const n = this.writeSync(fd, buf);
				callback(null, n);
			},
			chmod(path, mode, callback) { callback(enosys()); },
			chown(path, uid, gid, callback) { callback(enosys()); },
			close(fd, callback) { callback(enosys()); },
			fchmod(fd, mode, callback) { callback(enosys()); },
			fchown(fd, uid, gid, callback) { callback(enosys()); },
			fstat(fd, callback) { callback(enosys()); },
			fsync(fd, callback) { callback(null); },

	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
		goldenFile := filepath.Join("testdata", "src", "pkg", fi.Name(), "golden.txt")
		w := NewWalker(nil, "testdata/src/pkg")
		pkg, _ := w.import_(fi.Name())
		w.export(pkg)

pkg syscall (netbsd-arm64-cgo), type Cmsghdr struct, Type int32
pkg syscall (netbsd-arm64-cgo), type Credential struct
pkg syscall (netbsd-arm64-cgo), type Credential struct, Gid uint32
pkg syscall (netbsd-arm64-cgo), type Credential struct, Groups []uint32
pkg syscall (netbsd-arm64-cgo), type Credential struct, NoSetGroups bool
pkg syscall (netbsd-arm64-cgo), type Credential struct, Uid uint32

	}

	v7 := tw.blk.toV7()
	v7.typeFlag()[0] = hdr.Typeflag
	fmtStr(v7.name(), hdr.Name)
	fmtStr(v7.linkName(), hdr.Linkname)
	fmtNum(v7.mode(), hdr.Mode)
	fmtNum(v7.uid(), int64(hdr.Uid))
	fmtNum(v7.gid(), int64(hdr.Gid))
	fmtNum(v7.size(), hdr.Size)
	fmtNum(v7.modTime(), modTime.Unix())

	ustar := tw.blk.toUSTAR()
	fmtStr(ustar.userName(), hdr.Uname)
	fmtStr(ustar.groupName(), hdr.Gname)

pkg syscall (windows-386), type AddrinfoW struct, Socktype int32
pkg syscall (windows-386), type GUID struct
pkg syscall (windows-386), type GUID struct, Data1 uint32
pkg syscall (windows-386), type GUID struct, Data2 uint16
pkg syscall (windows-386), type GUID struct, Data3 uint16
pkg syscall (windows-386), type GUID struct, Data4 [8]uint8
pkg syscall (windows-386), type RawSockaddrInet6 struct, Family uint16

}

// userMap and groupMap caches UID and GID lookups for performance reasons.
// The downside is that renaming uname or gname by the OS never takes effect.
var userMap, groupMap sync.Map // map[int]string

func statUnix(fi fs.FileInfo, h *Header, doNameLookups bool) error {
	sys, ok := fi.Sys().(*syscall.Stat_t)
	if !ok {
		return nil
	}
	h.Uid = int(sys.Uid)
	h.Gid = int(sys.Gid)
	if doNameLookups {

pkg os/user, method (UnknownGroupError) Error() string
pkg os/user, method (UnknownGroupIdError) Error() string
pkg os/user, type Group struct
pkg os/user, type Group struct, Gid string
pkg os/user, type Group struct, Name string
pkg os/user, type UnknownGroupError string
pkg os/user, type UnknownGroupIdError string
pkg reflect, func StructOf([]StructField) Type

	MSR	R6, ERXFR_EL1                                    // ERROR "system register is not writable"
	MSR	R6, ERXPFGF_EL1                                  // ERROR "system register is not writable"
	MSR	R6, GMID_EL1                                     // ERROR "system register is not writable"
	MSR	R6, ICC_HPPIR0_EL1                               // ERROR "system register is not writable"

pkg syscall (windows-386), type WSAProtocolInfo struct, ProtocolName [256]uint16
pkg syscall (windows-386), type WSAProtocolInfo struct, ProviderFlags uint32
pkg syscall (windows-386), type WSAProtocolInfo struct, ProviderId GUID
pkg syscall (windows-386), type WSAProtocolInfo struct, ProviderReserved uint32
pkg syscall (windows-386), type WSAProtocolInfo struct, SecurityScheme int32

		{call: "Setregid(101,0)", fn: func() error { return syscall.Setregid(101, 0) }, filter: "Gid:", expect: "\t101\t0\t0\t0"},
		{call: "Setregid(0,102)", fn: func() error { return syscall.Setregid(0, 102) }, filter: "Gid:", expect: "\t0\t102\t102\t102"},
		{call: "Setregid(0,0)", fn: func() error { return syscall.Setregid(0, 0) }, filter: "Gid:", expect: "\t0\t0\t0\t0"},