fs: define the optional interface SetMetadata and implement it in wrapping backends

This also implements backend integration tests for the feature

backend/chunker/chunker_test.go

@@ -36,6 +36,7 @@ func TestIntegration(t *testing.T) {
 			"GetTier",
 			"SetTier",
 			"Metadata",
+			"SetMetadata",
 		},
 		UnimplementableFsMethods: []string{
 			"PublicLink",

backend/combine/combine.go

@@ -1119,6 +1119,17 @@ func (o *Object) Metadata(ctx context.Context) (fs.Metadata, error) {
 	return do.Metadata(ctx)
 }
 
+// SetMetadata sets metadata for an Object
+//
+// It should return fs.ErrorNotImplemented if it can't set metadata
+func (o *Object) SetMetadata(ctx context.Context, metadata fs.Metadata) error {
+	do, ok := o.Object.(fs.SetMetadataer)
+	if !ok {
+		return fs.ErrorNotImplemented
+	}
+	return do.SetMetadata(ctx, metadata)
+}
+
 // SetTier performs changing storage tier of the Object if
 // multiple storage classes supported
 func (o *Object) SetTier(tier string) error {

backend/compress/compress.go

@@ -1286,6 +1286,17 @@ func (o *Object) Metadata(ctx context.Context) (fs.Metadata, error) {
 	return do.Metadata(ctx)
 }
 
+// SetMetadata sets metadata for an Object
+//
+// It should return fs.ErrorNotImplemented if it can't set metadata
+func (o *Object) SetMetadata(ctx context.Context, metadata fs.Metadata) error {
+	do, ok := o.Object.(fs.SetMetadataer)
+	if !ok {
+		return fs.ErrorNotImplemented
+	}
+	return do.SetMetadata(ctx, metadata)
+}
+
 // Hash returns the selected checksum of the file
 // If no checksum is available it returns ""
 func (o *Object) Hash(ctx context.Context, ht hash.Type) (string, error) {

backend/crypt/crypt.go

@@ -1248,6 +1248,17 @@ func (o *Object) Metadata(ctx context.Context) (fs.Metadata, error) {
 	return do.Metadata(ctx)
 }
 
+// SetMetadata sets metadata for an Object
+//
+// It should return fs.ErrorNotImplemented if it can't set metadata
+func (o *Object) SetMetadata(ctx context.Context, metadata fs.Metadata) error {
+	do, ok := o.Object.(fs.SetMetadataer)
+	if !ok {
+		return fs.ErrorNotImplemented
+	}
+	return do.SetMetadata(ctx, metadata)
+}
+
 // MimeType returns the content type of the Object if
 // known, or "" if not
 //

backend/hasher/hasher.go

@@ -535,6 +535,17 @@ func (o *Object) Metadata(ctx context.Context) (fs.Metadata, error) {
 	return do.Metadata(ctx)
 }
 
+// SetMetadata sets metadata for an Object
+//
+// It should return fs.ErrorNotImplemented if it can't set metadata
+func (o *Object) SetMetadata(ctx context.Context, metadata fs.Metadata) error {
+	do, ok := o.Object.(fs.SetMetadataer)
+	if !ok {
+		return fs.ErrorNotImplemented
+	}
+	return do.SetMetadata(ctx, metadata)
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs              = (*Fs)(nil)

backend/union/upstream/upstream.go

@@ -322,6 +322,17 @@ func (o *Object) Metadata(ctx context.Context) (fs.Metadata, error) {
 	return do.Metadata(ctx)
 }
 
+// SetMetadata sets metadata for an Object
+//
+// It should return fs.ErrorNotImplemented if it can't set metadata
+func (o *Object) SetMetadata(ctx context.Context, metadata fs.Metadata) error {
+	do, ok := o.Object.(fs.SetMetadataer)
+	if !ok {
+		return fs.ErrorNotImplemented
+	}
+	return do.SetMetadata(ctx, metadata)
+}
+
 // Metadata returns metadata for an DirEntry
 //
 // It should return nil if there is no Metadata

fs/types.go

@@ -242,6 +242,7 @@ type FullObject interface {
 	GetTierer
 	SetTierer
 	Metadataer
+	SetMetadataer
 }
 
 // ObjectOptionalInterfaces returns the names of supported and
@@ -273,6 +274,9 @@ func ObjectOptionalInterfaces(o Object) (supported, unsupported []string) {
 	_, ok = o.(Metadataer)
 	store(ok, "Metadata")
 
+	_, ok = o.(SetMetadataer)
+	store(ok, "SetMetadata")
+
 	return supported, unsupported
 }
 

fstest/fstests/fstests.go

@@ -1668,6 +1668,67 @@ func Run(t *testing.T, opt *Opt) {
 				} // else: Have some metadata here we didn't write - can't really check it!
 			})
 
+			// TestObjectSetMetadata tests the SetMetadata of the object
+			t.Run("ObjectSetMetadata", func(t *testing.T) {
+				skipIfNotOk(t)
+				ctx, ci := fs.AddConfig(ctx)
+				ci.Metadata = true
+				features := f.Features()
+
+				// Test to see if SetMetadata is supported on an existing object before creating a new one
+				obj := fstest.NewObject(ctx, t, f, file1.Path)
+				_, objectHasSetMetadata := obj.(fs.SetMetadataer)
+				if !objectHasSetMetadata {
+					t.Skip("SetMetadata method not supported")
+				}
+				if !features.Overlay {
+					require.True(t, features.WriteMetadata, "Features.WriteMetadata is false but Object.SetMetadata found")
+				}
+				if !features.ReadMetadata {
+					t.Skip("SetMetadata can't be tested without ReadMetadata")
+				}
+
+				// Create file with metadata
+				const fileName = "test set metadata.txt"
+				t1 := fstest.Time("2003-02-03T04:05:06.499999999Z")
+				t2 := fstest.Time("2004-03-03T04:05:06.499999999Z")
+				contents := random.String(100)
+				file := fstest.NewItem(fileName, contents, t1)
+				var testMetadata = fs.Metadata{
+					// System metadata supported by all backends
+					"mtime": t1.Format(time.RFC3339Nano),
+					// User metadata
+					"potato": "jersey",
+				}
+				obj = PutTestContentsMetadata(ctx, t, f, &file, contents, true, "text/plain", testMetadata)
+				fstest.CheckEntryMetadata(ctx, t, f, obj, testMetadata)
+				do, objectHasSetMetadata := obj.(fs.SetMetadataer)
+				require.True(t, objectHasSetMetadata)
+
+				// Set new metadata
+				err := do.SetMetadata(ctx, fs.Metadata{
+					// System metadata supported by all backends
+					"mtime": t2.Format(time.RFC3339Nano),
+					// User metadata
+					"potato": "royal",
+				})
+				if err == fs.ErrorNotImplemented {
+					t.Log("SetMetadata returned fs.ErrorNotImplemented")
+				} else {
+					require.NoError(t, err)
+					file.ModTime = t2
+					fstest.CheckListing(t, f, []fstest.Item{file1, file2, file})
+
+					// Check metadata is correct
+					fstest.CheckEntryMetadata(ctx, t, f, obj, ci.MetadataSet)
+					obj = fstest.NewObject(ctx, t, f, fileName)
+					fstest.CheckEntryMetadata(ctx, t, f, obj, ci.MetadataSet)
+				}
+
+				// Remove test file
+				require.NoError(t, obj.Remove(ctx))
+			})
+
 			// TestObjectSetModTime tests that SetModTime works
 			t.Run("ObjectSetModTime", func(t *testing.T) {
 				skipIfNotOk(t)