view src/channel.c @ 35308:22c03485f222 v9.1.0456

patch 9.1.0456: Left shift is incorrect with vartabstop and shiftwidth=0 Commit: https://github.com/vim/vim/commit/88d4f255b7b7a19bb4f6489e0ad0956e47d51fed Author: Gary Johnson <garyjohn@spocom.com> Date: Sat Jun 1 20:51:33 2024 +0200 patch 9.1.0456: Left shift is incorrect with vartabstop and shiftwidth=0 Problem: Left shift is incorrect with vartabstop and shiftwidth=0 Solution: make tabstop_at() function aware of shift direction (Gary Johnson) The problem was that with 'vartabstop' set and 'shiftwidth' equal 0, left shifts using << were shifting the line to the wrong column. The tabstop to the right of the first character in the line was being used as the shift amount instead of the tabstop to the left of that first character. The reason was that the tabstop_at() function always returned the value of the tabstop to the right of the given column and was not accounting for the direction of the shift. The solution was to make tabstop_at() aware of the direction of the shift and to choose the tabtop accordingly. A test was added to check this behavior and make sure it doesn't regress. While at it, also fix a few indentation/alignment issues. fixes: #14864 closes: #14887 Signed-off-by: Gary Johnson <garyjohn@spocom.com> Signed-off-by: Christian Brabandt <cb@256bit.org>
author Christian Brabandt <cb@256bit.org>
date Sat, 01 Jun 2024 21:00:03 +0200
parents 9e093c96dff6
children f9d90d17c7a2
line wrap: on
line source

/* vi:set ts=8 sts=4 sw=4 noet:
 *
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 */

/*
 * Implements communication through a socket or any file handle.
 */

#include "vim.h"

#if defined(FEAT_JOB_CHANNEL) || defined(PROTO)

// TRUE when netbeans is running with a GUI.
#ifdef FEAT_GUI
# define CH_HAS_GUI (gui.in_use || gui.starting)
#endif

// Note: when making changes here also adjust configure.ac.
#ifdef MSWIN
// WinSock API is separated from C API, thus we can't use read(), write(),
// errno...
# define SOCK_ERRNO errno = WSAGetLastError()
# undef ECONNREFUSED
# define ECONNREFUSED WSAECONNREFUSED
# undef EWOULDBLOCK
# define EWOULDBLOCK WSAEWOULDBLOCK
# undef EINPROGRESS
# define EINPROGRESS WSAEINPROGRESS
# ifdef EINTR
#  undef EINTR
# endif
# define EINTR WSAEINTR
# define sock_write(sd, buf, len) send((SOCKET)sd, buf, len, 0)
# define sock_read(sd, buf, len) recv((SOCKET)sd, buf, len, 0)
# define sock_close(sd) closesocket((SOCKET)sd)
// Support for Unix-domain sockets was added in Windows SDK 17061.
# define UNIX_PATH_MAX 108
typedef struct sockaddr_un {
    ADDRESS_FAMILY sun_family;
    char sun_path[UNIX_PATH_MAX];
} SOCKADDR_UN, *PSOCKADDR_UN;
#else
# include <netdb.h>
# include <netinet/in.h>
# include <arpa/inet.h>
# include <sys/socket.h>
# include <sys/un.h>
# ifdef HAVE_LIBGEN_H
#  include <libgen.h>
# endif
# define SOCK_ERRNO
# define sock_write(sd, buf, len) write(sd, buf, len)
# define sock_read(sd, buf, len) read(sd, buf, len)
# define sock_close(sd) close(sd)
# define fd_read(fd, buf, len) read(fd, buf, len)
# define fd_write(sd, buf, len) write(sd, buf, len)
# define fd_close(sd) close(sd)
#endif

static void channel_read(channel_T *channel, ch_part_T part, char *func);
static ch_mode_T channel_get_mode(channel_T *channel, ch_part_T part);
static int channel_get_timeout(channel_T *channel, ch_part_T part);
static ch_part_T channel_part_send(channel_T *channel);
static ch_part_T channel_part_read(channel_T *channel);

#define FOR_ALL_CHANNELS(ch) \
    for ((ch) = first_channel; (ch) != NULL; (ch) = (ch)->ch_next)

// Whether we are inside channel_parse_messages() or another situation where it
// is safe to invoke callbacks.
static int safe_to_invoke_callback = 0;

#ifdef MSWIN
    static int
fd_read(sock_T fd, char *buf, size_t len)
{
    HANDLE h = (HANDLE)fd;
    DWORD nread;

    if (!ReadFile(h, buf, (DWORD)len, &nread, NULL))
	return -1;
    return (int)nread;
}

    static int
fd_write(sock_T fd, char *buf, size_t len)
{
    size_t	todo = len;
    HANDLE	h = (HANDLE)fd;
    DWORD	nwrite, size, done = 0;
    OVERLAPPED	ov;

    while (todo > 0)
    {
	if (todo > MAX_NAMED_PIPE_SIZE)
	    size = MAX_NAMED_PIPE_SIZE;
	else
	    size = (DWORD)todo;
	// If the pipe overflows while the job does not read the data,
	// WriteFile() will block forever. This abandons the write.
	CLEAR_FIELD(ov);
	nwrite = 0;
	if (!WriteFile(h, buf + done, size, &nwrite, &ov))
	{
	    DWORD err = GetLastError();

	    if (err != ERROR_IO_PENDING)
		return -1;
	    if (!GetOverlappedResult(h, &ov, &nwrite, FALSE))
		return -1;
	    FlushFileBuffers(h);
	}
	else if (nwrite == 0)
	    // WriteFile() returns TRUE but did not write anything. This causes
	    // a hang, so bail out.
	    break;
	todo -= nwrite;
	done += nwrite;
    }
    return (int)done;
}

    static void
fd_close(sock_T fd)
{
    HANDLE h = (HANDLE)fd;

    CloseHandle(h);
}
#endif

#ifdef MSWIN
# undef PERROR
# define PERROR(msg) (void)semsg("%s: %s", msg, strerror_win32(errno))

    static char *
strerror_win32(int eno)
{
    static LPVOID msgbuf = NULL;
    char_u *ptr;

    if (msgbuf)
    {
	LocalFree(msgbuf);
	msgbuf = NULL;
    }
    FormatMessage(
	FORMAT_MESSAGE_ALLOCATE_BUFFER |
	FORMAT_MESSAGE_FROM_SYSTEM |
	FORMAT_MESSAGE_IGNORE_INSERTS,
	NULL,
	eno,
	MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
	(LPTSTR) &msgbuf,
	0,
	NULL);
    if (msgbuf != NULL)
	// chomp \r or \n
	for (ptr = (char_u *)msgbuf; *ptr; ptr++)
	    switch (*ptr)
	    {
		case '\r':
		    STRMOVE(ptr, ptr + 1);
		    ptr--;
		    break;
		case '\n':
		    if (*(ptr + 1) == '\0')
			*ptr = '\0';
		    else
			*ptr = ' ';
		    break;
	    }
    return msgbuf;
}
#endif

/*
 * The list of all allocated channels.
 */
static channel_T *first_channel = NULL;
static int next_ch_id = 0;

/*
 * Allocate a new channel.  The refcount is set to 1.
 * The channel isn't actually used until it is opened.
 * Returns NULL if out of memory.
 */
    channel_T *
add_channel(void)
{
    ch_part_T	part;
    channel_T	*channel = ALLOC_CLEAR_ONE(channel_T);

    if (channel == NULL)
	return NULL;

    channel->ch_id = next_ch_id++;
    ch_log(channel, "Created channel");

    for (part = PART_SOCK; part < PART_COUNT; ++part)
    {
	channel->ch_part[part].ch_fd = INVALID_FD;
#ifdef FEAT_GUI_X11
	channel->ch_part[part].ch_inputHandler = (XtInputId)NULL;
#endif
#ifdef FEAT_GUI_GTK
	channel->ch_part[part].ch_inputHandler = 0;
#endif
	channel->ch_part[part].ch_timeout = 2000;
    }

    if (first_channel != NULL)
    {
	first_channel->ch_prev = channel;
	channel->ch_next = first_channel;
    }
    first_channel = channel;

    channel->ch_refcount = 1;
    return channel;
}

    int
has_any_channel(void)
{
    return first_channel != NULL;
}

/*
 * Called when the refcount of a channel is zero.
 * Return TRUE if "channel" has a callback and the associated job wasn't
 * killed.
 */
    int
channel_still_useful(channel_T *channel)
{
    int has_sock_msg;
    int	has_out_msg;
    int	has_err_msg;

    // If the job was killed the channel is not expected to work anymore.
    if (channel->ch_job_killed && channel->ch_job == NULL)
	return FALSE;

    // If there is a close callback it may still need to be invoked.
    if (channel->ch_close_cb.cb_name != NULL)
	return TRUE;

    // If reading from or a buffer it's still useful.
    if (channel->ch_part[PART_IN].ch_bufref.br_buf != NULL)
	return TRUE;

    // If there is no callback then nobody can get readahead.  If the fd is
    // closed and there is no readahead then the callback won't be called.
    has_sock_msg = channel->ch_part[PART_SOCK].ch_fd != INVALID_FD
		|| channel->ch_part[PART_SOCK].ch_head.rq_next != NULL
		|| channel->ch_part[PART_SOCK].ch_json_head.jq_next != NULL;
    has_out_msg = channel->ch_part[PART_OUT].ch_fd != INVALID_FD
		  || channel->ch_part[PART_OUT].ch_head.rq_next != NULL
		  || channel->ch_part[PART_OUT].ch_json_head.jq_next != NULL;
    has_err_msg = channel->ch_part[PART_ERR].ch_fd != INVALID_FD
		  || channel->ch_part[PART_ERR].ch_head.rq_next != NULL
		  || channel->ch_part[PART_ERR].ch_json_head.jq_next != NULL;
    return (channel->ch_callback.cb_name != NULL && (has_sock_msg
		|| has_out_msg || has_err_msg))
	    || ((channel->ch_part[PART_OUT].ch_callback.cb_name != NULL
		       || channel->ch_part[PART_OUT].ch_bufref.br_buf != NULL)
		    && has_out_msg)
	    || ((channel->ch_part[PART_ERR].ch_callback.cb_name != NULL
		       || channel->ch_part[PART_ERR].ch_bufref.br_buf != NULL)
		    && has_err_msg);
}

/*
 * Return TRUE if "channel" is closeable (i.e. all readable fds are closed).
 */
    int
channel_can_close(channel_T *channel)
{
    return channel->ch_to_be_closed == 0;
}

/*
 * Close a channel and free all its resources.
 * The "channel" pointer remains valid.
 */
    static void
channel_free_contents(channel_T *channel)
{
    channel_close(channel, TRUE);
    channel_clear(channel);
    ch_log(channel, "Freeing channel");
}

/*
 * Unlink "channel" from the list of channels and free it.
 */
    static void
channel_free_channel(channel_T *channel)
{
    if (channel->ch_next != NULL)
	channel->ch_next->ch_prev = channel->ch_prev;
    if (channel->ch_prev == NULL)
	first_channel = channel->ch_next;
    else
	channel->ch_prev->ch_next = channel->ch_next;
    vim_free(channel);
}

    static void
channel_free(channel_T *channel)
{
    if (in_free_unref_items)
	return;

    if (safe_to_invoke_callback == 0)
	channel->ch_to_be_freed = TRUE;
    else
    {
	channel_free_contents(channel);
	channel_free_channel(channel);
    }
}

/*
 * Close a channel and free all its resources if there is no further action
 * possible, there is no callback to be invoked or the associated job was
 * killed.
 * Return TRUE if the channel was freed.
 */
    static int
channel_may_free(channel_T *channel)
{
    if (!channel_still_useful(channel))
    {
	channel_free(channel);
	return TRUE;
    }
    return FALSE;
}

/*
 * Decrement the reference count on "channel" and maybe free it when it goes
 * down to zero.  Don't free it if there is a pending action.
 * Returns TRUE when the channel is no longer referenced.
 */
    int
channel_unref(channel_T *channel)
{
    if (channel != NULL && --channel->ch_refcount <= 0)
	return channel_may_free(channel);
    return FALSE;
}

    int
free_unused_channels_contents(int copyID, int mask)
{
    int		did_free = FALSE;
    channel_T	*ch;

    // This is invoked from the garbage collector, which only runs at a safe
    // point.
    ++safe_to_invoke_callback;

    FOR_ALL_CHANNELS(ch)
	if (!channel_still_useful(ch)
				 && (ch->ch_copyID & mask) != (copyID & mask))
	{
	    // Free the channel and ordinary items it contains, but don't
	    // recurse into Lists, Dictionaries etc.
	    channel_free_contents(ch);
	    did_free = TRUE;
	}

    --safe_to_invoke_callback;
    return did_free;
}

    void
free_unused_channels(int copyID, int mask)
{
    channel_T	*ch;
    channel_T	*ch_next;

    for (ch = first_channel; ch != NULL; ch = ch_next)
    {
	ch_next = ch->ch_next;
	if (!channel_still_useful(ch)
				 && (ch->ch_copyID & mask) != (copyID & mask))
	    // Free the channel struct itself.
	    channel_free_channel(ch);
    }
}

#if defined(FEAT_GUI) || defined(PROTO)

# if defined(FEAT_GUI_X11) || defined(FEAT_GUI_GTK)
/*
 * Lookup the channel from the socket.  Set "partp" to the fd index.
 * Returns NULL when the socket isn't found.
 */
    static channel_T *
channel_fd2channel(sock_T fd, ch_part_T *partp)
{
    channel_T	*channel;
    ch_part_T	part;

    if (fd == INVALID_FD)
	return NULL;

    FOR_ALL_CHANNELS(channel)
    {
	for (part = PART_SOCK; part < PART_IN; ++part)
	    if (channel->ch_part[part].ch_fd == fd)
	    {
		*partp = part;
		return channel;
	    }
    }
    return NULL;
}

    static void
channel_read_fd(int fd)
{
    channel_T	*channel;
    ch_part_T	part;

    channel = channel_fd2channel(fd, &part);
    if (channel == NULL)
	ch_error(NULL, "Channel for fd %d not found", fd);
    else
	channel_read(channel, part, "channel_read_fd");
}
# endif

/*
 * Read a command from netbeans.
 */
# ifdef FEAT_GUI_X11
    static void
messageFromServerX11(XtPointer clientData,
		  int *unused1 UNUSED,
		  XtInputId *unused2 UNUSED)
{
    channel_read_fd((int)(long)clientData);
}
# endif

# ifdef FEAT_GUI_GTK
#  if GTK_CHECK_VERSION(3,0,0)
    static gboolean
messageFromServerGtk3(GIOChannel *unused1 UNUSED,
		  GIOCondition unused2 UNUSED,
		  gpointer clientData)
{
    channel_read_fd(GPOINTER_TO_INT(clientData));
    return TRUE; // Return FALSE instead in case the event source is to
		 // be removed after this function returns.
}
#  else
    static void
messageFromServerGtk2(gpointer clientData,
		  gint unused1 UNUSED,
		  GdkInputCondition unused2 UNUSED)
{
    channel_read_fd((int)(long)clientData);
}
#  endif
# endif

    static void
channel_gui_register_one(channel_T *channel, ch_part_T part UNUSED)
{
    if (!CH_HAS_GUI)
	return;

    // gets stuck in handling events for a not connected channel
    if (channel->ch_keep_open)
	return;

# ifdef FEAT_GUI_X11
    // Tell notifier we are interested in being called when there is input on
    // the editor connection socket.
    if (channel->ch_part[part].ch_inputHandler == (XtInputId)NULL)
    {
	ch_log(channel, "Registering part %s with fd %d",
		ch_part_names[part], channel->ch_part[part].ch_fd);

	channel->ch_part[part].ch_inputHandler = XtAppAddInput(
		(XtAppContext)app_context,
		channel->ch_part[part].ch_fd,
		(XtPointer)(XtInputReadMask + XtInputExceptMask),
		messageFromServerX11,
		(XtPointer)(long)channel->ch_part[part].ch_fd);
    }
# else
#  ifdef FEAT_GUI_GTK
    // Tell gdk we are interested in being called when there is input on the
    // editor connection socket.
    if (channel->ch_part[part].ch_inputHandler == 0)
    {
	ch_log(channel, "Registering part %s with fd %d",
		ch_part_names[part], channel->ch_part[part].ch_fd);
#   if GTK_CHECK_VERSION(3,0,0)
	GIOChannel *chnnl = g_io_channel_unix_new(
		(gint)channel->ch_part[part].ch_fd);

	channel->ch_part[part].ch_inputHandler = g_io_add_watch(
		chnnl,
		G_IO_IN|G_IO_HUP|G_IO_ERR|G_IO_PRI,
		messageFromServerGtk3,
		GINT_TO_POINTER(channel->ch_part[part].ch_fd));

	g_io_channel_unref(chnnl);
#   else
	channel->ch_part[part].ch_inputHandler = gdk_input_add(
		(gint)channel->ch_part[part].ch_fd,
		(GdkInputCondition)
			     ((int)GDK_INPUT_READ + (int)GDK_INPUT_EXCEPTION),
		messageFromServerGtk2,
		(gpointer)(long)channel->ch_part[part].ch_fd);
#   endif
    }
#  endif
# endif
}

    static void
channel_gui_register(channel_T *channel)
{
    if (channel->CH_SOCK_FD != INVALID_FD)
	channel_gui_register_one(channel, PART_SOCK);
    if (channel->CH_OUT_FD != INVALID_FD
	    && channel->CH_OUT_FD != channel->CH_SOCK_FD)
	channel_gui_register_one(channel, PART_OUT);
    if (channel->CH_ERR_FD != INVALID_FD
	    && channel->CH_ERR_FD != channel->CH_SOCK_FD
	    && channel->CH_ERR_FD != channel->CH_OUT_FD)
	channel_gui_register_one(channel, PART_ERR);
}

/*
 * Register any of our file descriptors with the GUI event handling system.
 * Called when the GUI has started.
 */
    void
channel_gui_register_all(void)
{
    channel_T *channel;

    FOR_ALL_CHANNELS(channel)
	channel_gui_register(channel);
}

    static void
channel_gui_unregister_one(channel_T *channel UNUSED, ch_part_T part UNUSED)
{
# ifdef FEAT_GUI_X11
    if (channel->ch_part[part].ch_inputHandler != (XtInputId)NULL)
    {
	ch_log(channel, "Unregistering part %s", ch_part_names[part]);
	XtRemoveInput(channel->ch_part[part].ch_inputHandler);
	channel->ch_part[part].ch_inputHandler = (XtInputId)NULL;
    }
# else
#  ifdef FEAT_GUI_GTK
    if (channel->ch_part[part].ch_inputHandler != 0)
    {
	ch_log(channel, "Unregistering part %s", ch_part_names[part]);
#   if GTK_CHECK_VERSION(3,0,0)
	g_source_remove(channel->ch_part[part].ch_inputHandler);
#   else
	gdk_input_remove(channel->ch_part[part].ch_inputHandler);
#   endif
	channel->ch_part[part].ch_inputHandler = 0;
    }
#  endif
# endif
}

    static void
channel_gui_unregister(channel_T *channel)
{
    ch_part_T	part;

    for (part = PART_SOCK; part < PART_IN; ++part)
	channel_gui_unregister_one(channel, part);
}

#endif  // FEAT_GUI

/*
 * For Unix we need to call connect() again after connect() failed.
 * On Win32 one time is sufficient.
 */
    static int
channel_connect(
	channel_T *channel,
	const struct sockaddr *server_addr,
	int server_addrlen,
	int *waittime)
{
    int		sd = -1;
#ifdef MSWIN
    u_long	val = 1;
#endif

    while (TRUE)
    {
	long	elapsed_msec = 0;
	int	waitnow;
	int	ret;

	if (sd >= 0)
	    sock_close(sd);
	sd = socket(server_addr->sa_family, SOCK_STREAM, 0);
	if (sd == -1)
	{
	    ch_error(channel, "in socket() in channel_connect().");
	    PERROR(_(e_socket_in_channel_connect));
	    return -1;
	}

	if (*waittime >= 0)
	{
	    // Make connect() non-blocking.
	    if (
#ifdef MSWIN
		ioctlsocket(sd, FIONBIO, &val) < 0
#else
		fcntl(sd, F_SETFL, O_NONBLOCK) < 0
#endif
	       )
	    {
		SOCK_ERRNO;
		ch_error(channel,
		      "channel_connect: Connect failed with errno %d", errno);
		sock_close(sd);
		return -1;
	    }
	}

	// Try connecting to the server.
	ch_log(channel, "Connecting...");

	ret = connect(sd, server_addr, server_addrlen);
	if (ret == 0)
	    // The connection could be established.
	    break;

	SOCK_ERRNO;
	if (*waittime < 0 || (errno != EWOULDBLOCK
		&& errno != ECONNREFUSED
#ifdef EINPROGRESS
		&& errno != EINPROGRESS
#endif
		))
	{
	    ch_error(channel,
		      "channel_connect: Connect failed with errno %d", errno);
	    PERROR(_(e_cannot_connect_to_port));
	    sock_close(sd);
	    return -1;
	}
	else if (errno == ECONNREFUSED)
	{
	    ch_error(channel, "channel_connect: Connection refused");
	    sock_close(sd);
	    return -1;
	}

	// Limit the waittime to 50 msec.  If it doesn't work within this
	// time we close the socket and try creating it again.
	waitnow = *waittime > 50 ? 50 : *waittime;

	// If connect() didn't finish then try using select() to wait for the
	// connection to be made. For Win32 always use select() to wait.
	{
	    struct timeval	tv;
	    fd_set		rfds;
	    fd_set		wfds;
#ifndef MSWIN
	    int			so_error = 0;
	    socklen_t		so_error_len = sizeof(so_error);
	    struct timeval	start_tv;
	    struct timeval	end_tv;
#endif
	    FD_ZERO(&rfds);
	    FD_SET(sd, &rfds);
	    FD_ZERO(&wfds);
	    FD_SET(sd, &wfds);

	    tv.tv_sec = waitnow / 1000;
	    tv.tv_usec = (waitnow % 1000) * 1000;
#ifndef MSWIN
	    gettimeofday(&start_tv, NULL);
#endif
	    ch_log(channel,
		      "Waiting for connection (waiting %d msec)...", waitnow);

	    ret = select(sd + 1, &rfds, &wfds, NULL, &tv);
	    if (ret < 0)
	    {
		SOCK_ERRNO;
		ch_error(channel,
		      "channel_connect: Connect failed with errno %d", errno);
		PERROR(_(e_cannot_connect_to_port));
		sock_close(sd);
		return -1;
	    }

#ifdef MSWIN
	    // On Win32: select() is expected to work and wait for up to
	    // "waitnow" msec for the socket to be open.
	    if (FD_ISSET(sd, &wfds))
		break;
	    elapsed_msec = waitnow;
	    if (*waittime > 1 && elapsed_msec < *waittime)
	    {
		*waittime -= elapsed_msec;
		continue;
	    }
#else
	    // On Linux-like systems: See socket(7) for the behavior
	    // After putting the socket in non-blocking mode, connect() will
	    // return EINPROGRESS, select() will not wait (as if writing is
	    // possible), need to use getsockopt() to check if the socket is
	    // actually able to connect.
	    // We detect a failure to connect when either read and write fds
	    // are set.  Use getsockopt() to find out what kind of failure.
	    if (FD_ISSET(sd, &rfds) || FD_ISSET(sd, &wfds))
	    {
		ret = getsockopt(sd,
			      SOL_SOCKET, SO_ERROR, &so_error, &so_error_len);
		if (ret < 0 || (so_error != 0
			&& so_error != EWOULDBLOCK
			&& so_error != ECONNREFUSED
# ifdef EINPROGRESS
			&& so_error != EINPROGRESS
# endif
			))
		{
		    ch_error(channel,
			    "channel_connect: Connect failed with errno %d",
			    so_error);
		    PERROR(_(e_cannot_connect_to_port));
		    sock_close(sd);
		    return -1;
		}
		else if (errno == ECONNREFUSED)
		{
		    ch_error(channel, "channel_connect: Connection refused");
		    sock_close(sd);
		    return -1;
		}
	    }

	    if (FD_ISSET(sd, &wfds) && so_error == 0)
		// Did not detect an error, connection is established.
		break;

	    gettimeofday(&end_tv, NULL);
	    elapsed_msec = (end_tv.tv_sec - start_tv.tv_sec) * 1000
				 + (end_tv.tv_usec - start_tv.tv_usec) / 1000;
#endif
	}

#ifndef MSWIN
	if (*waittime > 1 && elapsed_msec < *waittime)
	{
	    // The port isn't ready but we also didn't get an error.
	    // This happens when the server didn't open the socket
	    // yet.  Select() may return early, wait until the remaining
	    // "waitnow"  and try again.
	    waitnow -= elapsed_msec;
	    *waittime -= elapsed_msec;
	    if (waitnow > 0)
	    {
		mch_delay((long)waitnow, MCH_DELAY_IGNOREINPUT);
		ui_breakcheck();
		*waittime -= waitnow;
	    }
	    if (!got_int)
	    {
		if (*waittime <= 0)
		    // give it one more try
		    *waittime = 1;
		continue;
	    }
	    // we were interrupted, behave as if timed out
	}
#endif

	// We timed out.
	ch_error(channel, "Connection timed out");
	sock_close(sd);
	return -1;
    }

    if (*waittime >= 0)
    {
#ifdef MSWIN
	val = 0;
	ioctlsocket(sd, FIONBIO, &val);
#else
	(void)fcntl(sd, F_SETFL, 0);
#endif
    }

    return sd;
}

/*
 * Open a socket channel to the UNIX socket at "path".
 * Returns the channel for success.
 * Returns NULL for failure.
 */
    static channel_T *
channel_open_unix(
	const char *path,
	void (*nb_close_cb)(void))
{
    channel_T		*channel = NULL;
    int			sd = -1;
    size_t		path_len = STRLEN(path);
    struct sockaddr_un	server;
    size_t		server_len;
    int			waittime = -1;

    if (*path == NUL || path_len >= sizeof(server.sun_path))
    {
	semsg(_(e_invalid_argument_str), path);
	return NULL;
    }

    channel = add_channel();
    if (channel == NULL)
    {
	ch_error(NULL, "Cannot allocate channel.");
	return NULL;
    }

    CLEAR_FIELD(server);
    server.sun_family = AF_UNIX;
    STRNCPY(server.sun_path, path, sizeof(server.sun_path) - 1);

    ch_log(channel, "Trying to connect to %s", path);

    server_len = offsetof(struct sockaddr_un, sun_path) + path_len + 1;
    sd = channel_connect(channel, (struct sockaddr *)&server, (int)server_len,
								   &waittime);

    if (sd < 0)
    {
	channel_free(channel);
	return NULL;
    }

    ch_log(channel, "Connection made");

    channel->CH_SOCK_FD = (sock_T)sd;
    channel->ch_nb_close_cb = nb_close_cb;
    channel->ch_hostname = (char *)vim_strsave((char_u *)path);
    channel->ch_port = 0;
    channel->ch_to_be_closed |= (1U << PART_SOCK);

#ifdef FEAT_GUI
    channel_gui_register_one(channel, PART_SOCK);
#endif

    return channel;
}

/*
 * Open a socket channel to "hostname":"port".
 * "waittime" is the time in msec to wait for the connection.
 * When negative wait forever.
 * Returns the channel for success.
 * Returns NULL for failure.
 */
    channel_T *
channel_open(
	const char *hostname,
	int port,
	int waittime,
	void (*nb_close_cb)(void))
{
    int			sd = -1;
    channel_T		*channel = NULL;
#ifdef FEAT_IPV6
    int			err;
    struct addrinfo	hints;
    struct addrinfo	*res = NULL;
    struct addrinfo	*addr = NULL;
#else
    struct sockaddr_in	server;
    struct hostent	*host = NULL;
#endif

#ifdef MSWIN
    channel_init_winsock();
#endif

    channel = add_channel();
    if (channel == NULL)
    {
	ch_error(NULL, "Cannot allocate channel.");
	return NULL;
    }

    // Get the server internet address and put into addr structure fill in the
    // socket address structure and connect to server.
#ifdef FEAT_IPV6
    CLEAR_FIELD(hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
# if defined(__ANDROID__)
    hints.ai_flags = AI_ADDRCONFIG;
# elif defined(AI_ADDRCONFIG) && defined(AI_V4MAPPED)
    hints.ai_flags = AI_ADDRCONFIG | AI_V4MAPPED;
# endif
    // Set port number manually in order to prevent name resolution services
    // from being invoked in the environment where AI_NUMERICSERV is not
    // defined.
    if ((err = getaddrinfo(hostname, NULL, &hints, &res)) != 0)
    {
	ch_error(channel, "in getaddrinfo() in channel_open()");
	semsg(_(e_getaddrinfo_in_channel_open_str), gai_strerror(err));
	channel_free(channel);
	return NULL;
    }

    for (addr = res; addr != NULL; addr = addr->ai_next)
    {
	const char  *dst = hostname;
# ifdef HAVE_INET_NTOP
	const void  *src = NULL;
	char	    buf[NUMBUFLEN];
# endif

	if (addr->ai_family == AF_INET6)
	{
	    struct sockaddr_in6 *sai = (struct sockaddr_in6 *)addr->ai_addr;

	    sai->sin6_port = htons(port);
# ifdef HAVE_INET_NTOP
	    src = &sai->sin6_addr;
# endif
	}
	else if (addr->ai_family == AF_INET)
	{
	    struct sockaddr_in *sai = (struct sockaddr_in *)addr->ai_addr;

	    sai->sin_port = htons(port);
# ifdef HAVE_INET_NTOP
	    src = &sai->sin_addr;
#endif
	}
# ifdef HAVE_INET_NTOP
	if (src != NULL)
	{
	    dst = inet_ntop(addr->ai_family, src, buf, sizeof(buf));
	    if (dst == NULL)
		dst = hostname;
	    else if (STRCMP(hostname, dst) != 0)
		ch_log(channel, "Resolved %s to %s", hostname, dst);
	}
# endif

	ch_log(channel, "Trying to connect to %s port %d", dst, port);

	// On Mac and Solaris a zero timeout almost never works.  Waiting for
	// one millisecond already helps a lot.  Later Mac systems (using IPv6)
	// need more time, 15 milliseconds appears to work well.
	// Let's do it for all systems, because we don't know why this is
	// needed.
	if (waittime == 0)
	    waittime = 15;

	sd = channel_connect(channel, addr->ai_addr, (int)addr->ai_addrlen,
								   &waittime);
	if (sd >= 0)
	    break;
    }

    freeaddrinfo(res);
#else
    CLEAR_FIELD(server);
    server.sin_family = AF_INET;
    server.sin_port = htons(port);
    if ((host = gethostbyname(hostname)) == NULL)
    {
	ch_error(channel, "in gethostbyname() in channel_open()");
	PERROR(_(e_gethostbyname_in_channel_open));
	channel_free(channel);
	return NULL;
    }
    {
	char *p;

	// When using host->h_addr_list[0] directly ubsan warns for it to not
	// be aligned.  First copy the pointer to avoid that.
	memcpy(&p, &host->h_addr_list[0], sizeof(p));
	memcpy((char *)&server.sin_addr, p, host->h_length);
    }

    ch_log(channel, "Trying to connect to %s port %d", hostname, port);

    // On Mac and Solaris a zero timeout almost never works.  At least wait one
    // millisecond.  Let's do it for all systems, because we don't know why
    // this is needed.
    if (waittime == 0)
	waittime = 1;

    sd = channel_connect(channel, (struct sockaddr *)&server, sizeof(server),
								   &waittime);
#endif

    if (sd < 0)
    {
	channel_free(channel);
	return NULL;
    }

    ch_log(channel, "Connection made");

    channel->CH_SOCK_FD = (sock_T)sd;
    channel->ch_nb_close_cb = nb_close_cb;
    channel->ch_hostname = (char *)vim_strsave((char_u *)hostname);
    channel->ch_port = port;
    channel->ch_to_be_closed |= (1U << PART_SOCK);

#ifdef FEAT_GUI
    channel_gui_register_one(channel, PART_SOCK);
#endif

    return channel;
}

    static void
free_set_callback(callback_T *cbp, callback_T *callback)
{
    free_callback(cbp);

    if (callback->cb_name != NULL && *callback->cb_name != NUL)
	copy_callback(cbp, callback);
    else
	cbp->cb_name = NULL;
}

/*
 * Prepare buffer "buf" for writing channel output to.
 */
	static void
prepare_buffer(buf_T *buf)
{
    buf_T *save_curbuf = curbuf;

    buf_copy_options(buf, BCO_ENTER);
    curbuf = buf;
#ifdef FEAT_QUICKFIX
    set_option_value_give_err((char_u *)"bt",
					    0L, (char_u *)"nofile", OPT_LOCAL);
    set_option_value_give_err((char_u *)"bh", 0L, (char_u *)"hide", OPT_LOCAL);
#endif
    if (curbuf->b_ml.ml_mfp == NULL)
	ml_open(curbuf);
    curbuf = save_curbuf;
}

/*
 * Find a buffer matching "name" or create a new one.
 * Returns NULL if there is something very wrong (error already reported).
 */
    static buf_T *
channel_find_buffer(char_u *name, int err, int msg)
{
    buf_T *buf = NULL;
    buf_T *save_curbuf = curbuf;

    if (name != NULL && *name != NUL)
    {
	buf = buflist_findname(name);
	if (buf == NULL)
	    buf = buflist_findname_exp(name);
    }

    if (buf != NULL)
	return buf;

    buf = buflist_new(name == NULL || *name == NUL ? NULL : name,
	    NULL, (linenr_T)0, BLN_LISTED | BLN_NEW);
    if (buf == NULL)
	return NULL;
    prepare_buffer(buf);

    curbuf = buf;
    if (msg)
	ml_replace(1, (char_u *)(err ? "Reading from channel error..."
		    : "Reading from channel output..."), TRUE);
    changed_bytes(1, 0);
    curbuf = save_curbuf;

    return buf;
}

/*
 * Set various properties from an "opt" argument.
 */
    static void
channel_set_options(channel_T *channel, jobopt_T *opt)
{
    ch_part_T	part;

    if (opt->jo_set & JO_MODE)
	for (part = PART_SOCK; part < PART_COUNT; ++part)
	    channel->ch_part[part].ch_mode = opt->jo_mode;
    if (opt->jo_set & JO_IN_MODE)
	channel->ch_part[PART_IN].ch_mode = opt->jo_in_mode;
    if (opt->jo_set & JO_OUT_MODE)
	channel->ch_part[PART_OUT].ch_mode = opt->jo_out_mode;
    if (opt->jo_set & JO_ERR_MODE)
	channel->ch_part[PART_ERR].ch_mode = opt->jo_err_mode;
    channel->ch_nonblock = opt->jo_noblock;

    if (opt->jo_set & JO_TIMEOUT)
	for (part = PART_SOCK; part < PART_COUNT; ++part)
	    channel->ch_part[part].ch_timeout = opt->jo_timeout;
    if (opt->jo_set & JO_OUT_TIMEOUT)
	channel->ch_part[PART_OUT].ch_timeout = opt->jo_out_timeout;
    if (opt->jo_set & JO_ERR_TIMEOUT)
	channel->ch_part[PART_ERR].ch_timeout = opt->jo_err_timeout;
    if (opt->jo_set & JO_BLOCK_WRITE)
	channel->ch_part[PART_IN].ch_block_write = 1;

    if (opt->jo_set & JO_CALLBACK)
	free_set_callback(&channel->ch_callback, &opt->jo_callback);
    if (opt->jo_set & JO_OUT_CALLBACK)
	free_set_callback(&channel->ch_part[PART_OUT].ch_callback,
							      &opt->jo_out_cb);
    if (opt->jo_set & JO_ERR_CALLBACK)
	free_set_callback(&channel->ch_part[PART_ERR].ch_callback,
							      &opt->jo_err_cb);
    if (opt->jo_set & JO_CLOSE_CALLBACK)
	free_set_callback(&channel->ch_close_cb, &opt->jo_close_cb);
    channel->ch_drop_never = opt->jo_drop_never;

    if ((opt->jo_set & JO_OUT_IO) && opt->jo_io[PART_OUT] == JIO_BUFFER)
    {
	buf_T *buf;

	// writing output to a buffer. Default mode is NL.
	if (!(opt->jo_set & JO_OUT_MODE))
	    channel->ch_part[PART_OUT].ch_mode = CH_MODE_NL;
	if (opt->jo_set & JO_OUT_BUF)
	{
	    buf = buflist_findnr(opt->jo_io_buf[PART_OUT]);
	    if (buf == NULL)
		semsg(_(e_buffer_nr_does_not_exist),
					       (long)opt->jo_io_buf[PART_OUT]);
	}
	else
	{
	    int msg = TRUE;

	    if (opt->jo_set2 & JO2_OUT_MSG)
		msg = opt->jo_message[PART_OUT];
	    buf = channel_find_buffer(opt->jo_io_name[PART_OUT], FALSE, msg);
	}
	if (buf != NULL)
	{
	    if (opt->jo_set & JO_OUT_MODIFIABLE)
		channel->ch_part[PART_OUT].ch_nomodifiable =
						!opt->jo_modifiable[PART_OUT];

	    if (!buf->b_p_ma && !channel->ch_part[PART_OUT].ch_nomodifiable)
	    {
		emsg(_(e_cannot_make_changes_modifiable_is_off));
	    }
	    else
	    {
		ch_log(channel, "writing out to buffer '%s'",
						       (char *)buf->b_ffname);
		set_bufref(&channel->ch_part[PART_OUT].ch_bufref, buf);
		// if the buffer was deleted or unloaded resurrect it
		if (buf->b_ml.ml_mfp == NULL)
		    prepare_buffer(buf);
	    }
	}
    }

    if ((opt->jo_set & JO_ERR_IO) && (opt->jo_io[PART_ERR] == JIO_BUFFER
	 || (opt->jo_io[PART_ERR] == JIO_OUT && (opt->jo_set & JO_OUT_IO)
				       && opt->jo_io[PART_OUT] == JIO_BUFFER)))
    {
	buf_T *buf;

	// writing err to a buffer. Default mode is NL.
	if (!(opt->jo_set & JO_ERR_MODE))
	    channel->ch_part[PART_ERR].ch_mode = CH_MODE_NL;
	if (opt->jo_io[PART_ERR] == JIO_OUT)
	    buf = channel->ch_part[PART_OUT].ch_bufref.br_buf;
	else if (opt->jo_set & JO_ERR_BUF)
	{
	    buf = buflist_findnr(opt->jo_io_buf[PART_ERR]);
	    if (buf == NULL)
		semsg(_(e_buffer_nr_does_not_exist),
					       (long)opt->jo_io_buf[PART_ERR]);
	}
	else
	{
	    int msg = TRUE;

	    if (opt->jo_set2 & JO2_ERR_MSG)
		msg = opt->jo_message[PART_ERR];
	    buf = channel_find_buffer(opt->jo_io_name[PART_ERR], TRUE, msg);
	}
	if (buf != NULL)
	{
	    if (opt->jo_set & JO_ERR_MODIFIABLE)
		channel->ch_part[PART_ERR].ch_nomodifiable =
						!opt->jo_modifiable[PART_ERR];
	    if (!buf->b_p_ma && !channel->ch_part[PART_ERR].ch_nomodifiable)
	    {
		emsg(_(e_cannot_make_changes_modifiable_is_off));
	    }
	    else
	    {
		ch_log(channel, "writing err to buffer '%s'",
						       (char *)buf->b_ffname);
		set_bufref(&channel->ch_part[PART_ERR].ch_bufref, buf);
		// if the buffer was deleted or unloaded resurrect it
		if (buf->b_ml.ml_mfp == NULL)
		    prepare_buffer(buf);
	    }
	}
    }

    channel->ch_part[PART_OUT].ch_io = opt->jo_io[PART_OUT];
    channel->ch_part[PART_ERR].ch_io = opt->jo_io[PART_ERR];
    channel->ch_part[PART_IN].ch_io = opt->jo_io[PART_IN];
}

/*
 * Implements ch_open().
 */
    static channel_T *
channel_open_func(typval_T *argvars)
{
    char_u	*address;
    char_u	*p;
    char	*rest;
    int		port = 0;
    int		is_ipv6 = FALSE;
    int		is_unix = FALSE;
    jobopt_T    opt;
    channel_T	*channel = NULL;

    if (in_vim9script()
	    && (check_for_string_arg(argvars, 0) == FAIL
		|| check_for_opt_dict_arg(argvars, 1) == FAIL))
	return NULL;

    address = tv_get_string(&argvars[0]);
    if (argvars[1].v_type != VAR_UNKNOWN
	    && check_for_nonnull_dict_arg(argvars, 1) == FAIL)
	return NULL;

    if (*address == NUL)
    {
	semsg(_(e_invalid_argument_str), address);
	return NULL;
    }

    if (!STRNCMP(address, "unix:", 5))
    {
	is_unix = TRUE;
	address += 5;
    }
    else if (*address == '[')
    {
	// ipv6 address
	is_ipv6 = TRUE;
	p = vim_strchr(address + 1, ']');
	if (p == NULL || *++p != ':')
	{
	    semsg(_(e_invalid_argument_str), address);
	    return NULL;
	}
    }
    else
    {
	// ipv4 address
	p = vim_strchr(address, ':');
	if (p == NULL)
	{
	    semsg(_(e_invalid_argument_str), address);
	    return NULL;
	}
    }

    if (!is_unix)
    {
	port = strtol((char *)(p + 1), &rest, 10);
	if (port <= 0 || port >= 65536 || *rest != NUL)
	{
	    semsg(_(e_invalid_argument_str), address);
	    return NULL;
	}
	if (is_ipv6)
	{
	    // strip '[' and ']'
	    ++address;
	    *(p - 1) = NUL;
	}
	else
	    *p = NUL;
    }

    // parse options
    clear_job_options(&opt);
    opt.jo_mode = CH_MODE_JSON;
    opt.jo_timeout = 2000;
    if (get_job_options(&argvars[1], &opt,
	    JO_MODE_ALL + JO_CB_ALL + JO_TIMEOUT_ALL
		+ (is_unix? 0 : JO_WAITTIME), 0) == FAIL)
	goto theend;
    if (opt.jo_timeout < 0)
    {
	emsg(_(e_invalid_argument));
	goto theend;
    }

    if (is_unix)
	channel = channel_open_unix((char *)address, NULL);
    else
	channel = channel_open((char *)address, port, opt.jo_waittime, NULL);
    if (channel != NULL)
    {
	opt.jo_set = JO_ALL;
	channel_set_options(channel, &opt);
    }
theend:
    free_job_options(&opt);
    return channel;
}

    void
ch_close_part(channel_T *channel, ch_part_T part)
{
    sock_T *fd = &channel->ch_part[part].ch_fd;

    if (*fd == INVALID_FD)
	return;

    if (part == PART_SOCK)
	sock_close(*fd);
    else
    {
	// When using a pty the same FD is set on multiple parts, only
	// close it when the last reference is closed.
	if ((part == PART_IN || channel->CH_IN_FD != *fd)
		&& (part == PART_OUT || channel->CH_OUT_FD != *fd)
		&& (part == PART_ERR || channel->CH_ERR_FD != *fd))
	{
#ifdef MSWIN
	    if (channel->ch_named_pipe)
		DisconnectNamedPipe((HANDLE)fd);
#endif
	    fd_close(*fd);
	}
    }
    *fd = INVALID_FD;

    // channel is closed, may want to end the job if it was the last
    channel->ch_to_be_closed &= ~(1U << part);
}

    void
channel_set_pipes(channel_T *channel, sock_T in, sock_T out, sock_T err)
{
    if (in != INVALID_FD)
    {
	ch_close_part(channel, PART_IN);
	channel->CH_IN_FD = in;
# if defined(UNIX)
	// Do not end the job when all output channels are closed, wait until
	// the job ended.
	if (mch_isatty(in))
	    channel->ch_to_be_closed |= (1U << PART_IN);
# endif
    }
    if (out != INVALID_FD)
    {
# if defined(FEAT_GUI)
	channel_gui_unregister_one(channel, PART_OUT);
# endif
	ch_close_part(channel, PART_OUT);
	channel->CH_OUT_FD = out;
	channel->ch_to_be_closed |= (1U << PART_OUT);
# if defined(FEAT_GUI)
	channel_gui_register_one(channel, PART_OUT);
# endif
    }
    if (err != INVALID_FD)
    {
# if defined(FEAT_GUI)
	channel_gui_unregister_one(channel, PART_ERR);
# endif
	ch_close_part(channel, PART_ERR);
	channel->CH_ERR_FD = err;
	channel->ch_to_be_closed |= (1U << PART_ERR);
# if defined(FEAT_GUI)
	channel_gui_register_one(channel, PART_ERR);
# endif
    }
}

/*
 * Sets the job the channel is associated with and associated options.
 * This does not keep a refcount, when the job is freed ch_job is cleared.
 */
    void
channel_set_job(channel_T *channel, job_T *job, jobopt_T *options)
{
    channel->ch_job = job;

    channel_set_options(channel, options);

    if (job->jv_in_buf == NULL)
	return;

    chanpart_T *in_part = &channel->ch_part[PART_IN];

    set_bufref(&in_part->ch_bufref, job->jv_in_buf);
    ch_log(channel, "reading from buffer '%s'",
	    (char *)in_part->ch_bufref.br_buf->b_ffname);
    if (options->jo_set & JO_IN_TOP)
    {
	if (options->jo_in_top == 0 && !(options->jo_set & JO_IN_BOT))
	{
	    // Special mode: send last-but-one line when appending a line
	    // to the buffer.
	    in_part->ch_bufref.br_buf->b_write_to_channel = TRUE;
	    in_part->ch_buf_append = TRUE;
	    in_part->ch_buf_top =
		in_part->ch_bufref.br_buf->b_ml.ml_line_count + 1;
	}
	else
	    in_part->ch_buf_top = options->jo_in_top;
    }
    else
	in_part->ch_buf_top = 1;
    if (options->jo_set & JO_IN_BOT)
	in_part->ch_buf_bot = options->jo_in_bot;
    else
	in_part->ch_buf_bot = in_part->ch_bufref.br_buf->b_ml.ml_line_count;
}

/*
 * Set the callback for "channel"/"part" for the response with "id".
 */
    static void
channel_set_req_callback(
	channel_T   *channel,
	ch_part_T   part,
	callback_T  *callback,
	int	    id)
{
    cbq_T *head = &channel->ch_part[part].ch_cb_head;
    cbq_T *item = ALLOC_ONE(cbq_T);

    if (item == NULL)
	return;

    copy_callback(&item->cq_callback, callback);
    item->cq_seq_nr = id;
    item->cq_prev = head->cq_prev;
    head->cq_prev = item;
    item->cq_next = NULL;
    if (item->cq_prev == NULL)
	head->cq_next = item;
    else
	item->cq_prev->cq_next = item;
}

    static void
write_buf_line(buf_T *buf, linenr_T lnum, channel_T *channel)
{
    char_u  *line = ml_get_buf(buf, lnum, FALSE);
    int	    len = ml_get_buf_len(buf, lnum);
    char_u  *p;
    int	    i;

    // Need to make a copy to be able to append a NL.
    if ((p = alloc(len + 2)) == NULL)
	return;
    memcpy((char *)p, (char *)line, len);

    if (channel->ch_write_text_mode)
	p[len] = CAR;
    else
    {
	for (i = 0; i < len; ++i)
	    if (p[i] == NL)
		p[i] = NUL;

	p[len] = NL;
    }
    p[len + 1] = NUL;
    channel_send(channel, PART_IN, p, len + 1, "write_buf_line");
    vim_free(p);
}

/*
 * Return TRUE if "channel" can be written to.
 * Returns FALSE if the input is closed or the write would block.
 */
    static int
can_write_buf_line(channel_T *channel)
{
    chanpart_T *in_part = &channel->ch_part[PART_IN];

    if (in_part->ch_fd == INVALID_FD)
	return FALSE;  // pipe was closed

    // for testing: block every other attempt to write
    if (in_part->ch_block_write == 1)
	in_part->ch_block_write = -1;
    else if (in_part->ch_block_write == -1)
	in_part->ch_block_write = 1;

    // TODO: Win32 implementation, probably using WaitForMultipleObjects()
#ifndef MSWIN
    {
# if defined(HAVE_SELECT)
	struct timeval	tval;
	fd_set		wfds;
	int		ret;

	FD_ZERO(&wfds);
	FD_SET((int)in_part->ch_fd, &wfds);
	tval.tv_sec = 0;
	tval.tv_usec = 0;
	for (;;)
	{
	    ret = select((int)in_part->ch_fd + 1, NULL, &wfds, NULL, &tval);
#  ifdef EINTR
	    SOCK_ERRNO;
	    if (ret == -1 && errno == EINTR)
		continue;
#  endif
	    if (ret <= 0 || in_part->ch_block_write == 1)
	    {
		if (ret > 0)
		    ch_log(channel, "FAKED Input not ready for writing");
		else
		    ch_log(channel, "Input not ready for writing");
		return FALSE;
	    }
	    break;
	}
# else
	struct pollfd	fds;

	fds.fd = in_part->ch_fd;
	fds.events = POLLOUT;
	if (poll(&fds, 1, 0) <= 0)
	{
	    ch_log(channel, "Input not ready for writing");
	    return FALSE;
	}
	if (in_part->ch_block_write == 1)
	{
	    ch_log(channel, "FAKED Input not ready for writing");
	    return FALSE;
	}
# endif
    }
#endif
    return TRUE;
}

/*
 * Write any buffer lines to the input channel.
 */
    void
channel_write_in(channel_T *channel)
{
    chanpart_T *in_part = &channel->ch_part[PART_IN];
    linenr_T    lnum;
    buf_T	*buf = in_part->ch_bufref.br_buf;
    int		written = 0;

    if (buf == NULL || in_part->ch_buf_append)
	return;  // no buffer or using appending
    if (!bufref_valid(&in_part->ch_bufref) || buf->b_ml.ml_mfp == NULL)
    {
	// buffer was wiped out or unloaded
	ch_log(channel, "input buffer has been wiped out");
	in_part->ch_bufref.br_buf = NULL;
	return;
    }

    for (lnum = in_part->ch_buf_top; lnum <= in_part->ch_buf_bot
				   && lnum <= buf->b_ml.ml_line_count; ++lnum)
    {
	if (!can_write_buf_line(channel))
	    break;
	write_buf_line(buf, lnum, channel);
	++written;
    }

    if (written == 1)
	ch_log(channel, "written line %d to channel", (int)lnum - 1);
    else if (written > 1)
	ch_log(channel, "written %d lines to channel", written);

    in_part->ch_buf_top = lnum;
    if (lnum > buf->b_ml.ml_line_count || lnum > in_part->ch_buf_bot)
    {
#if defined(FEAT_TERMINAL)
	// Send CTRL-D or "eof_chars" to close stdin on MS-Windows.
	if (channel->ch_job != NULL)
	    term_send_eof(channel);
#endif

	// Writing is done, no longer need the buffer.
	in_part->ch_bufref.br_buf = NULL;
	ch_log(channel, "Finished writing all lines to channel");

	// Close the pipe/socket, so that the other side gets EOF.
	ch_close_part(channel, PART_IN);
    }
    else
	ch_log(channel, "Still %ld more lines to write",
				   (long)(buf->b_ml.ml_line_count - lnum + 1));
}

/*
 * Handle buffer "buf" being freed, remove it from any channels.
 */
    void
channel_buffer_free(buf_T *buf)
{
    channel_T	*channel;
    ch_part_T	part;

    FOR_ALL_CHANNELS(channel)
	for (part = PART_SOCK; part < PART_COUNT; ++part)
	{
	    chanpart_T  *ch_part = &channel->ch_part[part];

	    if (ch_part->ch_bufref.br_buf == buf)
	    {
		ch_log(channel, "%s buffer has been wiped out",
							  ch_part_names[part]);
		ch_part->ch_bufref.br_buf = NULL;
	    }
	}
}

/*
 * Write any lines waiting to be written to "channel".
 */
    static void
channel_write_input(channel_T *channel)
{
    chanpart_T	*in_part = &channel->ch_part[PART_IN];

    if (in_part->ch_writeque.wq_next != NULL)
	channel_send(channel, PART_IN, (char_u *)"", 0, "channel_write_input");
    else if (in_part->ch_bufref.br_buf != NULL)
    {
	if (in_part->ch_buf_append)
	    channel_write_new_lines(in_part->ch_bufref.br_buf);
	else
	    channel_write_in(channel);
    }
}

/*
 * Write any lines waiting to be written to a channel.
 */
    void
channel_write_any_lines(void)
{
    channel_T	*channel;

    FOR_ALL_CHANNELS(channel)
	channel_write_input(channel);
}

/*
 * Write appended lines above the last one in "buf" to the channel.
 */
    void
channel_write_new_lines(buf_T *buf)
{
    channel_T	*channel;
    int		found_one = FALSE;

    // There could be more than one channel for the buffer, loop over all of
    // them.
    FOR_ALL_CHANNELS(channel)
    {
	chanpart_T  *in_part = &channel->ch_part[PART_IN];
	linenr_T    lnum;
	int	    written = 0;

	if (in_part->ch_bufref.br_buf == buf && in_part->ch_buf_append)
	{
	    if (in_part->ch_fd == INVALID_FD)
		continue;  // pipe was closed
	    found_one = TRUE;
	    for (lnum = in_part->ch_buf_bot; lnum < buf->b_ml.ml_line_count;
								       ++lnum)
	    {
		if (!can_write_buf_line(channel))
		    break;
		write_buf_line(buf, lnum, channel);
		++written;
	    }

	    if (written == 1)
		ch_log(channel, "written line %d to channel", (int)lnum - 1);
	    else if (written > 1)
		ch_log(channel, "written %d lines to channel", written);
	    if (lnum < buf->b_ml.ml_line_count)
		ch_log(channel, "Still %ld more lines to write",
				       (long)(buf->b_ml.ml_line_count - lnum));

	    in_part->ch_buf_bot = lnum;
	}
    }
    if (!found_one)
	buf->b_write_to_channel = FALSE;
}

/*
 * Invoke the "callback" on channel "channel".
 * This does not redraw but sets channel_need_redraw;
 */
    static void
invoke_callback(channel_T *channel, callback_T *callback, typval_T *argv)
{
    typval_T	rettv;

    if (safe_to_invoke_callback == 0)
	iemsg("Invoking callback when it is not safe");

    argv[0].v_type = VAR_CHANNEL;
    argv[0].vval.v_channel = channel;

    call_callback(callback, -1, &rettv, 2, argv);
    clear_tv(&rettv);
    channel_need_redraw = TRUE;
}

/*
 * Return the first node from "channel"/"part" without removing it.
 * Returns NULL if there is nothing.
 */
    readq_T *
channel_peek(channel_T *channel, ch_part_T part)
{
    readq_T *head = &channel->ch_part[part].ch_head;

    return head->rq_next;
}

/*
 * Return a pointer to the first NL in "node".
 * Skips over NUL characters.
 * Returns NULL if there is no NL.
 */
    char_u *
channel_first_nl(readq_T *node)
{
    char_u  *buffer = node->rq_buffer;
    long_u  i;

    for (i = 0; i < node->rq_buflen; ++i)
	if (buffer[i] == NL)
	    return buffer + i;
    return NULL;
}

/*
 * Return the first buffer from channel "channel"/"part" and remove it.
 * The caller must free it.
 * Returns NULL if there is nothing.
 */
    char_u *
channel_get(channel_T *channel, ch_part_T part, int *outlen)
{
    readq_T *head = &channel->ch_part[part].ch_head;
    readq_T *node = head->rq_next;
    char_u *p;

    if (node == NULL)
	return NULL;
    if (outlen != NULL)
	*outlen += node->rq_buflen;
    // dispose of the node but keep the buffer
    p = node->rq_buffer;
    head->rq_next = node->rq_next;
    if (node->rq_next == NULL)
	head->rq_prev = NULL;
    else
	node->rq_next->rq_prev = NULL;
    vim_free(node);
    return p;
}

/*
 * Returns the whole buffer contents concatenated for "channel"/"part".
 * Replaces NUL bytes with NL.
 */
    static char_u *
channel_get_all(channel_T *channel, ch_part_T part, int *outlen)
{
    readq_T *head = &channel->ch_part[part].ch_head;
    readq_T *node;
    long_u  len = 0;
    char_u  *res;
    char_u  *p;

    // Concatenate everything into one buffer.
    for (node = head->rq_next; node != NULL; node = node->rq_next)
	len += node->rq_buflen;
    res = alloc(len + 1);
    if (res == NULL)
	return NULL;
    p = res;
    for (node = head->rq_next; node != NULL; node = node->rq_next)
    {
	mch_memmove(p, node->rq_buffer, node->rq_buflen);
	p += node->rq_buflen;
    }
    *p = NUL;

    // Free all buffers
    do
    {
	p = channel_get(channel, part, NULL);
	vim_free(p);
    } while (p != NULL);

    if (outlen != NULL)
    {
	// Returning the length, keep NUL characters.
	*outlen += len;
	return res;
    }

    // Turn all NUL into NL, so that the result can be used as a string.
    p = res;
    while (p < res + len)
    {
	if (*p == NUL)
	    *p = NL;
#ifdef MSWIN
	else if (*p == 0x1b)
	{
	    // crush the escape sequence OSC 0/1/2: ESC ]0;
	    if (p + 3 < res + len
		    && p[1] == ']'
		    && (p[2] == '0' || p[2] == '1' || p[2] == '2')
		    && p[3] == ';')
	    {
		// '\a' becomes a NL
		while (p < res + (len - 1) && *p != '\a')
		    ++p;
		// BEL is zero width characters, suppress display mistake
		// ConPTY (after 10.0.18317) requires advance checking
		if (p[-1] == NUL)
		    p[-1] = 0x07;
	    }
	}
#endif
	++p;
    }

    return res;
}

/*
 * Consume "len" bytes from the head of "node".
 * Caller must check these bytes are available.
 */
    void
channel_consume(channel_T *channel, ch_part_T part, int len)
{
    readq_T *head = &channel->ch_part[part].ch_head;
    readq_T *node = head->rq_next;
    char_u *buf = node->rq_buffer;

    mch_memmove(buf, buf + len, node->rq_buflen - len);
    node->rq_buflen -= len;
    node->rq_buffer[node->rq_buflen] = NUL;
}

/*
 * Collapses the first and second buffer for "channel"/"part".
 * Returns FAIL if nothing was done.
 * When "want_nl" is TRUE collapse more buffers until a NL is found.
 * When the channel part mode is "lsp", collapse all the buffers as the http
 * header and the JSON content can be present in multiple buffers.
 */
    int
channel_collapse(channel_T *channel, ch_part_T part, int want_nl)
{
    ch_mode_T	mode = channel->ch_part[part].ch_mode;
    readq_T	*head = &channel->ch_part[part].ch_head;
    readq_T	*node = head->rq_next;
    readq_T	*last_node;
    readq_T	*n;
    char_u	*newbuf;
    char_u	*p;
    long_u	len;

    if (node == NULL || node->rq_next == NULL)
	return FAIL;

    last_node = node->rq_next;
    len = node->rq_buflen + last_node->rq_buflen;
    if (want_nl || mode == CH_MODE_LSP)
	while (last_node->rq_next != NULL
		&& (mode == CH_MODE_LSP
		    || channel_first_nl(last_node) == NULL))
	{
	    last_node = last_node->rq_next;
	    len += last_node->rq_buflen;
	}

    p = newbuf = alloc(len + 1);
    if (newbuf == NULL)
	return FAIL;	    // out of memory
    mch_memmove(p, node->rq_buffer, node->rq_buflen);
    p += node->rq_buflen;
    vim_free(node->rq_buffer);
    node->rq_buffer = newbuf;
    for (n = node; n != last_node; )
    {
	n = n->rq_next;
	mch_memmove(p, n->rq_buffer, n->rq_buflen);
	p += n->rq_buflen;
	vim_free(n->rq_buffer);
    }
    *p = NUL;
    node->rq_buflen = (long_u)(p - newbuf);

    // dispose of the collapsed nodes and their buffers
    for (n = node->rq_next; n != last_node; )
    {
	n = n->rq_next;
	vim_free(n->rq_prev);
    }
    node->rq_next = last_node->rq_next;
    if (last_node->rq_next == NULL)
	head->rq_prev = node;
    else
	last_node->rq_next->rq_prev = node;
    vim_free(last_node);
    return OK;
}

/*
 * Store "buf[len]" on "channel"/"part".
 * When "prepend" is TRUE put in front, otherwise append at the end.
 * Returns OK or FAIL.
 */
    static int
channel_save(channel_T *channel, ch_part_T part, char_u *buf, int len,
						      int prepend, char *lead)
{
    readq_T *node;
    readq_T *head = &channel->ch_part[part].ch_head;
    char_u  *p;
    int	    i;

    node = ALLOC_ONE(readq_T);
    if (node == NULL)
	return FAIL;	    // out of memory
    // A NUL is added at the end, because netbeans code expects that.
    // Otherwise a NUL may appear inside the text.
    node->rq_buffer = alloc(len + 1);
    if (node->rq_buffer == NULL)
    {
	vim_free(node);
	return FAIL;	    // out of memory
    }

    if (channel->ch_part[part].ch_mode == CH_MODE_NL)
    {
	// Drop any CR before a NL.
	p = node->rq_buffer;
	for (i = 0; i < len; ++i)
	    if (buf[i] != CAR || i + 1 >= len || buf[i + 1] != NL)
		*p++ = buf[i];
	*p = NUL;
	node->rq_buflen = (long_u)(p - node->rq_buffer);
    }
    else
    {
	mch_memmove(node->rq_buffer, buf, len);
	node->rq_buffer[len] = NUL;
	node->rq_buflen = (long_u)len;
    }

    if (prepend)
    {
	// prepend node to the head of the queue
	node->rq_next = head->rq_next;
	node->rq_prev = NULL;
	if (head->rq_next == NULL)
	    head->rq_prev = node;
	else
	    head->rq_next->rq_prev = node;
	head->rq_next = node;
    }
    else
    {
	// append node to the tail of the queue
	node->rq_next = NULL;
	node->rq_prev = head->rq_prev;
	if (head->rq_prev == NULL)
	    head->rq_next = node;
	else
	    head->rq_prev->rq_next = node;
	head->rq_prev = node;
    }

    if (ch_log_active() && lead != NULL)
	ch_log_literal(lead, channel, part, buf, len);

    return OK;
}

/*
 * Try to fill the buffer of "reader".
 * Returns FALSE when nothing was added.
 */
    static int
channel_fill(js_read_T *reader)
{
    channel_T	*channel = (channel_T *)reader->js_cookie;
    ch_part_T	part = reader->js_cookie_arg;
    char_u	*next = channel_get(channel, part, NULL);
    int		keeplen;
    int		addlen;
    char_u	*p;

    if (next == NULL)
	return FALSE;

    keeplen = reader->js_end - reader->js_buf;
    if (keeplen > 0)
    {
	// Prepend unused text.
	addlen = (int)STRLEN(next);
	p = alloc(keeplen + addlen + 1);
	if (p == NULL)
	{
	    vim_free(next);
	    return FALSE;
	}
	mch_memmove(p, reader->js_buf, keeplen);
	mch_memmove(p + keeplen, next, addlen + 1);
	vim_free(next);
	next = p;
    }

    vim_free(reader->js_buf);
    reader->js_buf = next;
    return TRUE;
}

/*
 * Process the HTTP header in a Language Server Protocol (LSP) message.
 *
 * The message format is described in the LSP specification:
 * https://microsoft.github.io/language-server-protocol/specification
 *
 * It has the following two fields:
 *
 *	Content-Length: ...
 *	Content-Type: application/vscode-jsonrpc; charset=utf-8
 *
 * Each field ends with "\r\n". The header ends with an additional "\r\n".
 *
 * Returns OK if a valid header is received and FAIL if some fields in the
 * header are not correct. Returns MAYBE if a partial header is received and
 * need to wait for more data to arrive.
 */
    static int
channel_process_lsp_http_hdr(js_read_T *reader)
{
    char_u	*line_start;
    char_u	*p;
    int_u	hdr_len;
    int		payload_len = -1;
    int_u	jsbuf_len;

    // We find the end once, to avoid calling strlen() many times.
    jsbuf_len = (int_u)STRLEN(reader->js_buf);
    reader->js_end = reader->js_buf + jsbuf_len;

    p = reader->js_buf;

    // Process each line in the header till an empty line is read (header
    // separator).
    while (TRUE)
    {
	line_start = p;
	while (*p != NUL && *p != '\n')
	    p++;
	if (*p == NUL)			// partial header
	    return MAYBE;
	p++;

	// process the content length field (if present)
	if ((p - line_start > 16)
		&& STRNICMP(line_start, "Content-Length: ", 16) == 0)
	{
	    errno = 0;
	    payload_len = strtol((char *)line_start + 16, NULL, 10);
	    if (errno == ERANGE || payload_len < 0)
		// invalid length, discard the payload
		return FAIL;
	}

	if ((p - line_start) == 2 && line_start[0] == '\r' &&
		line_start[1] == '\n')
	    // reached the empty line
	    break;
    }

    if (payload_len == -1)
	// Content-Length field is not present in the header
	return FAIL;

    hdr_len = p - reader->js_buf;

    // if the entire payload is not received, wait for more data to arrive
    if (jsbuf_len < hdr_len + payload_len)
	return MAYBE;

    reader->js_used += hdr_len;
    // recalculate the end based on the length read from the header.
    reader->js_end = reader->js_buf + hdr_len + payload_len;

    return OK;
}

/*
 * Use the read buffer of "channel"/"part" and parse a JSON message that is
 * complete.  The messages are added to the queue.
 * Return TRUE if there is more to read.
 */
    static int
channel_parse_json(channel_T *channel, ch_part_T part)
{
    js_read_T	reader;
    typval_T	listtv;
    jsonq_T	*item;
    chanpart_T	*chanpart = &channel->ch_part[part];
    jsonq_T	*head = &chanpart->ch_json_head;
    int		status = OK;
    int		ret;

    if (channel_peek(channel, part) == NULL)
	return FALSE;

    reader.js_buf = channel_get(channel, part, NULL);
    reader.js_used = 0;
    reader.js_fill = channel_fill;
    reader.js_cookie = channel;
    reader.js_cookie_arg = part;

    if (chanpart->ch_mode == CH_MODE_LSP)
	status = channel_process_lsp_http_hdr(&reader);

    // When a message is incomplete we wait for a short while for more to
    // arrive.  After the delay drop the input, otherwise a truncated string
    // or list will make us hang.
    // Do not generate error messages, they will be written in a channel log.
    if (status == OK)
    {
	++emsg_silent;
	status = json_decode(&reader, &listtv,
				chanpart->ch_mode == CH_MODE_JS ? JSON_JS : 0);
	--emsg_silent;
    }
    if (status == OK)
    {
	// Only accept the response when it is a list with at least two
	// items.
	if (chanpart->ch_mode == CH_MODE_LSP && listtv.v_type != VAR_DICT)
	{
	    ch_error(channel, "Did not receive a LSP dict, discarding");
	    clear_tv(&listtv);
	}
	else if (chanpart->ch_mode != CH_MODE_LSP
	      && (listtv.v_type != VAR_LIST || listtv.vval.v_list->lv_len < 2))
	{
	    if (listtv.v_type != VAR_LIST)
		ch_error(channel, "Did not receive a list, discarding");
	    else
		ch_error(channel, "Expected list with two items, got %d",
						  listtv.vval.v_list->lv_len);
	    clear_tv(&listtv);
	}
	else
	{
	    item = ALLOC_ONE(jsonq_T);
	    if (item == NULL)
		clear_tv(&listtv);
	    else
	    {
		item->jq_no_callback = FALSE;
		item->jq_value = alloc_tv();
		if (item->jq_value == NULL)
		{
		    vim_free(item);
		    clear_tv(&listtv);
		}
		else
		{
		    *item->jq_value = listtv;
		    item->jq_prev = head->jq_prev;
		    head->jq_prev = item;
		    item->jq_next = NULL;
		    if (item->jq_prev == NULL)
			head->jq_next = item;
		    else
			item->jq_prev->jq_next = item;
		}
	    }
	}
    }

    if (status == OK)
	chanpart->ch_wait_len = 0;
    else if (status == MAYBE)
    {
	size_t buflen = STRLEN(reader.js_buf);

	if (chanpart->ch_wait_len < buflen)
	{
	    // First time encountering incomplete message or after receiving
	    // more (but still incomplete): set a deadline of 100 msec.
	    ch_log(channel,
		    "Incomplete message (%d bytes) - wait 100 msec for more",
		    (int)buflen);
	    reader.js_used = 0;
	    chanpart->ch_wait_len = buflen;
#ifdef MSWIN
	    chanpart->ch_deadline = GetTickCount() + 100L;
#else
	    gettimeofday(&chanpart->ch_deadline, NULL);
	    chanpart->ch_deadline.tv_usec += 100 * 1000;
	    if (chanpart->ch_deadline.tv_usec > 1000 * 1000)
	    {
		chanpart->ch_deadline.tv_usec -= 1000 * 1000;
		++chanpart->ch_deadline.tv_sec;
	    }
#endif
	}
	else
	{
	    int timeout;
#ifdef MSWIN
	    timeout = GetTickCount() > chanpart->ch_deadline;
#else
	    {
		struct timeval now_tv;

		gettimeofday(&now_tv, NULL);
		timeout = now_tv.tv_sec > chanpart->ch_deadline.tv_sec
		      || (now_tv.tv_sec == chanpart->ch_deadline.tv_sec
			   && now_tv.tv_usec > chanpart->ch_deadline.tv_usec);
	    }
#endif
	    if (timeout)
	    {
		status = FAIL;
		chanpart->ch_wait_len = 0;
		ch_log(channel, "timed out");
	    }
	    else
	    {
		reader.js_used = 0;
		ch_log(channel, "still waiting on incomplete message");
	    }
	}
    }

    if (status == FAIL)
    {
	ch_error(channel, "Decoding failed - discarding input");
	ret = FALSE;
	chanpart->ch_wait_len = 0;
    }
    else if (reader.js_buf[reader.js_used] != NUL)
    {
	// Put the unread part back into the channel.
	channel_save(channel, part, reader.js_buf + reader.js_used,
			(int)(reader.js_end - reader.js_buf) - reader.js_used,
								  TRUE, NULL);
	ret = status == MAYBE ? FALSE: TRUE;
    }
    else
	ret = FALSE;

    vim_free(reader.js_buf);
    return ret;
}

/*
 * Remove "node" from the queue that it is in.  Does not free it.
 */
    static void
remove_cb_node(cbq_T *head, cbq_T *node)
{
    if (node->cq_prev == NULL)
	head->cq_next = node->cq_next;
    else
	node->cq_prev->cq_next = node->cq_next;
    if (node->cq_next == NULL)
	head->cq_prev = node->cq_prev;
    else
	node->cq_next->cq_prev = node->cq_prev;
}

/*
 * Remove "node" from the queue that it is in and free it.
 * Caller should have freed or used node->jq_value.
 */
    static void
remove_json_node(jsonq_T *head, jsonq_T *node)
{
    if (node->jq_prev == NULL)
	head->jq_next = node->jq_next;
    else
	node->jq_prev->jq_next = node->jq_next;
    if (node->jq_next == NULL)
	head->jq_prev = node->jq_prev;
    else
	node->jq_next->jq_prev = node->jq_prev;
    vim_free(node);
}

/*
 * Add "id" to the list of JSON message IDs we are waiting on.
 */
    static void
channel_add_block_id(chanpart_T *chanpart, int id)
{
    garray_T *gap = &chanpart->ch_block_ids;

    if (gap->ga_growsize == 0)
	ga_init2(gap, sizeof(int), 10);
    if (ga_grow(gap, 1) == OK)
    {
	((int *)gap->ga_data)[gap->ga_len] = id;
	++gap->ga_len;
    }
}

/*
 * Remove "id" from the list of JSON message IDs we are waiting on.
 */
    static void
channel_remove_block_id(chanpart_T *chanpart, int id)
{
    garray_T	*gap = &chanpart->ch_block_ids;
    int		i;

    for (i = 0; i < gap->ga_len; ++i)
	if (((int *)gap->ga_data)[i] == id)
	{
	    --gap->ga_len;
	    if (i < gap->ga_len)
	    {
		int *p = ((int *)gap->ga_data) + i;

		mch_memmove(p, p + 1, (gap->ga_len - i) * sizeof(int));
	    }
	    return;
	}
    siemsg("channel_remove_block_id(): cannot find id %d", id);
}

/*
 * Return TRUE if "id" is in the list of JSON message IDs we are waiting on.
 */
    static int
channel_has_block_id(chanpart_T *chanpart, int id)
{
    garray_T	*gap = &chanpart->ch_block_ids;
    int		i;

    for (i = 0; i < gap->ga_len; ++i)
	if (((int *)gap->ga_data)[i] == id)
	    return TRUE;
    return FALSE;
}

/*
 * Get a message from the JSON queue for channel "channel".
 * When "id" is positive it must match the first number in the list.
 * When "id" is zero or negative jut get the first message.  But not one
 * in the ch_block_ids list.
 * When "without_callback" is TRUE also get messages that were pushed back.
 * Return OK when found and return the value in "rettv".
 * Return FAIL otherwise.
 */
    static int
channel_get_json(
	channel_T   *channel,
	ch_part_T   part,
	int	    id,
	int	    without_callback,
	typval_T    **rettv)
{
    jsonq_T   *head = &channel->ch_part[part].ch_json_head;
    jsonq_T   *item = head->jq_next;

    while (item != NULL)
    {
	list_T	    *l;
	typval_T    *tv;

	if (channel->ch_part[part].ch_mode != CH_MODE_LSP)
	{
	    l = item->jq_value->vval.v_list;
	    CHECK_LIST_MATERIALIZE(l);
	    tv = &l->lv_first->li_tv;
	}
	else
	{
	    dict_T	*d;
	    dictitem_T	*di;

	    // LSP message payload is a JSON-RPC dict.
	    // For RPC requests and responses, the 'id' item will be present.
	    // For notifications, it will not be present.
	    if (id > 0)
	    {
		if (item->jq_value->v_type != VAR_DICT)
		    goto nextitem;
		d = item->jq_value->vval.v_dict;
		if (d == NULL)
		    goto nextitem;
		// When looking for a response message from the LSP server,
		// ignore new LSP request and notification messages.  LSP
		// request and notification messages have the "method" field in
		// the header and the response messages do not have this field.
		if (dict_has_key(d, "method"))
		    goto nextitem;
		di = dict_find(d, (char_u *)"id", -1);
		if (di == NULL)
		    goto nextitem;
		tv = &di->di_tv;
	    }
	    else
		tv = item->jq_value;
	}

	if ((without_callback || !item->jq_no_callback)
	    && ((id > 0 && tv->v_type == VAR_NUMBER && tv->vval.v_number == id)
	      || (id <= 0 && (tv->v_type != VAR_NUMBER
		 || tv->vval.v_number == 0
		 || !channel_has_block_id(
				&channel->ch_part[part], tv->vval.v_number)))))
	{
	    *rettv = item->jq_value;
	    if (tv->v_type == VAR_NUMBER)
		ch_log(channel, "Getting JSON message %ld",
						      (long)tv->vval.v_number);
	    remove_json_node(head, item);
	    return OK;
	}
nextitem:
	item = item->jq_next;
    }
    return FAIL;
}

/*
 * Put back "rettv" into the JSON queue, there was no callback for it.
 * Takes over the values in "rettv".
 */
    static void
channel_push_json(channel_T *channel, ch_part_T part, typval_T *rettv)
{
    jsonq_T   *head = &channel->ch_part[part].ch_json_head;
    jsonq_T   *item = head->jq_next;
    jsonq_T   *newitem;

    if (head->jq_prev != NULL && head->jq_prev->jq_no_callback)
	// last item was pushed back, append to the end
	item = NULL;
    else while (item != NULL && item->jq_no_callback)
	// append after the last item that was pushed back
	item = item->jq_next;

    newitem = ALLOC_ONE(jsonq_T);
    if (newitem == NULL)
    {
	clear_tv(rettv);
	return;
    }

    newitem->jq_value = alloc_tv();
    if (newitem->jq_value == NULL)
    {
	vim_free(newitem);
	clear_tv(rettv);
	return;
    }

    newitem->jq_no_callback = FALSE;
    *newitem->jq_value = *rettv;
    if (item == NULL)
    {
	// append to the end
	newitem->jq_prev = head->jq_prev;
	head->jq_prev = newitem;
	newitem->jq_next = NULL;
	if (newitem->jq_prev == NULL)
	    head->jq_next = newitem;
	else
	    newitem->jq_prev->jq_next = newitem;
    }
    else
    {
	// append after "item"
	newitem->jq_prev = item;
	newitem->jq_next = item->jq_next;
	item->jq_next = newitem;
	if (newitem->jq_next == NULL)
	    head->jq_prev = newitem;
	else
	    newitem->jq_next->jq_prev = newitem;
    }
}

#define CH_JSON_MAX_ARGS 4

/*
 * Execute a command received over "channel"/"part"
 * "argv[0]" is the command string.
 * "argv[1]" etc. have further arguments, type is VAR_UNKNOWN if missing.
 */
    static void
channel_exe_cmd(channel_T *channel, ch_part_T part, typval_T *argv)
{
    char_u  *cmd = argv[0].vval.v_string;
    char_u  *arg;
    int	    options = channel->ch_part[part].ch_mode == CH_MODE_JS
								 ? JSON_JS : 0;

    if (argv[1].v_type != VAR_STRING)
    {
	ch_error(channel, "received command with non-string argument");
	if (p_verbose > 2)
	    emsg(_(e_received_command_with_non_string_argument));
	return;
    }
    arg = argv[1].vval.v_string;
    if (arg == NULL)
	arg = (char_u *)"";

    if (STRCMP(cmd, "ex") == 0)
    {
	int	called_emsg_before = called_emsg;
	char_u	*p = arg;
	int	do_emsg_silent;

	ch_log(channel, "Executing ex command '%s'", (char *)arg);
	do_emsg_silent = !checkforcmd(&p, "echoerr", 5);
	if (do_emsg_silent)
	    ++emsg_silent;
	do_cmdline_cmd(arg);
	if (do_emsg_silent)
	    --emsg_silent;
	if (called_emsg > called_emsg_before)
	    ch_log(channel, "Ex command error: '%s'",
					  (char *)get_vim_var_str(VV_ERRMSG));
    }
    else if (STRCMP(cmd, "normal") == 0)
    {
	exarg_T ea;

	ch_log(channel, "Executing normal command '%s'", (char *)arg);
	CLEAR_FIELD(ea);
	ea.arg = arg;
	ea.addr_count = 0;
	ea.forceit = TRUE; // no mapping
	ex_normal(&ea);
    }
    else if (STRCMP(cmd, "redraw") == 0)
    {
	ch_log(channel, "redraw");
	redraw_cmd(*arg != NUL);
	showruler(FALSE);
	setcursor();
	out_flush_cursor(TRUE, FALSE);
    }
    else if (STRCMP(cmd, "expr") == 0 || STRCMP(cmd, "call") == 0)
    {
	int is_call = cmd[0] == 'c';
	int id_idx = is_call ? 3 : 2;

	if (argv[id_idx].v_type != VAR_UNKNOWN
					 && argv[id_idx].v_type != VAR_NUMBER)
	{
	    ch_error(channel, "last argument for expr/call must be a number");
	    if (p_verbose > 2)
		emsg(_(e_last_argument_for_expr_call_must_be_number));
	}
	else if (is_call && argv[2].v_type != VAR_LIST)
	{
	    ch_error(channel, "third argument for call must be a list");
	    if (p_verbose > 2)
		emsg(_(e_third_argument_for_call_must_be_list));
	}
	else
	{
	    typval_T	*tv = NULL;
	    typval_T	res_tv;
	    typval_T	err_tv;
	    char_u	*json = NULL;

	    // Don't pollute the display with errors.
	    // Do generate the errors so that try/catch works.
	    ++emsg_silent;
	    if (!is_call)
	    {
		ch_log(channel, "Evaluating expression '%s'", (char *)arg);
		tv = eval_expr(arg, NULL);
	    }
	    else
	    {
		ch_log(channel, "Calling '%s'", (char *)arg);
		if (func_call(arg, &argv[2], NULL, NULL, &res_tv) == OK)
		    tv = &res_tv;
	    }

	    if (argv[id_idx].v_type == VAR_NUMBER)
	    {
		int id = argv[id_idx].vval.v_number;

		if (tv != NULL)
		    json = json_encode_nr_expr(id, tv, options | JSON_NL);
		if (tv == NULL || (json != NULL && *json == NUL))
		{
		    // If evaluation failed or the result can't be encoded
		    // then return the string "ERROR".
		    vim_free(json);
		    err_tv.v_type = VAR_STRING;
		    err_tv.vval.v_string = (char_u *)"ERROR";
		    json = json_encode_nr_expr(id, &err_tv, options | JSON_NL);
		}
		if (json != NULL)
		{
		    channel_send(channel,
				 part == PART_SOCK ? PART_SOCK : PART_IN,
				 json, (int)STRLEN(json), (char *)cmd);
		    vim_free(json);
		}
	    }
	    --emsg_silent;
	    if (tv == &res_tv)
		clear_tv(tv);
	    else
		free_tv(tv);
	}
    }
    else if (p_verbose > 2)
    {
	ch_error(channel, "Received unknown command: %s", (char *)cmd);
	semsg(_(e_received_unknown_command_str), cmd);
    }
}

/*
 * Invoke the callback at "cbhead".
 * Does not redraw but sets channel_need_redraw.
 */
    static void
invoke_one_time_callback(
	channel_T   *channel,
	cbq_T	    *cbhead,
	cbq_T	    *item,
	typval_T    *argv)
{
    ch_log(channel, "Invoking one-time callback %s",
					    (char *)item->cq_callback.cb_name);
    // Remove the item from the list first, if the callback
    // invokes ch_close() the list will be cleared.
    remove_cb_node(cbhead, item);
    invoke_callback(channel, &item->cq_callback, argv);
    free_callback(&item->cq_callback);
    vim_free(item);
}

    static void
append_to_buffer(buf_T *buffer, char_u *msg, channel_T *channel, ch_part_T part)
{
    aco_save_T	aco;
    linenr_T    lnum = buffer->b_ml.ml_line_count;
    int		save_write_to = buffer->b_write_to_channel;
    chanpart_T  *ch_part = &channel->ch_part[part];
    int		save_p_ma = buffer->b_p_ma;
    int		empty = (buffer->b_ml.ml_flags & ML_EMPTY) ? 1 : 0;

    if (!buffer->b_p_ma && !ch_part->ch_nomodifiable)
    {
	if (!ch_part->ch_nomod_error)
	{
	    ch_error(channel, "Buffer is not modifiable, cannot append");
	    ch_part->ch_nomod_error = TRUE;
	}
	return;
    }

    // If the buffer is also used as input insert above the last
    // line. Don't write these lines.
    if (save_write_to)
    {
	--lnum;
	buffer->b_write_to_channel = FALSE;
    }

    // Append to the buffer
    ch_log(channel, "appending line %d to buffer %s",
				       (int)lnum + 1 - empty, buffer->b_fname);

    buffer->b_p_ma = TRUE;

    // Set curbuf to "buffer", temporarily.
    aucmd_prepbuf(&aco, buffer);
    if (curbuf != buffer)
    {
	// Could not find a window for this buffer, the following might cause
	// trouble, better bail out.
	return;
    }

    u_sync(TRUE);
    // ignore undo failure, undo is not very useful here
    vim_ignored = u_save(lnum - empty, lnum + 1);

    if (empty)
    {
	// The buffer is empty, replace the first (dummy) line.
	ml_replace(lnum, msg, TRUE);
	lnum = 0;
    }
    else
	ml_append(lnum, msg, 0, FALSE);
    appended_lines_mark(lnum, 1L);

    // reset notion of buffer
    aucmd_restbuf(&aco);

    if (ch_part->ch_nomodifiable)
	buffer->b_p_ma = FALSE;
    else
	buffer->b_p_ma = save_p_ma;

    if (buffer->b_nwindows > 0)
    {
	win_T	*wp;

	FOR_ALL_WINDOWS(wp)
	{
	    if (wp->w_buffer == buffer)
	    {
		int move_cursor = save_write_to
			    ? wp->w_cursor.lnum == lnum + 1
			    : (wp->w_cursor.lnum == lnum
				&& wp->w_cursor.col == 0);

		// If the cursor is at or above the new line, move it one line
		// down.  If the topline is outdated update it now.
		if (move_cursor || wp->w_topline > buffer->b_ml.ml_line_count)
		{
		    win_T *save_curwin = curwin;

		    if (move_cursor)
			++wp->w_cursor.lnum;
		    curwin = wp;
		    curbuf = curwin->w_buffer;
		    scroll_cursor_bot(0, FALSE);
		    curwin = save_curwin;
		    curbuf = curwin->w_buffer;
		}
	    }
	}
	redraw_buf_and_status_later(buffer, UPD_VALID);
	channel_need_redraw = TRUE;
    }

    if (save_write_to)
    {
	channel_T *ch;

	// Find channels reading from this buffer and adjust their
	// next-to-read line number.
	buffer->b_write_to_channel = TRUE;
	FOR_ALL_CHANNELS(ch)
	{
	    chanpart_T  *in_part = &ch->ch_part[PART_IN];

	    if (in_part->ch_bufref.br_buf == buffer)
		in_part->ch_buf_bot = buffer->b_ml.ml_line_count;
	}
    }
}

    static void
drop_messages(channel_T *channel, ch_part_T part)
{
    char_u *msg;

    while ((msg = channel_get(channel, part, NULL)) != NULL)
    {
	ch_log(channel, "Dropping message '%s'", (char *)msg);
	vim_free(msg);
    }
}

/*
 * Return TRUE if for "channel" / "part" ch_json_head should be used.
 */
    static int
channel_use_json_head(channel_T *channel, ch_part_T part)
{
    ch_mode_T	ch_mode = channel->ch_part[part].ch_mode;

    return ch_mode == CH_MODE_JSON || ch_mode == CH_MODE_JS
						     || ch_mode == CH_MODE_LSP;
}

/*
 * Invoke a callback for "channel"/"part" if needed.
 * This does not redraw but sets channel_need_redraw when redraw is needed.
 * Return TRUE when a message was handled, there might be another one.
 */
    static int
may_invoke_callback(channel_T *channel, ch_part_T part)
{
    char_u	*msg = NULL;
    typval_T	*listtv = NULL;
    typval_T	argv[CH_JSON_MAX_ARGS];
    int		seq_nr = -1;
    chanpart_T	*ch_part = &channel->ch_part[part];
    ch_mode_T	ch_mode = ch_part->ch_mode;
    cbq_T	*cbhead = &ch_part->ch_cb_head;
    cbq_T	*cbitem;
    callback_T	*callback = NULL;
    buf_T	*buffer = NULL;
    char_u	*p;
    int		called_otc;		// one time callbackup

    if (channel->ch_nb_close_cb != NULL)
	// this channel is handled elsewhere (netbeans)
	return FALSE;

    // Use a message-specific callback, part callback or channel callback
    for (cbitem = cbhead->cq_next; cbitem != NULL; cbitem = cbitem->cq_next)
	if (cbitem->cq_seq_nr == 0)
	    break;
    if (cbitem != NULL)
	callback = &cbitem->cq_callback;
    else if (ch_part->ch_callback.cb_name != NULL)
	callback = &ch_part->ch_callback;
    else if (channel->ch_callback.cb_name != NULL)
	callback = &channel->ch_callback;

    buffer = ch_part->ch_bufref.br_buf;
    if (buffer != NULL && (!bufref_valid(&ch_part->ch_bufref)
					       || buffer->b_ml.ml_mfp == NULL))
    {
	// buffer was wiped out or unloaded
	ch_log(channel, "%s buffer has been wiped out", ch_part_names[part]);
	ch_part->ch_bufref.br_buf = NULL;
	buffer = NULL;
    }

    if (channel_use_json_head(channel, part))
    {
	listitem_T	*item;
	int		argc = 0;

	// Get any json message in the queue.
	if (channel_get_json(channel, part, -1, FALSE, &listtv) == FAIL)
	{
	    if (ch_mode == CH_MODE_LSP)
		// In the "lsp" mode, the http header and the json payload may
		// be received in multiple messages. So concatenate all the
		// received messages.
		(void)channel_collapse(channel, part, FALSE);

	    // Parse readahead, return when there is still no message.
	    channel_parse_json(channel, part);
	    if (channel_get_json(channel, part, -1, FALSE, &listtv) == FAIL)
		return FALSE;
	}

	if (ch_mode == CH_MODE_LSP)
	{
	    dict_T	*d = listtv->vval.v_dict;
	    dictitem_T	*di;

	    seq_nr = 0;
	    if (d != NULL)
	    {
		di = dict_find(d, (char_u *)"id", -1);
		if (di != NULL && di->di_tv.v_type == VAR_NUMBER)
		    seq_nr = di->di_tv.vval.v_number;
	    }

	    argv[1] = *listtv;
	}
	else
	{
	    for (item = listtv->vval.v_list->lv_first;
		    item != NULL && argc < CH_JSON_MAX_ARGS;
		    item = item->li_next)
		argv[argc++] = item->li_tv;
	    while (argc < CH_JSON_MAX_ARGS)
		argv[argc++].v_type = VAR_UNKNOWN;

	    if (argv[0].v_type == VAR_STRING)
	    {
		// ["cmd", arg] or ["cmd", arg, arg] or ["cmd", arg, arg, arg]
		channel_exe_cmd(channel, part, argv);
		free_tv(listtv);
		return TRUE;
	    }

	    if (argv[0].v_type != VAR_NUMBER)
	    {
		ch_error(channel,
			"Dropping message with invalid sequence number type");
		free_tv(listtv);
		return FALSE;
	    }
	    seq_nr = argv[0].vval.v_number;
	}
    }
    else if (channel_peek(channel, part) == NULL)
    {
	// nothing to read on RAW or NL channel
	return FALSE;
    }
    else
    {
	// If there is no callback or buffer drop the message.
	if (callback == NULL && buffer == NULL)
	{
	    // If there is a close callback it may use ch_read() to get the
	    // messages.
	    if (channel->ch_close_cb.cb_name == NULL && !channel->ch_drop_never)
		drop_messages(channel, part);
	    return FALSE;
	}

	if (ch_mode == CH_MODE_NL)
	{
	    char_u  *nl = NULL;
	    char_u  *buf;
	    readq_T *node;

	    // See if we have a message ending in NL in the first buffer.  If
	    // not try to concatenate the first and the second buffer.
	    while (TRUE)
	    {
		node = channel_peek(channel, part);
		nl = channel_first_nl(node);
		if (nl != NULL)
		    break;
		if (channel_collapse(channel, part, TRUE) == FAIL)
		{
		    if (ch_part->ch_fd == INVALID_FD && node->rq_buflen > 0)
			break;
		    return FALSE; // incomplete message
		}
	    }
	    buf = node->rq_buffer;

	    // Convert NUL to NL, the internal representation.
	    for (p = buf; (nl == NULL || p < nl)
					    && p < buf + node->rq_buflen; ++p)
		if (*p == NUL)
		    *p = NL;

	    if (nl == NULL)
	    {
		// get the whole buffer, drop the NL
		msg = channel_get(channel, part, NULL);
	    }
	    else if (nl + 1 == buf + node->rq_buflen)
	    {
		// get the whole buffer
		msg = channel_get(channel, part, NULL);
		*nl = NUL;
	    }
	    else
	    {
		// Copy the message into allocated memory (excluding the NL)
		// and remove it from the buffer (including the NL).
		msg = vim_strnsave(buf, nl - buf);
		channel_consume(channel, part, (int)(nl - buf) + 1);
	    }
	}
	else
	{
	    // For a raw channel we don't know where the message ends, just
	    // get everything we have.
	    // Convert NUL to NL, the internal representation.
	    msg = channel_get_all(channel, part, NULL);
	}

	if (msg == NULL)
	    return FALSE; // out of memory (and avoids Coverity warning)

	argv[1].v_type = VAR_STRING;
	argv[1].vval.v_string = msg;
    }

    called_otc = FALSE;
    if (seq_nr > 0)
    {
	// JSON or JS or LSP mode: invoke the one-time callback with the
	// matching nr
	int lsp_req_msg = FALSE;

	// Don't use a LSP server request message with the same sequence number
	// as the client request message as the response message.
	if (ch_mode == CH_MODE_LSP && argv[1].v_type == VAR_DICT
		&& dict_has_key(argv[1].vval.v_dict, "method"))
	    lsp_req_msg = TRUE;

	if (!lsp_req_msg)
	{
	    for (cbitem = cbhead->cq_next; cbitem != NULL;
		    cbitem = cbitem->cq_next)
	    {
		if (cbitem->cq_seq_nr == seq_nr)
		{
		    invoke_one_time_callback(channel, cbhead, cbitem, argv);
		    called_otc = TRUE;
		    break;
		}
	    }
	}
    }

    if (seq_nr > 0 && (ch_mode != CH_MODE_LSP || called_otc))
    {
	if (!called_otc)
	{
	    // If the 'drop' channel attribute is set to 'never' or if
	    // ch_evalexpr() is waiting for this response message, then don't
	    // drop this message.
	    if (channel->ch_drop_never)
	    {
		// message must be read with ch_read()
		channel_push_json(channel, part, listtv);

		// Change the type to avoid the value being freed.
		listtv->v_type = VAR_NUMBER;
		free_tv(listtv);
		listtv = NULL;
	    }
	    else
		ch_log(channel, "Dropping message %d without callback",
								       seq_nr);
	}
    }
    else if (callback != NULL || buffer != NULL)
    {
	if (buffer != NULL)
	{
	    if (msg == NULL)
		// JSON or JS mode: re-encode the message.
		msg = json_encode(listtv, ch_mode);
	    if (msg != NULL)
	    {
#ifdef FEAT_TERMINAL
		if (buffer->b_term != NULL)
		    write_to_term(buffer, msg, channel);
		else
#endif
		    append_to_buffer(buffer, msg, channel, part);
	    }
	}

	if (callback != NULL)
	{
	    if (cbitem != NULL)
		invoke_one_time_callback(channel, cbhead, cbitem, argv);
	    else
	    {
		// invoke the channel callback
		ch_log(channel, "Invoking channel callback %s",
						    (char *)callback->cb_name);
		invoke_callback(channel, callback, argv);
	    }
	}
    }
    else
	ch_log(channel, "Dropping message %d", seq_nr);

    if (listtv != NULL)
	free_tv(listtv);
    vim_free(msg);

    return TRUE;
}

#if defined(FEAT_NETBEANS_INTG) || defined(PROTO)
/*
 * Return TRUE when channel "channel" is open for writing to.
 * Also returns FALSE or invalid "channel".
 */
    int
channel_can_write_to(channel_T *channel)
{
    return channel != NULL && (channel->CH_SOCK_FD != INVALID_FD
			  || channel->CH_IN_FD != INVALID_FD);
}
#endif

/*
 * Return TRUE when channel "channel" is open for reading or writing.
 * Also returns FALSE for invalid "channel".
 */
    int
channel_is_open(channel_T *channel)
{
    return channel != NULL && (channel->CH_SOCK_FD != INVALID_FD
			  || channel->CH_IN_FD != INVALID_FD
			  || channel->CH_OUT_FD != INVALID_FD
			  || channel->CH_ERR_FD != INVALID_FD);
}

/*
 * Return a pointer indicating the readahead.  Can only be compared between
 * calls.  Returns NULL if there is no readahead.
 */
    static void *
channel_readahead_pointer(channel_T *channel, ch_part_T part)
{
    if (channel_use_json_head(channel, part))
    {
	jsonq_T   *head = &channel->ch_part[part].ch_json_head;

	if (head->jq_next == NULL)
	    // Parse json from readahead, there might be a complete message to
	    // process.
	    channel_parse_json(channel, part);

	return head->jq_next;
    }
    return channel_peek(channel, part);
}

/*
 * Return TRUE if "channel" has JSON or other typeahead.
 */
    static int
channel_has_readahead(channel_T *channel, ch_part_T part)
{
    return channel_readahead_pointer(channel, part) != NULL;
}

/*
 * Return a string indicating the status of the channel.
 * If "req_part" is not negative check that part.
 */
    static char *
channel_status(channel_T *channel, int req_part)
{
    ch_part_T part;
    int has_readahead = FALSE;

    if (channel == NULL)
	 return "fail";
    if (req_part == PART_OUT)
    {
	if (channel->CH_OUT_FD != INVALID_FD)
	    return "open";
	if (channel_has_readahead(channel, PART_OUT))
	    has_readahead = TRUE;
    }
    else if (req_part == PART_ERR)
    {
	if (channel->CH_ERR_FD != INVALID_FD)
	    return "open";
	if (channel_has_readahead(channel, PART_ERR))
	    has_readahead = TRUE;
    }
    else
    {
	if (channel_is_open(channel))
	    return "open";
	for (part = PART_SOCK; part < PART_IN; ++part)
	    if (channel_has_readahead(channel, part))
	    {
		has_readahead = TRUE;
		break;
	    }
    }

    if (has_readahead)
	return "buffered";
    return "closed";
}

    static void
channel_part_info(channel_T *channel, dict_T *dict, char *name, ch_part_T part)
{
    chanpart_T *chanpart = &channel->ch_part[part];
    char	namebuf[20];  // longest is "sock_timeout"
    size_t	tail;
    char	*status;
    char	*s = "";

    vim_strncpy((char_u *)namebuf, (char_u *)name, 4);
    STRCAT(namebuf, "_");
    tail = STRLEN(namebuf);

    STRCPY(namebuf + tail, "status");
    if (chanpart->ch_fd != INVALID_FD)
	status = "open";
    else if (channel_has_readahead(channel, part))
	status = "buffered";
    else
	status = "closed";
    dict_add_string(dict, namebuf, (char_u *)status);

    STRCPY(namebuf + tail, "mode");
    switch (chanpart->ch_mode)
    {
	case CH_MODE_NL: s = "NL"; break;
	case CH_MODE_RAW: s = "RAW"; break;
	case CH_MODE_JSON: s = "JSON"; break;
	case CH_MODE_JS: s = "JS"; break;
	case CH_MODE_LSP: s = "LSP"; break;
    }
    dict_add_string(dict, namebuf, (char_u *)s);

    STRCPY(namebuf + tail, "io");
    if (part == PART_SOCK)
	s = "socket";
    else switch (chanpart->ch_io)
    {
	case JIO_NULL: s = "null"; break;
	case JIO_PIPE: s = "pipe"; break;
	case JIO_FILE: s = "file"; break;
	case JIO_BUFFER: s = "buffer"; break;
	case JIO_OUT: s = "out"; break;
    }
    dict_add_string(dict, namebuf, (char_u *)s);

    STRCPY(namebuf + tail, "timeout");
    dict_add_number(dict, namebuf, chanpart->ch_timeout);
}

    static void
channel_info(channel_T *channel, dict_T *dict)
{
    dict_add_number(dict, "id", channel->ch_id);
    dict_add_string(dict, "status", (char_u *)channel_status(channel, -1));

    if (channel->ch_hostname != NULL)
    {
	if (channel->ch_port)
	{
	    dict_add_string(dict, "hostname", (char_u *)channel->ch_hostname);
	    dict_add_number(dict, "port", channel->ch_port);
	}
	else
	    // Unix-domain socket.
	    dict_add_string(dict, "path", (char_u *)channel->ch_hostname);
	channel_part_info(channel, dict, "sock", PART_SOCK);
    }
    else
    {
	channel_part_info(channel, dict, "out", PART_OUT);
	channel_part_info(channel, dict, "err", PART_ERR);
	channel_part_info(channel, dict, "in", PART_IN);
    }
}

/*
 * Close channel "channel".
 * Trigger the close callback if "invoke_close_cb" is TRUE.
 * Does not clear the buffers.
 */
    void
channel_close(channel_T *channel, int invoke_close_cb)
{
    ch_log(channel, "Closing channel");

#ifdef FEAT_GUI
    channel_gui_unregister(channel);
#endif

    ch_close_part(channel, PART_SOCK);
    ch_close_part(channel, PART_IN);
    ch_close_part(channel, PART_OUT);
    ch_close_part(channel, PART_ERR);

    if (invoke_close_cb)
    {
	ch_part_T	part;

#ifdef FEAT_TERMINAL
	// let the terminal know it is closing to avoid getting stuck
	term_channel_closing(channel);
#endif
	// Invoke callbacks and flush buffers before the close callback.
	if (channel->ch_close_cb.cb_name != NULL)
	    ch_log(channel,
		     "Invoking callbacks and flushing buffers before closing");
	for (part = PART_SOCK; part < PART_IN; ++part)
	{
	    if (channel->ch_close_cb.cb_name != NULL
			    || channel->ch_part[part].ch_bufref.br_buf != NULL)
	    {
		// Increment the refcount to avoid the channel being freed
		// halfway.
		++channel->ch_refcount;
		if (channel->ch_close_cb.cb_name == NULL)
		    ch_log(channel, "flushing %s buffers before closing",
							  ch_part_names[part]);
		while (may_invoke_callback(channel, part))
		    ;
		--channel->ch_refcount;
	    }
	}

	if (channel->ch_close_cb.cb_name != NULL)
	{
	      typval_T	argv[1];
	      typval_T	rettv;

	      // Increment the refcount to avoid the channel being freed
	      // halfway.
	      ++channel->ch_refcount;
	      ch_log(channel, "Invoking close callback %s",
					 (char *)channel->ch_close_cb.cb_name);
	      argv[0].v_type = VAR_CHANNEL;
	      argv[0].vval.v_channel = channel;
	      call_callback(&channel->ch_close_cb, -1, &rettv, 1, argv);
	      clear_tv(&rettv);
	      channel_need_redraw = TRUE;

	      // the callback is only called once
	      free_callback(&channel->ch_close_cb);

	      if (channel_need_redraw)
	      {
		  channel_need_redraw = FALSE;
		  redraw_after_callback(TRUE, FALSE);
	      }

	      if (!channel->ch_drop_never)
		  // any remaining messages are useless now
		  for (part = PART_SOCK; part < PART_IN; ++part)
		      drop_messages(channel, part);

	      --channel->ch_refcount;
	}
    }

    channel->ch_nb_close_cb = NULL;

#ifdef FEAT_TERMINAL
    term_channel_closed(channel);
#endif
}

/*
 * Close the "in" part channel "channel".
 */
    static void
channel_close_in(channel_T *channel)
{
    ch_close_part(channel, PART_IN);
}

    static void
remove_from_writeque(writeq_T *wq, writeq_T *entry)
{
    ga_clear(&entry->wq_ga);
    wq->wq_next = entry->wq_next;
    if (wq->wq_next == NULL)
	wq->wq_prev = NULL;
    else
	wq->wq_next->wq_prev = NULL;
    vim_free(entry);
}

/*
 * Clear the read buffer on "channel"/"part".
 */
    static void
channel_clear_one(channel_T *channel, ch_part_T part)
{
    chanpart_T *ch_part = &channel->ch_part[part];
    jsonq_T *json_head = &ch_part->ch_json_head;
    cbq_T   *cb_head = &ch_part->ch_cb_head;

    while (channel_peek(channel, part) != NULL)
	vim_free(channel_get(channel, part, NULL));

    while (cb_head->cq_next != NULL)
    {
	cbq_T *node = cb_head->cq_next;

	remove_cb_node(cb_head, node);
	free_callback(&node->cq_callback);
	vim_free(node);
    }

    while (json_head->jq_next != NULL)
    {
	free_tv(json_head->jq_next->jq_value);
	remove_json_node(json_head, json_head->jq_next);
    }

    free_callback(&ch_part->ch_callback);
    ga_clear(&ch_part->ch_block_ids);

    while (ch_part->ch_writeque.wq_next != NULL)
	remove_from_writeque(&ch_part->ch_writeque,
						 ch_part->ch_writeque.wq_next);
}

/*
 * Clear all the read buffers on "channel".
 */
    void
channel_clear(channel_T *channel)
{
    ch_log(channel, "Clearing channel");
    VIM_CLEAR(channel->ch_hostname);
    channel_clear_one(channel, PART_SOCK);
    channel_clear_one(channel, PART_OUT);
    channel_clear_one(channel, PART_ERR);
    channel_clear_one(channel, PART_IN);
    free_callback(&channel->ch_callback);
    free_callback(&channel->ch_close_cb);
}

#if defined(EXITFREE) || defined(PROTO)
    void
channel_free_all(void)
{
    channel_T *channel;

    ch_log(NULL, "channel_free_all()");
    FOR_ALL_CHANNELS(channel)
	channel_clear(channel);
}
#endif


// Sent when the netbeans channel is found closed when reading.
#define DETACH_MSG_RAW "DETACH\n"

// Buffer size for reading incoming messages.
#define MAXMSGSIZE 4096

/*
 * Check if there are remaining data that should be written for "in_part".
 */
    static int
is_channel_write_remaining(chanpart_T *in_part)
{
    buf_T *buf = in_part->ch_bufref.br_buf;

    if (in_part->ch_writeque.wq_next != NULL)
	return TRUE;
    if (buf == NULL)
	return FALSE;
    return in_part->ch_buf_append
	    ? (in_part->ch_buf_bot < buf->b_ml.ml_line_count)
	    : (in_part->ch_buf_top <= in_part->ch_buf_bot
			    && in_part->ch_buf_top <= buf->b_ml.ml_line_count);
}

#if defined(HAVE_SELECT)
/*
 * Add write fds where we are waiting for writing to be possible.
 */
    static int
channel_fill_wfds(int maxfd_arg, fd_set *wfds)
{
    int		maxfd = maxfd_arg;
    channel_T	*ch;

    FOR_ALL_CHANNELS(ch)
    {
	chanpart_T  *in_part = &ch->ch_part[PART_IN];

	if (in_part->ch_fd != INVALID_FD
		&& is_channel_write_remaining(in_part))
	{
	    FD_SET((int)in_part->ch_fd, wfds);
	    if ((int)in_part->ch_fd >= maxfd)
		maxfd = (int)in_part->ch_fd + 1;
	}
    }
    return maxfd;
}
#else
/*
 * Add write fds where we are waiting for writing to be possible.
 */
    static int
channel_fill_poll_write(int nfd_in, struct pollfd *fds)
{
    int		nfd = nfd_in;
    channel_T	*ch;

    FOR_ALL_CHANNELS(ch)
    {
	chanpart_T  *in_part = &ch->ch_part[PART_IN];

	if (in_part->ch_fd != INVALID_FD
		&& is_channel_write_remaining(in_part))
	{
	    in_part->ch_poll_idx = nfd;
	    fds[nfd].fd = in_part->ch_fd;
	    fds[nfd].events = POLLOUT;
	    ++nfd;
	}
	else
	    in_part->ch_poll_idx = -1;
    }
    return nfd;
}
#endif

typedef enum {
    CW_READY,
    CW_NOT_READY,
    CW_ERROR
} channel_wait_result;

/*
 * Check for reading from "fd" with "timeout" msec.
 * Return CW_READY when there is something to read.
 * Return CW_NOT_READY when there is nothing to read.
 * Return CW_ERROR when there is an error.
 */
    static channel_wait_result
channel_wait(channel_T *channel, sock_T fd, int timeout)
{
    if (timeout > 0)
	ch_log(channel, "Waiting for up to %d msec", timeout);

# ifdef MSWIN
    if (fd != channel->CH_SOCK_FD)
    {
	DWORD	nread;
	int	sleep_time;
	DWORD	deadline = GetTickCount() + timeout;
	int	delay = 1;

	// reading from a pipe, not a socket
	while (TRUE)
	{
	    int r = PeekNamedPipe((HANDLE)fd, NULL, 0, NULL, &nread, NULL);

	    if (r && nread > 0)
		return CW_READY;

	    if (channel->ch_named_pipe)
	    {
		DisconnectNamedPipe((HANDLE)fd);
		ConnectNamedPipe((HANDLE)fd, NULL);
	    }
	    else if (r == 0)
		return CW_ERROR;

	    // perhaps write some buffer lines
	    channel_write_any_lines();

	    sleep_time = deadline - GetTickCount();
	    if (sleep_time <= 0)
		break;
	    // Wait for a little while.  Very short at first, up to 10 msec
	    // after looping a few times.
	    if (sleep_time > delay)
		sleep_time = delay;
	    Sleep(sleep_time);
	    delay = delay * 2;
	    if (delay > 10)
		delay = 10;
	}
    }
    else
#endif
    {
#if defined(HAVE_SELECT)
	struct timeval	tval;
	fd_set		rfds;
	fd_set		wfds;
	int		ret;
	int		maxfd;

	tval.tv_sec = timeout / 1000;
	tval.tv_usec = (timeout % 1000) * 1000;
	for (;;)
	{
	    FD_ZERO(&rfds);
	    FD_SET((int)fd, &rfds);

	    // Write lines to a pipe when a pipe can be written to.  Need to
	    // set this every time, some buffers may be done.
	    maxfd = (int)fd + 1;
	    FD_ZERO(&wfds);
	    maxfd = channel_fill_wfds(maxfd, &wfds);

	    ret = select(maxfd, &rfds, &wfds, NULL, &tval);
# ifdef EINTR
	    SOCK_ERRNO;
	    if (ret == -1 && errno == EINTR)
		continue;
# endif
	    if (ret > 0)
	    {
		if (FD_ISSET(fd, &rfds))
		    return CW_READY;
		channel_write_any_lines();
		continue;
	    }
	    break;
	}
#else
	for (;;)
	{
	    struct pollfd   fds[MAX_OPEN_CHANNELS + 1];
	    int		    nfd = 1;

	    fds[0].fd = fd;
	    fds[0].events = POLLIN;
	    nfd = channel_fill_poll_write(nfd, fds);
	    if (poll(fds, nfd, timeout) > 0)
	    {
		if (fds[0].revents & POLLIN)
		    return CW_READY;
		channel_write_any_lines();
		continue;
	    }
	    break;
	}
#endif
    }
    return CW_NOT_READY;
}

    static void
ch_close_part_on_error(
	channel_T *channel, ch_part_T part, int is_err, char *func)
{
    char	msg[] = "%s(): Read %s from ch_part[%d], closing";

    if (is_err)
	// Do not call emsg(), most likely the other end just exited.
	ch_error(channel, msg, func, "error", part);
    else
	ch_log(channel, msg, func, "EOF", part);

    // Queue a "DETACH" netbeans message in the command queue in order to
    // terminate the netbeans session later. Do not end the session here
    // directly as we may be running in the context of a call to
    // netbeans_parse_messages():
    //	netbeans_parse_messages
    //	    -> autocmd triggered while processing the netbeans cmd
    //		-> ui_breakcheck
    //		    -> gui event loop or select loop
    //			-> channel_read()
    // Only send "DETACH" for a netbeans channel.
    if (channel->ch_nb_close_cb != NULL)
	channel_save(channel, PART_SOCK, (char_u *)DETACH_MSG_RAW,
			      (int)STRLEN(DETACH_MSG_RAW), FALSE, "PUT ");

    // When reading is not possible close this part of the channel.  Don't
    // close the channel yet, there may be something to read on another part.
    // When stdout and stderr use the same FD we get the error only on one of
    // them, also close the other.
    if (part == PART_OUT || part == PART_ERR)
    {
	ch_part_T other = part == PART_OUT ? PART_ERR : PART_OUT;

	if (channel->ch_part[part].ch_fd == channel->ch_part[other].ch_fd)
	    ch_close_part(channel, other);
    }
    ch_close_part(channel, part);

#ifdef FEAT_GUI
    // Stop listening to GUI events right away.
    channel_gui_unregister_one(channel, part);
#endif
}

    static void
channel_close_now(channel_T *channel)
{
    ch_log(channel, "Closing channel because all readable fds are closed");
    if (channel->ch_nb_close_cb != NULL)
	(*channel->ch_nb_close_cb)();
    channel_close(channel, TRUE);
}

/*
 * Read from channel "channel" for as long as there is something to read.
 * "part" is PART_SOCK, PART_OUT or PART_ERR.
 * The data is put in the read queue.  No callbacks are invoked here.
 */
    static void
channel_read(channel_T *channel, ch_part_T part, char *func)
{
    static char_u	*buf = NULL;
    int			len = 0;
    int			readlen = 0;
    sock_T		fd;
    int			use_socket = FALSE;

    fd = channel->ch_part[part].ch_fd;
    if (fd == INVALID_FD)
    {
	ch_error(channel, "channel_read() called while %s part is closed",
							  ch_part_names[part]);
	return;
    }
    use_socket = fd == channel->CH_SOCK_FD;

    // Allocate a buffer to read into.
    if (buf == NULL)
    {
	buf = alloc(MAXMSGSIZE);
	if (buf == NULL)
	    return;	// out of memory!
    }

    // Keep on reading for as long as there is something to read.
    // Use select() or poll() to avoid blocking on a message that is exactly
    // MAXMSGSIZE long.
    for (;;)
    {
	if (channel_wait(channel, fd, 0) != CW_READY)
	    break;
	if (use_socket)
	    len = sock_read(fd, (char *)buf, MAXMSGSIZE);
	else
	    len = fd_read(fd, (char *)buf, MAXMSGSIZE);
	if (len <= 0)
	    break;	// error or nothing more to read

	// Store the read message in the queue.
	channel_save(channel, part, buf, len, FALSE, "RECV ");
	readlen += len;
    }

    // Reading a disconnection (readlen == 0), or an error.
    if (readlen <= 0)
    {
	if (!channel->ch_keep_open)
	    ch_close_part_on_error(channel, part, (len < 0), func);
    }
#if defined(CH_HAS_GUI) && defined(FEAT_GUI_GTK)
    else if (CH_HAS_GUI && gtk_main_level() > 0)
	// signal the main loop that there is something to read
	gtk_main_quit();
#endif
}

/*
 * Read from RAW or NL "channel"/"part".  Blocks until there is something to
 * read or the timeout expires.
 * When "raw" is TRUE don't block waiting on a NL.
 * Does not trigger timers or handle messages.
 * Returns what was read in allocated memory.
 * Returns NULL in case of error or timeout.
 */
    static char_u *
channel_read_block(
	channel_T *channel, ch_part_T part, int timeout, int raw, int *outlen)
{
    char_u	*buf;
    char_u	*msg;
    ch_mode_T	mode = channel->ch_part[part].ch_mode;
    sock_T	fd = channel->ch_part[part].ch_fd;
    char_u	*nl;
    readq_T	*node;

    ch_log(channel, "Blocking %s read, timeout: %d msec",
				  mode == CH_MODE_RAW ? "RAW" : "NL", timeout);

    while (TRUE)
    {
	node = channel_peek(channel, part);
	if (node != NULL)
	{
	    if (mode == CH_MODE_RAW || (mode == CH_MODE_NL
					   && channel_first_nl(node) != NULL))
		// got a complete message
		break;
	    if (channel_collapse(channel, part, mode == CH_MODE_NL) == OK)
		continue;
	    // If not blocking or nothing more is coming then return what we
	    // have.
	    if (raw || fd == INVALID_FD)
		break;
	}

	// Wait for up to the channel timeout.
	if (fd == INVALID_FD)
	    return NULL;
	if (channel_wait(channel, fd, timeout) != CW_READY)
	{
	    ch_log(channel, "Timed out");
	    return NULL;
	}
	channel_read(channel, part, "channel_read_block");
    }

    // We have a complete message now.
    if (mode == CH_MODE_RAW || outlen != NULL)
    {
	msg = channel_get_all(channel, part, outlen);
    }
    else
    {
	char_u *p;

	buf = node->rq_buffer;
	nl = channel_first_nl(node);

	// Convert NUL to NL, the internal representation.
	for (p = buf; (nl == NULL || p < nl) && p < buf + node->rq_buflen; ++p)
	    if (*p == NUL)
		*p = NL;

	if (nl == NULL)
	{
	    // must be a closed channel with missing NL
	    msg = channel_get(channel, part, NULL);
	}
	else if (nl + 1 == buf + node->rq_buflen)
	{
	    // get the whole buffer
	    msg = channel_get(channel, part, NULL);
	    *nl = NUL;
	}
	else
	{
	    // Copy the message into allocated memory and remove it from the
	    // buffer.
	    msg = vim_strnsave(buf, nl - buf);
	    channel_consume(channel, part, (int)(nl - buf) + 1);
	}
    }
    if (ch_log_active())
	ch_log(channel, "Returning %d bytes", (int)STRLEN(msg));
    return msg;
}

static int channel_blocking_wait = 0;

/*
 * Return TRUE if in a blocking wait that might trigger callbacks.
 */
    int
channel_in_blocking_wait(void)
{
    return channel_blocking_wait > 0;
}

/*
 * Read one JSON message with ID "id" from "channel"/"part" and store the
 * result in "rettv".
 * When "id" is -1 accept any message;
 * Blocks until the message is received or the timeout is reached.
 * In corner cases this can be called recursively, that is why ch_block_ids is
 * a list.
 */
    static int
channel_read_json_block(
	channel_T   *channel,
	ch_part_T   part,
	int	    timeout_arg,
	int	    id,
	typval_T    **rettv)
{
    int		more;
    sock_T	fd;
    int		timeout;
    chanpart_T	*chanpart = &channel->ch_part[part];
    ch_mode_T	mode = channel->ch_part[part].ch_mode;
    int		retval = FAIL;

    ch_log(channel, "Blocking read JSON for id %d", id);
    ++channel_blocking_wait;

    if (id >= 0)
	channel_add_block_id(chanpart, id);

    for (;;)
    {
	if (mode == CH_MODE_LSP)
	    // In the "lsp" mode, the http header and the json payload may be
	    // received in multiple messages. So concatenate all the received
	    // messages.
	    (void)channel_collapse(channel, part, FALSE);

	more = channel_parse_json(channel, part);

	// search for message "id"
	if (channel_get_json(channel, part, id, TRUE, rettv) == OK)
	{
	    ch_log(channel, "Received JSON for id %d", id);
	    retval = OK;
	    break;
	}

	if (!more)
	{
	    void *prev_readahead_ptr = channel_readahead_pointer(channel, part);
	    void *readahead_ptr;

	    // Handle any other messages in the queue.  If done some more
	    // messages may have arrived.
	    if (channel_parse_messages())
		continue;

	    // channel_parse_messages() may fill the queue with new data to
	    // process.  Only loop when the readahead changed, otherwise we
	    // would busy-loop.
	    readahead_ptr = channel_readahead_pointer(channel, part);
	    if (readahead_ptr != NULL && readahead_ptr != prev_readahead_ptr)
		continue;

	    // Wait for up to the timeout.  If there was an incomplete message
	    // use the deadline for that.
	    timeout = timeout_arg;
	    if (chanpart->ch_wait_len > 0)
	    {
#ifdef MSWIN
		timeout = chanpart->ch_deadline - GetTickCount() + 1;
#else
		{
		    struct timeval now_tv;

		    gettimeofday(&now_tv, NULL);
		    timeout = (chanpart->ch_deadline.tv_sec
						       - now_tv.tv_sec) * 1000
			+ (chanpart->ch_deadline.tv_usec
						     - now_tv.tv_usec) / 1000
			+ 1;
		}
#endif
		if (timeout < 0)
		{
		    // Something went wrong, channel_parse_json() didn't
		    // discard message.  Cancel waiting.
		    chanpart->ch_wait_len = 0;
		    timeout = timeout_arg;
		}
		else if (timeout > timeout_arg)
		    timeout = timeout_arg;
	    }
	    fd = chanpart->ch_fd;
	    if (fd == INVALID_FD
			    || channel_wait(channel, fd, timeout) != CW_READY)
	    {
		if (timeout == timeout_arg)
		{
		    if (fd != INVALID_FD)
			ch_log(channel, "Timed out on id %d", id);
		    break;
		}
	    }
	    else
		channel_read(channel, part, "channel_read_json_block");
	}
    }
    if (id >= 0)
	channel_remove_block_id(chanpart, id);
    --channel_blocking_wait;

    return retval;
}

/*
 * Get the channel from the argument.
 * Returns NULL if the handle is invalid.
 * When "check_open" is TRUE check that the channel can be used.
 * When "reading" is TRUE "check_open" considers typeahead useful.
 * "part" is used to check typeahead, when PART_COUNT use the default part.
 */
    channel_T *
get_channel_arg(typval_T *tv, int check_open, int reading, ch_part_T part)
{
    channel_T	*channel = NULL;
    int		has_readahead = FALSE;

    if (tv->v_type == VAR_JOB)
    {
	if (tv->vval.v_job != NULL)
	    channel = tv->vval.v_job->jv_channel;
    }
    else if (tv->v_type == VAR_CHANNEL)
    {
	channel = tv->vval.v_channel;
    }
    else
    {
	semsg(_(e_invalid_argument_str), tv_get_string(tv));
	return NULL;
    }
    if (channel != NULL && reading)
	has_readahead = channel_has_readahead(channel,
		       part != PART_COUNT ? part : channel_part_read(channel));

    if (check_open && (channel == NULL || (!channel_is_open(channel)
					     && !(reading && has_readahead))))
    {
	emsg(_(e_not_an_open_channel));
	return NULL;
    }
    return channel;
}

/*
 * Common for ch_read() and ch_readraw().
 */
    static void
common_channel_read(typval_T *argvars, typval_T *rettv, int raw, int blob)
{
    channel_T	*channel;
    ch_part_T	part = PART_COUNT;
    jobopt_T	opt;
    int		mode;
    int		timeout;
    int		id = -1;
    typval_T	*listtv = NULL;

    // return an empty string by default
    rettv->v_type = VAR_STRING;
    rettv->vval.v_string = NULL;

    if (in_vim9script()
	    && (check_for_chan_or_job_arg(argvars, 0) == FAIL
		|| check_for_opt_dict_arg(argvars, 1) == FAIL))
	return;

    clear_job_options(&opt);
    if (get_job_options(&argvars[1], &opt, JO_TIMEOUT + JO_PART + JO_ID, 0)
								      == FAIL)
	goto theend;

    if (opt.jo_set & JO_PART)
	part = opt.jo_part;
    channel = get_channel_arg(&argvars[0], TRUE, TRUE, part);
    if (channel == NULL)
	goto theend;

    if (part == PART_COUNT)
	part = channel_part_read(channel);
    mode = channel_get_mode(channel, part);
    timeout = channel_get_timeout(channel, part);
    if (opt.jo_set & JO_TIMEOUT)
	timeout = opt.jo_timeout;

    if (blob)
    {
	int	    outlen = 0;
	char_u  *p = channel_read_block(channel, part,
		timeout, TRUE, &outlen);
	if (p != NULL)
	{
	    blob_T	*b = blob_alloc();

	    if (b != NULL)
	    {
		b->bv_ga.ga_len = outlen;
		if (ga_grow(&b->bv_ga, outlen) == FAIL)
		    blob_free(b);
		else
		{
		    memcpy(b->bv_ga.ga_data, p, outlen);
		    rettv_blob_set(rettv, b);
		}
	    }
	    vim_free(p);
	}
    }
    else if (raw || mode == CH_MODE_RAW || mode == CH_MODE_NL)
	rettv->vval.v_string = channel_read_block(channel, part,
		timeout, raw, NULL);
    else
    {
	if (opt.jo_set & JO_ID)
	    id = opt.jo_id;
	channel_read_json_block(channel, part, timeout, id, &listtv);
	if (listtv != NULL)
	{
	    *rettv = *listtv;
	    vim_free(listtv);
	}
	else
	{
	    rettv->v_type = VAR_SPECIAL;
	    rettv->vval.v_number = VVAL_NONE;
	}
    }

theend:
    free_job_options(&opt);
}

#if defined(MSWIN) || defined(__HAIKU__) || defined(FEAT_GUI) || defined(PROTO)
/*
 * Check the channels for anything that is ready to be read.
 * The data is put in the read queue.
 * if "only_keep_open" is TRUE only check channels where ch_keep_open is set.
 */
    void
channel_handle_events(int only_keep_open)
{
    channel_T	*channel;
    ch_part_T	part;
    sock_T	fd;

    FOR_ALL_CHANNELS(channel)
    {
	if (only_keep_open && !channel->ch_keep_open)
	    continue;

	// check the socket and pipes
	for (part = PART_SOCK; part < PART_IN; ++part)
	{
	    fd = channel->ch_part[part].ch_fd;
	    if (fd == INVALID_FD)
		continue;

	    int r = channel_wait(channel, fd, 0);

	    if (r == CW_READY)
		channel_read(channel, part, "channel_handle_events");
	    else if (r == CW_ERROR)
		ch_close_part_on_error(channel, part, TRUE,
			"channel_handle_events");
	}

# ifdef __HAIKU__
	// Workaround for Haiku: Since select/poll cannot detect EOF from tty,
	// should close fds when the job has finished if 'channel' connects to
	// the pty.
	if (channel->ch_job != NULL)
	{
	    job_T *job = channel->ch_job;

	    if (job->jv_tty_out != NULL && job->jv_status == JOB_FINISHED)
		for (part = PART_SOCK; part < PART_COUNT; ++part)
		    ch_close_part(channel, part);
	}
# endif
    }
}
#endif

# if defined(FEAT_GUI) || defined(PROTO)
/*
 * Return TRUE when there is any channel with a keep_open flag.
 */
    int
channel_any_keep_open(void)
{
    channel_T	*channel;

    FOR_ALL_CHANNELS(channel)
	if (channel->ch_keep_open)
	    return TRUE;
    return FALSE;
}
# endif

/*
 * Set "channel"/"part" to non-blocking.
 * Only works for sockets and pipes.
 */
    void
channel_set_nonblock(channel_T *channel, ch_part_T part)
{
    chanpart_T *ch_part = &channel->ch_part[part];
    int		fd = ch_part->ch_fd;

    if (fd == INVALID_FD)
	return;

#ifdef MSWIN
    u_long	val = 1;

    ioctlsocket(fd, FIONBIO, &val);
#else
    (void)fcntl(fd, F_SETFL, O_NONBLOCK);
#endif
    ch_part->ch_nonblocking = TRUE;
}

/*
 * Write "buf" (NUL terminated string) to "channel"/"part".
 * When "fun" is not NULL an error message might be given.
 * Return FAIL or OK.
 */
    int
channel_send(
	channel_T *channel,
	ch_part_T part,
	char_u	  *buf_arg,
	int	  len_arg,
	char	  *fun)
{
    int		res;
    sock_T	fd;
    chanpart_T	*ch_part = &channel->ch_part[part];
    int		did_use_queue = FALSE;

    fd = ch_part->ch_fd;
    if (fd == INVALID_FD)
    {
	if (!channel->ch_error && fun != NULL)
	{
	    ch_error(channel, "%s(): write while not connected", fun);
	    semsg(_(e_str_write_while_not_connected), fun);
	}
	channel->ch_error = TRUE;
	return FAIL;
    }

    if (channel->ch_nonblock && !ch_part->ch_nonblocking)
	channel_set_nonblock(channel, part);

    if (ch_log_active())
    {
	ch_log_literal("SEND ", channel, part, buf_arg, len_arg);
	did_repeated_msg = 0;
    }

    for (;;)
    {
	writeq_T    *wq = &ch_part->ch_writeque;
	char_u	    *buf;
	int	    len;

	if (wq->wq_next != NULL)
	{
	    // first write what was queued
	    buf = wq->wq_next->wq_ga.ga_data;
	    len = wq->wq_next->wq_ga.ga_len;
	    did_use_queue = TRUE;
	}
	else
	{
	    if (len_arg == 0)
		// nothing to write, called from channel_select_check()
		return OK;
	    buf = buf_arg;
	    len = len_arg;
	}

	if (part == PART_SOCK)
	    res = sock_write(fd, (char *)buf, len);
	else
	{
	    res = fd_write(fd, (char *)buf, len);
#ifdef MSWIN
	    if (channel->ch_named_pipe && res < 0)
	    {
		DisconnectNamedPipe((HANDLE)fd);
		ConnectNamedPipe((HANDLE)fd, NULL);
	    }
#endif
	}
	if (res < 0 && (errno == EWOULDBLOCK
#ifdef EAGAIN
			|| errno == EAGAIN
#endif
		    ))
	    res = 0; // nothing got written

	if (res >= 0 && ch_part->ch_nonblocking)
	{
	    writeq_T *entry = wq->wq_next;

	    if (did_use_queue)
		ch_log(channel, "Sent %d bytes now", res);
	    if (res == len)
	    {
		// Wrote all the buf[len] bytes.
		if (entry != NULL)
		{
		    // Remove the entry from the write queue.
		    remove_from_writeque(wq, entry);
		    continue;
		}
		if (did_use_queue)
		    ch_log(channel, "Write queue empty");
	    }
	    else
	    {
		// Wrote only buf[res] bytes, can't write more now.
		if (entry != NULL)
		{
		    if (res > 0)
		    {
			// Remove the bytes that were written.
			mch_memmove(entry->wq_ga.ga_data,
				    (char *)entry->wq_ga.ga_data + res,
				    len - res);
			entry->wq_ga.ga_len -= res;
		    }
		    buf = buf_arg;
		    len = len_arg;
		}
		else
		{
		    buf += res;
		    len -= res;
		}
		ch_log(channel, "Adding %d bytes to the write queue", len);

		// Append the not written bytes of the argument to the write
		// buffer.  Limit entries to 4000 bytes.
		if (wq->wq_prev != NULL
			&& wq->wq_prev->wq_ga.ga_len + len < 4000)
		{
		    writeq_T *last = wq->wq_prev;

		    // append to the last entry
		    if (len > 0 && ga_grow(&last->wq_ga, len) == OK)
		    {
			mch_memmove((char *)last->wq_ga.ga_data
							  + last->wq_ga.ga_len,
				    buf, len);
			last->wq_ga.ga_len += len;
		    }
		}
		else
		{
		    writeq_T *last = ALLOC_ONE(writeq_T);

		    if (last != NULL)
		    {
			last->wq_prev = wq->wq_prev;
			last->wq_next = NULL;
			if (wq->wq_prev == NULL)
			    wq->wq_next = last;
			else
			    wq->wq_prev->wq_next = last;
			wq->wq_prev = last;
			ga_init2(&last->wq_ga, 1, 1000);
			if (len > 0 && ga_grow(&last->wq_ga, len) == OK)
			{
			    mch_memmove(last->wq_ga.ga_data, buf, len);
			    last->wq_ga.ga_len = len;
			}
		    }
		}
	    }
	}
	else if (res != len)
	{
	    if (!channel->ch_error && fun != NULL)
	    {
		ch_error(channel, "%s(): write failed", fun);
		semsg(_(e_str_write_failed), fun);
	    }
	    channel->ch_error = TRUE;
	    return FAIL;
	}

	channel->ch_error = FALSE;
	return OK;
    }
}

/*
 * Common for "ch_sendexpr()" and "ch_sendraw()".
 * Returns the channel if the caller should read the response.
 * Sets "part_read" to the read fd.
 * Otherwise returns NULL.
 */
    static channel_T *
send_common(
	typval_T    *argvars,
	char_u	    *text,
	int	    len,
	int	    id,
	int	    eval,
	jobopt_T    *opt,
	char	    *fun,
	ch_part_T   *part_read)
{
    channel_T	*channel;
    ch_part_T	part_send;

    clear_job_options(opt);
    channel = get_channel_arg(&argvars[0], TRUE, FALSE, 0);
    if (channel == NULL)
	return NULL;
    part_send = channel_part_send(channel);
    *part_read = channel_part_read(channel);

    if (get_job_options(&argvars[2], opt, JO_CALLBACK + JO_TIMEOUT, 0) == FAIL)
	return NULL;

    // Set the callback. An empty callback means no callback and not reading
    // the response. With "ch_evalexpr()" and "ch_evalraw()" a callback is not
    // allowed.
    if (opt->jo_callback.cb_name != NULL && *opt->jo_callback.cb_name != NUL)
    {
	if (eval)
	{
	    semsg(_(e_cannot_use_callback_with_str), fun);
	    return NULL;
	}
	channel_set_req_callback(channel, *part_read, &opt->jo_callback, id);
    }

    if (channel_send(channel, part_send, text, len, fun) == OK
					   && opt->jo_callback.cb_name == NULL)
	return channel;
    return NULL;
}

/*
 * common for "ch_evalexpr()" and "ch_sendexpr()"
 */
    static void
ch_expr_common(typval_T *argvars, typval_T *rettv, int eval)
{
    char_u	*text;
    typval_T	*listtv;
    channel_T	*channel;
    int		id;
    ch_mode_T	ch_mode;
    ch_part_T	part_send;
    ch_part_T	part_read;
    jobopt_T    opt;
    int		timeout;
    int		callback_present = FALSE;

    // return an empty string by default
    rettv->v_type = VAR_STRING;
    rettv->vval.v_string = NULL;

    if (in_vim9script()
	    && (check_for_chan_or_job_arg(argvars, 0) == FAIL
		|| check_for_opt_dict_arg(argvars, 2) == FAIL))
	return;

    channel = get_channel_arg(&argvars[0], TRUE, FALSE, 0);
    if (channel == NULL)
	return;
    part_send = channel_part_send(channel);

    ch_mode = channel_get_mode(channel, part_send);
    if (ch_mode == CH_MODE_RAW || ch_mode == CH_MODE_NL)
    {
	emsg(_(e_cannot_use_evalexpr_sendexpr_with_raw_or_nl_channel));
	return;
    }

    if (ch_mode == CH_MODE_LSP)
    {
	dict_T		*d;
	dictitem_T	*di;

	// return an empty dict by default
	if (rettv_dict_alloc(rettv) == FAIL)
	    return;

	if (check_for_dict_arg(argvars, 1) == FAIL)
	    return;

	d = argvars[1].vval.v_dict;
	di = dict_find(d, (char_u *)"id", -1);
	if (di != NULL && di->di_tv.v_type != VAR_NUMBER)
	{
	    // only number type is supported for the 'id' item
	    semsg(_(e_invalid_value_for_argument_str), "id");
	    return;
	}

	if (argvars[2].v_type == VAR_DICT)
	    if (dict_has_key(argvars[2].vval.v_dict, "callback"))
		callback_present = TRUE;

	if (eval || callback_present)
	{
	    // When evaluating an expression or sending an expression with a
	    // callback, always assign a generated ID
	    id = ++channel->ch_last_msg_id;
	    if (di == NULL)
		dict_add_number(d, "id", id);
	    else
		di->di_tv.vval.v_number = id;
	}
	else
	{
	    // When sending an expression, if the message has an 'id' item,
	    // then use it.
	    id = 0;
	    if (di != NULL)
		id = di->di_tv.vval.v_number;
	}
	if (!dict_has_key(d, "jsonrpc"))
	    dict_add_string(d, "jsonrpc", (char_u *)"2.0");
	text = json_encode_lsp_msg(&argvars[1]);
    }
    else
    {
	id = ++channel->ch_last_msg_id;
	text = json_encode_nr_expr(id, &argvars[1],
			      (ch_mode == CH_MODE_JS ? JSON_JS : 0) | JSON_NL);
    }
    if (text == NULL)
	return;

    channel = send_common(argvars, text, (int)STRLEN(text), id, eval, &opt,
			    eval ? "ch_evalexpr" : "ch_sendexpr", &part_read);
    vim_free(text);
    if (channel != NULL && eval)
    {
	if (opt.jo_set & JO_TIMEOUT)
	    timeout = opt.jo_timeout;
	else
	    timeout = channel_get_timeout(channel, part_read);
	if (channel_read_json_block(channel, part_read, timeout, id, &listtv)
									== OK)
	{
	    if (ch_mode == CH_MODE_LSP)
	    {
		*rettv = *listtv;
		// Change the type to avoid the value being freed.
		listtv->v_type = VAR_NUMBER;
		free_tv(listtv);
	    }
	    else
	    {
		list_T *list = listtv->vval.v_list;

		// Move the item from the list and then change the type to
		// avoid the value being freed.
		*rettv = list->lv_u.mat.lv_last->li_tv;
		list->lv_u.mat.lv_last->li_tv.v_type = VAR_NUMBER;
		free_tv(listtv);
	    }
	}
    }
    free_job_options(&opt);
    if (ch_mode == CH_MODE_LSP && !eval && callback_present)
    {
	// if ch_sendexpr() is used to send a LSP message and a callback
	// function is specified, then return the generated identifier for the
	// message.  The user can use this to cancel the request (if needed).
	if (rettv->vval.v_dict != NULL)
	    dict_add_number(rettv->vval.v_dict, "id", id);
    }
}

/*
 * common for "ch_evalraw()" and "ch_sendraw()"
 */
    static void
ch_raw_common(typval_T *argvars, typval_T *rettv, int eval)
{
    char_u	buf[NUMBUFLEN];
    char_u	*text;
    int		len;
    channel_T	*channel;
    ch_part_T	part_read;
    jobopt_T    opt;
    int		timeout;

    // return an empty string by default
    rettv->v_type = VAR_STRING;
    rettv->vval.v_string = NULL;

    if (in_vim9script()
	    && (check_for_chan_or_job_arg(argvars, 0) == FAIL
		|| check_for_string_or_blob_arg(argvars, 1) == FAIL
		|| check_for_opt_dict_arg(argvars, 2) == FAIL))
	return;

    if (argvars[1].v_type == VAR_BLOB)
    {
	text = argvars[1].vval.v_blob->bv_ga.ga_data;
	len = argvars[1].vval.v_blob->bv_ga.ga_len;
    }
    else
    {
	text = tv_get_string_buf(&argvars[1], buf);
	len = (int)STRLEN(text);
    }
    channel = send_common(argvars, text, len, 0, eval, &opt,
			      eval ? "ch_evalraw" : "ch_sendraw", &part_read);
    if (channel != NULL && eval)
    {
	if (opt.jo_set & JO_TIMEOUT)
	    timeout = opt.jo_timeout;
	else
	    timeout = channel_get_timeout(channel, part_read);
	rettv->vval.v_string = channel_read_block(channel, part_read,
							timeout, TRUE, NULL);
    }
    free_job_options(&opt);
}

#define KEEP_OPEN_TIME 20  // msec

#if (defined(UNIX) && !defined(HAVE_SELECT)) || defined(PROTO)
/*
 * Add open channels to the poll struct.
 * Return the adjusted struct index.
 * The type of "fds" is hidden to avoid problems with the function proto.
 */
    int
channel_poll_setup(int nfd_in, void *fds_in, int *towait)
{
    int		nfd = nfd_in;
    channel_T	*channel;
    struct	pollfd *fds = fds_in;
    ch_part_T	part;

    FOR_ALL_CHANNELS(channel)
    {
	for (part = PART_SOCK; part < PART_IN; ++part)
	{
	    chanpart_T	*ch_part = &channel->ch_part[part];

	    if (ch_part->ch_fd != INVALID_FD)
	    {
		if (channel->ch_keep_open)
		{
		    // For unknown reason poll() returns immediately for a
		    // keep-open channel.  Instead of adding it to the fds add
		    // a short timeout and check, like polling.
		    if (*towait < 0 || *towait > KEEP_OPEN_TIME)
			*towait = KEEP_OPEN_TIME;
		}
		else
		{
		    ch_part->ch_poll_idx = nfd;
		    fds[nfd].fd = ch_part->ch_fd;
		    fds[nfd].events = POLLIN;
		    nfd++;
		}
	    }
	    else
		channel->ch_part[part].ch_poll_idx = -1;
	}
    }

    nfd = channel_fill_poll_write(nfd, fds);

    return nfd;
}

/*
 * The type of "fds" is hidden to avoid problems with the function proto.
 */
    int
channel_poll_check(int ret_in, void *fds_in)
{
    int		ret = ret_in;
    channel_T	*channel;
    struct	pollfd *fds = fds_in;
    ch_part_T	part;
    int		idx;
    chanpart_T	*in_part;

    FOR_ALL_CHANNELS(channel)
    {
	for (part = PART_SOCK; part < PART_IN; ++part)
	{
	    idx = channel->ch_part[part].ch_poll_idx;

	    if (ret > 0 && idx != -1 && (fds[idx].revents & POLLIN))
	    {
		channel_read(channel, part, "channel_poll_check");
		--ret;
	    }
	    else if (channel->ch_part[part].ch_fd != INVALID_FD
						      && channel->ch_keep_open)
	    {
		// polling a keep-open channel
		channel_read(channel, part, "channel_poll_check_keep_open");
	    }
	}

	in_part = &channel->ch_part[PART_IN];
	idx = in_part->ch_poll_idx;
	if (ret > 0 && idx != -1 && (fds[idx].revents & POLLOUT))
	{
	    channel_write_input(channel);
	    --ret;
	}
    }

    return ret;
}
#endif // UNIX && !HAVE_SELECT

#if (!defined(MSWIN) && defined(HAVE_SELECT)) || defined(PROTO)

/*
 * The "fd_set" type is hidden to avoid problems with the function proto.
 */
    int
channel_select_setup(
	int maxfd_in,
	void *rfds_in,
	void *wfds_in,
	struct timeval *tv,
	struct timeval **tvp)
{
    int		maxfd = maxfd_in;
    channel_T	*channel;
    fd_set	*rfds = rfds_in;
    fd_set	*wfds = wfds_in;
    ch_part_T	part;

    FOR_ALL_CHANNELS(channel)
    {
	for (part = PART_SOCK; part < PART_IN; ++part)
	{
	    sock_T fd = channel->ch_part[part].ch_fd;

	    if (fd != INVALID_FD)
	    {
		if (channel->ch_keep_open)
		{
		    // For unknown reason select() returns immediately for a
		    // keep-open channel.  Instead of adding it to the rfds add
		    // a short timeout and check, like polling.
		    if (*tvp == NULL || tv->tv_sec > 0
					|| tv->tv_usec > KEEP_OPEN_TIME * 1000)
		    {
			*tvp = tv;
			tv->tv_sec = 0;
			tv->tv_usec = KEEP_OPEN_TIME * 1000;
		    }
		}
		else
		{
		    FD_SET((int)fd, rfds);
		    if (maxfd < (int)fd)
			maxfd = (int)fd;
		}
	    }
	}
    }

    maxfd = channel_fill_wfds(maxfd, wfds);

    return maxfd;
}

/*
 * The "fd_set" type is hidden to avoid problems with the function proto.
 */
    int
channel_select_check(int ret_in, void *rfds_in, void *wfds_in)
{
    int		ret = ret_in;
    channel_T	*channel;
    fd_set	*rfds = rfds_in;
    fd_set	*wfds = wfds_in;
    ch_part_T	part;
    chanpart_T	*in_part;

    FOR_ALL_CHANNELS(channel)
    {
	for (part = PART_SOCK; part < PART_IN; ++part)
	{
	    sock_T fd = channel->ch_part[part].ch_fd;

	    if (ret > 0 && fd != INVALID_FD && FD_ISSET(fd, rfds))
	    {
		channel_read(channel, part, "channel_select_check");
		FD_CLR(fd, rfds);
		--ret;
	    }
	    else if (fd != INVALID_FD && channel->ch_keep_open)
	    {
		// polling a keep-open channel
		channel_read(channel, part, "channel_select_check_keep_open");
	    }
	}

	in_part = &channel->ch_part[PART_IN];
	if (ret > 0 && in_part->ch_fd != INVALID_FD
					    && FD_ISSET(in_part->ch_fd, wfds))
	{
	    // Clear the flag first, ch_fd may change in channel_write_input().
	    FD_CLR(in_part->ch_fd, wfds);
	    channel_write_input(channel);
	    --ret;
	}

# ifdef __HAIKU__
	// Workaround for Haiku: Since select/poll cannot detect EOF from tty,
	// should close fds when the job has finished if 'channel' connects to
	// the pty.
	if (channel->ch_job != NULL)
	{
	    job_T *job = channel->ch_job;

	    if (job->jv_tty_out != NULL && job->jv_status == JOB_FINISHED)
		for (part = PART_SOCK; part < PART_COUNT; ++part)
		    ch_close_part(channel, part);
	}
# endif
    }

    return ret;
}
#endif // !MSWIN && HAVE_SELECT

/*
 * Execute queued up commands.
 * Invoked from the main loop when it's safe to execute received commands,
 * and during a blocking wait for ch_evalexpr().
 * Return TRUE when something was done.
 */
    int
channel_parse_messages(void)
{
    channel_T	*channel = first_channel;
    int		ret = FALSE;
    int		r;
    ch_part_T	part = PART_SOCK;
    static int	recursive = 0;
#ifdef ELAPSED_FUNC
    elapsed_T	start_tv;
#endif

    // The code below may invoke callbacks, which might call us back.
    // In a recursive call channels will not be closed.
    ++recursive;
    ++safe_to_invoke_callback;

#ifdef ELAPSED_FUNC
    ELAPSED_INIT(start_tv);
#endif

    // Only do this message when another message was given, otherwise we get
    // lots of them.
    if ((did_repeated_msg & REPEATED_MSG_LOOKING) == 0)
    {
	ch_log(NULL, "looking for messages on channels");
	// now we should also give the message for SafeState
	did_repeated_msg = REPEATED_MSG_LOOKING;
    }
    while (channel != NULL)
    {
	if (recursive == 1)
	{
	    if (channel_can_close(channel))
	    {
		channel->ch_to_be_closed = (1U << PART_COUNT);
		channel_close_now(channel);
		// channel may have been freed, start over
		channel = first_channel;
		continue;
	    }
	    if (channel->ch_to_be_freed || channel->ch_killing)
	    {
		channel_free_contents(channel);
		if (channel->ch_job != NULL)
		    channel->ch_job->jv_channel = NULL;

		// free the channel and then start over
		channel_free_channel(channel);
		channel = first_channel;
		continue;
	    }
	    if (channel->ch_refcount == 0 && !channel_still_useful(channel))
	    {
		// channel is no longer useful, free it
		channel_free(channel);
		channel = first_channel;
		part = PART_SOCK;
		continue;
	    }
	}

	if (channel->ch_part[part].ch_fd != INVALID_FD
				      || channel_has_readahead(channel, part))
	{
	    // Increase the refcount, in case the handler causes the channel
	    // to be unreferenced or closed.
	    ++channel->ch_refcount;
	    r = may_invoke_callback(channel, part);
	    if (r == OK)
		ret = TRUE;
	    if (channel_unref(channel) || (r == OK
#ifdef ELAPSED_FUNC
			// Limit the time we loop here to 100 msec, otherwise
			// Vim becomes unresponsive when the callback takes
			// more than a bit of time.
			&& ELAPSED_FUNC(start_tv) < 100L
#endif
			))
	    {
		// channel was freed or something was done, start over
		channel = first_channel;
		part = PART_SOCK;
		continue;
	    }
	}
	if (part < PART_ERR)
	    ++part;
	else
	{
	    channel = channel->ch_next;
	    part = PART_SOCK;
	}
    }

    if (channel_need_redraw)
    {
	channel_need_redraw = FALSE;
	redraw_after_callback(TRUE, FALSE);
    }

    --safe_to_invoke_callback;
    --recursive;

    return ret;
}

/*
 * Return TRUE if any channel has readahead.  That means we should not block on
 * waiting for input.
 */
    int
channel_any_readahead(void)
{
    channel_T	*channel = first_channel;
    ch_part_T	part = PART_SOCK;

    while (channel != NULL)
    {
	if (channel_has_readahead(channel, part))
	    return TRUE;
	if (part < PART_ERR)
	    ++part;
	else
	{
	    channel = channel->ch_next;
	    part = PART_SOCK;
	}
    }
    return FALSE;
}

/*
 * Mark references to lists used in channels.
 */
    int
set_ref_in_channel(int copyID)
{
    int		abort = FALSE;
    channel_T	*channel;
    typval_T	tv;

    for (channel = first_channel; !abort && channel != NULL;
						   channel = channel->ch_next)
	if (channel_still_useful(channel))
	{
	    tv.v_type = VAR_CHANNEL;
	    tv.vval.v_channel = channel;
	    abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
	}
    return abort;
}

/*
 * Return the "part" to write to for "channel".
 */
    static ch_part_T
channel_part_send(channel_T *channel)
{
    if (channel->CH_SOCK_FD == INVALID_FD)
	return PART_IN;
    return PART_SOCK;
}

/*
 * Return the default "part" to read from for "channel".
 */
    static ch_part_T
channel_part_read(channel_T *channel)
{
    if (channel->CH_SOCK_FD == INVALID_FD)
	return PART_OUT;
    return PART_SOCK;
}

/*
 * Return the mode of "channel"/"part"
 * If "channel" is invalid returns CH_MODE_JSON.
 */
    static ch_mode_T
channel_get_mode(channel_T *channel, ch_part_T part)
{
    if (channel == NULL)
	return CH_MODE_JSON;
    return channel->ch_part[part].ch_mode;
}

/*
 * Return the timeout of "channel"/"part"
 */
    static int
channel_get_timeout(channel_T *channel, ch_part_T part)
{
    return channel->ch_part[part].ch_timeout;
}

/*
 * "ch_canread()" function
 */
    void
f_ch_canread(typval_T *argvars, typval_T *rettv)
{
    channel_T *channel;

    rettv->vval.v_number = 0;
    if (in_vim9script() && check_for_chan_or_job_arg(argvars, 0) == FAIL)
	return;

    channel = get_channel_arg(&argvars[0], FALSE, FALSE, 0);
    if (channel != NULL)
	rettv->vval.v_number = channel_has_readahead(channel, PART_SOCK)
			    || channel_has_readahead(channel, PART_OUT)
			    || channel_has_readahead(channel, PART_ERR);
}

/*
 * "ch_close()" function
 */
    void
f_ch_close(typval_T *argvars, typval_T *rettv UNUSED)
{
    channel_T *channel;

    if (in_vim9script() && check_for_chan_or_job_arg(argvars, 0) == FAIL)
	return;

    channel = get_channel_arg(&argvars[0], TRUE, FALSE, 0);
    if (channel != NULL)
    {
	channel_close(channel, FALSE);
	channel_clear(channel);
    }
}

/*
 * "ch_close()" function
 */
    void
f_ch_close_in(typval_T *argvars, typval_T *rettv UNUSED)
{
    channel_T *channel;

    if (in_vim9script() && check_for_chan_or_job_arg(argvars, 0) == FAIL)
	return;

    channel = get_channel_arg(&argvars[0], TRUE, FALSE, 0);
    if (channel != NULL)
	channel_close_in(channel);
}

/*
 * "ch_getbufnr()" function
 */
    void
f_ch_getbufnr(typval_T *argvars, typval_T *rettv)
{
    channel_T	*channel;

    rettv->vval.v_number = -1;

    if (in_vim9script()
	    && (check_for_chan_or_job_arg(argvars, 0) == FAIL
		|| check_for_string_arg(argvars, 1) == FAIL))
	return;

    channel = get_channel_arg(&argvars[0], FALSE, FALSE, 0);
    if (channel == NULL)
	return;

    char_u	*what = tv_get_string(&argvars[1]);
    int		part;
    if (STRCMP(what, "err") == 0)
	part = PART_ERR;
    else if (STRCMP(what, "out") == 0)
	part = PART_OUT;
    else if (STRCMP(what, "in") == 0)
	part = PART_IN;
    else
	part = PART_SOCK;
    if (channel->ch_part[part].ch_bufref.br_buf != NULL)
	rettv->vval.v_number =
	    channel->ch_part[part].ch_bufref.br_buf->b_fnum;
}

/*
 * "ch_getjob()" function
 */
    void
f_ch_getjob(typval_T *argvars, typval_T *rettv)
{
    channel_T *channel;

    if (in_vim9script() && check_for_chan_or_job_arg(argvars, 0) == FAIL)
	return;

    channel = get_channel_arg(&argvars[0], FALSE, FALSE, 0);
    if (channel == NULL)
	return;

    rettv->v_type = VAR_JOB;
    rettv->vval.v_job = channel->ch_job;
    if (channel->ch_job != NULL)
	++channel->ch_job->jv_refcount;
}

/*
 * "ch_info()" function
 */
    void
f_ch_info(typval_T *argvars, typval_T *rettv UNUSED)
{
    channel_T *channel;

    if (in_vim9script() && check_for_chan_or_job_arg(argvars, 0) == FAIL)
	return;

    channel = get_channel_arg(&argvars[0], FALSE, FALSE, 0);
    if (channel != NULL && rettv_dict_alloc(rettv) == OK)
	channel_info(channel, rettv->vval.v_dict);
}

/*
 * "ch_open()" function
 */
    void
f_ch_open(typval_T *argvars, typval_T *rettv)
{
    rettv->v_type = VAR_CHANNEL;
    if (check_restricted() || check_secure())
	return;
    rettv->vval.v_channel = channel_open_func(argvars);
}

/*
 * "ch_read()" function
 */
    void
f_ch_read(typval_T *argvars, typval_T *rettv)
{
    common_channel_read(argvars, rettv, FALSE, FALSE);
}

/*
 * "ch_readblob()" function
 */
    void
f_ch_readblob(typval_T *argvars, typval_T *rettv)
{
    common_channel_read(argvars, rettv, TRUE, TRUE);
}

/*
 * "ch_readraw()" function
 */
    void
f_ch_readraw(typval_T *argvars, typval_T *rettv)
{
    common_channel_read(argvars, rettv, TRUE, FALSE);
}

/*
 * "ch_evalexpr()" function
 */
    void
f_ch_evalexpr(typval_T *argvars, typval_T *rettv)
{
    ch_expr_common(argvars, rettv, TRUE);
}

/*
 * "ch_sendexpr()" function
 */
    void
f_ch_sendexpr(typval_T *argvars, typval_T *rettv)
{
    ch_expr_common(argvars, rettv, FALSE);
}

/*
 * "ch_evalraw()" function
 */
    void
f_ch_evalraw(typval_T *argvars, typval_T *rettv)
{
    ch_raw_common(argvars, rettv, TRUE);
}

/*
 * "ch_sendraw()" function
 */
    void
f_ch_sendraw(typval_T *argvars, typval_T *rettv)
{
    ch_raw_common(argvars, rettv, FALSE);
}

/*
 * "ch_setoptions()" function
 */
    void
f_ch_setoptions(typval_T *argvars, typval_T *rettv UNUSED)
{
    channel_T	*channel;
    jobopt_T	opt;

    if (in_vim9script()
	    && (check_for_chan_or_job_arg(argvars, 0) == FAIL
		|| check_for_dict_arg(argvars, 1) == FAIL))
	return;

    channel = get_channel_arg(&argvars[0], FALSE, FALSE, 0);
    if (channel == NULL)
	return;
    clear_job_options(&opt);
    if (get_job_options(&argvars[1], &opt,
			    JO_CB_ALL + JO_TIMEOUT_ALL + JO_MODE_ALL, 0) == OK)
	channel_set_options(channel, &opt);
    free_job_options(&opt);
}

/*
 * "ch_status()" function
 */
    void
f_ch_status(typval_T *argvars, typval_T *rettv)
{
    channel_T	*channel;
    jobopt_T	opt;
    int		part = -1;

    // return an empty string by default
    rettv->v_type = VAR_STRING;
    rettv->vval.v_string = NULL;

    if (in_vim9script()
	    && (check_for_chan_or_job_arg(argvars, 0) == FAIL
		|| check_for_opt_dict_arg(argvars, 1) == FAIL))
	return;

    channel = get_channel_arg(&argvars[0], FALSE, FALSE, 0);

    if (argvars[1].v_type != VAR_UNKNOWN)
    {
	clear_job_options(&opt);
	if (get_job_options(&argvars[1], &opt, JO_PART, 0) == OK
						     && (opt.jo_set & JO_PART))
	    part = opt.jo_part;
    }

    rettv->vval.v_string = vim_strsave((char_u *)channel_status(channel, part));
}

/*
 * Get a string with information about the channel in "varp" in "buf".
 * "buf" must be at least NUMBUFLEN long.
 */
    char_u *
channel_to_string_buf(typval_T *varp, char_u *buf)
{
    channel_T *channel = varp->vval.v_channel;
    char      *status = channel_status(channel, -1);

    if (channel == NULL)
	vim_snprintf((char *)buf, NUMBUFLEN, "channel %s", status);
    else
	vim_snprintf((char *)buf, NUMBUFLEN,
				      "channel %d %s", channel->ch_id, status);
    return buf;
}

#endif // FEAT_JOB_CHANNEL