Fix malformed uname string (#2727)

* Fix malformed uname string

* Make fix better

* Reformat code for simplicity

cmd/prometheus/uname_linux.go

@@ -25,6 +25,7 @@ func Uname() string {
 	if err != nil {
 		log.Fatal("Error!")
 	}
+
 	str := "(" + charsToString(buf.Sysname[:])
 	str += " " + charsToString(buf.Release[:])
 	str += " " + charsToString(buf.Version[:])

cmd/prometheus/uname_linux_int8.go

@@ -17,9 +17,12 @@
 package main
 
 func charsToString(ca []int8) string {
-	s := make([]byte, len(ca))
+	s := make([]byte, 0, len(ca))
-	for i, c := range ca {
+	for _, c := range ca {
-		s[i] = byte(c)
+		if byte(c) == 0 {
+			break
+		}
+		s = append(s, byte(c))
 	}
-	return string(s[0:len(ca)])
+	return string(s)
 }

cmd/prometheus/uname_linux_uint8.go

@@ -17,9 +17,12 @@
 package main
 
 func charsToString(ca []uint8) string {
-	s := make([]byte, len(ca))
+	s := make([]byte, 0, len(ca))
-	for i, c := range ca {
+	for _, c := range ca {
-		s[i] = byte(c)
+		if byte(c) == 0 {
+			break
+		}
+		s = append(s, byte(c))
 	}
-	return string(s[0:len(ca)])
+	return string(s)
 }