Try to use Peek for peeking progress if available

Signed-off-by: Andrea Waltlova <awaltlov@redhat.com>

Author: andywaltlova

src/runner.go

@@ -114,24 +114,32 @@ func runCommandWithOutput(cmd *exec.Cmd, outputCh chan string, doneCh chan bool)
 	defer close(dataReadCh)
 
 	go func() {
-		defer func() {
-			dataReadCh <- true
-		}()
-
 		reader := bufio.NewReader(cmdOutput)
+		readBuffer := 1024
 
 		for {
-			line, err := reader.ReadString('\n')
-			if errors.Is(err, io.EOF) {
+			data, err := reader.Peek(readBuffer)
+			switch {
+			case errors.Is(err, io.EOF):
 				log.Infoln("Read ended with EOF")
-				break
-			} else if err != nil {
-				log.Infoln("Read ended with error", err)
-				outputCh <- fmt.Sprintf("Error reading from stdout: %v", err)
+				outputCh <- string(data)
+				dataReadCh <- true
 				return
+			case errors.Is(err, io.ErrShortBuffer):
+				log.Infoln("Shorter read than wanted", err, data)
+				if len(data) != 0 {
+					log.Infoln("Not empty", data)
+					outputCh <- string(data)
+					_, err := reader.Discard(len(data))
+					if err != nil {
+						// TODO: what should I do if I want to move the reader
+						// If I do nothing it can only cause it to be read twice
+						log.Errorln("Discard failed", err)
+					}
+				}
+			default:
+				log.Infoln(data, err)
 			}
-			log.Infoln("Read line: ", line)
-			outputCh <- line
 		}
 	}()
 
@@ -174,18 +182,15 @@ func executeCommandWithProgress(command string, interpreter string, variables ma
 	for {
 		select {
 		case output := <-outputCh:
-			// TODO: this has to be sent to dispatcher back to report to UI
-			// the idea is to send partial output if buffer with given size sent the output to channel
-			log.Info(output)
-
-			// Append partial to all output
 			bufferedOutput += output
 		case <-ticker.C:
 			// NOTE: If just message without output is also okay we could send just still running
 			log.Infoln("Still running ...")
+			log.Infoln(bufferedOutput)
 		case <-doneCh:
 			// Execution is done
 			log.Infoln("Execution done ...")
+			log.Infoln(bufferedOutput)
 			return bufferedOutput
 		}
 	}