local: add Metadata support #111

backend/local/xattr.go

@@ -0,0 +1,87 @@
+//go:build !openbsd && !plan9
+// +build !openbsd,!plan9
+
+package local
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/pkg/xattr"
+	"github.com/rclone/rclone/fs"
+)
+
+const (
+	xattrPrefix    = "user." // FIXME is this correct for all unixes?
+	xattrSupported = xattr.XATTR_SUPPORTED
+)
+
+// getXattr returns the extended attributes for an object
+//
+// It doesn't return any attributes owned by this backend in
+// metadataKeys
+func (o *Object) getXattr() (metadata fs.Metadata, err error) {
+	if !xattrSupported {
+		return nil, nil
+	}
+	var list []string
+	if o.fs.opt.FollowSymlinks {
+		list, err = xattr.List(o.path)
+	} else {
+		list, err = xattr.LList(o.path)
+	}
+	if err != nil {
+		return nil, fmt.Errorf("failed to read xattr: %w", err)
+	}
+	if len(list) == 0 {
+		return nil, nil
+	}
+	metadata = make(fs.Metadata, len(list))
+	for _, k := range list {
+		var v []byte
+		if o.fs.opt.FollowSymlinks {
+			v, err = xattr.Get(o.path, k)
+		} else {
+			v, err = xattr.LGet(o.path, k)
+		}
+		if err != nil {
+			return nil, fmt.Errorf("failed to read xattr key %q: %w", k, err)
+		}
+		k = strings.ToLower(k)
+		if !strings.HasPrefix(k, xattrPrefix) {
+			continue
+		}
+		k = k[len(xattrPrefix):]
+		if _, found := systemMetadataInfo[k]; found {
+			continue
+		}
+		metadata[k] = string(v)
+	}
+	return metadata, nil
+}
+
+// setXattr sets the metadata on the file Xattrs
+//
+// It doesn't set any attributes owned by this backend in metadataKeys
+func (o *Object) setXattr(metadata fs.Metadata) (err error) {
+	if !xattrSupported {
+		return nil
+	}
+	for k, value := range metadata {
+		k = strings.ToLower(k)
+		if _, found := systemMetadataInfo[k]; found {
+			continue
+		}
+		k = xattrPrefix + k
+		v := []byte(value)
+		if o.fs.opt.FollowSymlinks {
+			err = xattr.Set(o.path, k, v)
+		} else {
+			err = xattr.LSet(o.path, k, v)
+		}
+		if err != nil {
+			return fmt.Errorf("failed to set xattr key %q: %w", k, err)
+		}
+	}
+	return nil
+}