For security reasons, only a limited set of flags are allowed, notably -D, -U, -I, and -l.
To allow additional flags, set CGO_CFLAGS_ALLOW to a regular expression
matching the new flags. To disallow flags that would otherwise be allowed,
set CGO_CFLAGS_DISALLOW to a regular expression matching arguments
that must be disallowed. In both cases the regular expression must match

func TestReadEmptyAtEOF(t *testing.T) {
	b := new(Buffer)
	slice := make([]byte, 0)
	n, err := b.Read(slice)
	if err != nil {
		t.Errorf("read error: %v", err)
	}
	if n != 0 {
		t.Errorf("wrong count; got %d want 0", n)
	}
}

func TestUnreadByte(t *testing.T) {
	b := new(Buffer)

	// check at EOF
	if err := b.UnreadByte(); err == nil {

var tarinsecurepath = godebug.New("tarinsecurepath")

var (
	ErrHeader          = errors.New("archive/tar: invalid tar header")
	ErrWriteTooLong    = errors.New("archive/tar: write too long")
	ErrFieldTooLong    = errors.New("archive/tar: header field too long")
	ErrWriteAfterClose = errors.New("archive/tar: write after close")
	ErrInsecurePath    = errors.New("archive/tar: insecure file path")

There are, however, times when we cannot maintain complete compatibility.
If code depends on buggy (including insecure) behavior,
then fixing the bug will break that code.
New features can also have similar impacts:
enabling the HTTP/2 use by the HTTP client broke programs
connecting to servers with buggy HTTP/2 implementations.
These kinds of changes are unavoidable and

type ComplexType complex64

// The append built-in function appends elements to the end of a slice. If
// it has sufficient capacity, the destination is resliced to accommodate the
// new elements. If it does not, a new underlying array will be allocated.
// Append returns the updated slice. It is therefore necessary to store the
// result of append, often in the variable holding the slice itself:
//

	"io"
	"runtime"
	"sort"
	"strings"
	"testing"
	"time"
)

func TestOver65kFiles(t *testing.T) {
	if testing.Short() && testenv.Builder() == "" {
		t.Skip("skipping in short mode")
	}
	buf := new(strings.Builder)
	w := NewWriter(buf)
	const nFiles = (1 << 16) + 42
	for i := 0; i < nFiles; i++ {
		_, err := w.CreateHeader(&FileHeader{
			Name:   fmt.Sprintf("%d.dat", i),

package zip

import (
	"bufio"
	"encoding/binary"
	"errors"
	"hash"
	"hash/crc32"
	"io"
	"io/fs"
	"strings"
	"unicode/utf8"
)

var (
	errLongName  = errors.New("zip: FileHeader.Name too long")
	errLongExtra = errors.New("zip: FileHeader.Extra too long")
)

// Writer implements a zip file writer.
type Writer struct {
	cw          *countWriter
	dir         []*header
	last        *fileWriter

		}
	})

	t.Run("NegativeSize", func(t *testing.T) {
		tw := NewWriter(new(bytes.Buffer))
		hdr := &Header{Name: "small.txt", Size: -1}
		if err := tw.WriteHeader(hdr); err == nil {
			t.Fatalf("WriteHeader() = nil, want non-nil error")
		}
	})

	t.Run("BeforeHeader", func(t *testing.T) {
		tw := NewWriter(new(bytes.Buffer))
		if _, err := tw.Write([]byte("Kilts")); err != ErrWriteTooLong {

	s, ok := f.ops[0].(string)
	if !ok {
		return 0, errors.New("unexpected Read operation")
	}

	n := copy(b, s)
	if len(s) > n {
		f.ops[0] = s[n:]
	} else {
		f.ops = f.ops[1:]
	}
	f.pos += int64(len(b))
	return n, nil
}

func (f *testFile) Write(b []byte) (int, error) {
	if len(b) == 0 {
		return 0, nil
	}
	if len(f.ops) == 0 {
		return 0, errors.New("unexpected Write operation")
	}

	// ensure that this error is sticky.
	err error
}

type fileReader interface {
	io.Reader
	fileState

	WriteTo(io.Writer) (int64, error)
}

// NewReader creates a new [Reader] reading from r.
func NewReader(r io.Reader) *Reader {
	return &Reader{r: r, curr: &regFileReader{r, 0}}
}

// Next advances to the next entry in the tar archive.