Correct implicit username for MSYS2 eg. xs @server.com

Signed-off-by: Russ Magee <rmagee@gmail.com>

xs/xs.go

@@ -256,7 +256,7 @@ func buildCmdRemoteToLocal(copyQuiet bool, copyLimitBPS uint, destPath, files st
 		cmd = xs.GetTool("tar")
 
 		args = []string{"-xz", "-C", destPath}
-} else {
+	} else {
 		// TODO: Query remote side for total file/dir size
 		bandwidthInBytesPerSec := " -L " + fmt.Sprintf("%d ", copyLimitBPS)
 		displayOpts := " -pre "
@@ -309,7 +309,7 @@ func buildCmdLocalToRemote(copyQuiet bool, copyLimitBPS uint, files string) (cap
 		bandwidthInBytesPerSec := " -L " + fmt.Sprintf("%d", copyLimitBPS)
 		displayOpts := " -pre "
 		cmd = xs.GetTool("bash")
-		args = []string{"-c", xs.GetTool("tar")+" -cz -f /dev/stdout "}
+		args = []string{"-c", xs.GetTool("tar") + " -cz -f /dev/stdout "}
 		files = strings.TrimSpace(files)
 		// Awesome fact: tar actually can take multiple -C args, and
 		// changes to the dest dir *as it sees each one*. This enables
@@ -769,7 +769,7 @@ func main() {
 	var uname string
 	if remoteUser == "" {
 		u, _ := user.Current() // nolint: gosec
-		uname = u.Username
+		uname = localUserName(u)
 	} else {
 		uname = remoteUser
 	}
@@ -1037,6 +1037,19 @@ func main() {
 	exitWithStatus(int(rec.Status()))
 }
 
+// currentUser returns the current username minus any OS-specific prefixes
+// such as MS Windows workgroup prefixes (eg. workgroup\user).
+func localUserName(u *user.User) string {
+	if u == nil {
+		log.Fatal("null User?!")
+	}
+
+	// WinAPI: username may have CIFS prefix %USERDOMAIN%\
+	userspec := strings.Split(u.Username, `\`)
+	username := userspec[len(userspec)-1]
+	return username
+}
+
 func restoreTermState(oldState *xs.State) {
 	_ = xs.Restore(os.Stdin.Fd(), oldState) // nolint: errcheck,gosec
 }