storage: shallow storage (#180)

* storage: shallow storage

* changes

* changes

1 files changed, 51 insertions, 0 deletions

diff --git a/storage/filesystem/shallow.go b/storage/filesystem/shallow.go
new file mode 100644
index 0000000..ec8d20e
--- /dev/null
+++ b/storage/filesystem/shallow.go
@@ -0,0 +1,51 @@
+package filesystem
+
+import (
+	"bufio"
+	"fmt"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/storage/filesystem/internal/dotgit"
+)
+
+// ShallowStorage where the shallow commits are stored, an internal to
+// manipulate the shallow file
+type ShallowStorage struct {
+	dir *dotgit.DotGit
+}
+
+// SetShallow save the shallows in the shallow file in the .git folder as one
+// commit per line represented by 40-byte hexadecimal object terminated by a
+// newline.
+func (s *ShallowStorage) SetShallow(commits []plumbing.Hash) error {
+	f, err := s.dir.ShallowWriter()
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+	for _, h := range commits {
+		if _, err := fmt.Fprintf(f, "%s\n", h); err != err {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Shallow return the shallow commits reading from shallo file from .git
+func (s *ShallowStorage) Shallow() ([]plumbing.Hash, error) {
+	f, err := s.dir.Shallow()
+	if err != nil {
+		return nil, err
+	}
+
+	var hash []plumbing.Hash
+
+	scn := bufio.NewScanner(f)
+	for scn.Scan() {
+		hash = append(hash, plumbing.NewHash(scn.Text()))
+	}
+
+	return hash, scn.Err()
+}