"ESTALE":          ESTALE,
	"ENOTSUP":         ENOTSUP,
	"ENOMEDIUM":       ENOMEDIUM,
	"ECANCELED":       ECANCELED,
	"ELBIN":           ELBIN,
	"EFTYPE":          EFTYPE,
	"ENMFILE":         ENMFILE,
	"EPROCLIM":        EPROCLIM,
	"ENOSHARE":        ENOSHARE,
	"ECASECLASH":      ECASECLASH,
	"EWOULDBLOCK":     EWOULDBLOCK,

	if err != nil {
		t.Fatalf("Socketpair: %v", err)
	}
	writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
	readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
	defer writeFile.Close()
	defer readFile.Close()

	cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")

// from io.Copy.
type writerOnly struct {
	io.Writer
}

// ReadFrom is here to optimize copying from an [*os.File] regular file
// to a [*net.TCPConn] with sendfile, or from a supported src type such
// as a *net.TCPConn on Linux with splice.
func (w *response) ReadFrom(src io.Reader) (n int64, err error) {
	buf := getCopyBuf()
	defer putCopyBuf(buf)

func TestReadFile(t *testing.T) {
	// Test that ReadFile uses the method when present.
	data, err := ReadFile(readFileOnly{testFsys}, "hello.txt")
	if string(data) != "hello, world" || err != nil {
		t.Fatalf(`ReadFile(readFileOnly, "hello.txt") = %q, %v, want %q, nil`, data, err, "hello, world")
	}

	// Test that ReadFile uses Open when the method is not present.
	data, err = ReadFile(openOnly{testFsys}, "hello.txt")

pkg syscall (freebsd-386-cgo), func Seek(int, int64, int) (int64, error)
pkg syscall (freebsd-386-cgo), func Select(int, *FdSet, *FdSet, *FdSet, *Timeval) error
pkg syscall (freebsd-386-cgo), func Sendfile(int, int, *int64, int) (int, error)
pkg syscall (freebsd-386-cgo), func Sendmsg(int, []uint8, []uint8, Sockaddr, int) error
pkg syscall (freebsd-386-cgo), func Sendto(int, []uint8, int, Sockaddr) error

	}
}

func TestReadFile(t *testing.T) {
	filename := "rumpelstilzchen"
	contents, err := ReadFile(filename)
	if err == nil {
		t.Fatalf("ReadFile %s: error expected, none found", filename)
	}

	filename = "ioutil_test.go"
	contents, err = ReadFile(filename)
	if err != nil {
		t.Fatalf("ReadFile %s: %v", filename, err)
	}

	checkSize(t, filename, int64(len(contents)))
}

		rxOp, err := regexp.Compile(pattern)
		if err != nil {
			log.Fatalf("bad opcode regexp %s: %v", pattern, err)
		}

		src, err := os.ReadFile(a.genfile)
		if err != nil {
			log.Fatalf("can't read %s: %v", a.genfile, err)
		}
		seen := make(map[string]bool, len(a.ops))
		for _, m := range rxOp.FindAllSubmatch(src, -1) {
			seen[string(m[1])] = true
		}
		for _, op := range a.ops {

	}
}

func TestReadFile(t *testing.T) {
	t.Parallel()

	filename := "rumpelstilzchen"
	contents, err := ReadFile(filename)
	if err == nil {
		t.Fatalf("ReadFile %s: error expected, none found", filename)
	}

	filename = "read_test.go"
	contents, err = ReadFile(filename)
	if err != nil {
		t.Fatalf("ReadFile %s: %v", filename, err)
	}

	checkNamedSize(t, filename, int64(len(contents)))
}

			continue
		}
		defer os.Remove(f)
		id, err := ReadFile(f)
		if id != expectedID || err != nil {
			t.Errorf("ReadFile(testdata/%s) = %q, %v, want %q, nil", f, id, err, expectedID)
		}
		old := readSize
		readSize = 2048
		id, err = ReadFile(f)
		readSize = old
		if id != expectedID || err != nil {
			t.Errorf("ReadFile(%s) [readSize=2k] = %q, %v, want %q, nil", f, id, err, expectedID)
		}

func GetVersion() (*version.Version, error) {
	return getVersion(os.ReadFile)
}

// getVersion reads os release file from the give readFile function.
func getVersion(readFile readFileFunc) (*version.Version, error) {
	kernelVersionFile := "/proc/sys/kernel/osrelease"
	fileContent, err := readFile(kernelVersionFile)
	if err != nil {
		return nil, fmt.Errorf("failed to read os-release file: %s", err.Error())