func (sc *ServerConn) Read() (*http.Request, error) {
	var req *http.Request
	var err error

	// Ensure ordered execution of Reads and Writes
	id := sc.pipe.Next()
	sc.pipe.StartRequest(id)
	defer func() {
		sc.pipe.EndRequest(id)
		if req == nil {
			sc.pipe.StartResponse(id)
			sc.pipe.EndResponse(id)
		} else {
			// Remember the pipeline id of this request
			sc.mu.Lock()
			sc.pipereq[req] = id
			sc.mu.Unlock()
		}

	NodeType
	Pos
	tr   *Tree
	Line int       // The line number in the input. Deprecated: Kept for compatibility.
	Pipe *PipeNode // The pipeline in the action.
}

func (t *Tree) newAction(pos Pos, line int, pipe *PipeNode) *ActionNode {
	return &ActionNode{tr: t, NodeType: NodeAction, Pos: pos, Line: line, Pipe: pipe}
}

func (a *ActionNode) String() string {
	var sb strings.Builder
	a.writeTo(&sb)
	return sb.String()

        "The security ID structure is invalid.", "The file system is full.", "All pipe instances are busy.", "All pipe instances are busy.",
        "The pipe state is invalid.", "All pipe instances are busy.", "No process is on the other end of the pipe.", "The pipe is being closed.",
        "Waiting for a process to open the other end of the pipe.", "File is a directory.", "A duplicate name exists on the network.",

	// so that pass 2 won't stomp on an fd it needs later.
	if pipe < nextfd {
		r1, _, _ = RawSyscall(SYS_DUP, uintptr(pipe), uintptr(nextfd), 0)
		if int32(r1) == -1 {
			goto childerror
		}
		pipe = nextfd
		nextfd++
	}
	for i = 0; i < len(fd); i++ {
		if fd[i] >= 0 && fd[i] < i {
			if nextfd == pipe { // don't stomp on pipe
				nextfd++
			}

        "The security ID structure is invalid.",
        "All pipe instances are busy.",
        "All pipe instances are busy.",
        "The pipe state is invalid.",
        "All pipe instances are busy.",
        "No process is on the other end of the pipe.",
        "The pipe is being closed.",
        "Waiting for a process to open the other end of the pipe.",
        "Access is denied.",

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "EDEADLK", "resource deadlock avoided"},
	{36, "ENAMETOOLONG", "file name too long"},

	val, _ := indirect(s.evalPipeline(dot, r.Pipe))
	// mark top of stack before any variables in the body are pushed.
	mark := s.mark()
	oneIteration := func(index, elem reflect.Value) {
		if len(r.Pipe.Decl) > 0 {
			if r.Pipe.IsAssign {
				// With two variables, index comes first.
				// With one, we use the element.
				if len(r.Pipe.Decl) > 1 {
					s.setVar(r.Pipe.Decl[0].Ident[0], index)
				} else {

	// so that pass 2 won't stomp on an fd it needs later.
	if pipe < nextfd {
		_, _, err1 = RawSyscall(SYS_DUP3, uintptr(pipe), uintptr(nextfd), O_CLOEXEC)
		if err1 != 0 {
			goto childerror
		}
		pipe = nextfd
		nextfd++
	}
	for i = 0; i < len(fd); i++ {
		if fd[i] >= 0 && fd[i] < i {
			if nextfd == pipe { // don't stomp on pipe
				nextfd++
			}

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "ENOMSG", "no message of desired type"},
	{36, "EIDRM", "identifier removed"},

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "EDEADLK", "resource deadlock avoided"},
	{36, "ENAMETOOLONG", "file name too long"},