Adding upstream version 2:9.1.0016.upstream/2%9.1.0016

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 5329 insertions, 0 deletions

diff --git a/src/channel.c b/src/channel.c
new file mode 100644
index 0000000..8d850c6
--- /dev/null
+++ b/src/channel.c
@@ -0,0 +1,5329 @@
+/* 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 = (int)STRLEN(line);
+    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