// Trace contains a set of hooks for tracing events within
// the net package. Any specific hook may be nil.
type Trace struct {
	// DNSStart is called with the hostname of a DNS lookup
	// before it begins.
	DNSStart func(name string)

	// DNSDone is called after a DNS lookup completes (or fails).
	// The coalesced parameter is whether singleflight de-duped
	// the call. The addrs are of type net.IPAddr but can't

	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
		return nil
	}
	return fs.ErrPermission
}

// LookPath searches for an executable named file in the
// directories named by the path environment variable.
// If file begins with "/", "#", "./", or "../", it is tried
// directly and the path is not consulted.
// On success, the result is an absolute path.
//
// In older versions of Go, LookPath could return a path relative to the current directory.

			return
		}
	}

	// Now at __.PKGDEF in archive or still at beginning of file.
	// Either way, line should begin with "go object ".
	if !strings.HasPrefix(string(line), "go object ") {
		err = fmt.Errorf("not a Go object file")
		return
	}
	size -= len(line)

	// Skip over object header to export data.
	// Begins after first line starting with $$.
	for line[0] != '$' {
		if line, err = r.ReadSlice('\n'); err != nil {

void CopyAttributes(Operation *from, Operation *to, Predicate P) {
  for (const NamedAttribute &attr : from->getAttrs())
    if (P(attr)) to->setAttr(attr.getName(), attr.getValue());
}

// Copies attributes whose name begins with an _ from `from` to `to`.
inline void CopyUnderscoredAttributes(Operation *from, Operation *to) {
  CopyAttributes(from, to, [](const NamedAttribute &attr) {
    return attr.getName().strref().front() == '_';
  });

// [errors.Is](err, [ErrDot]). See the package documentation for more details.
func LookPath(file string) (string, error) {
	// NOTE(rsc): I wish we could use the Plan 9 behavior here
	// (only bypass the path if file begins with / or ./ or ../)
	// but that would not match all the Unix shells.

	if strings.Contains(file, "/") {
		err := findExecutable(file)
		if err == nil {
			return file, nil
		}
		return "", &Error{file, err}

The following is the format for a full module:

“go index v2\n”
str uint32 - offset of string table
n uint32 - number of packages
for each rawPackage:
	dirname - string offset
	package - offset where package begins
for each rawPackage:
	error uint32 - string offset // error is produced by fsys.ReadDir or fmt.Errorf
	dir uint32 - string offset (directory path relative to module root)
	len(sourceFiles) uint32

In general script files should have short names: a few words, not whole sentences.
The first word should be the general category of behavior being tested,
often the name of a go subcommand (list, build, test, ...) or concept (vendor, pattern).

Each script is a text archive (go doc internal/txtar).
The script begins with an actual command script to run
followed by the content of zero or more supporting files to

	buf := make([]byte, 256)
	f, err := os.Open(file)
	if err != nil {
		return "", err
	}
	defer f.Close()

	if _, err := f.ReadAt(buf[:64], 0); err != nil {
		return "", err
	}

	// ELF file begins with \x7F E L F.
	if buf[0] != 0x7F || buf[1] != 'E' || buf[2] != 'L' || buf[3] != 'F' {
		return "", errBadELF
	}

	var byteOrder binary.ByteOrder
	switch buf[5] {
	default:
		return "", errBadELF

	Got1xxResponse func(code int, header textproto.MIMEHeader) error

	// DNSStart is called when a DNS lookup begins.
	DNSStart func(DNSStartInfo)

	// DNSDone is called when a DNS lookup ends.
	DNSDone func(DNSDoneInfo)

	// ConnectStart is called when a new connection's Dial begins.
	// If net.Dialer.DualStack (IPv6 "Happy Eyeballs") support is
	// enabled, this may be called multiple times.

func (f *machoFile) symbols() ([]Sym, error) {
	if f.macho.Symtab == nil {
		return nil, nil
	}

	// Build sorted list of addresses of all symbols.
	// We infer the size of a symbol by looking at where the next symbol begins.
	var addrs []uint64
	for _, s := range f.macho.Symtab.Syms {
		// Skip stab debug info.
		if s.Type&stabTypeMask == 0 {
			addrs = append(addrs, s.Value)
		}
	}
	sort.Sort(uint64s(addrs))

	var syms []Sym