storage: Storage entity support, and DotGit support for References

1 files changed, 105 insertions, 0 deletions

diff --git a/storage/filesystem/internal/dotgit/dotgit.go b/storage/filesystem/internal/dotgit/dotgit.go
new file mode 100644
index 0000000..f365f13
--- /dev/null
+++ b/storage/filesystem/internal/dotgit/dotgit.go
@@ -0,0 +1,105 @@
+package dotgit
+
+import (
+	"errors"
+	"os"
+	"strings"
+
+	"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 DotGit type represents a local git repository on disk. This
+// type is not zero-value-safe, use the New function to initialize it.
+type DotGit struct {
+	fs   fs.FS
+	path string
+}
+
+// New returns a DotGit 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) (*DotGit, error) {
+	d := &DotGit{fs: fs, path: path}
+	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 *DotGit) Refs() ([]*core.Reference, error) {
+	var refs []*core.Reference
+	if err := d.addRefsFromPackedRefs(&refs); err != nil {
+		return nil, err
+	}
+
+	if err := d.addRefsFromRefDir(&refs); err != nil {
+		return nil, err
+	}
+
+	if err := d.addRefFromHEAD(&refs); err != nil {
+		return nil, err
+	}
+
+	return refs, 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 *DotGit) Packfile() (fs.FS, string, error) {
+	packDir := d.fs.Join(d.path, "objects", "pack")
+	files, err := d.fs.ReadDir(packDir)
+	if err != nil {
+		return nil, "", err
+	}
+
+	for _, f := range files {
+		if strings.HasSuffix(f.Name(), ".pack") {
+			return d.fs, d.fs.Join(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 *DotGit) Idxfile() (fs.FS, string, error) {
+	packDir := d.fs.Join(d.path, "objects", "pack")
+	files, err := d.fs.ReadDir(packDir)
+	if err != nil {
+		return nil, "", err
+	}
+
+	for _, f := range files {
+		if strings.HasSuffix(f.Name(), ".idx") {
+			return d.fs, d.fs.Join(packDir, f.Name()), nil
+		}
+	}
+
+	return nil, "", ErrIdxNotFound
+}