mmvdump: fix some lint warnings

mmvdump/cmd/mmvdump/main.go

@@ -25,7 +25,7 @@ func printMetric(offset uint64) {
 	fmt.Printf("\t\ttype=%v (0x%x), sem=%v (0x%x), pad=0x%x\n", m.Typ, int(m.Typ), m.Sem, int(m.Sem), m.Padding)
 	fmt.Printf("\t\tunits=%v\n", m.Unit)
 
-	if m.Indom == mmvdump.NO_INDOM {
+	if m.Indom == mmvdump.NoIndom {
 		fmt.Printf("\t\t(no indom)\n")
 	} else {
 		fmt.Printf("\t\tindom=%d\n", m.Indom)
@@ -61,7 +61,7 @@ func printValue(offset uint64) {
 		a, err = mmvdump.StringVal(v.Val, strings)
 	}
 
-	if m.Indom != mmvdump.NO_INDOM {
+	if m.Indom != mmvdump.NoIndom {
 		i := instances[v.Instance]
 		fmt.Printf("[%d or \"%s\"]", i.Internal, string(i.External[:]))
 	}
@@ -77,15 +77,7 @@ func printString(offset uint64) {
 	fmt.Printf("\t[%v] %v\n", offset, string(strings[offset].Payload[:]))
 }
 
-func main() {
-	flag.Parse()
-
-	if flag.NArg() < 1 {
-		panic("Usage: mmvdump <file>")
-	}
-
-	file := flag.Arg(0)
-
+func data(file string) []byte {
 	f, err := os.Open(file)
 	if err != nil {
 		panic(err)
@@ -104,7 +96,20 @@ func main() {
 		panic(err)
 	}
 
-	header, tocs, metrics, values, instances, indoms, strings, err = mmvdump.Dump(data)
+	return data
+}
+
+func main() {
+	flag.Parse()
+
+	if flag.NArg() < 1 {
+		panic("Usage: mmvdump <file>")
+	}
+
+	file := flag.Arg(0)
+	d := data(file)
+
+	header, tocs, metrics, values, instances, indoms, strings, err = mmvdump.Dump(d)
 	if err != nil {
 		panic(err)
 	}
@@ -120,30 +125,30 @@ Flags     = 0x%x
 
 `, file, header.Version, header.G1, header.Toc, header.Cluster, header.Process, int(header.Flag))
 
-	offset := mmvdump.HeaderLength
+	toff := mmvdump.HeaderLength
 
 	for _, toc := range tocs {
 		switch toc.Type {
 		case mmvdump.TocMetrics:
-			fmt.Printf("TOC[%v], offset: %v, metrics offset: %v (%v entries)\n", int(toc.Type), offset, toc.Offset, toc.Count)
+			fmt.Printf("TOC[%v], offset: %v, metrics offset: %v (%v entries)\n", int(toc.Type), toff, toc.Offset, toc.Count)
 			for i, offset := int32(0), toc.Offset; i < toc.Count; i, offset = i+1, offset+mmvdump.MetricLength {
 				printMetric(offset)
 			}
 
 		case mmvdump.TocValues:
-			fmt.Printf("TOC[%v], offset: %v, values offset: %v (%v entries)\n", int(toc.Type), offset, toc.Offset, toc.Count)
+			fmt.Printf("TOC[%v], offset: %v, values offset: %v (%v entries)\n", int(toc.Type), toff, toc.Offset, toc.Count)
 			for i, offset := int32(0), toc.Offset; i < toc.Count; i, offset = i+1, offset+mmvdump.ValueLength {
 				printValue(offset)
 			}
 
 		case mmvdump.TocStrings:
-			fmt.Printf("TOC[%v], offset: %v, strings offset: %v (%v entries)\n", int(toc.Type), offset, toc.Offset, toc.Count)
+			fmt.Printf("TOC[%v], offset: %v, strings offset: %v (%v entries)\n", int(toc.Type), toff, toc.Offset, toc.Count)
 			for i, offset := int32(0), toc.Offset; i < toc.Count; i, offset = i+1, offset+mmvdump.StringLength {
 				printString(offset)
 			}
 		}
 
 		fmt.Println()
-		offset += mmvdump.TocLength
+		toff += mmvdump.TocLength
 	}
 }

mmvdump/pcp.go

@@ -1,11 +1,17 @@
 package mmvdump
 
+// MMVVersion is the current mmv format version
 const MMVVersion = 1
 
 const (
-	NAMEMAX   = 64
-	STRINGMAX = 256
-	NO_INDOM  = -1
+	// Maximum allowed length of a name
+	NameMax = 64
+
+	// Maximum allowed length of a string
+	StringMax = 256
+
+	// Constant used to indicate abscence of an indom from a metric
+	NoIndom = -1
 )
 
 // Header describes the data in a MMV header
@@ -21,6 +27,7 @@ type Header struct {
 // TocType is an enumerated type with different types as values
 type TocType int32
 
+// Values for TocType
 const (
 	TocIndoms TocType = iota + 1
 	TocInstances
@@ -43,18 +50,18 @@ type Instance struct {
 	Indom    uint64
 	Padding  uint32
 	Internal int32
-	External [NAMEMAX]byte
+	External [NameMax]byte
 }
 
 // InstanceDomain defines the contents in a valid instance domain
 type InstanceDomain struct {
 	Serial, Count               uint32
-	offset, shorttext, longtext uint64
+	Offset, Shorttext, Longtext uint64
 }
 
 // Metric defines the contents in a valid Metric
 type Metric struct {
-	Name                [NAMEMAX]byte
+	Name                [NameMax]byte
 	Item                uint32
 	Typ                 Type
 	Sem                 Semantics
@@ -77,7 +84,7 @@ type Value struct {
 
 // String wraps the payload for a PCP String
 type String struct {
-	Payload [STRINGMAX]byte
+	Payload [StringMax]byte
 }
 
 // Type is an enumerated type representing all valid types for a metric
@@ -101,6 +108,7 @@ const (
 // Unit is an enumerated type with all possible units as values
 type Unit uint32
 
+// Values for Space Units
 const (
 	ByteUnit Unit = 1<<28 | iota<<16
 	KilobyteUnit
@@ -111,6 +119,7 @@ const (
 	ExabyteUnit
 )
 
+// Values for Time Units
 const (
 	NanosecondUnit Unit = 1<<24 | iota<<12
 	MicrosecondUnit
@@ -120,6 +129,7 @@ const (
 	HourUnit
 )
 
+// Values for Count Units
 const OneUnit Unit = 1<<20 | iota<<8
 
 //go:generate stringer --type=Unit
@@ -136,6 +146,7 @@ const (
 
 //go:generate stringer -type=Semantics
 
+// Byte Lengths for Different Components
 const (
 	HeaderLength         uint64 = 40
 	TocLength                   = 16