Simplify how proc stat line is read

bufio is ugly ...

cmd/main.go

@@ -1,39 +1,23 @@
 package main
 
 import (
-	"bufio"
+	"bytes"
 	"flag"
 	"fmt"
 	"github.com/oz123/gupta"
-	"log"
 	"os"
 	"time"
 )
 
-func readFirstLine(rd *bufio.Reader, f *os.File) string {
-	line, err := rd.ReadString('\n')
-	if err != nil {
-		log.Fatalf("could not read /proc/stat, error: %v", err)
-	}
-	rd.Reset(f)
-	f.Seek(0, 0)
+func readProcStatLine(r *os.File) string {
+	buf := make([]byte, 80)
+	r.ReadAt(buf, 0)
+	idx := bytes.Index(buf, []byte("cpu0"))
+	line := string(buf[:idx])
+	r.Seek(0, 0)
 	return line
 }
 
-func readProcStatLines(freq int) (string, string) {
-	var line, newline string
-	f, err := os.Open("/proc/stat")
-	if err != nil {
-		log.Fatalf("could not read /proc/stat, error: %v", err)
-	}
-	defer f.Close()
-	rd := bufio.NewReader(f)
-	line = readFirstLine(rd, f)
-	time.Sleep(time.Duration(freq) * time.Second)
-	newline = readFirstLine(rd, f)
-	return line, newline
-}
-
 func main() {
 	var freq int
 	var partition, netInterface string
@@ -50,9 +34,12 @@ func main() {
 	flag.Parse()
 
 	fmt.Println(gupta.Hello())
+	r, _ := os.Open("/proc/stat")
 
 	for true {
-		line, lineNew := readProcStatLines(freq)
+		line := readProcStatLine(r)
+		time.Sleep(time.Second)
+		lineNew := readProcStatLine(r)
 		cpustat := gupta.NewCPUStat(line, lineNew)
 		fmt.Printf("CPU usage %.2f%%\n", cpustat.CPUUsage())
 	}