cmd: extract obj's Biobuf code into new bio package

API could still be made more Go-ey.

Updates #15165.

Change-Id: I514ffceffa43c293ae5d7e5f1e9193fda0098865
Reviewed-on: https://go-review.googlesource.com/21644
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/internal/obj/util.go

@@ -5,10 +5,8 @@
 package obj
 
 import (
-	"bufio"
 	"bytes"
 	"fmt"
-	"io"
 	"log"
 	"os"
 	"strings"
@@ -26,144 +24,6 @@ func Cputime() float64 {
 	return time.Since(start).Seconds()
 }
 
-type Biobuf struct {
-	f       *os.File
-	r       *bufio.Reader
-	w       *bufio.Writer
-	linelen int
-}
-
-func (b *Biobuf) Reader() *bufio.Reader { return b.r }
-
-func Bopenw(name string) (*Biobuf, error) {
-	f, err := os.Create(name)
-	if err != nil {
-		return nil, err
-	}
-	return &Biobuf{f: f, w: bufio.NewWriter(f)}, nil
-}
-
-func Bopenr(name string) (*Biobuf, error) {
-	f, err := os.Open(name)
-	if err != nil {
-		return nil, err
-	}
-	return &Biobuf{f: f, r: bufio.NewReader(f)}, nil
-}
-
-func Binitw(w io.Writer) *Biobuf {
-	return &Biobuf{w: bufio.NewWriter(w)}
-}
-
-func Binitr(r io.Reader) *Biobuf {
-	return &Biobuf{r: bufio.NewReader(r)}
-}
-
-func (b *Biobuf) Write(p []byte) (int, error) {
-	return b.w.Write(p)
-}
-
-func Bwritestring(b *Biobuf, p string) (int, error) {
-	return b.w.WriteString(p)
-}
-
-func Bseek(b *Biobuf, offset int64, whence int) int64 {
-	if b.w != nil {
-		if err := b.w.Flush(); err != nil {
-			log.Fatalf("writing output: %v", err)
-		}
-	} else if b.r != nil {
-		if whence == 1 {
-			offset -= int64(b.r.Buffered())
-		}
-	}
-	off, err := b.f.Seek(offset, whence)
-	if err != nil {
-		log.Fatalf("seeking in output: %v", err)
-	}
-	if b.r != nil {
-		b.r.Reset(b.f)
-	}
-	return off
-}
-
-func Boffset(b *Biobuf) int64 {
-	if b.w != nil {
-		if err := b.w.Flush(); err != nil {
-			log.Fatalf("writing output: %v", err)
-		}
-	}
-	off, err := b.f.Seek(0, 1)
-	if err != nil {
-		log.Fatalf("seeking in output [0, 1]: %v", err)
-	}
-	if b.r != nil {
-		off -= int64(b.r.Buffered())
-	}
-	return off
-}
-
-func (b *Biobuf) Flush() error {
-	return b.w.Flush()
-}
-
-func Bputc(b *Biobuf, c byte) {
-	b.w.WriteByte(c)
-}
-
-const Beof = -1
-
-func Bread(b *Biobuf, p []byte) int {
-	n, err := io.ReadFull(b.r, p)
-	if n == 0 {
-		if err != nil && err != io.EOF {
-			n = -1
-		}
-	}
-	return n
-}
-
-func Bgetc(b *Biobuf) int {
-	c, err := b.r.ReadByte()
-	if err != nil {
-		return -1
-	}
-	return int(c)
-}
-
-func (b *Biobuf) Read(p []byte) (int, error) {
-	return b.r.Read(p)
-}
-
-func (b *Biobuf) Peek(n int) ([]byte, error) {
-	return b.r.Peek(n)
-}
-
-func Brdline(b *Biobuf, delim int) string {
-	s, err := b.r.ReadBytes(byte(delim))
-	if err != nil {
-		log.Fatalf("reading input: %v", err)
-	}
-	b.linelen = len(s)
-	return string(s)
-}
-
-func Blinelen(b *Biobuf) int {
-	return b.linelen
-}
-
-func Bterm(b *Biobuf) error {
-	var err error
-	if b.w != nil {
-		err = b.w.Flush()
-	}
-	err1 := b.f.Close()
-	if err == nil {
-		err = err1
-	}
-	return err
-}
-
 func envOr(key, value string) string {
 	if x := os.Getenv(key); x != "" {
 		return x