Implement error on pointers

This improves type-assertion safety.

PiperOrigin-RevId: 353931228

pkg/sentry/fs/fdpipe/pipe_state.go

@@ -34,7 +34,9 @@ func (p *pipeOperations) beforeSave() {
 	} else if p.flags.Write {
 		file, err := p.opener.NonBlockingOpen(context.Background(), fs.PermMask{Write: true})
 		if err != nil {
-			panic(fs.ErrSaveRejection{fmt.Errorf("write-only pipe end cannot be re-opened as %v: %v", p, err)})
+			panic(&fs.ErrSaveRejection{
+				Err: fmt.Errorf("write-only pipe end cannot be re-opened as %#v: %w", p, err),
+			})
 		}
 		file.Close()
 	}

pkg/sentry/fs/fs.go

@@ -144,7 +144,7 @@ type ErrSaveRejection struct {
 }
 
 // Error returns a sensible description of the save rejection error.
-func (e ErrSaveRejection) Error() string {
+func (e *ErrSaveRejection) Error() string {
 	return "save rejected due to unsupported file system state: " + e.Err.Error()
 }
 

pkg/sentry/fs/gofer/inode_state.go

@@ -67,7 +67,9 @@ func (i *inodeFileState) beforeSave() {
 	if i.sattr.Type == fs.RegularFile {
 		uattr, err := i.unstableAttr(&dummyClockContext{context.Background()})
 		if err != nil {
-			panic(fs.ErrSaveRejection{fmt.Errorf("failed to get unstable atttribute of %s: %v", i.s.inodeMappings[i.sattr.InodeID], err)})
+			panic(&fs.ErrSaveRejection{
+				Err: fmt.Errorf("failed to get unstable atttribute of %s: %w", i.s.inodeMappings[i.sattr.InodeID], err),
+			})
 		}
 		i.savedUAttr = &uattr
 	}

pkg/sentry/kernel/kernel.go

@@ -593,8 +593,8 @@ func (k *Kernel) flushWritesToFiles(ctx context.Context) error {
 			// Wrap this error in ErrSaveRejection so that it will trigger a save
 			// error, rather than a panic. This also allows us to distinguish Fsync
 			// errors from state file errors in state.Save.
-			return fs.ErrSaveRejection{
-				Err: fmt.Errorf("%q was not sufficiently synced: %v", name, err),
+			return &fs.ErrSaveRejection{
+				Err: fmt.Errorf("%q was not sufficiently synced: %w", name, err),
 			}
 		}
 		return nil

pkg/tcpip/tcpip.go

@@ -195,7 +195,7 @@ type ErrSaveRejection struct {
 }
 
 // Error returns a sensible description of the save rejection error.
-func (e ErrSaveRejection) Error() string {
+func (e *ErrSaveRejection) Error() string {
 	return "save rejected due to unsupported networking state: " + e.Err.Error()
 }
 

pkg/tcpip/transport/tcp/endpoint_state.go

@@ -55,7 +55,9 @@ func (e *endpoint) beforeSave() {
 	case epState.connected() || epState.handshake():
 		if !e.route.HasSaveRestoreCapability() {
 			if !e.route.HasDisconncetOkCapability() {
-				panic(tcpip.ErrSaveRejection{fmt.Errorf("endpoint cannot be saved in connected state: local %v:%d, remote %v:%d", e.ID.LocalAddress, e.ID.LocalPort, e.ID.RemoteAddress, e.ID.RemotePort)})
+				panic(&tcpip.ErrSaveRejection{
+					Err: fmt.Errorf("endpoint cannot be saved in connected state: local %s:%d, remote %s:%d", e.ID.LocalAddress, e.ID.LocalPort, e.ID.RemoteAddress, e.ID.RemotePort),
+				})
 			}
 			e.resetConnectionLocked(tcpip.ErrConnectionAborted)
 			e.mu.Unlock()