all: Support syncing extended attributes (fixes #2698) (#8513)

This adds support for syncing extended attributes on supported filesystem on Linux, macOS, FreeBSD and NetBSD. Windows is currently excluded because the APIs seem onerous and annoying and frankly the uses cases seem few and far between. On Unixes this also covers ACLs as those are stored as extended attributes. Similar to ownership syncing this will optional & opt-in, which two settings controlling the main behavior: one to "sync" xattrs (read & write) and another one to "scan" xattrs (only read them so other devices can "sync" them, but not apply any locally). Co-authored-by: Tomasz Wilczyński <twilczynski@naver.com>
2022-09-14 09:50:55 +02:00
parent 8065cf7e97
commit 6cac308bcd
37 changed files with 2720 additions and 527 deletions
@@ -17,42 +17,48 @@ import (
 // unixPlatformData is used on all platforms, because apart from being the
 // implementation for BasicFilesystem on Unixes it's also the implementation
 // in fakeFS.
-func unixPlatformData(fs Filesystem, name string, userCache *userCache, groupCache *groupCache) (protocol.PlatformData, error) {
-	stat, err := fs.Lstat(name)
-	if err != nil {
-		return protocol.PlatformData{}, err
+func unixPlatformData(fs Filesystem, name string, userCache *userCache, groupCache *groupCache, scanOwnership, scanXattrs bool, xattrFilter XattrFilter) (protocol.PlatformData, error) {
+	var pd protocol.PlatformData
+	if scanOwnership {
+		var ud protocol.UnixData
+
+		stat, err := fs.Lstat(name)
+		if err != nil {
+			return protocol.PlatformData{}, err
+		}
+
+		ud.UID = stat.Owner()
+		if user := userCache.lookup(strconv.Itoa(ud.UID)); user != nil {
+			ud.OwnerName = user.Username
+		} else if ud.UID == 0 {
+			// We couldn't look up a name, but UID zero should be "root". This
+			// fixup works around the (unlikely) situation where the ownership
+			// is 0:0 but we can't look up a name for either uid zero or gid
+			// zero. If that were the case we'd return a zero PlatformData which
+			// wouldn't get serialized over the wire and the other side would
+			// assume a lack of ownership info...
+			ud.OwnerName = "root"
+		}
+
+		ud.GID = stat.Group()
+		if group := groupCache.lookup(strconv.Itoa(ud.GID)); group != nil {
+			ud.GroupName = group.Name
+		} else if ud.GID == 0 {
+			ud.GroupName = "root"
+		}
+
+		pd.Unix = &ud
 	}

-	ownerUID := stat.Owner()
-	ownerName := ""
-	if user := userCache.lookup(strconv.Itoa(ownerUID)); user != nil {
-		ownerName = user.Username
-	} else if ownerUID == 0 {
-		// We couldn't look up a name, but UID zero should be "root". This
-		// fixup works around the (unlikely) situation where the ownership
-		// is 0:0 but we can't look up a name for either uid zero or gid
-		// zero. If that were the case we'd return a zero PlatformData which
-		// wouldn't get serialized over the wire and the other side would
-		// assume a lack of ownership info...
-		ownerName = "root"
+	if scanXattrs {
+		xattrs, err := fs.GetXattr(name, xattrFilter)
+		if err != nil {
+			return protocol.PlatformData{}, err
+		}
+		pd.SetXattrs(xattrs)
 	}

-	groupID := stat.Group()
-	groupName := ""
-	if group := groupCache.lookup(strconv.Itoa(ownerUID)); group != nil {
-		groupName = group.Name
-	} else if groupID == 0 {
-		groupName = "root"
-	}
-
-	return protocol.PlatformData{
-		Unix: &protocol.UnixData{
-			OwnerName: ownerName,
-			GroupName: groupName,
-			UID:       ownerUID,
-			GID:       groupID,
-		},
-	}, nil
+	return pd, nil
 }

 type valueCache[K comparable, V any] struct {