// Check that UnreadRune works
	buf.Reset()

	// check at EOF
	if err := buf.UnreadRune(); err == nil {
		t.Fatal("UnreadRune at EOF: got no error")
	}
	if _, _, err := buf.ReadRune(); err == nil {
		t.Fatal("ReadRune at EOF: got no error")
	}
	if err := buf.UnreadRune(); err == nil {
		t.Fatal("UnreadRune after ReadRune at EOF: got no error")
	}

	// check not at EOF
	buf.Write(b)

		// slow, not worth repeating in -check
		t.Skip("skipping with -check set")
	}

	testenv.MustHaveGoBuild(t)

	td, err := os.Open("testdata/src/pkg")
	if err != nil {
		t.Fatal(err)
	}
	fis, err := td.Readdir(0)
	if err != nil {
		t.Fatal(err)
	}
	for _, fi := range fis {
		if !fi.IsDir() {
			continue
		}

		// TODO(gri) remove extra pkg directory eventually

//			log.Fatal(err)
//		}
//
//		biggerZip := makeZip("big.zip", bytes.NewReader(bigZip))
//		if err := os.WriteFile("/tmp/bigger.zip", biggerZip, 0666); err != nil {
//			log.Fatal(err)
//		}
//
//		biggestZip := makeZip("bigger.zip", bytes.NewReader(biggerZip))
//		if err := os.WriteFile("/tmp/biggest.zip", biggestZip, 0666); err != nil {
//			log.Fatal(err)
//		}
//	}
//

			CRC32:              crc32.ChecksumIEEE(data),
		})
		if err != nil {
			log.Fatal(err)
		}
		if _, err := w.Write(data); err != nil {
			log.Fatal(err)
		}
		seen[name] = true
		return nil
	})
	if err != nil {
		log.Fatal(err)
	}
	if err := zw.Close(); err != nil {
		log.Fatal(err)
	}
	if len(seen) == 0 {
		log.Fatalf("did not find any files to add")
	}
	if !seen["US/Eastern"] {

		if err != nil {
			t.Fatal("write chunk:", err)
		}
	}
	end := []byte("END\n")
	_, err = f.Write(end)
	if err != nil {
		t.Fatal("write end:", err)
	}
	if err := w.Close(); err != nil {
		t.Fatal(err)
	}

	// read back zip file and check that we get to the end of it
	r, err := NewReader(buf, buf.Size())
	if err != nil {
		t.Fatal("reader:", err)
	}
	f0 := r.File[0]

func addr2linePath(t testing.TB) string {
	t.Helper()
	testenv.MustHaveExec(t)

	addr2linePathOnce.Do(func() {
		addr2lineExePath, addr2linePathErr = os.Executable()
	})
	if addr2linePathErr != nil {
		t.Fatal(addr2linePathErr)
	}
	return addr2lineExePath
}

var (
	addr2linePathOnce sync.Once
	addr2lineExePath  string
	addr2linePathErr  error
)

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

func bmIndexRune(index func([]byte, rune) int) func(b *testing.B, n int) {
	return func(b *testing.B, n int) {
		buf := bmbuf[0:n]
		utf8.EncodeRune(buf[n-3:], '世')
		for i := 0; i < b.N; i++ {
			j := index(buf, '世')
			if j != n-3 {
				b.Fatal("bad index", j)
			}
		}
		buf[n-3] = '\x00'

	if err := writer.WriteHeader(hdr); err != nil {
		t.Fatal(err)
	}
	if _, err = writer.Write([]byte(contents)); err != nil {
		t.Fatal(err)
	}
	if err := writer.Close(); err != nil {
		t.Fatal(err)
	}
	// Simple test to make sure PAX extensions are in effect
	if !bytes.Contains(buf.Bytes(), []byte("PaxHeaders.0")) {
		t.Fatal("Expected at least one PAX header to be written.")
	}

The [SetCrashOutput] function allows the user to specify an alternate
file to which the runtime should write its fatal crash report.
It may be used to construct an automated reporting mechanism for all
unexpected crashes, not just those in goroutines that explicitly use

	link := filepath.Join(tmpdir, "link")
	target := tmpdir
	if err := os.Symlink(target, link); err != nil {
		t.Fatal(err)
	}
	fi, err := os.Lstat(link)
	if err != nil {
		t.Fatal(err)
	}

	h, err := FileInfoHeader(fi, target)
	if err != nil {
		t.Fatal(err)
	}
	if g, e := h.Name, fi.Name(); g != e {
		t.Errorf("Name = %q; want %q", g, e)
	}
	if g, e := h.Linkname, target; g != e {