all: use {bytes,strings}.NewReader instead of bytes.Buffers

Use the smaller read-only bytes.NewReader/strings.NewReader instead
of a bytes.Buffer when possible.

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/54660045

8 files changed, 20 insertions, 19 deletions

diff --git a/src/pkg/encoding/ascii85/ascii85_test.go b/src/pkg/encoding/ascii85/ascii85_test.go
index dc1134dccd..77bc465d59 100644
--- a/src/pkg/encoding/ascii85/ascii85_test.go
+++ b/src/pkg/encoding/ascii85/ascii85_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"io"
 	"io/ioutil"
+	"strings"
 	"testing"
 )
 
@@ -115,7 +116,7 @@ func TestDecode(t *testing.T) {
 
 func TestDecoder(t *testing.T) {
 	for _, p := range pairs {
-		decoder := NewDecoder(bytes.NewBufferString(p.encoded))
+		decoder := NewDecoder(strings.NewReader(p.encoded))
 		dbuf, err := ioutil.ReadAll(decoder)
 		if err != nil {
 			t.Fatal("Read failed", err)
@@ -130,7 +131,7 @@ func TestDecoder(t *testing.T) {
 
 func TestDecoderBuffering(t *testing.T) {
 	for bs := 1; bs <= 12; bs++ {
-		decoder := NewDecoder(bytes.NewBufferString(bigtest.encoded))
+		decoder := NewDecoder(strings.NewReader(bigtest.encoded))
 		buf := make([]byte, len(bigtest.decoded)+12)
 		var total int
 		for total = 0; total < len(bigtest.decoded); {
diff --git a/src/pkg/encoding/base32/base32_test.go b/src/pkg/encoding/base32/base32_test.go
index 63298d1c94..f56b996faa 100644
--- a/src/pkg/encoding/base32/base32_test.go
+++ b/src/pkg/encoding/base32/base32_test.go
@@ -108,7 +108,7 @@ func TestDecode(t *testing.T) {
 
 func TestDecoder(t *testing.T) {
 	for _, p := range pairs {
-		decoder := NewDecoder(StdEncoding, bytes.NewBufferString(p.encoded))
+		decoder := NewDecoder(StdEncoding, strings.NewReader(p.encoded))
 		dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)))
 		count, err := decoder.Read(dbuf)
 		if err != nil && err != io.EOF {
@@ -125,7 +125,7 @@ func TestDecoder(t *testing.T) {
 
 func TestDecoderBuffering(t *testing.T) {
 	for bs := 1; bs <= 12; bs++ {
-		decoder := NewDecoder(StdEncoding, bytes.NewBufferString(bigtest.encoded))
+		decoder := NewDecoder(StdEncoding, strings.NewReader(bigtest.encoded))
 		buf := make([]byte, len(bigtest.decoded)+12)
 		var total int
 		for total = 0; total < len(bigtest.decoded); {
@@ -267,13 +267,13 @@ LNEBUWIIDFON2CA3DBMJXXE5LNFY==
 ====`
 	encodedShort := strings.Replace(encoded, "\n", "", -1)
 
-	dec := NewDecoder(StdEncoding, bytes.NewBufferString(encoded))
+	dec := NewDecoder(StdEncoding, strings.NewReader(encoded))
 	res1, err := ioutil.ReadAll(dec)
 	if err != nil {
 		t.Errorf("ReadAll failed: %v", err)
 	}
 
-	dec = NewDecoder(StdEncoding, bytes.NewBufferString(encodedShort))
+	dec = NewDecoder(StdEncoding, strings.NewReader(encodedShort))
 	var res2 []byte
 	res2, err = ioutil.ReadAll(dec)
 	if err != nil {
diff --git a/src/pkg/encoding/base64/base64_test.go b/src/pkg/encoding/base64/base64_test.go
index 579591a88d..6bcc724d9b 100644
--- a/src/pkg/encoding/base64/base64_test.go
+++ b/src/pkg/encoding/base64/base64_test.go
@@ -113,7 +113,7 @@ func TestDecode(t *testing.T) {
 
 func TestDecoder(t *testing.T) {
 	for _, p := range pairs {
-		decoder := NewDecoder(StdEncoding, bytes.NewBufferString(p.encoded))
+		decoder := NewDecoder(StdEncoding, strings.NewReader(p.encoded))
 		dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)))
 		count, err := decoder.Read(dbuf)
 		if err != nil && err != io.EOF {
@@ -130,7 +130,7 @@ func TestDecoder(t *testing.T) {
 
 func TestDecoderBuffering(t *testing.T) {
 	for bs := 1; bs <= 12; bs++ {
-		decoder := NewDecoder(StdEncoding, bytes.NewBufferString(bigtest.encoded))
+		decoder := NewDecoder(StdEncoding, strings.NewReader(bigtest.encoded))
 		buf := make([]byte, len(bigtest.decoded)+12)
 		var total int
 		for total = 0; total < len(bigtest.decoded); {
@@ -308,13 +308,13 @@ bqbPb06551Y4
 `
 	encodedShort := strings.Replace(encoded, "\n", "", -1)
 
-	dec := NewDecoder(StdEncoding, bytes.NewBufferString(encoded))
+	dec := NewDecoder(StdEncoding, strings.NewReader(encoded))
 	res1, err := ioutil.ReadAll(dec)
 	if err != nil {
 		t.Errorf("ReadAll failed: %v", err)
 	}
 
-	dec = NewDecoder(StdEncoding, bytes.NewBufferString(encodedShort))
+	dec = NewDecoder(StdEncoding, strings.NewReader(encodedShort))
 	var res2 []byte
 	res2, err = ioutil.ReadAll(dec)
 	if err != nil {
diff --git a/src/pkg/encoding/binary/binary_test.go b/src/pkg/encoding/binary/binary_test.go
index fdfee7d871..1aa6ecd248 100644
--- a/src/pkg/encoding/binary/binary_test.go
+++ b/src/pkg/encoding/binary/binary_test.go
@@ -111,7 +111,7 @@ func checkResult(t *testing.T, dir string, order ByteOrder, err error, have, wan
 
 func testRead(t *testing.T, order ByteOrder, b []byte, s1 interface{}) {
 	var s2 Struct
-	err := Read(bytes.NewBuffer(b), order, &s2)
+	err := Read(bytes.NewReader(b), order, &s2)
 	checkResult(t, "Read", order, err, s2, s1)
 }
 
@@ -131,7 +131,7 @@ func TestBigEndianPtrWrite(t *testing.T) { testWrite(t, BigEndian, big, &s) }
 
 func TestReadSlice(t *testing.T) {
 	slice := make([]int32, 2)
-	err := Read(bytes.NewBuffer(src), BigEndian, slice)
+	err := Read(bytes.NewReader(src), BigEndian, slice)
 	checkResult(t, "ReadSlice", BigEndian, err, slice, res)
 }
 
diff --git a/src/pkg/encoding/binary/varint_test.go b/src/pkg/encoding/binary/varint_test.go
index 9476bd5fb7..ca411ecbd6 100644
--- a/src/pkg/encoding/binary/varint_test.go
+++ b/src/pkg/encoding/binary/varint_test.go
@@ -35,7 +35,7 @@ func testVarint(t *testing.T, x int64) {
 		t.Errorf("Varint(%d): got n = %d; want %d", x, m, n)
 	}
 
-	y, err := ReadVarint(bytes.NewBuffer(buf))
+	y, err := ReadVarint(bytes.NewReader(buf))
 	if err != nil {
 		t.Errorf("ReadVarint(%d): %s", x, err)
 	}
@@ -55,7 +55,7 @@ func testUvarint(t *testing.T, x uint64) {
 		t.Errorf("Uvarint(%d): got n = %d; want %d", x, m, n)
 	}
 
-	y, err := ReadUvarint(bytes.NewBuffer(buf))
+	y, err := ReadUvarint(bytes.NewReader(buf))
 	if err != nil {
 		t.Errorf("ReadUvarint(%d): %s", x, err)
 	}
@@ -114,7 +114,7 @@ func TestBufferTooSmall(t *testing.T) {
 			t.Errorf("Uvarint(%v): got x = %d, n = %d", buf, x, n)
 		}
 
-		x, err := ReadUvarint(bytes.NewBuffer(buf))
+		x, err := ReadUvarint(bytes.NewReader(buf))
 		if x != 0 || err != io.EOF {
 			t.Errorf("ReadUvarint(%v): got x = %d, err = %s", buf, x, err)
 		}
@@ -127,7 +127,7 @@ func testOverflow(t *testing.T, buf []byte, n0 int, err0 error) {
 		t.Errorf("Uvarint(%v): got x = %d, n = %d; want 0, %d", buf, x, n, n0)
 	}
 
-	x, err := ReadUvarint(bytes.NewBuffer(buf))
+	x, err := ReadUvarint(bytes.NewReader(buf))
 	if x != 0 || err != err0 {
 		t.Errorf("ReadUvarint(%v): got x = %d, err = %s; want 0, %s", buf, x, err, err0)
 	}
diff --git a/src/pkg/encoding/gob/encoder_test.go b/src/pkg/encoding/gob/encoder_test.go
index 4ecf51d122..299a19914a 100644
--- a/src/pkg/encoding/gob/encoder_test.go
+++ b/src/pkg/encoding/gob/encoder_test.go
@@ -630,7 +630,7 @@ func TestSliceReusesMemory(t *testing.T) {
 // Used to crash: negative count in recvMessage.
 func TestBadCount(t *testing.T) {
 	b := []byte{0xfb, 0xa5, 0x82, 0x2f, 0xca, 0x1}
-	if err := NewDecoder(bytes.NewBuffer(b)).Decode(nil); err == nil {
+	if err := NewDecoder(bytes.NewReader(b)).Decode(nil); err == nil {
 		t.Error("expected error from bad count")
 	} else if err.Error() != errBadCount.Error() {
 		t.Error("expected bad count error; got", err)
diff --git a/src/pkg/encoding/json/encode_test.go b/src/pkg/encoding/json/encode_test.go
index 265a237e44..2e89a78eb9 100644
--- a/src/pkg/encoding/json/encode_test.go
+++ b/src/pkg/encoding/json/encode_test.go
@@ -93,7 +93,7 @@ func TestStringTag(t *testing.T) {
 
 	// Verify that it round-trips.
 	var s2 StringTag
-	err = NewDecoder(bytes.NewBuffer(got)).Decode(&s2)
+	err = NewDecoder(bytes.NewReader(got)).Decode(&s2)
 	if err != nil {
 		t.Fatalf("Decode: %v", err)
 	}
diff --git a/src/pkg/encoding/xml/read.go b/src/pkg/encoding/xml/read.go
index 8890508f85..651d13d4d0 100644
--- a/src/pkg/encoding/xml/read.go
+++ b/src/pkg/encoding/xml/read.go
@@ -112,7 +112,7 @@ import (
 // to a freshly allocated value and then mapping the element to that value.
 //
 func Unmarshal(data []byte, v interface{}) error {
-	return NewDecoder(bytes.NewBuffer(data)).Decode(v)
+	return NewDecoder(bytes.NewReader(data)).Decode(v)
 }
 
 // Decode works like xml.Unmarshal, except it reads the decoder