/bar/.git").
+func New(fs fs.FS, path string) (*GitDir, error) {
+	d := &GitDir{}
+	d.fs = fs
+	d.path = path
+	d.packDir = d.fs.Join(d.path, "objects", "pack")
+
+	if _, err := fs.Stat(path); err != nil {
+		if os.IsNotExist(err) {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+
+	return d, nil
+}
+
+// Refs scans the git directory collecting references, which it returns.
+// Symbolic references are resolved and included in the output.
+func (d *GitDir) Refs() (map[string]core.Hash, error) {
+	var err error
+
+	d.refs = make(map[string]core.Hash)
+
+	if err = d.addRefsFromPackedRefs(); err != nil {
+		return nil, err
+	}
+
+	if err = d.addRefsFromRefDir(); err != nil {
+		return nil, err
+	}
+
+	return d.refs, err
+}
+
+// Capabilities scans the git directory collection capabilities, which it returns.
+func (d *GitDir) Capabilities() (*common.Capabilities, error) {
+	c := common.NewCapabilities()
+
+	err := d.addSymRefCapability(c)
+
+	return c, err
+}
+
+func (d *GitDir) addSymRefCapability(cap *common.Capabilities) (err error) {
+	f, err := d.fs.Open(d.fs.Join(d.path, "HEAD"))
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		errClose := f.Close()
+		if err == nil {
+			err = errClose
+		}
+	}()
+
+	b, err := ioutil.ReadAll(f)
+	if err != nil {
+		return err
+	}
+	data := strings.TrimSpace(string(b))
+
+	c := "symref"
+	ref := strings.TrimPrefix(data, symRefPrefix)
+	cap.Set(c, "HEAD:"+ref)
+
+	return nil
+}
+
+// Packfile returns the path of the packfile (really, it returns the
+// path of the first file in the "objects/pack/" directory with a
+// ".pack" extension.
+func (d *GitDir) Packfile() (fs.FS, string, error) {
+	files, err := d.fs.ReadDir(d.packDir)
+	if err != nil {
+		return nil, "", err
+	}
+
+	for _, f := range files {
+		if strings.HasSuffix(f.Name(), ".pack") {
+			return d.fs, d.fs.Join(d.packDir, f.Name()), nil
+		}
+	}
+
+	return nil, "", ErrPackfileNotFound
+}
+
+// Idxfile returns the path of the idx file (really, it returns the
+// path of the first file in the "objects/pack/" directory with an
+// ".idx" extension.
+func (d *GitDir) Idxfile() (fs.FS, string, error) {
+	files, err := d.fs.ReadDir(d.packDir)
+	if err != nil {
+		return nil, "", err
+	}
+
+	for _, f := range files {
+		if strings.HasSuffix(f.Name(), ".idx") {
+			return d.fs, d.fs.Join(d.packDir, f.Name()), nil
+		}
+	}
+
+	return nil, "", ErrIdxNotFound
+}