return messWith("crc32-not-streamed.zip", func(b []byte) {
		// Corrupt foo.txt's final crc32 byte, in both
		// the file header and TOC. (0x7e -> 0x7f)
		b[0x11]++
		b[0x9d]++

		// TODO(bradfitz): add a new test that only corrupts
		// one of these values, and verify that that's also an
		// error. Currently, the reader code doesn't verify the
		// fileheader and TOC's crc32 match if they're both

		if err != nil {
			return
		}

		type file struct {
			header  *FileHeader
			content []byte
		}
		files := []file{}

		for _, f := range r.File {
			fr, err := f.Open()
			if err != nil {
				continue
			}
			content, err := io.ReadAll(fr)
			if err != nil {
				continue
			}
			files = append(files, file{header: &f.FileHeader, content: content})
			if _, err := r.Open(f.Name); err != nil {

//go:linkname runtime_arena_newArena
func runtime_arena_newArena() unsafe.Pointer

//go:linkname runtime_arena_arena_New
func runtime_arena_arena_New(arena unsafe.Pointer, typ any) any

// Mark as noescape to avoid escaping the slice header.
//
//go:noescape
//go:linkname runtime_arena_arena_Slice
func runtime_arena_arena_Slice(arena unsafe.Pointer, slice any, cap int)

//go:linkname runtime_arena_arena_Free

The Go code can then refer to types such as C.size_t, variables such
as C.stdout, or functions such as C.putchar.

If the import of "C" is immediately preceded by a comment, that
comment, called the preamble, is used as a header when compiling
the C parts of the package. For example:

	// #include <stdio.h>
	// #include <errno.h>
	import "C"

The preamble may contain any C code, including function and variable

pkg syscall (netbsd-arm64), type InterfaceAnnounceMessage struct
pkg syscall (netbsd-arm64), type InterfaceAnnounceMessage struct, Header IfAnnounceMsghdr
pkg syscall (netbsd-arm64), type InterfaceMessage struct
pkg syscall (netbsd-arm64), type InterfaceMessage struct, Data []uint8
pkg syscall (netbsd-arm64), type InterfaceMessage struct, Header IfMsghdr

pkg archive/tar, const TypeGNUSparse = 83
pkg archive/tar, const TypeGNUSparse ideal-char
pkg archive/tar, type Header struct, Xattrs map[string]string
pkg compress/gzip, method (*Reader) Reset(io.Reader) error
pkg crypto/tls, const CurveP256 = 23
pkg crypto/tls, const CurveP256 CurveID
pkg crypto/tls, const CurveP384 = 24
pkg crypto/tls, const CurveP384 CurveID
pkg crypto/tls, const CurveP521 = 25
pkg crypto/tls, const CurveP521 CurveID

			for i, hdr := range hdrs {
				if i >= len(v.headers) {
					t.Fatalf("entry %d: unexpected header:\ngot %+v", i, *hdr)
				}
				if !reflect.DeepEqual(*hdr, *v.headers[i]) {
					t.Fatalf("entry %d: incorrect header:\ngot  %+v\nwant %+v", i, *hdr, *v.headers[i])
				}
			}
			if len(hdrs) != len(v.headers) {
				t.Fatalf("got %d headers, want %d headers", len(hdrs), len(v.headers))
			}

			for i, sum := range chksums {

	}
	b = b[22:] // skip over most of the header
	filenameLen := int(b.uint16())
	extraLen := int(b.uint16())
	return int64(fileHeaderLen + filenameLen + extraLen), nil
}

// readDirectoryHeader attempts to read a directory header from r.
// It returns io.ErrUnexpectedEOF if it cannot read a complete header,
// and ErrFormat if it doesn't find a valid header signature.

// For forward compatibility, users that retrieve a Header from Reader.Next,
// mutate it in some ways, and then pass it back to Writer.WriteHeader
// should do so by creating a new Header and copying the fields
// that they are interested in preserving.
type Header struct {
	// Typeflag is the type of header entry.
	// The zero value is automatically promoted to either TypeReg or TypeDir
	// depending on the presence of a trailing slash in Name.

	*b = block{}
}

type headerV7 [blockSize]byte

func (h *headerV7) name() []byte     { return h[000:][:100] }
func (h *headerV7) mode() []byte     { return h[100:][:8] }
func (h *headerV7) uid() []byte      { return h[108:][:8] }
func (h *headerV7) gid() []byte      { return h[116:][:8] }
func (h *headerV7) size() []byte     { return h[124:][:12] }
func (h *headerV7) modTime() []byte  { return h[136:][:12] }