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

2 files changed, 10 insertions, 10 deletions

diff --git a/src/pkg/debug/elf/file.go b/src/pkg/debug/elf/file.go
index 07661aa166..a406170996 100644
--- a/src/pkg/debug/elf/file.go
+++ b/src/pkg/debug/elf/file.go
@@ -412,7 +412,7 @@ func (f *File) getSymbols32(typ SectionType) ([]Symbol, []byte, error) {
 	if err != nil {
 		return nil, nil, errors.New("cannot load symbol section")
 	}
-	symtab := bytes.NewBuffer(data)
+	symtab := bytes.NewReader(data)
 	if symtab.Len()%Sym32Size != 0 {
 		return nil, nil, errors.New("length of symbol section is not a multiple of SymSize")
 	}
@@ -455,7 +455,7 @@ func (f *File) getSymbols64(typ SectionType) ([]Symbol, []byte, error) {
 	if err != nil {
 		return nil, nil, errors.New("cannot load symbol section")
 	}
-	symtab := bytes.NewBuffer(data)
+	symtab := bytes.NewReader(data)
 	if symtab.Len()%Sym64Size != 0 {
 		return nil, nil, errors.New("length of symbol section is not a multiple of Sym64Size")
 	}
@@ -533,7 +533,7 @@ func (f *File) applyRelocationsAMD64(dst []byte, rels []byte) error {
 		return err
 	}
 
-	b := bytes.NewBuffer(rels)
+	b := bytes.NewReader(rels)
 	var rela Rela64
 
 	for b.Len() > 0 {
diff --git a/src/pkg/debug/macho/file.go b/src/pkg/debug/macho/file.go
index f5f0dedb7c..c799fa49df 100644
--- a/src/pkg/debug/macho/file.go
+++ b/src/pkg/debug/macho/file.go
@@ -246,7 +246,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdDylib:
 			var hdr DylibCmd
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &hdr); err != nil {
 				return nil, err
 			}
@@ -263,7 +263,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdSymtab:
 			var hdr SymtabCmd
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &hdr); err != nil {
 				return nil, err
 			}
@@ -290,7 +290,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdDysymtab:
 			var hdr DysymtabCmd
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &hdr); err != nil {
 				return nil, err
 			}
@@ -299,7 +299,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 				return nil, err
 			}
 			x := make([]uint32, hdr.Nindirectsyms)
-			if err := binary.Read(bytes.NewBuffer(dat), bo, x); err != nil {
+			if err := binary.Read(bytes.NewReader(dat), bo, x); err != nil {
 				return nil, err
 			}
 			st := new(Dysymtab)
@@ -311,7 +311,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdSegment:
 			var seg32 Segment32
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &seg32); err != nil {
 				return nil, err
 			}
@@ -349,7 +349,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 
 		case LoadCmdSegment64:
 			var seg64 Segment64
-			b := bytes.NewBuffer(cmddat)
+			b := bytes.NewReader(cmddat)
 			if err := binary.Read(b, bo, &seg64); err != nil {
 				return nil, err
 			}
@@ -396,7 +396,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 func (f *File) parseSymtab(symdat, strtab, cmddat []byte, hdr *SymtabCmd, offset int64) (*Symtab, error) {
 	bo := f.ByteOrder
 	symtab := make([]Symbol, hdr.Nsyms)
-	b := bytes.NewBuffer(symdat)
+	b := bytes.NewReader(symdat)
 	for i := range symtab {
 		var n Nlist64
 		if f.Magic == Magic64 {