storage: Storage entity support, and DotGit support for References

1 files changed, 144 insertions, 0 deletions

diff --git a/storage/filesystem/internal/dotgit/refs.go b/storage/filesystem/internal/dotgit/refs.go
new file mode 100644
index 0000000..894732f
--- /dev/null
+++ b/storage/filesystem/internal/dotgit/refs.go
@@ -0,0 +1,144 @@
+package dotgit
+
+import (
+	"bufio"
+	"errors"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"gopkg.in/src-d/go-git.v4/core"
+)
+
+var (
+	// ErrPackedRefsDuplicatedRef is returned when a duplicated
+	// reference is found in the packed-ref file. This is usually the
+	// case for corrupted git repositories.
+	ErrPackedRefsDuplicatedRef = errors.New("duplicated ref found in packed-ref file")
+	// ErrPackedRefsBadFormat is returned when the packed-ref file
+	// corrupt.
+	ErrPackedRefsBadFormat = errors.New("malformed packed-ref")
+	// ErrSymRefTargetNotFound is returned when a symbolic reference is
+	// targeting a non-existing object. This usually means the
+	// repository is corrupt.
+	ErrSymRefTargetNotFound = errors.New("symbolic reference target not found")
+)
+
+const (
+	refsPath = "refs"
+)
+
+func (d *DotGit) addRefsFromPackedRefs(refs *[]*core.Reference) (err error) {
+	path := d.fs.Join(d.path, packedRefsPath)
+	f, err := d.fs.Open(path)
+	if err != nil {
+		if err == os.ErrNotExist {
+			return nil
+		}
+
+		return err
+	}
+
+	defer func() {
+		if errClose := f.Close(); err == nil {
+			err = errClose
+		}
+	}()
+
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		ref, err := d.processLine(s.Text())
+		if err != nil {
+			return err
+		}
+
+		if ref != nil {
+			*refs = append(*refs, ref)
+		}
+	}
+
+	return s.Err()
+}
+
+// process lines from a packed-refs file
+func (d *DotGit) processLine(line string) (*core.Reference, error) {
+	switch line[0] {
+	case '#': // comment - ignore
+		return nil, nil
+	case '^': // annotated tag commit of the previous line - ignore
+		return nil, nil
+	default:
+		ws := strings.Split(line, " ") // hash then ref
+		if len(ws) != 2 {
+			return nil, ErrPackedRefsBadFormat
+		}
+
+		return core.NewReferenceFromStrings(ws[1], ws[0]), nil
+	}
+}
+
+func (d *DotGit) addRefsFromRefDir(refs *[]*core.Reference) error {
+	return d.walkReferencesTree(refs, refsPath)
+}
+
+func (d *DotGit) walkReferencesTree(refs *[]*core.Reference, relPath string) error {
+	files, err := d.fs.ReadDir(d.fs.Join(d.path, relPath))
+	if err != nil {
+		return err
+	}
+
+	for _, f := range files {
+		newRelPath := d.fs.Join(relPath, f.Name())
+		if f.IsDir() {
+			if err = d.walkReferencesTree(refs, newRelPath); err != nil {
+				return err
+			}
+
+			continue
+		}
+
+		ref, err := d.readReferenceFile(d.path, newRelPath)
+		if err != nil {
+			return err
+		}
+
+		if ref != nil {
+			*refs = append(*refs, ref)
+		}
+	}
+
+	return nil
+}
+
+func (d *DotGit) addRefFromHEAD(refs *[]*core.Reference) error {
+	ref, err := d.readReferenceFile(d.path, "HEAD")
+	if err != nil {
+		return err
+	}
+
+	*refs = append(*refs, ref)
+	return nil
+}
+
+func (d *DotGit) readReferenceFile(refsPath, refFile string) (ref *core.Reference, err error) {
+	path := d.fs.Join(refsPath, refFile)
+
+	f, err := d.fs.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		if errClose := f.Close(); err == nil {
+			err = errClose
+		}
+	}()
+
+	b, err := ioutil.ReadAll(f)
+	if err != nil {
+		return nil, err
+	}
+
+	line := strings.TrimSpace(string(b))
+	return core.NewReferenceFromStrings(refFile, line), nil
+}