Replace strings.SplitN usages with strings.Cut

cmd/main.go

@@ -387,11 +387,11 @@ func parseEnvFile(envInput io.Reader) (map[string]string, error) {
 		}
 
 		// split line into key and value
-		fields := strings.SplitN(line, "=", 2)
-		if len(fields) != 2 {
+		before, after, isCut := strings.Cut(line, "=")
+		if !isCut {
 			return nil, fmt.Errorf("can't parse line %d; line should be in KEY=VALUE format", lineNumber)
 		}
-		key, val := fields[0], fields[1]
+		key, val := before, after
 
 		// sometimes keys are prefixed by "export " so file can be sourced in bash; ignore it here
 		key = strings.TrimPrefix(key, "export ")

listeners.go

@@ -468,15 +468,15 @@ func ParseNetworkAddress(addr string) (NetworkAddress, error) {
 	}
 	var start, end uint64
 	if port != "" {
-		ports := strings.SplitN(port, "-", 2)
-		if len(ports) == 1 {
-			ports = append(ports, ports[0])
+		before, after, found := strings.Cut(port, "-")
+		if !found {
+			after = before
 		}
-		start, err = strconv.ParseUint(ports[0], 10, 16)
+		start, err = strconv.ParseUint(before, 10, 16)
 		if err != nil {
 			return NetworkAddress{}, fmt.Errorf("invalid start port: %v", err)
 		}
-		end, err = strconv.ParseUint(ports[1], 10, 16)
+		end, err = strconv.ParseUint(after, 10, 16)
 		if err != nil {
 			return NetworkAddress{}, fmt.Errorf("invalid end port: %v", err)
 		}

modules.go

@@ -324,11 +324,11 @@ func ParseStructTag(tag string) (map[string]string, error) {
 		if pair == "" {
 			continue
 		}
-		parts := strings.SplitN(pair, "=", 2)
-		if len(parts) != 2 {
+		before, after, isCut := strings.Cut(pair, "=")
+		if !isCut {
 			return nil, fmt.Errorf("missing key in '%s' (pair %d)", pair, i)
 		}
-		results[parts[0]] = parts[1]
+		results[before] = after
 	}
 	return results, nil
 }

modules/caddyhttp/matchers.go

@@ -610,11 +610,11 @@ func (m *MatchQuery) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 			if query == "" {
 				continue
 			}
-			parts := strings.SplitN(query, "=", 2)
-			if len(parts) != 2 {
+			before, after, found := strings.Cut(query, "=")
+			if !found {
 				return d.Errf("malformed query matcher token: %s; must be in param=val format", d.Val())
 			}
-			url.Values(*m).Add(parts[0], parts[1])
+			url.Values(*m).Add(before, after)
 		}
 		if d.NextBlock(0) {
 			return d.Err("malformed query matcher: blocks are not supported")

modules/caddyhttp/push/link.go

@@ -52,17 +52,16 @@ func parseLinkHeader(header string) []linkResource {
 		l.uri = strings.TrimSpace(link[li+1 : ri])
 
 		for _, param := range strings.Split(strings.TrimSpace(link[ri+1:]), semicolon) {
-			parts := strings.SplitN(strings.TrimSpace(param), equal, 2)
-			key := strings.TrimSpace(parts[0])
+			before, after, isCut := strings.Cut(strings.TrimSpace(param), equal)
+			key := strings.TrimSpace(before)
 			if key == "" {
 				continue
 			}
-			if len(parts) == 1 {
+			if isCut {
+				l.params[key] = strings.TrimSpace(after)
+			} else {
 				l.params[key] = key
 			}
-			if len(parts) == 2 {
-				l.params[key] = strings.TrimSpace(parts[1])
-			}
 		}
 
 		resources = append(resources, l)

modules/caddyhttp/reverseproxy/fastcgi/client.go

@@ -424,13 +424,13 @@ func (c *FCGIClient) Request(p map[string]string, req io.Reader) (resp *http.Res
 	resp.Header = http.Header(mimeHeader)
 
 	if resp.Header.Get("Status") != "" {
-		statusParts := strings.SplitN(resp.Header.Get("Status"), " ", 2)
-		resp.StatusCode, err = strconv.Atoi(statusParts[0])
+		statusNumber, statusInfo, statusIsCut := strings.Cut(resp.Header.Get("Status"), " ")
+		resp.StatusCode, err = strconv.Atoi(statusNumber)
 		if err != nil {
 			return
 		}
-		if len(statusParts) > 1 {
-			resp.Status = statusParts[1]
+		if statusIsCut {
+			resp.Status = statusInfo
 		}
 
 	} else {