Refactor xattr error handler to be a simple function

Changed ignoreSELinuxXAttrErrorHandler from a function that returns
a function to a direct error handler function. This simplifies the
code while maintaining the same functionality.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>
Signed-off-by: Tiger Kaovilai <[email protected]>

Author: kaovilai

solver/llbsolver/ops/exec_binfmt.go

@@ -65,7 +65,7 @@ func (m *staticEmulatorMount) Mount() ([]mount.Mount, func() error, error) {
 	if err := copy.Copy(context.TODO(), filepath.Dir(m.path), filepath.Base(m.path), tmpdir, qemuMountName, func(ci *copy.CopyInfo) {
 		m := 0555
 		ci.Mode = &m
-	}, copy.WithChown(uid, gid), copy.WithXAttrErrorHandler(createSELinuxXAttrErrorHandler())); err != nil {
+	}, copy.WithChown(uid, gid), copy.WithXAttrErrorHandler(ignoreSELinuxXAttrErrorHandler)); err != nil {
 		return nil, nil, err
 	}
 
@@ -125,21 +125,19 @@ func getEmulator(ctx context.Context, p *pb.Platform) (*emulator, error) {
 	return &emulator{path: fn}, nil
 }
 
-// createSELinuxXAttrErrorHandler creates an error handler for xattr copy operations
+// ignoreSELinuxXAttrErrorHandler is an error handler for xattr copy operations
 // that specifically ignores ENOTSUP errors for security.selinux extended attributes.
 // This addresses SELinux compatibility issues where copying files to filesystems that
 // don't support SELinux xattrs (like tmpfs) would fail with ENOTSUP, preventing
 // qemu emulator setup on SELinux-enabled systems. Since the security.selinux xattr
 // is not critical for the emulator functionality, we safely ignore these errors
 // while preserving other xattr error handling.
-func createSELinuxXAttrErrorHandler() func(dst, src, xattrKey string, err error) error {
-	return func(dst, src, xattrKey string, err error) error {
-		// Ignore ENOTSUP errors specifically for security.selinux xattr
-		// This allows qemu emulator setup to succeed on SELinux systems
-		// when copying to filesystems that don't support SELinux xattrs
-		if errors.Is(err, syscall.ENOTSUP) && xattrKey == "security.selinux" {
-			return nil
-		}
-		return err
+func ignoreSELinuxXAttrErrorHandler(dst, src, xattrKey string, err error) error {
+	// Ignore ENOTSUP errors specifically for security.selinux xattr
+	// This allows qemu emulator setup to succeed on SELinux systems
+	// when copying to filesystems that don't support SELinux xattrs
+	if errors.Is(err, syscall.ENOTSUP) && xattrKey == "security.selinux" {
+		return nil
 	}
+	return err
 }

solver/llbsolver/ops/exec_binfmt_test.go

@@ -9,8 +9,6 @@ import (
 )
 
 func TestBinfmtXAttrErrorHandler(t *testing.T) {
-	handler := createSELinuxXAttrErrorHandler()
-
 	tests := []struct {
 		name        string
 		dst         string
@@ -80,7 +78,7 @@ func TestBinfmtXAttrErrorHandler(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			result := handler(tt.dst, tt.src, tt.xattrKey, tt.inputErr)
+			result := ignoreSELinuxXAttrErrorHandler(tt.dst, tt.src, tt.xattrKey, tt.inputErr)
 
 			if tt.expectErr {
 				require.Error(t, result, tt.description)