.github/workflows: adding golangci-lint as new job (#453)

In order to follow golang's best practices, we should lint the code base properly beyond usual syntax mistakes.

server/handlers.go

@@ -462,14 +462,13 @@ func (s *Server) putHandler(w http.ResponseWriter, r *http.Request) {
 
 	reader = r.Body
 
-	defer r.Body.Close()
+	defer CloseCheck(r.Body.Close)
 
 	if contentLength == -1 {
 		// queue file to disk, because s3 needs content length
 		var err error
-		var f io.Reader
 
-		f = reader
+		f := reader
 
 		var b bytes.Buffer
 
@@ -575,13 +574,9 @@ func resolveURL(r *http.Request, u *url.URL, proxyPort string) string {
 }
 
 func resolveKey(key, proxyPath string) string {
-	if strings.HasPrefix(key, "/") {
-		key = key[1:]
-	}
+	key = strings.TrimPrefix(key, "/")
 
-	if strings.HasPrefix(key, proxyPath) {
-		key = key[len(proxyPath):]
-	}
+	key = strings.TrimPrefix(key, proxyPath)
 
 	key = strings.Replace(key, "\\", "/", -1)
 
@@ -660,7 +655,7 @@ func (metadata metadata) remainingLimitHeaderValues() (remainingDownloads, remai
 	if metadata.MaxDate.IsZero() {
 		remainingDays = "n/a"
 	} else {
-		timeDifference := metadata.MaxDate.Sub(time.Now())
+		timeDifference := time.Until(metadata.MaxDate)
 		remainingDays = strconv.Itoa(int(timeDifference.Hours()/24) + 1)
 	}
 
@@ -679,8 +674,6 @@ func (s *Server) lock(token, filename string) {
 	lock, _ := s.locks.LoadOrStore(key, &sync.Mutex{})
 
 	lock.(*sync.Mutex).Lock()
-
-	return
 }
 
 func (s *Server) unlock(token, filename string) {
@@ -702,7 +695,7 @@ func (s *Server) checkMetadata(token, filename string, increaseDownload bool) (m
 		return metadata, err
 	}
 
-	defer r.Close()
+	defer CloseCheck(r.Close)
 
 	if err := json.NewDecoder(r).Decode(&metadata); err != nil {
 		return metadata, err
@@ -740,7 +733,7 @@ func (s *Server) checkDeletionToken(deletionToken, token, filename string) error
 		return err
 	}
 
-	defer r.Close()
+	defer CloseCheck(r.Close)
 
 	if err := json.NewDecoder(r).Decode(&metadata); err != nil {
 		return err
@@ -755,9 +748,9 @@ func (s *Server) purgeHandler() {
 	ticker := time.NewTicker(s.purgeInterval)
 	go func() {
 		for {
-			select {
-			case <-ticker.C:
-				err := s.storage.Purge(s.purgeDays)
+			<-ticker.C
+			err := s.storage.Purge(s.purgeDays)
+			if err != nil {
 				s.logger.Printf("error cleaning up expired files: %v", err)
 			}
 		}
@@ -825,7 +818,7 @@ func (s *Server) zipHandler(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		defer reader.Close()
+		defer CloseCheck(reader.Close)
 
 		header := &zip.FileHeader{
 			Name:         strings.Split(key, "/")[1],
@@ -868,10 +861,10 @@ func (s *Server) tarGzHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Connection", "close")
 
 	os := gzip.NewWriter(w)
-	defer os.Close()
+	defer CloseCheck(os.Close)
 
 	zw := tar.NewWriter(os)
-	defer zw.Close()
+	defer CloseCheck(zw.Close)
 
 	for _, key := range strings.Split(files, ",") {
 		key = resolveKey(key, s.proxyPath)
@@ -896,7 +889,7 @@ func (s *Server) tarGzHandler(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		defer reader.Close()
+		defer CloseCheck(reader.Close)
 
 		header := &tar.Header{
 			Name: strings.Split(key, "/")[1],
@@ -930,7 +923,7 @@ func (s *Server) tarHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Connection", "close")
 
 	zw := tar.NewWriter(w)
-	defer zw.Close()
+	defer CloseCheck(zw.Close)
 
 	for _, key := range strings.Split(files, ",") {
 		key = resolveKey(key, s.proxyPath)
@@ -955,7 +948,7 @@ func (s *Server) tarHandler(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		defer reader.Close()
+		defer CloseCheck(reader.Close)
 
 		header := &tar.Header{
 			Name: strings.Split(key, "/")[1],
@@ -1037,7 +1030,7 @@ func (s *Server) getHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	defer reader.Close()
+	defer CloseCheck(reader.Close)
 
 	var disposition string
 
@@ -1086,8 +1079,6 @@ func (s *Server) getHandler(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "Error occurred copying to output stream", 500)
 		return
 	}
-
-	return
 }
 
 // RedirectHandler handles redirect
@@ -1142,7 +1133,6 @@ func ipFilterHandler(h http.Handler, ipFilterOptions *IPFilterOptions) http.Hand
 		} else {
 			WrapIPFilter(h, *ipFilterOptions).ServeHTTP(w, r)
 		}
-		return
 	}
 }
 
@@ -1156,7 +1146,7 @@ func (s *Server) basicAuthHandler(h http.Handler) http.HandlerFunc {
 		w.Header().Set("WWW-Authenticate", "Basic realm=\"Restricted\"")
 
 		username, password, authOK := r.BasicAuth()
-		if authOK == false {
+		if !authOK {
 			http.Error(w, "Not authorized", 401)
 			return
 		}