Using OS targeted go files to separate out the username logic.

klog_file.go

@@ -22,9 +22,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"os/user"
 	"path/filepath"
-	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -57,38 +55,6 @@ func init() {
 	}
 }
 
-func getUserName() string {
-	userNameOnce.Do(func() {
-		// On Windows, the Go 'user' package requires netapi32.dll.
-		// This affects Windows Nano Server:
-		//   https://github.com/golang/go/issues/21867
-		// Fallback to using environment variables.
-		if runtime.GOOS == "windows" {
-			u := os.Getenv("USERNAME")
-			if len(u) == 0 {
-				return
-			}
-			// Sanitize the USERNAME since it may contain filepath separators.
-			u = strings.Replace(u, `\`, "_", -1)
-
-			// user.Current().Username normally produces something like 'USERDOMAIN\USERNAME'
-			d := os.Getenv("USERDOMAIN")
-			if len(d) != 0 {
-				userName = d + "_" + u
-			} else {
-				userName = u
-			}
-		} else {
-			current, err := user.Current()
-			if err == nil {
-				userName = current.Username
-			}
-		}
-	})
-
-	return userName
-}
-
 // shortHostname returns its argument, truncating at the first period.
 // For instance, given "www.google.com" it returns "www".
 func shortHostname(hostname string) string {

klog_file_others.go

@@ -0,0 +1,19 @@
+//go:build !windows
+// +build !windows
+
+package klog
+
+import (
+	"os/user"
+)
+
+func getUserName() string {
+	userNameOnce.Do(func() {
+		current, err := user.Current()
+		if err == nil {
+			userName = current.Username
+		}
+	})
+
+	return userName
+}

klog_file_windows.go

@@ -0,0 +1,34 @@
+//go:build windows
+// +build windows
+
+package klog
+
+import (
+	"os"
+	"strings"
+)
+
+func getUserName() string {
+	userNameOnce.Do(func() {
+		// On Windows, the Go 'user' package requires netapi32.dll.
+		// This affects Windows Nano Server:
+		//   https://github.com/golang/go/issues/21867
+		// Fallback to using environment variables.
+		u := os.Getenv("USERNAME")
+		if len(u) == 0 {
+			return
+		}
+		// Sanitize the USERNAME since it may contain filepath separators.
+		u = strings.Replace(u, `\`, "_", -1)
+
+		// user.Current().Username normally produces something like 'USERDOMAIN\USERNAME'
+		d := os.Getenv("USERDOMAIN")
+		if len(d) != 0 {
+			userName = d + "_" + u
+		} else {
+			userName = u
+		}
+	})
+
+	return userName
+}