chore: stop treating dirs as having size 128 (#10750)

Resp. directories for the database, and both dirs and symlinks for
`FileInfo.FileSize`. Instead handle it in the UI progress percentage. We
even already have special cases there for deletions, might as well
handle directories just like any other zero-sized needed item there.

This went through the very thorough testing of running it on my laptop,
the migration was applied and it seemed to be working fine after.

---------

Signed-off-by: Simon Frei <freisim93@gmail.com>

gui/default/syncthing/core/syncthingController.js

@@ -1139,20 +1139,20 @@ angular.module('syncthing.core')
         };
 
         $scope.syncPercentage = function (folder) {
-            if (typeof $scope.model[folder] === 'undefined') {
+            var model = $scope.model[folder];
+            if (typeof model === 'undefined') {
                 return 100;
             }
-            if ($scope.model[folder].needTotalItems === 0) {
+            if (model.needTotalItems === 0) {
                 return 100;
             }
-            if (($scope.model[folder].needBytes == 0 && $scope.model[folder].needDeletes > 0) || $scope.model[folder].globalBytes == 0) {
-                // We don't need any data, but we have deletes that we need
-                // to do. Drop down the completion percentage to indicate
-                // that we have stuff to do.
-                // Do the same thing in case we only have zero byte files to sync.
+            if (model.needBytes == 0 && model.needTotalItems > 0) {
+                // We don't need any data, but we have deletes, directories,
+                // symlinks or zero byte files that we need to do. Drop down the
+                // completion percentage to indicate that we have stuff to do.
                 return 95;
             }
-            return progressIntegerPercentage($scope.model[folder].inSyncBytes, $scope.model[folder].globalBytes);
+            return progressIntegerPercentage(model.inSyncBytes, model.globalBytes);
         };
 
         $scope.scanPercentage = function (folder) {

internal/db/sqlite/db_test.go

@@ -29,7 +29,6 @@ import (
 const (
 	folderID  = "test"
 	blockSize = 128 << 10
-	dirSize   = 128
 )
 
 func TestBasics(t *testing.T) {
@@ -72,11 +71,11 @@ func TestBasics(t *testing.T) {
 		t.Fatal(err)
 	}
 	const (
-		localSize      = (1+2+3)*blockSize + dirSize
+		localSize      = (1+2+3)*blockSize
 		remoteSize     = (3 + 4 + 5) * blockSize
-		globalSize     = (2+3+3+4+5)*blockSize + dirSize
+		globalSize     = (2+3+3+4+5)*blockSize
 		needSizeLocal  = remoteSize
-		needSizeRemote = (2+3)*blockSize + dirSize
+		needSizeRemote = (2+3)*blockSize
 	)
 
 	t.Run("SchemaVersion", func(t *testing.T) {

internal/db/sqlite/folderdb_update.go

@@ -111,10 +111,6 @@ func (s *folderDB) Update(device protocol.DeviceID, fs []protocol.FileInfo, opti
 			f.BlocksHash = nil
 		}
 
-		if f.Type == protocol.FileInfoTypeDirectory {
-			f.Size = 128 // synthetic directory size
-		}
-
 		// Insert the file.
 		//
 		// If it is a remote file, set remote_sequence otherwise leave it at

internal/db/sqlite/sql/migrations/folder/06-zero-size-dirs.sql

@@ -0,0 +1,12 @@
+-- Copyright (C) 2026 The Syncthing Authors.
+--
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this file,
+-- You can obtain one at https://mozilla.org/MPL/2.0/.
+
+-- All non-file entries should have size zero.
+-- Directories were previously stored with a "synthetic" size of 128.
+UPDATE files
+    SET size = 0
+    WHERE type != 0
+;

internal/db/sqlite/util.go

@@ -106,6 +106,10 @@ func (i indirectFI) FileInfo() (protocol.FileInfo, error) {
 		fi.Blocks = bl.Blocks
 	}
 	fi.Name = osutil.NativeFilename(fi.Name)
+	// Undo earlier behaviour of setting a synthetic size on dirs.
+	if fi.Type != protocol.FileInfoTypeFile && fi.Size > 0 {
+		fi.Size = 0
+	}
 	return protocol.FileInfoFromDB(&fi), nil
 }
 

lib/api/api.go

@@ -1774,7 +1774,7 @@ func fileIntfJSONMap(f protocol.FileInfo) map[string]interface{} {
 	out := map[string]interface{}{
 		"name":               f.FileName(),
 		"type":               f.FileType().String(),
-		"size":               f.FileSize(),
+		"size":               f.Size,
 		"deleted":            f.IsDeleted(),
 		"invalid":            f.IsInvalid(),
 		"ignored":            f.IsIgnored(),

lib/model/folder_recvonly_test.go

@@ -163,12 +163,11 @@ func TestRecvOnlyRevertNeeds(t *testing.T) {
 	// We now have a newer file than the rest of the cluster. Global state should reflect this.
 
 	size = mustV(m.GlobalSize("ro"))
-	const sizeOfDir = 128
-	if size.Files != 1 || size.Bytes != sizeOfDir+int64(len(oldData)) {
+	if size.Files != 1 || size.Bytes != int64(len(oldData)) {
 		t.Fatalf("Global: expected no change due to the new file: %+v", size)
 	}
 	size = mustV(m.LocalSize("ro", protocol.LocalDeviceID))
-	if size.Files != 1 || size.Bytes != sizeOfDir+int64(len(newData)) {
+	if size.Files != 1 || size.Bytes != int64(len(newData)) {
 		t.Fatalf("Local: expected the new file to be reflected: %+v", size)
 	}
 	size = mustV(m.NeedSize("ro", protocol.LocalDeviceID))
@@ -185,11 +184,11 @@ func TestRecvOnlyRevertNeeds(t *testing.T) {
 	m.Revert("ro")
 
 	size = mustV(m.GlobalSize("ro"))
-	if size.Files != 1 || size.Bytes != sizeOfDir+int64(len(oldData)) {
+	if size.Files != 1 || size.Bytes != int64(len(oldData)) {
 		t.Fatalf("Global: expected the global size to revert: %+v", size)
 	}
 	size = mustV(m.LocalSize("ro", protocol.LocalDeviceID))
-	if size.Files != 1 || size.Bytes != sizeOfDir+int64(len(newData)) {
+	if size.Files != 1 || size.Bytes != int64(len(newData)) {
 		t.Fatalf("Local: expected the local size to remain: %+v", size)
 	}
 	size = mustV(m.NeedSize("ro", protocol.LocalDeviceID))

lib/model/model_test.go

@@ -1787,10 +1787,12 @@ func TestGlobalDirectoryTree(t *testing.T) {
 	b := func(isfile bool, path ...string) protocol.FileInfo {
 		typ := protocol.FileInfoTypeDirectory
 		var blocks []protocol.BlockInfo
+		var size int64
 
 		if isfile {
 			typ = protocol.FileInfoTypeFile
 			blocks = []protocol.BlockInfo{{Offset: 0x0, Size: 0xa, Hash: []uint8{0x2f, 0x72, 0xcc, 0x11, 0xa6, 0xfc, 0xd0, 0x27, 0x1e, 0xce, 0xf8, 0xc6, 0x10, 0x56, 0xee, 0x1e, 0xb1, 0x24, 0x3b, 0xe3, 0x80, 0x5b, 0xf9, 0xa9, 0xdf, 0x98, 0xf9, 0x2f, 0x76, 0x36, 0xb0, 0x5c}}}
+			size = 0xa
 		}
 		seq++
 		return protocol.FileInfo{
@@ -1798,7 +1800,7 @@ func TestGlobalDirectoryTree(t *testing.T) {
 			Type:      typ,
 			ModifiedS: 0x666,
 			Blocks:    blocks,
-			Size:      0xa,
+			Size:      size,
 			Sequence:  seq,
 		}
 	}
@@ -1814,7 +1816,7 @@ func TestGlobalDirectoryTree(t *testing.T) {
 		return &TreeEntry{
 			Name:     name,
 			ModTime:  time.Unix(0x666, 0),
-			Size:     128,
+			Size:     0,
 			Type:     protocol.FileInfoTypeDirectory.String(),
 			Children: entries,
 		}

lib/protocol/bep_fileinfo.go

@@ -389,16 +389,6 @@ func (f FileInfo) HasPermissionBits() bool {
 	return !f.NoPermissions
 }
 
-func (f FileInfo) FileSize() int64 {
-	if f.Deleted {
-		return 0
-	}
-	if f.IsDirectory() || f.IsSymlink() {
-		return SyntheticDirectorySize
-	}
-	return f.Size
-}
-
 func (f FileInfo) BlockSize() int {
 	if f.RawBlockSize < MinBlockSize {
 		return MinBlockSize

lib/protocol/protocol.go

@@ -56,7 +56,8 @@ const (
 	// DesiredPerFileBlocks is the number of blocks we aim for per file
 	DesiredPerFileBlocks = 2000
 
-	SyntheticDirectorySize = 128
+	// We used to send this size for directories and still accept that for compat.
+	deprecatedSyntheticDirectorySize = 128
 
 	// don't bother compressing messages smaller than this many bytes
 	compressionThreshold = 128
@@ -640,7 +641,7 @@ func checkFileInfoConsistency(f FileInfo) error {
 		// Only files should have blocks
 		return errNonFileHasBlocks
 
-	case f.IsDirectory() && f.Size != 0 && f.Size != SyntheticDirectorySize:
+	case f.IsDirectory() && f.Size != 0 && f.Size != deprecatedSyntheticDirectorySize:
 		// Directories should be size zero or the synthetic directory size
 		return errNonFileHasSize
 

lib/protocol/protocol_test.go

@@ -464,7 +464,7 @@ func TestCheckConsistency(t *testing.T) {
 			fi: FileInfo{
 				Name: "foo",
 				Type: FileInfoTypeDirectory,
-				Size: SyntheticDirectorySize,
+				Size: deprecatedSyntheticDirectorySize,
 			},
 			ok: true,
 		},
@@ -492,7 +492,7 @@ func TestCheckConsistency(t *testing.T) {
 				Name:          "foo",
 				Type:          FileInfoTypeSymlink,
 				SymlinkTarget: []byte("bar"),
-				Size:          SyntheticDirectorySize,
+				Size:          deprecatedSyntheticDirectorySize,
 			},
 			ok: false,
 		},

lib/scanner/walk_test.go

@@ -41,9 +41,9 @@ type testfileList []testfile
 
 var testdata = testfileList{
 	{"afile", 4, "b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c"},
-	{"dir1", 128, ""},
+	{"dir1", 0, ""},
 	{filepath.Join("dir1", "dfile"), 5, "49ae93732fcf8d63fe1cce759664982dbd5b23161f007dba8561862adc96d063"},
-	{"dir2", 128, ""},
+	{"dir2", 0, ""},
 	{filepath.Join("dir2", "cfile"), 4, "bf07a7fbb825fc0aae7bf4a1177b2b31fcf8a3feeaf7092761e18c859ee52a9c"},
 	{"excludes", 37, "df90b52f0c55dba7a7a940affe482571563b1ac57bd5be4d8a0291e7de928e06"},
 	{"further-excludes", 5, "7eb0a548094fa6295f7fd9200d69973e5f5ec5c04f2a86d998080ac43ecf89f1"},
@@ -601,7 +601,7 @@ func (l fileList) testfiles() testfileList {
 		if len(f.Blocks) > 1 {
 			panic("simple test case stuff only supports a single block per file")
 		}
-		testfiles[i] = testfile{name: f.Name, length: f.FileSize()}
+		testfiles[i] = testfile{name: f.Name, length: f.Size}
 		if len(f.Blocks) == 1 {
 			testfiles[i].hash = fmt.Sprintf("%x", f.Blocks[0].Hash)
 		}