Prevent bucket renaming in filer, fuse mount, and S3 (#8048)

* prevent bucket renaming in filer, fuse mount, s3

* refactor CanRename to support context propagation

* harden bucket rename validation to fail closed on find error

weed/filer/filer_rename.go

@@ -1,18 +1,29 @@
 package filer
 
 import (
+	"context"
 	"fmt"
 	"strings"
 
 	"github.com/seaweedfs/seaweedfs/weed/util"
 )
 
-func (f *Filer) CanRename(source, target util.FullPath, oldName string) error {
+func (f *Filer) CanRename(ctx context.Context, source, target util.FullPath, oldName string) error {
 	sourcePath := source.Child(oldName)
 	if strings.HasPrefix(string(target), string(sourcePath)) {
 		return fmt.Errorf("mv: can not move directory to a subdirectory of itself")
 	}
 
+	// Check if attempting to rename a bucket itself
+	// Need to load the entry to check if it's a bucket
+	entry, err := f.FindEntry(ctx, sourcePath)
+	if err != nil {
+		return err
+	}
+	if f.IsBucket(entry) {
+		return fmt.Errorf("bucket renaming is not allowed")
+	}
+
 	sourceBucket := f.DetectBucket(source)
 	targetBucket := f.DetectBucket(target)
 	if sourceBucket != targetBucket {