lib/ascii: change signature of ToLower and ToUpper

Using pointer to slice on method or function is not a Go idiom.
It is created when I still new to Go.

6 files changed, 55 insertions, 41 deletions

diff --git a/lib/ascii/ascii.go b/lib/ascii/ascii.go
index 145006a8..b12e8789 100644
--- a/lib/ascii/ascii.go
+++ b/lib/ascii/ascii.go
@@ -110,25 +110,29 @@ func Random(source []byte, n int) []byte {
 }
 
 //
-// ToLower convert slice of ASCII characters to lower cases, in places.
+// ToLower convert slice of ASCII characters to lower cases, in places, which
+// means it will return the same slice instead of creating new one.
 //
-func ToLower(data *[]byte) {
-	for x := 0; x < len(*data); x++ {
-		if (*data)[x] < 'A' || (*data)[x] > 'Z' {
+func ToLower(data []byte) []byte {
+	for x := 0; x < len(data); x++ {
+		if data[x] < 'A' || data[x] > 'Z' {
 			continue
 		}
-		(*data)[x] += 32
+		data[x] += 32
 	}
+	return data
 }
 
 //
-// ToUpper convert slice of ASCII characters to upper cases, in places.
+// ToUpper convert slice of ASCII characters to upper cases, in places, which
+// means it will return the same slice instead of creating new one.
 //
-func ToUpper(data *[]byte) {
-	for x := 0; x < len(*data); x++ {
-		if (*data)[x] < 'a' || (*data)[x] > 'z' {
+func ToUpper(data []byte) []byte {
+	for x := 0; x < len(data); x++ {
+		if data[x] < 'a' || data[x] > 'z' {
 			continue
 		}
-		(*data)[x] -= 32
+		data[x] -= 32
 	}
+	return data
 }
diff --git a/lib/ascii/ascii_example_test.go b/lib/ascii/ascii_example_test.go
index b835e779..7f651117 100644
--- a/lib/ascii/ascii_example_test.go
+++ b/lib/ascii/ascii_example_test.go
@@ -126,20 +126,14 @@ func ExampleRandom() {
 
 func ExampleToLower() {
 	in := []byte("@ABCDEFGhijklmnoPQRSTUVWxyz{12345678")
-
-	ToLower(&in)
-
-	fmt.Println(string(in))
+	fmt.Printf("%s\n", ToLower(in))
 	// Output:
 	// @abcdefghijklmnopqrstuvwxyz{12345678
 }
 
 func ExampleToUpper() {
 	in := []byte("@ABCDEFGhijklmnoPQRSTUVWxyz{12345678")
-
-	ToUpper(&in)
-
-	fmt.Println(string(in))
+	fmt.Printf("%s\n", ToUpper(in))
 	// Output:
 	// @ABCDEFGHIJKLMNOPQRSTUVWXYZ{12345678
 }
diff --git a/lib/ascii/benchmark_test.go b/lib/ascii/benchmark_test.go
index 1a2d4a4b..f3f95e45 100644
--- a/lib/ascii/benchmark_test.go
+++ b/lib/ascii/benchmark_test.go
@@ -31,19 +31,35 @@ func BenchmarkToLower(b *testing.B) {
 	b.ResetTimer()
 
 	for x := 0; x < b.N; x++ {
-		ToLower(&in)
-		copy(in, randomInput256)
+		ToLower(in)
+		copy(in, randomInput256) // Copy original input back.
 	}
 }
 
-//
-// Output of above benchmarks,
-//
-// goos: linux
-// goarch: amd64
-// pkg: github.com/shuLhan/share/lib/ascii
-// BenchmarkToLowerStd-4            2066588               563 ns/op             256 B/op          1 allocs/op
-// BenchmarkToLower-4               5476693               213 ns/op               0 B/op          0 allocs/op
-// PASS
-// ok      github.com/shuLhan/share/lib/ascii      3.149s
-//
+/****
+Output of above benchmarks,
+
+=== go version devel go1.18-d38f31d805
+
+Wed 13 Oct 17:45:42 UTC 2021
+
+goos: linux
+goarch: amd64
+pkg: github.com/shuLhan/share/lib/ascii
+cpu: 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
+BenchmarkToLowerStd-8            3683070               328.9 ns/op           256 B/op          1 allocs/op
+BenchmarkToLower-8               5221684               232.0 ns/op             0 B/op          0 allocs/op
+PASS
+ok      github.com/shuLhan/share/lib/ascii      2.990s
+
+=== go version ???
+
+goos: linux
+goarch: amd64
+pkg: github.com/shuLhan/share/lib/ascii
+BenchmarkToLowerStd-4            2066588               563 ns/op             256 B/op          1 allocs/op
+BenchmarkToLower-4               5476693               213 ns/op               0 B/op          0 allocs/op
+PASS
+ok      github.com/shuLhan/share/lib/ascii      3.149s
+
+****/
diff --git a/lib/dns/message.go b/lib/dns/message.go
index ff90e31d..d32f84f4 100644
--- a/lib/dns/message.go
+++ b/lib/dns/message.go
@@ -109,7 +109,7 @@ func NewMessageAddress(hname []byte, addresses [][]byte) (msg *Message) {
 		return nil
 	}
 
-	ascii.ToLower(&hname)
+	hname = ascii.ToLower(hname)
 
 	rr := ResourceRecord{
 		Name:  string(hname),
@@ -237,7 +237,7 @@ func (msg *Message) packDomainName(dname []byte, doCompress bool) (n int) {
 		d  int
 	)
 
-	ascii.ToLower(&dname)
+	dname = ascii.ToLower(dname)
 	msg.dname = string(dname)
 
 	if doCompress {
diff --git a/lib/dns/zone_parser.go b/lib/dns/zone_parser.go
index 731f8c7d..059c6cda 100644
--- a/lib/dns/zone_parser.go
+++ b/lib/dns/zone_parser.go
@@ -178,7 +178,7 @@ func (m *zoneParser) parse() (err error) {
 				m.lineno, m.reader.Rest())
 		}
 
-		ascii.ToUpper(&tok)
+		tok = ascii.ToUpper(tok)
 		stok := string(tok)
 
 		switch stok {
@@ -272,7 +272,7 @@ func (m *zoneParser) parseDirectiveInclude() (err error) {
 
 	var incfile, dname string
 
-	ascii.ToLower(&tok)
+	tok = ascii.ToLower(tok)
 	incfile = string(tok)
 
 	// check if include followed by domain name.
@@ -330,7 +330,7 @@ func (m *zoneParser) parseDirectiveTTL() (err error) {
 		return fmt.Errorf("line %d: empty $ttl directive", m.lineno)
 	}
 
-	ascii.ToLower(&tok)
+	tok = ascii.ToLower(tok)
 	stok := string(tok)
 
 	m.ttl, err = parseTTL(tok, stok)
@@ -462,7 +462,7 @@ func (m *zoneParser) parseRR(prevRR *ResourceRecord, tok []byte) (
 		}
 
 		orgtok := libbytes.Copy(tok)
-		ascii.ToUpper(&tok)
+		tok = ascii.ToUpper(tok)
 		stok = string(tok)
 
 		switch m.flag {
@@ -630,7 +630,7 @@ func (m *zoneParser) parseRRData(rr *ResourceRecord, tok []byte) (err error) {
 }
 
 func (m *zoneParser) parseSOA(rr *ResourceRecord, tok []byte) (err error) {
-	ascii.ToLower(&tok)
+	tok = ascii.ToLower(tok)
 
 	rrSOA := &RDataSOA{
 		MName: m.generateDomainName(tok),
@@ -648,7 +648,7 @@ func (m *zoneParser) parseSOA(rr *ResourceRecord, tok []byte) (err error) {
 		return fmt.Errorf("line %d: Invalid SOA RNAME '%s'", m.lineno, tok)
 	}
 
-	ascii.ToLower(&tok)
+	tok = ascii.ToLower(tok)
 	rrSOA.RName = m.generateDomainName(tok)
 
 	var v int64
@@ -956,7 +956,7 @@ out:
 }
 
 func (m *zoneParser) generateDomainName(dname []byte) (out string) {
-	ascii.ToLower(&dname)
+	dname = ascii.ToLower(dname)
 	switch {
 	case dname[0] == '@':
 		out = m.origin
diff --git a/lib/net/resolvconf.go b/lib/net/resolvconf.go
index da435ad2..24c3621f 100644
--- a/lib/net/resolvconf.go
+++ b/lib/net/resolvconf.go
@@ -165,7 +165,7 @@ func (rc *ResolvConf) parse(reader *libio.Reader) {
 			continue
 		}
 
-		ascii.ToLower(&tok)
+		tok = ascii.ToLower(tok)
 		v := string(tok)
 		switch v {
 		case "domain":