diff --git a/internal/api/runner/judge.go b/internal/api/runner/judge.go
index 09242e4..113c5a5 100644
--- a/internal/api/runner/judge.go
+++ b/internal/api/runner/judge.go
@@ -29,10 +29,10 @@ func (h *handler) Judge(_ context.Context, t *asynq.Task) error {
 
 		// 1. write user code
 		userCode := filepath.Join(runner.UserDir, user, fmt.Sprintf("%s.%s", user, p.Submission.Language))
-		if !file.FileTouch(userCode) {
+		if !file.Touch(userCode) {
 			return e.InternalError, 0, systemError
 		}
-		err := file.FileWrite(userCode, []byte(p.Submission.Code))
+		err := file.Write(userCode, []byte(p.Submission.Code))
 		if err != nil {
 			return e.InternalError, 0, systemError
 		}
diff --git a/internal/misc/config/conf.go b/internal/misc/config/conf.go
index ca3adf2..d47e0e8 100644
--- a/internal/misc/config/conf.go
+++ b/internal/misc/config/conf.go
@@ -19,7 +19,7 @@ type Service interface {
 func NewService(i *do.Injector) (Service, error) {
 	cliCtx := do.MustInvoke[*cli.Context](i)
 
-	data, err := file.FileRead(cliCtx.String("config"))
+	data, err := file.Read(cliCtx.String("config"))
 	if err != nil {
 		log.Printf("Failed to setup config: %s\n", err.Error())
 		return nil, err
diff --git a/internal/service/runner/common.go b/internal/service/runner/common.go
index e1aa973..378186f 100644
--- a/internal/service/runner/common.go
+++ b/internal/service/runner/common.go
@@ -57,10 +57,10 @@ func (s *service) checkAndExecute(version uint, user string, lang string, script
 
 func (s *service) ProblemExists(version uint) bool {
 	problemPath := filepath.Join(ProblemDir, fmt.Sprintf("%d", version))
-	return file.FileExist(problemPath)
+	return file.Exist(problemPath)
 }
 
 func (s *service) userExists(user string, name string) bool {
 	userPath := filepath.Join(UserDir, user, name)
-	return file.FileExist(userPath)
+	return file.Exist(userPath)
 }
diff --git a/internal/service/runner/compile.go b/internal/service/runner/compile.go
index ce2699b..6b794d1 100644
--- a/internal/service/runner/compile.go
+++ b/internal/service/runner/compile.go
@@ -20,7 +20,7 @@ func (s *service) Compile(version uint, user string, lang string) (JudgeStatus,
 	msg = utils.If(err == nil, msg, nil)
 	msgText := string(msg)
 
-	if !file.FileExist(target) || file.FileEmpty(target) {
+	if !file.Exist(targetFile) || file.Empty(targetFile) {
 		return JudgeStatus{
 				Message: "compile failed",
 				Tasks:   []TaskStatus{{Verdict: VerdictCompileError, Message: msgText}}},
diff --git a/internal/service/runner/deps.go b/internal/service/runner/deps.go
index d798b4c..1c3b88e 100644
--- a/internal/service/runner/deps.go
+++ b/internal/service/runner/deps.go
@@ -21,7 +21,7 @@ func (s *service) loadImage(cfg *depConfig) e.Status {
 	err := utils.NewTryErr().
 		Try(func() error {
 			// import from tarball
-			if !file.FileExist(cfg.tarball) {
+			if !file.Exist(cfg.tarball) {
 				return errors.New("tarball not exists")
 			}
 			return s.execute("bash", "-c", fmt.Sprintf("gzip -d -c %s | podman load", cfg.tarball))
@@ -32,7 +32,7 @@ func (s *service) loadImage(cfg *depConfig) e.Status {
 		}).
 		Or(func() error {
 			// build from dockerfile
-			if !file.FileExist(cfg.dockerfile) {
+			if !file.Exist(cfg.dockerfile) {
 				return errors.New("dockerfile not exists")
 			}
 			return s.execute("podman", "build", "-f", cfg.dockerfile, "-t", cfg.image, ".")
@@ -53,7 +53,7 @@ func (s *service) EnsureDeps(force bool) e.Status {
 	// check mark
 	if force {
 		_ = os.Remove(mark)
-	} else if file.FileExist(mark) {
+	} else if file.Exist(mark) {
 		return e.Success
 	}
 
diff --git a/internal/service/runner/new_problem.go b/internal/service/runner/new_problem.go
index ec8b3de..c93a43b 100644
--- a/internal/service/runner/new_problem.go
+++ b/internal/service/runner/new_problem.go
@@ -39,22 +39,22 @@ func (s *service) prebuild(version uint, force bool) e.Status {
 	mark := filepath.Join(ProblemDir, fmt.Sprintf("%d", version), ".mark.prebuild")
 	if force {
 		_ = os.Remove(mark)
-	} else if file.FileExist(mark) {
+	} else if file.Exist(mark) {
 		return e.Success
 	}
 
 	prebuildScript := filepath.Join(ProblemDir, fmt.Sprintf("%d", version), "judge", "prebuild.Makefile")
-	if !file.FileExist(prebuildScript) {
+	if !file.Exist(prebuildScript) {
 		s.log.Info("prebuild script not found", zap.String("path", prebuildScript), zap.Uint("version", version))
 		return e.Success
 	}
 
-	dataPath := filepath.Join(ProblemDir, fmt.Sprintf("%d", version), "data")
-	judgePath := filepath.Join(ProblemDir, fmt.Sprintf("%d", version), "judge")
+	dataDir := filepath.Join(ProblemDir, fmt.Sprintf("%d", version), "data")
+	judgeDir := filepath.Join(ProblemDir, fmt.Sprintf("%d", version), "judge")
 
 	args := []string{
-		"-v", dataPath + ":/woj/problem/data",
-		"-v", judgePath + ":/woj/problem/judge",
+		"-v", dataDir + ":/woj/problem/data",
+		"-v", judgeDir + ":/woj/problem/judge",
 		"-e", "PREFIX=/woj/problem",
 		"git.0x7f.app/woj/ubuntu-full:latest",
 		"sh", "-c", "cd /woj/problem/judge && make -f prebuild.Makefile prebuild && touch .mark.prebuild",
diff --git a/internal/service/runner/status.go b/internal/service/runner/status.go
index c751792..95ddfd8 100644
--- a/internal/service/runner/status.go
+++ b/internal/service/runner/status.go
@@ -57,7 +57,7 @@ func (t *TaskStatus) getInfoText(infoFile string) *TaskStatus {
 	}
 
 	var err error
-	t.infoText, err = file.FileRead(infoFile)
+	t.infoText, err = file.Read(infoFile)
 	if err != nil {
 		t.Verdict = VerdictSystemError
 		t.Message = "cannot read info file"
@@ -128,7 +128,7 @@ func (t *TaskStatus) getJudgeText(judgeFile string) *TaskStatus {
 		return t
 	}
 
-	j, err := file.FileRead(judgeFile)
+	j, err := file.Read(judgeFile)
 	if err != nil {
 		t.Verdict = VerdictSystemError
 		t.Message = "cannot read judge file"
diff --git a/pkg/file/file.go b/pkg/file/file.go
index d0ad4a6..9c34dab 100644
--- a/pkg/file/file.go
+++ b/pkg/file/file.go
@@ -7,7 +7,7 @@ import (
 	"path/filepath"
 )
 
-func FileRead(filePath string) ([]byte, error) {
+func Read(filePath string) ([]byte, error) {
 	f, err := os.Open(filePath)
 	if err != nil {
 		return nil, err
@@ -15,16 +15,16 @@ func FileRead(filePath string) ([]byte, error) {
 	return io.ReadAll(f)
 }
 
-func FileWrite(filePath string, content []byte) error {
+func Write(filePath string, content []byte) error {
 	return os.WriteFile(filePath, content, 0644)
 }
 
-func FileExist(filePath string) bool {
+func Exist(filePath string) bool {
 	_, err := os.Stat(filePath)
 	return utils.If(err == nil || os.IsExist(err), true, false)
 }
 
-func FileEmpty(filePath string) bool {
+func Empty(filePath string) bool {
 	stat, err := os.Stat(filePath)
 	if err != nil {
 		return true
@@ -32,9 +32,14 @@ func FileEmpty(filePath string) bool {
 	return stat.Size() == 0
 }
 
-func FileTouch(filePath string) bool {
+func Touch(filePath string) bool {
+	err := TouchErr(filePath)
+	return utils.If(err == nil, true, false)
+}
+
+func TouchErr(filePath string) error {
 	base := filepath.Dir(filePath)
 	_ = os.MkdirAll(base, 0755)
 	_, err := os.OpenFile(filePath, os.O_RDONLY|os.O_CREATE, 0644)
-	return utils.If(err == nil, true, false)
+	return err
 }
diff --git a/pkg/utils/must.go b/pkg/utils/must.go
new file mode 100644
index 0000000..75b24e3
--- /dev/null
+++ b/pkg/utils/must.go
@@ -0,0 +1,20 @@
+package utils
+
+type MustChain struct {
+	err error
+}
+
+func NewMust() *MustChain {
+	return &MustChain{}
+}
+
+func (c *MustChain) Do(callback func() error) *MustChain {
+	if c.err == nil {
+		c.err = callback()
+	}
+	return c
+}
+
+func (c *MustChain) Done() error {
+	return c.err
+}