init

internal/cas/store.go

@@ -0,0 +1,57 @@
+package cas
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+type Store struct{ dir string }
+
+func New(dir string) *Store { os.MkdirAll(dir, 0o755); return &Store{dir: dir} }
+
+func (s *Store) pathOf(hash string) string {
+	if len(hash) < 2 {
+		return filepath.Join(s.dir, hash)
+	}
+	return filepath.Join(s.dir, hash[:2], hash)
+}
+
+func (s *Store) Has(hash string) bool { _, err := os.Stat(s.pathOf(hash)); return err == nil }
+
+func (s *Store) PutStream(r io.Reader) (string, error) {
+	h := sha256.New()
+	tmp, err := os.CreateTemp(s.dir, "put-*.tmp")
+	if err != nil {
+		return "", err
+	}
+	defer os.Remove(tmp.Name())
+	mw := io.MultiWriter(h, tmp)
+	if _, err := io.Copy(mw, r); err != nil {
+		tmp.Close()
+		return "", err
+	}
+	tmp.Close()
+	sum := hex.EncodeToString(h.Sum(nil))
+	dst := s.pathOf(sum)
+	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
+		return "", err
+	}
+	if err := os.Rename(tmp.Name(), dst); err != nil {
+		return "", err
+	}
+	return sum, nil
+}
+
+func (s *Store) Get(hash string, w io.Writer) error {
+	f, err := os.Open(s.pathOf(hash))
+	if err != nil {
+		return errors.New("not found")
+	}
+	defer f.Close()
+	_, err = io.Copy(w, f)
+	return err
+}