buf, err := readSpecialFile(r)
	if err != nil {
		return nil, err
	}
	sbuf := string(buf)

	// For GNU PAX sparse format 0.0 support.
	// This function transforms the sparse format 0.0 headers into format 0.1
	// headers since 0.0 headers were not PAX compliant.
	var sparseMap []string

	paxHdrs := make(map[string]string)
	for len(sbuf) > 0 {

		// or space is needed.
		if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
			copy(s.buf, s.buf[s.start:s.end])
			s.end -= s.start
			s.start = 0
		}
		// Is the buffer full? If so, resize.
		if s.end == len(s.buf) {
			// Guarantee no overflow in the multiplication below.
			const maxInt = int(^uint(0) >> 1)
			if len(s.buf) >= s.maxTokenSize || len(s.buf) > maxInt/2 {
				s.setErr(ErrTooLong)
				return false

	defer ctxt.Bso.Flush()

	architecture.Init(ctxt)

	// Create object file, write header.
	buf, err := bio.Create(*flags.OutputFile)
	if err != nil {
		log.Fatal(err)
	}
	defer buf.Close()

	if !*flags.SymABIs {
		buf.WriteString(objabi.HeaderString())
		fmt.Fprintf(buf, "!\n")
	}

	// Set macros for GOEXPERIMENTs so we can easily switch
	// runtime assembly code based on them.

	var buf []byte
	var directoryEndOffset int64
	for i, bLen := range []int64{1024, 65 * 1024} {
		if bLen > size {
			bLen = size
		}
		buf = make([]byte, int(bLen))
		if _, err := r.ReadAt(buf, size-bLen); err != nil && err != io.EOF {
			return nil, 0, err
		}
		if p := findSignatureInBlock(buf); p >= 0 {
			buf = buf[p:]
			directoryEndOffset = size - bLen + int64(p)

			if j != n-7 {
				b.Fatal("bad index", j)
			}
		}
		buf[n-1] = '\x00'
		buf[n-7] = '\x00'
	})
}

func BenchmarkCount(b *testing.B) {
	benchBytes(b, indexSizes, func(b *testing.B, n int) {
		buf := bmbuf[0:n]
		buf[n-1] = 'x'
		for i := 0; i < b.N; i++ {
			j := Count(buf, buf[n-7:])
			if j != 1 {
				b.Fatal("bad count", j)
			}
		}
		buf[n-1] = '\x00'
	})

)

// godefs returns the output for -godefs mode.
func (p *Package) godefs(f *File, args []string) string {
	var buf strings.Builder

	fmt.Fprintf(&buf, "// Code generated by cmd/cgo -godefs; DO NOT EDIT.\n")
	fmt.Fprintf(&buf, "// %s %s\n", filepath.Base(args[0]), strings.Join(args[1:], " "))
	fmt.Fprintf(&buf, "\n")

	override := make(map[string]string)

	// Allow source file to specify override mappings.

	// A Buffer can turn a string or a []byte into an io.Reader.
	buf := bytes.NewBufferString("R29waGVycyBydWxlIQ==")
	dec := base64.NewDecoder(base64.StdEncoding, buf)
	io.Copy(os.Stdout, dec)
	// Output: Gophers rule!
}

func ExampleBuffer_Bytes() {
	buf := bytes.Buffer{}
	buf.Write([]byte{'h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd'})
	os.Stdout.Write(buf.Bytes())
	// Output: hello world
}

func (ss *suffixSaver) Suffix() []byte {
	if len(ss.buf) < ss.keep {
		return ss.buf
	}
	buf := make([]byte, ss.keep)
	n := copy(buf, ss.buf[ss.start:])
	copy(buf[n:], ss.buf[:])
	return buf
}

func (ss *suffixSaver) Write(p []byte) (n int, err error) {
	n = len(p)
	ss.size += int64(len(p))
	if len(ss.buf) < ss.keep {
		space := ss.keep - len(ss.buf)
		add := len(p)
		if add > space {
			add = space

		}
	}
}

func TestReaderDoubleUnreadRune(t *testing.T) {
	buf := NewBuffer([]byte("groucho"))
	if _, _, err := buf.ReadRune(); err != nil {
		// should not happen
		t.Fatal(err)
	}
	if err := buf.UnreadByte(); err != nil {
		// should not happen
		t.Fatal(err)
	}
	if err := buf.UnreadByte(); err == nil {
		t.Fatal("UnreadByte: expected error, got nil")
	}
}

package tar_test

import (
	"archive/tar"
	"bytes"
	"fmt"
	"io"
	"log"
	"os"
)

func Example_minimal() {
	// Create and add some files to the archive.
	var buf bytes.Buffer
	tw := tar.NewWriter(&buf)
	var files = []struct {
		Name, Body string
	}{
		{"readme.txt", "This archive contains some text files."},
		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},