Don't set up the screen too early

m/reader.go

@@ -531,7 +531,7 @@ func (reader *Reader) createStatusUnlocked(lastLine linenumbers.LineNumber) stri
 //
 // Used for making sudo work:
 // https://github.com/walles/moar/issues/199
-func (reader *Reader) AwaitFirstLine() {
+func (reader *Reader) AwaitFirstByte() {
 	<-reader.doneWaitingForFirstByte
 }
 

moar.go

@@ -661,17 +661,6 @@ func pagerFromArgs(
 		panic("Invariant broken: stdout is not a terminal")
 	}
 
-	screen, err := newScreen(*mouseMode, *terminalColorsCount)
-	if err != nil {
-		// Ref: https://github.com/walles/moar/issues/149
-		log.Debug("Failed to set up screen for paging, pumping to stdout instead: ", err)
-		err := pumpToStdout(flagSet.Args()...)
-		if err != nil {
-			return nil, nil, chroma.Style{}, nil, err
-		}
-		return nil, nil, chroma.Style{}, nil, nil
-	}
-
 	if len(flagSet.Args()) > 1 {
 		fmt.Fprintln(os.Stderr, "ERROR: Expected exactly one filename, or data piped from stdin")
 		fmt.Fprintln(os.Stderr)
@@ -705,6 +694,22 @@ func pagerFromArgs(
 		}
 	}
 
+	// This makes sudo xyz | moar work
+	reader.AwaitFirstByte()
+
+	// We got the first byte, this means sudo is done (if it was used) and we
+	// can set up the UI
+	screen, err := newScreen(*mouseMode, *terminalColorsCount)
+	if err != nil {
+		// Ref: https://github.com/walles/moar/issues/149
+		log.Debug("Failed to set up screen for paging, pumping to stdout instead: ", err)
+		err := pumpToStdout(flagSet.Args()...)
+		if err != nil {
+			return nil, nil, chroma.Style{}, nil, err
+		}
+		return nil, nil, chroma.Style{}, nil, nil
+	}
+
 	var style chroma.Style
 	if *styleOption == nil {
 		t0 := time.Now()
@@ -739,11 +744,8 @@ func pagerFromArgs(
 	} else {
 		style = **styleOption
 	}
-
 	reader.SetStyleForHighlighting(style)
 
-	reader.AwaitFirstLine()
-
 	pager := m.NewPager(reader)
 	pager.WrapLongLines = *wrap
 	pager.ShowLineNumbers = !*noLineNumbers