Fix TOTPCopier writing to error channel after client is likely done checking, which caused the TOTP routine to stall

clip/arguments.go

@@ -35,7 +35,7 @@ func CopyShortcut(realPath string, field int, rcwPassword []byte) error {
 
 		if field == 2 { // TOTP mode
 			fmt.Println(back.AnsiWarning + "[Starting]" + back.AnsiReset + " TOTP clipboard refresher")
-			errorChan := make(chan error)
+			errorChan := make(chan error, 1)
 			go TOTPCopier(decSlice[2], errorChan, nil) // "done" is not needed because the process runs until the program is killed
 			if err = <-errorChan; err != nil {         // handle error from first copy
 				return errors.New("error encountered in TOTP refresh process: " + err.Error())

clip/totp.go

@@ -10,19 +10,32 @@ import (
 
 // TOTPCopier is meant to be run as a goroutine to keep
 // the clipboard up-to-date with the latest TOTP token.
+//
+// Note that errorChan should be buffered with capacity 1.
+// This is because TOTPCopier only returns errors on the first
+// iteration, as subsequent errors are highly unlikely to occur
+// and allowing the caller to move on from error-checking is beneficial.
 func TOTPCopier(secret string, errorChan chan<- error, done <-chan bool) {
+	var firstRun = true
+	var currentTime time.Time
+	var token string
+	var err error
 	for {
-		currentTime := time.Now()
-		token, err := core.GenTOTP(secret, currentTime)
-		if err != nil {
+		currentTime = time.Now()
+		token, err = core.GenTOTP(secret, currentTime)
+		if firstRun && err != nil {
 			errorChan <- err
 		}
-		if err = CopyString(false, token); err != nil {
-			errorChan <- err
+		err = CopyString(false, token)
+		if firstRun {
+			if err != nil {
+				errorChan <- err
+			} else {
+				errorChan <- nil // indicate that first copy was successful
+			}
+			firstRun = false
 		}
 
-		errorChan <- nil // indicate that first copy was successful
-
 		// sleep till next 30-second interval
 		time.Sleep(time.Duration(30-(currentTime.Second()%30)) * time.Second)