channels: allow bytes sockets and stdio, and buffered bytes output

14 files changed, 574 insertions, 421 deletions

diff --git a/src/nvim/channel.c b/src/nvim/channel.c
index e61ec9c19b..5ee4e5be09 100644
--- a/src/nvim/channel.c
+++ b/src/nvim/channel.c
@@ -3,10 +3,25 @@
 
 #include "nvim/api/ui.h"
 #include "nvim/channel.h"
+#include "nvim/eval.h"
+#include "nvim/event/socket.h"
 #include "nvim/msgpack_rpc/channel.h"
+#include "nvim/msgpack_rpc/server.h"
+#include "nvim/os/shell.h"
+#include "nvim/path.h"
+#include "nvim/ascii.h"
 
+static bool did_stdio = false;
 PMap(uint64_t) *channels = NULL;
 
+typedef struct {
+  Channel *data;
+  Callback *callback;
+  const char *type;
+  list_T *received;
+  int status;
+} ChannelEvent;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "channel.c.generated.h"
 #endif
@@ -32,6 +47,21 @@ void channel_init(void)
   remote_ui_init();
 }
 
+/// Allocates a channel.
+///
+/// Channel is allocated with refcount 1, which should be decreased
+/// when the underlying stream closes.
+static Channel *channel_alloc(ChannelStreamType type)
+{
+  Channel *chan = xcalloc(1, sizeof(*chan));
+  chan->id = type == kChannelStreamStdio ? 1 : next_chan_id++;
+  chan->events = multiqueue_new_child(main_loop.events);
+  chan->refcount = 1;
+  chan->streamtype = type;
+  pmap_put(uint64_t)(channels, chan->id, chan);
+  return chan;
+}
+
 void channel_incref(Channel *channel)
 {
   channel->refcount++;
@@ -44,6 +74,21 @@ void channel_decref(Channel *channel)
   }
 }
 
+void callback_reader_free(CallbackReader *reader)
+{
+  callback_free(&reader->cb);
+  if (reader->buffered) {
+    ga_clear(&reader->buffer);
+  }
+}
+
+void callback_reader_start(CallbackReader *reader)
+{
+  if (reader->buffered) {
+    ga_init(&reader->buffer, sizeof(char *), 1);
+  }
+}
+
 static void free_channel_event(void **argv)
 {
   Channel *channel = argv[0];
@@ -51,11 +96,379 @@ static void free_channel_event(void **argv)
     rpc_free(channel);
   }
 
-  callback_free(&channel->on_stdout);
-  callback_free(&channel->on_stderr);
+  callback_reader_free(&channel->on_stdout);
+  callback_reader_free(&channel->on_stderr);
   callback_free(&channel->on_exit);
 
   pmap_del(uint64_t)(channels, channel->id);
   multiqueue_free(channel->events);
   xfree(channel);
 }
+
+static void channel_destroy_early(Channel *chan)
+{
+  if ((chan->id != --next_chan_id)) {
+    abort();
+  }
+
+  if ((--chan->refcount != 0)) {
+    abort();
+  }
+
+  free_channel_event((void **)&chan);
+}
+
+
+static void close_cb(Stream *stream, void *data)
+{
+  channel_decref(data);
+}
+
+Channel *channel_job_start(char **argv, CallbackReader on_stdout,
+                           CallbackReader on_stderr, Callback on_exit,
+                           bool pty, bool rpc, bool detach, const char *cwd,
+                           uint16_t pty_width, uint16_t pty_height,
+                           char *term_name, varnumber_T *status_out)
+{
+  Channel *chan = channel_alloc(kChannelStreamProc);
+  chan->on_stdout = on_stdout;
+  chan->on_stderr = on_stderr;
+  chan->on_exit = on_exit;
+  chan->is_rpc = rpc;
+
+  if (pty) {
+    if (detach) {
+      EMSG2(_(e_invarg2), "terminal/pty job cannot be detached");
+      shell_free_argv(argv);
+      xfree(term_name);
+      channel_destroy_early(chan);
+      *status_out = 0;
+      return NULL;
+    }
+    chan->stream.pty = pty_process_init(&main_loop, chan);
+    if (pty_width > 0) {
+      chan->stream.pty.width = pty_width;
+    }
+    if (pty_height > 0) {
+      chan->stream.pty.height = pty_height;
+    }
+    if (term_name) {
+      chan->stream.pty.term_name = term_name;
+    }
+  } else {
+    chan->stream.uv = libuv_process_init(&main_loop, chan);
+  }
+
+  Process *proc = (Process *)&chan->stream.proc;
+  proc->argv = argv;
+  proc->cb = channel_process_exit_cb;
+  proc->events = chan->events;
+  proc->detach = detach;
+  proc->cwd = cwd;
+
+  char *cmd = xstrdup(proc->argv[0]);
+  bool has_out, has_err;
+  if (proc->type == kProcessTypePty) {
+    has_out = true;
+    has_err = false;
+  } else {
+    has_out = chan->is_rpc || callback_reader_set(chan->on_stdout);
+    has_err = callback_reader_set(chan->on_stderr);
+  }
+  int status = process_spawn(proc, true, has_out, has_err);
+  if (has_err) {
+    proc->err.events = chan->events;
+  }
+  if (status) {
+    EMSG3(_(e_jobspawn), os_strerror(status), cmd);
+    xfree(cmd);
+    if (proc->type == kProcessTypePty) {
+      xfree(chan->stream.pty.term_name);
+    }
+    channel_destroy_early(chan);
+    *status_out = proc->status;
+    return NULL;
+  }
+  xfree(cmd);
+
+  wstream_init(&proc->in, 0);
+  if (has_out) {
+    rstream_init(&proc->out, 0);
+  }
+
+  if (chan->is_rpc) {
+    // the rpc takes over the in and out streams
+    rpc_start(chan);
+  } else {
+    proc->in.events = chan->events;
+    if (has_out) {
+      callback_reader_start(&chan->on_stdout);
+      proc->out.events = chan->events;
+      rstream_start(&proc->out, on_job_stdout, chan);
+    }
+  }
+
+  if (has_err) {
+    callback_reader_start(&chan->on_stderr);
+    rstream_init(&proc->err, 0);
+    rstream_start(&proc->err, on_job_stderr, chan);
+  }
+  *status_out = (varnumber_T)chan->id;
+  return chan;
+}
+
+
+uint64_t channel_connect(bool tcp, const char *address,
+                         bool rpc, CallbackReader on_output,
+                         int timeout, const char **error)
+{
+  if (!tcp && rpc) {
+    char *path = fix_fname(address);
+    if (server_owns_pipe_address(path)) {
+      // avoid deadlock
+      xfree(path);
+      return channel_create_internal_rpc();
+    }
+    xfree(path);
+  }
+
+  Channel *channel = channel_alloc(kChannelStreamSocket);
+  if (!socket_connect(&main_loop, &channel->stream.socket,
+                      tcp, address, timeout, error)) {
+    channel_destroy_early(channel);
+    return 0;
+  }
+
+  channel_incref(channel);  // close channel only after the stream is closed
+  channel->stream.socket.internal_close_cb = close_cb;
+  channel->stream.socket.internal_data = channel;
+  wstream_init(&channel->stream.socket, 0);
+  rstream_init(&channel->stream.socket, 0);
+
+  if (rpc) {
+    rpc_start(channel);
+  } else {
+    channel->on_stdout = on_output;
+    callback_reader_start(&channel->on_stdout);
+    channel->stream.socket.events = channel->events;
+    rstream_start(&channel->stream.socket, on_socket_output, channel);
+  }
+
+  return channel->id;
+}
+
+/// Creates an RPC channel from a tcp/pipe socket connection
+///
+/// @param watcher The SocketWatcher ready to accept the connection
+void channel_from_connection(SocketWatcher *watcher)
+{
+  Channel *channel = channel_alloc(kChannelStreamSocket);
+  socket_watcher_accept(watcher, &channel->stream.socket);
+  channel_incref(channel);  // close channel only after the stream is closed
+  channel->stream.socket.internal_close_cb = close_cb;
+  channel->stream.socket.internal_data = channel;
+  wstream_init(&channel->stream.socket, 0);
+  rstream_init(&channel->stream.socket, 0);
+  rpc_start(channel);
+}
+
+/// Creates a loopback channel. This is used to avoid deadlock
+/// when an instance connects to its own named pipe.
+static uint64_t channel_create_internal_rpc(void)
+{
+  Channel *channel = channel_alloc(kChannelStreamInternal);
+  channel_incref(channel);  // internal channel lives until process exit
+  rpc_start(channel);
+  return channel->id;
+}
+
+/// Creates an API channel from stdin/stdout. This is used when embedding
+/// Neovim
+uint64_t channel_from_stdio(bool rpc, CallbackReader on_output,
+                            const char **error)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (!headless_mode) {
+    *error = _("can only be opened in headless mode");
+    return 0;
+  }
+
+  if (did_stdio) {
+    *error = _("channel was already open");
+    return 0;
+  }
+  did_stdio = true;
+
+  Channel *channel = channel_alloc(kChannelStreamStdio);
+
+  rstream_init_fd(&main_loop, &channel->stream.stdio.in, 0, 0);
+  wstream_init_fd(&main_loop, &channel->stream.stdio.out, 1, 0);
+
+  if (rpc) {
+    rpc_start(channel);
+  } else {
+    channel->on_stdout = on_output;
+    callback_reader_start(&channel->on_stdout);
+    channel->stream.stdio.in.events = channel->events;
+    channel->stream.stdio.out.events = channel->events;
+    rstream_start(&channel->stream.stdio.in, on_stdio_input, channel);
+  }
+
+  return channel->id;
+}
+
+// vimscript job callbacks must be executed on Nvim main loop
+static inline void process_channel_event(Channel *chan, Callback *callback,
+                                         const char *type, char *buf,
+                                         size_t count, int status)
+{
+  ChannelEvent event_data;
+  event_data.received = NULL;
+  if (buf) {
+    event_data.received = tv_list_alloc();
+    char *ptr = buf;
+    size_t remaining = count;
+    size_t off = 0;
+
+    while (off < remaining) {
+      // append the line
+      if (ptr[off] == NL) {
+        tv_list_append_string(event_data.received, ptr, (ssize_t)off);
+        size_t skip = off + 1;
+        ptr += skip;
+        remaining -= skip;
+        off = 0;
+        continue;
+      }
+      if (ptr[off] == NUL) {
+        // Translate NUL to NL
+        ptr[off] = NL;
+      }
+      off++;
+    }
+    tv_list_append_string(event_data.received, ptr, (ssize_t)off);
+  } else {
+    event_data.status = status;
+  }
+  event_data.data = chan;
+  event_data.callback = callback;
+  event_data.type = type;
+  on_channel_event(&event_data);
+}
+
+void on_job_stdout(Stream *stream, RBuffer *buf, size_t count,
+                   void *data, bool eof)
+{
+  Channel *chan = data;
+  on_channel_output(stream, chan, buf, count, eof, &chan->on_stdout, "stdout");
+}
+
+void on_job_stderr(Stream *stream, RBuffer *buf, size_t count,
+                   void *data, bool eof)
+{
+  Channel *chan = data;
+  on_channel_output(stream, chan, buf, count, eof, &chan->on_stderr, "stderr");
+}
+
+static void on_socket_output(Stream *stream, RBuffer *buf, size_t count,
+                             void *data, bool eof)
+{
+  Channel *chan = data;
+  on_channel_output(stream, chan, buf, count, eof, &chan->on_stdout, "data");
+}
+
+static void on_stdio_input(Stream *stream, RBuffer *buf, size_t count,
+                           void *data, bool eof)
+{
+  Channel *chan = data;
+  on_channel_output(stream, chan, buf, count, eof, &chan->on_stdout, "stdin");
+}
+
+static void on_channel_output(Stream *stream, Channel *chan, RBuffer *buf,
+                              size_t count, bool eof, CallbackReader *reader,
+                              const char *type)
+{
+  // stub variable, to keep reading consistent with the order of events, only
+  // consider the count parameter.
+  size_t r;
+  char *ptr = rbuffer_read_ptr(buf, &r);
+
+  if (eof) {
+    if (reader->buffered) {
+      process_channel_event(chan, &reader->cb, type, reader->buffer.ga_data,
+                        (size_t)reader->buffer.ga_len, 0);
+      ga_clear(&reader->buffer);
+    } else if (callback_reader_set(*reader)) {
+      process_channel_event(chan, &reader->cb, type, ptr, 0, 0);
+    }
+    return;
+  }
+
+  // The order here matters, the terminal must receive the data first because
+  // process_channel_event will modify the read buffer(convert NULs into NLs)
+  if (chan->term) {
+    terminal_receive(chan->term, ptr, count);
+  }
+
+  rbuffer_consumed(buf, count);
+  if (reader->buffered) {
+    ga_concat_len(&reader->buffer, ptr, count);
+  } else if (callback_reader_set(*reader)) {
+    process_channel_event(chan, &reader->cb, type, ptr, count, 0);
+  }
+}
+
+static void channel_process_exit_cb(Process *proc, int status, void *data)
+{
+  Channel *chan = data;
+  if (chan->term && !chan->stream.proc.exited) {
+    chan->stream.proc.exited = true;
+    char msg[sizeof("\r\n[Process exited ]") + NUMBUFLEN];
+    snprintf(msg, sizeof msg, "\r\n[Process exited %d]", proc->status);
+    terminal_close(chan->term, msg);
+  }
+  if (chan->is_rpc) {
+    channel_process_exit(chan->id, status);
+  }
+
+  if (chan->status_ptr) {
+    *chan->status_ptr = status;
+  }
+
+  process_channel_event(chan, &chan->on_exit, "exit", NULL, 0, status);
+
+  channel_decref(chan);
+}
+
+static void on_channel_event(ChannelEvent *ev)
+{
+  if (!ev->callback) {
+    return;
+  }
+
+  typval_T argv[4];
+
+  argv[0].v_type = VAR_NUMBER;
+  argv[0].v_lock = VAR_UNLOCKED;
+  argv[0].vval.v_number = (varnumber_T)ev->data->id;
+
+  if (ev->received) {
+    argv[1].v_type = VAR_LIST;
+    argv[1].v_lock = VAR_UNLOCKED;
+    argv[1].vval.v_list = ev->received;
+    argv[1].vval.v_list->lv_refcount++;
+  } else {
+    argv[1].v_type = VAR_NUMBER;
+    argv[1].v_lock = VAR_UNLOCKED;
+    argv[1].vval.v_number = ev->status;
+  }
+
+  argv[2].v_type = VAR_STRING;
+  argv[2].v_lock = VAR_UNLOCKED;
+  argv[2].vval.v_string = (uint8_t *)ev->type;
+
+  typval_T rettv = TV_INITIAL_VALUE;
+  callback_call(ev->callback, 3, argv, &rettv);
+  tv_clear(&rettv);
+}
+
diff --git a/src/nvim/channel.h b/src/nvim/channel.h
index b48f508722..8ead6749a6 100644
--- a/src/nvim/channel.h
+++ b/src/nvim/channel.h
@@ -21,14 +21,19 @@ typedef struct {
   Stream out;
 } StdioPair;
 
-// typedef struct {
-//   Callback on_out;
-//   Callback on_close;
-//   Garray buffer;
-//   bool buffering;
-// } CallbackReader
-
-#define CallbackReader Callback
+typedef struct {
+  Callback cb;
+  garray_T buffer;
+  bool buffered;
+} CallbackReader;
+
+#define CALLBACK_READER_INIT ((CallbackReader){ .cb = CALLBACK_NONE, \
+                                                .buffer = GA_EMPTY_INIT_VALUE, \
+                                                .buffered = false })
+static inline bool callback_reader_set(CallbackReader reader)
+{
+  return reader.cb.type != kCallbackNone;
+}
 
 struct Channel {
   uint64_t id;
@@ -61,17 +66,6 @@ EXTERN PMap(uint64_t) *channels;
 # include "channel.h.generated.h"
 #endif
 
-static inline Channel *channel_alloc(ChannelStreamType type)
-{
-  Channel *chan = xcalloc(1, sizeof(*chan));
-  chan->id = next_chan_id++;
-  chan->events = multiqueue_new_child(main_loop.events);
-  chan->refcount = 1;
-  chan->streamtype = type;
-  pmap_put(uint64_t)(channels, chan->id, chan);
-  return chan;
-}
-
 /// @returns Channel with the id or NULL if not found
 static inline Channel *find_channel(uint64_t id)
 {
@@ -89,7 +83,7 @@ static inline Stream *channel_instream(Channel *chan)
       return &chan->stream.socket;
 
     case kChannelStreamStdio:
-      return &chan->stream.stdio.in;
+      return &chan->stream.stdio.out;
 
     case kChannelStreamInternal:
       abort();
@@ -108,7 +102,7 @@ static inline Stream *channel_outstream(Channel *chan)
       return &chan->stream.socket;
 
     case kChannelStreamStdio:
-      return &chan->stream.stdio.out;
+      return &chan->stream.stdio.in;
 
     case kChannelStreamInternal:
       abort();
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 013cfce78d..c2fd7ac19c 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -438,14 +438,6 @@ static ScopeDictDictItem vimvars_var;
 #define vimvarht  vimvardict.dv_hashtab
 
 typedef struct {
-  Channel *data;
-  Callback *callback;
-  const char *type;
-  list_T *received;
-  int status;
-} ChannelEvent;
-
-typedef struct {
   TimeWatcher tw;
   int timer_id;
   int repeat_count;
@@ -5121,12 +5113,12 @@ bool garbage_collect(bool testing)
   // named functions (matters for closures)
   ABORTING(set_ref_in_functions(copyID));
 
-  // Jobs
+  // Channels
   {
     Channel *data;
     map_foreach_value(channels, data, {
-      set_ref_in_callback(&data->on_stdout, copyID, NULL, NULL);
-      set_ref_in_callback(&data->on_stderr, copyID, NULL, NULL);
+      set_ref_in_callback_reader(&data->on_stdout, copyID, NULL, NULL);
+      set_ref_in_callback_reader(&data->on_stderr, copyID, NULL, NULL);
       set_ref_in_callback(&data->on_exit, copyID, NULL, NULL);
     })
   }
@@ -11643,8 +11635,8 @@ static void f_jobstart(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   bool detach = false;
   bool rpc = false;
   bool pty = false;
-  Callback on_stdout = CALLBACK_NONE;
-  Callback on_stderr = CALLBACK_NONE;
+  CallbackReader on_stdout = CALLBACK_READER_INIT,
+                 on_stderr = CALLBACK_READER_INIT;
   Callback on_exit = CALLBACK_NONE;
   char *cwd = NULL;
   if (argvars[1].v_type == VAR_DICT) {
@@ -11676,26 +11668,17 @@ static void f_jobstart(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     }
   }
 
-  Channel *data = common_job_init(argv, on_stdout, on_stderr, on_exit,
-                                          pty, rpc, detach, cwd);
+  uint16_t width = 0, height = 0;
+  char *term_name = NULL;
 
   if (pty) {
-    PtyProcess *pty = &data->stream.pty;
-    uint16_t width = (uint16_t)tv_dict_get_number(job_opts, "width");
-    if (width > 0) {
-      pty->width = width;
-    }
-    uint16_t height = (uint16_t)tv_dict_get_number(job_opts, "height");
-    if (height > 0) {
-      pty->height = height;
-    }
-    char *term = tv_dict_get_string(job_opts, "TERM", true);
-    if (term) {
-      pty->term_name = term;
-    }
+    width = (uint16_t)tv_dict_get_number(job_opts, "width");
+    height = (uint16_t)tv_dict_get_number(job_opts, "height");
+    term_name = tv_dict_get_string(job_opts, "TERM", true);
   }
 
-  common_job_start(data, rettv);
+  channel_job_start(argv, on_stdout, on_stderr, on_exit, pty, rpc, detach,
+                    cwd, width, height, term_name, &rettv->vval.v_number);
 }
 
 // "jobstop()" function
@@ -11782,7 +11765,8 @@ static void f_jobwait(typval_T *argvars, typval_T *rettv, FunPtr fptr)
         || !(data = find_job(arg->li_tv.vval.v_number, false))) {
       continue;
     }
-    int status = process_wait((Process *)&data->stream.proc, remaining, waiting_jobs);
+    int status = process_wait((Process *)&data->stream.proc, remaining,
+                              waiting_jobs);
     if (status < 0) {
       // interrupted or timed out, skip remaining jobs.
       if (status == -2) {
@@ -13922,10 +13906,9 @@ static void f_rpcstart(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   // The last item of argv must be NULL
   argv[i] = NULL;
 
-  Channel *data = common_job_init(argv, CALLBACK_NONE, CALLBACK_NONE,
-                                          CALLBACK_NONE, false, true, false,
-                                          NULL);
-  common_job_start(data, rettv);
+  channel_job_start(argv, CALLBACK_READER_INIT, CALLBACK_READER_INIT,
+                    CALLBACK_NONE, false, true, false, NULL, 0, 0, NULL,
+                    &rettv->vval.v_number);
 }
 
 // "rpcstop()" function
@@ -13946,7 +13929,7 @@ static void f_rpcstop(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
   // if called with a job, stop it, else closes the channel
   uint64_t id = argvars[0].vval.v_number;
-  if (find_job(id, false)) { // FIXME
+  if (find_job(id, false)) {
     f_jobstop(argvars, rettv, NULL);
   } else {
     rettv->vval.v_number = channel_close(id);
@@ -15126,18 +15109,19 @@ static void f_sockconnect(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 
   bool rpc = false;
+  CallbackReader on_data = CALLBACK_READER_INIT;
   if (argvars[2].v_type == VAR_DICT) {
     dict_T *opts = argvars[2].vval.v_dict;
     rpc = tv_dict_get_number(opts, "rpc") != 0;
-  }
 
-  if (!rpc) {
-    EMSG2(_(e_invarg2), "rpc option must be true");
-    return;
+    if (!tv_dict_get_callback(opts, S_LEN("on_data"), &on_data.cb)) {
+      return;
+    }
+    on_data.buffered = tv_dict_get_number(opts, "data_buffered");
   }
 
   const char *error = NULL;
-  uint64_t id = channel_connect(tcp, address, 50, &error);
+  uint64_t id = channel_connect(tcp, address, rpc, on_data, 50, &error);
 
   if (error) {
     EMSG2(_("connection failed: %s"), error);
@@ -15517,6 +15501,35 @@ static void f_sort(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   do_sort_uniq(argvars, rettv, true);
 }
 
+/// "stdioopen()" function
+static void f_stdioopen(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  if (argvars[0].v_type != VAR_DICT) {
+    EMSG(_(e_invarg));
+    return;
+  }
+
+
+  bool rpc = false;
+  CallbackReader on_stdin = CALLBACK_READER_INIT;
+  dict_T *opts = argvars[0].vval.v_dict;
+  rpc = tv_dict_get_number(opts, "rpc") != 0;
+
+  if (!tv_dict_get_callback(opts, S_LEN("on_stdin"), &on_stdin.cb)) {
+    return;
+  }
+
+  const char *error;
+  uint64_t id = channel_from_stdio(rpc, on_stdin, &error);
+  if (!id) {
+    EMSG2(e_stdiochan2, error);
+  }
+
+
+  rettv->vval.v_number = (varnumber_T)id;
+  rettv->v_type = VAR_NUMBER;
+}
+
 /// "uniq({list})" function
 static void f_uniq(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
@@ -16633,8 +16646,9 @@ static void f_termopen(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     return;
   }
 
-  Callback on_stdout = CALLBACK_NONE, on_stderr = CALLBACK_NONE,
-           on_exit = CALLBACK_NONE;
+  CallbackReader on_stdout = CALLBACK_READER_INIT,
+                 on_stderr = CALLBACK_READER_INIT;
+  Callback on_exit = CALLBACK_NONE;
   dict_T *job_opts = NULL;
   const char *cwd = ".";
   if (argvars[1].v_type == VAR_DICT) {
@@ -16658,23 +16672,23 @@ static void f_termopen(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 
   uint16_t term_width = MAX(0, curwin->w_width - win_col_off(curwin));
-  Channel *data = common_job_init(argv, on_stdout, on_stderr, on_exit,
-                                          true, false, false, cwd);
-  data->stream.pty.width = term_width;
-  data->stream.pty.height = curwin->w_height;
-  data->stream.pty.term_name = xstrdup("xterm-256color");
-  if (!common_job_start(data, rettv)) {
+  Channel *chan = channel_job_start(argv, on_stdout, on_stderr, on_exit,
+                                    true, false, false, cwd,
+                                    term_width, curwin->w_height,
+                                    xstrdup("xterm-256color"),
+                                    &rettv->vval.v_number);
+  if (rettv->vval.v_number <= 0) {
     return;
   }
   TerminalOptions topts;
-  topts.data = data;
+  topts.data = chan;
   topts.width = term_width;
   topts.height = curwin->w_height;
   topts.write_cb = term_write;
   topts.resize_cb = term_resize;
   topts.close_cb = term_close;
 
-  int pid = data->stream.pty.process.pid;
+  int pid = chan->stream.pty.process.pid;
 
   char buf[1024];
   // format the title with the pid to conform with the term:// URI
@@ -16685,16 +16699,19 @@ static void f_termopen(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   (void)setfname(curbuf, (char_u *)buf, NULL, true);
   // Save the job id and pid in b:terminal_job_{id,pid}
   Error err = ERROR_INIT;
+  dict_set_var(curbuf->b_vars, cstr_as_string("terminal_channel_id"),
+               INTEGER_OBJ(chan->id), false, false, &err);
+  // deprecated name:
   dict_set_var(curbuf->b_vars, cstr_as_string("terminal_job_id"),
-               INTEGER_OBJ(rettv->vval.v_number), false, false, &err);
+               INTEGER_OBJ(chan->id), false, false, &err);
   api_clear_error(&err);
   dict_set_var(curbuf->b_vars, cstr_as_string("terminal_job_pid"),
                INTEGER_OBJ(pid), false, false, &err);
   api_clear_error(&err);
 
   Terminal *term = terminal_open(topts);
-  data->term = term;
-  channel_incref(data);
+  chan->term = term;
+  channel_incref(chan);
 
   return;
 }
@@ -16783,6 +16800,13 @@ static bool set_ref_in_callback(Callback *callback, int copyID,
   return false;
 }
 
+static bool set_ref_in_callback_reader(CallbackReader *reader, int copyID,
+                                       ht_stack_T **ht_stack,
+                                       list_stack_T **list_stack)
+{
+  return set_ref_in_callback(&reader->cb, copyID, ht_stack, list_stack);
+}
+
 static void add_timer_info(typval_T *rettv, timer_T *timer)
 {
   list_T *list = rettv->vval.v_list;
@@ -22347,206 +22371,29 @@ char_u *do_string_sub(char_u *str, char_u *pat, char_u *sub,
   return ret;
 }
 
-static inline Channel *common_job_init(char **argv,
-                                               Callback on_stdout,
-                                               Callback on_stderr,
-                                               Callback on_exit,
-                                               bool pty,
-                                               bool rpc,
-                                               bool detach,
-                                               const char *cwd)
-{
-  Channel *data = channel_alloc(kChannelStreamProc);
-  data->on_stdout = on_stdout;
-  data->on_stderr = on_stderr;
-  data->on_exit = on_exit;
-  data->is_rpc = rpc;
-  if (pty) {
-    data->stream.pty = pty_process_init(&main_loop, data);
-  } else {
-    data->stream.uv = libuv_process_init(&main_loop, data);
-  }
-  Process *proc = (Process *)&data->stream.proc;
-  proc->argv = argv;
-  proc->cb = eval_job_process_exit_cb;
-  proc->events = data->events;
-  proc->detach = detach;
-  proc->cwd = cwd;
-  return data;
-}
-
 /// common code for getting job callbacks for jobstart, termopen and rpcstart
 ///
 /// @return true/false on success/failure.
-static inline bool common_job_callbacks(dict_T *vopts, Callback *on_stdout,
-                                        Callback *on_stderr, Callback *on_exit)
+static inline bool common_job_callbacks(dict_T *vopts,
+                                        CallbackReader *on_stdout,
+                                        CallbackReader *on_stderr,
+                                        Callback *on_exit)
 {
-  if (tv_dict_get_callback(vopts, S_LEN("on_stdout"), on_stdout)
-      &&tv_dict_get_callback(vopts, S_LEN("on_stderr"), on_stderr)
+  if (tv_dict_get_callback(vopts, S_LEN("on_stdout"), &on_stdout->cb)
+      &&tv_dict_get_callback(vopts, S_LEN("on_stderr"), &on_stderr->cb)
       && tv_dict_get_callback(vopts, S_LEN("on_exit"), on_exit)) {
+    on_stdout->buffered = tv_dict_get_number(vopts, "stdout_buffered");
+    on_stderr->buffered = tv_dict_get_number(vopts, "stderr_buffered");
     vopts->dv_refcount++;
     return true;
   }
 
-  callback_free(on_stdout);
-  callback_free(on_stderr);
+  callback_reader_free(on_stdout);
+  callback_reader_free(on_stderr);
   callback_free(on_exit);
   return false;
 }
 
-static inline bool common_job_start(Channel *data, typval_T *rettv)
-{
-  Process *proc = (Process *)&data->stream.proc;
-  if (proc->type == kProcessTypePty && proc->detach) {
-    EMSG2(_(e_invarg2), "terminal/pty job cannot be detached");
-    xfree(data->stream.pty.term_name);
-    shell_free_argv(proc->argv);
-    channel_decref(data);
-    return false;
-  }
-
-  data->refcount++;
-  char *cmd = xstrdup(proc->argv[0]);
-  bool has_out, has_err;
-  if (proc->type == kProcessTypePty) {
-    has_out = true;
-    has_err = false;
-  } else {
-    has_out = data->is_rpc || data->on_stdout.type != kCallbackNone;
-    has_err = data->on_stderr.type != kCallbackNone;
-  }
-  int status = process_spawn(proc, true, has_out, has_err);
-  if (status) {
-    EMSG3(_(e_jobspawn), os_strerror(status), cmd);
-    xfree(cmd);
-    if (proc->type == kProcessTypePty) {
-      xfree(data->stream.pty.term_name);
-    }
-    rettv->vval.v_number = proc->status;
-    channel_decref(data);
-    return false;
-  }
-  xfree(cmd);
-
-
-  if (data->is_rpc) {
-    // the rpc takes over the in and out streams
-    rpc_start(data);
-  } else {
-    wstream_init(&proc->in, 0);
-    if (has_out) {
-      rstream_init(&proc->out, 0);
-      rstream_start(&proc->out, on_job_stdout, data);
-    }
-  }
-
-  if (has_err) {
-    rstream_init(&proc->err, 0);
-    rstream_start(&proc->err, on_job_stderr, data);
-  }
-  rettv->vval.v_number = data->id;
-  return true;
-}
-
-// vimscript job callbacks must be executed on Nvim main loop
-static inline void process_job_event(Channel *data, Callback *callback,
-                                     const char *type, char *buf, size_t count,
-                                     int status)
-{
-  ChannelEvent event_data;
-  event_data.received = NULL;
-  if (buf) {
-    event_data.received = tv_list_alloc();
-    char *ptr = buf;
-    size_t remaining = count;
-    size_t off = 0;
-
-    while (off < remaining) {
-      // append the line
-      if (ptr[off] == NL) {
-        tv_list_append_string(event_data.received, ptr, off);
-        size_t skip = off + 1;
-        ptr += skip;
-        remaining -= skip;
-        off = 0;
-        continue;
-      }
-      if (ptr[off] == NUL) {
-        // Translate NUL to NL
-        ptr[off] = NL;
-      }
-      off++;
-    }
-    tv_list_append_string(event_data.received, ptr, off);
-  } else {
-    event_data.status = status;
-  }
-  event_data.data = data;
-  event_data.callback = callback;
-  event_data.type = type;
-  on_job_event(&event_data);
-}
-
-static void on_job_stdout(Stream *stream, RBuffer *buf, size_t count,
-    void *job, bool eof)
-{
-  Channel *data = job;
-  on_job_output(stream, job, buf, count, eof, &data->on_stdout, "stdout");
-}
-
-static void on_job_stderr(Stream *stream, RBuffer *buf, size_t count,
-    void *job, bool eof)
-{
-  Channel *data = job;
-  on_job_output(stream, job, buf, count, eof, &data->on_stderr, "stderr");
-}
-
-static void on_job_output(Stream *stream, Channel *data, RBuffer *buf,
-                          size_t count, bool eof, Callback *callback,
-                          const char *type)
-{
-  if (eof) {
-    return;
-  }
-
-  // stub variable, to keep reading consistent with the order of events, only
-  // consider the count parameter.
-  size_t r;
-  char *ptr = rbuffer_read_ptr(buf, &r);
-
-  // The order here matters, the terminal must receive the data first because
-  // process_job_event will modify the read buffer(convert NULs into NLs)
-  if (data->term) {
-    terminal_receive(data->term, ptr, count);
-  }
-
-  rbuffer_consumed(buf, count);
-  if (callback->type != kCallbackNone) {
-    process_job_event(data, callback, type, ptr, count, 0);
-  }
-}
-
-static void eval_job_process_exit_cb(Process *proc, int status, void *d)
-{
-  Channel *data = d;
-  if (data->term && !data->stream.proc.exited) {
-    data->stream.proc.exited = true;
-    char msg[sizeof("\r\n[Process exited ]") + NUMBUFLEN];
-    snprintf(msg, sizeof msg, "\r\n[Process exited %d]", proc->status);
-    terminal_close(data->term, msg);
-  }
-  if (data->is_rpc) {
-    channel_process_exit(data->id, status);
-  }
-
-  if (data->status_ptr) {
-    *data->status_ptr = status;
-  }
-
-  process_job_event(data, &data->on_exit, "exit", NULL, 0, status);
-
-  channel_decref(data);
-}
 
 static void term_write(char *buf, size_t size, void *d)
 {
@@ -22589,38 +22436,6 @@ static void term_close(void *d)
   multiqueue_put(data->events, term_delayed_free, 1, data);
 }
 
-static void on_job_event(ChannelEvent *ev)
-{
-  if (!ev->callback) {
-    return;
-  }
-
-  typval_T argv[4];
-
-  argv[0].v_type = VAR_NUMBER;
-  argv[0].v_lock = 0;
-  argv[0].vval.v_number = ev->data->id;
-
-  if (ev->received) {
-    argv[1].v_type = VAR_LIST;
-    argv[1].v_lock = 0;
-    argv[1].vval.v_list = ev->received;
-    argv[1].vval.v_list->lv_refcount++;
-  } else {
-    argv[1].v_type = VAR_NUMBER;
-    argv[1].v_lock = 0;
-    argv[1].vval.v_number = ev->status;
-  }
-
-  argv[2].v_type = VAR_STRING;
-  argv[2].v_lock = 0;
-  argv[2].vval.v_string = (uint8_t *)ev->type;
-
-  typval_T rettv = TV_INITIAL_VALUE;
-  callback_call(ev->callback, 3, argv, &rettv);
-  tv_clear(&rettv);
-}
-
 static Channel *find_job(uint64_t id, bool show_error)
 {
   Channel *data = find_channel(id);
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index 070bc35bd5..7814a086fa 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -7,6 +7,9 @@
 #include "nvim/eval/typval.h"
 #include "nvim/profile.h"
 #include "nvim/garray.h"
+#include "nvim/event/rstream.h"
+#include "nvim/event/wstream.h"
+#include "nvim/channel.h"
 
 #define COPYID_INC 2
 #define COPYID_MASK (~0x1)
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 0e359fb61c..3150f26df6 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -273,6 +273,7 @@ return {
     sockconnect={args={2,3}},
     sort={args={1, 3}},
     soundfold={args=1},
+    stdioopen={args=1},
     spellbadword={args={0, 1}},
     spellsuggest={args={1, 3}},
     split={args={1, 3}},
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index 99382d2a24..4bc3a85efb 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -374,7 +374,7 @@ void tv_list_append_dict(list_T *const list, dict_T *const dict)
 ///                  case string is considered to be usual zero-terminated
 ///                  string or NULL “empty” string.
 void tv_list_append_string(list_T *const l, const char *const str,
-                           const ptrdiff_t len)
+                           const ssize_t len)
   FUNC_ATTR_NONNULL_ARG(1)
 {
   if (str == NULL) {
@@ -824,7 +824,7 @@ void tv_dict_watcher_add(dict_T *const dict, const char *const key_pattern,
 /// @param[in]  cb2  Second callback to check.
 ///
 /// @return True if they are equal, false otherwise.
-bool tv_callback_equal(const Callback *const cb1, const Callback *const cb2)
+bool tv_callback_equal(const Callback *cb1, const Callback *cb2)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
 {
   if (cb1->type != cb2->type) {
@@ -843,12 +843,12 @@ bool tv_callback_equal(const Callback *const cb1, const Callback *const cb2)
       return true;
     }
   }
-  assert(false);
+  abort();
   return false;
 }
 
 /// Unref/free callback
-void callback_free(Callback *const callback)
+void callback_free(Callback *callback)
   FUNC_ATTR_NONNULL_ALL
 {
   switch (callback->type) {
@@ -864,9 +864,6 @@ void callback_free(Callback *const callback)
     case kCallbackNone: {
       break;
     }
-    default: {
-      abort();
-    }
   }
   callback->type = kCallbackNone;
 }
diff --git a/src/nvim/event/process.c b/src/nvim/event/process.c
index 1bbe4d9cad..8946f049e2 100644
--- a/src/nvim/event/process.c
+++ b/src/nvim/event/process.c
@@ -92,7 +92,6 @@ int process_spawn(Process *proc, bool in, bool out, bool err)
   if (in) {
     stream_init(NULL, &proc->in, -1,
                 STRUCT_CAST(uv_stream_t, &proc->in.uv.pipe));
-    proc->in.events = proc->events;
     proc->in.internal_data = proc;
     proc->in.internal_close_cb = on_process_stream_close;
     proc->refcount++;
@@ -101,7 +100,6 @@ int process_spawn(Process *proc, bool in, bool out, bool err)
   if (out) {
     stream_init(NULL, &proc->out, -1,
                 STRUCT_CAST(uv_stream_t, &proc->out.uv.pipe));
-    proc->out.events = proc->events;
     proc->out.internal_data = proc;
     proc->out.internal_close_cb = on_process_stream_close;
     proc->refcount++;
@@ -110,7 +108,6 @@ int process_spawn(Process *proc, bool in, bool out, bool err)
   if (err) {
     stream_init(NULL, &proc->err, -1,
                 STRUCT_CAST(uv_stream_t, &proc->err.uv.pipe));
-    proc->err.events = proc->events;
     proc->err.internal_data = proc;
     proc->err.internal_close_cb = on_process_stream_close;
     proc->refcount++;
@@ -382,15 +379,15 @@ static void flush_stream(Process *proc, Stream *stream)
 
     // Poll for data and process the generated events.
     loop_poll_events(proc->loop, 0);
-    if (proc->events) {
-        multiqueue_process_events(proc->events);
+    if (stream->events) {
+        multiqueue_process_events(stream->events);
     }
 
     // Stream can be closed if it is empty.
     if (num_bytes == stream->num_bytes) {
-      if (stream->read_cb) {
+      if (stream->read_cb && !stream->did_eof) {
         // Stream callback could miss EOF handling if a child keeps the stream
-        // open.
+        // open. But only send EOF if we haven't already.
         stream->read_cb(stream, stream->buffer, 0, stream->cb_data, true);
       }
       break;
diff --git a/src/nvim/event/rstream.c b/src/nvim/event/rstream.c
index 2c4db08b30..e0500ba828 100644
--- a/src/nvim/event/rstream.c
+++ b/src/nvim/event/rstream.c
@@ -105,20 +105,20 @@ static void read_cb(uv_stream_t *uvstream, ssize_t cnt, const uv_buf_t *buf)
 {
   Stream *stream = uvstream->data;
 
-  if (cnt > 0) {
-    stream->num_bytes += (size_t)cnt;
-  }
-
   if (cnt <= 0) {
-    if (cnt != UV_ENOBUFS
-        // cnt == 0 means libuv asked for a buffer and decided it wasn't needed:
-        // http://docs.libuv.org/en/latest/stream.html#c.uv_read_start.
-        //
-        // We don't need to do anything with the RBuffer because the next call
-        // to `alloc_cb` will return the same unused pointer(`rbuffer_produced`
-        // won't be called)
-        && cnt != 0) {
-      DLOG("closing Stream: %p: %s (%s)", stream,
+    // cnt == 0 means libuv asked for a buffer and decided it wasn't needed:
+    // http://docs.libuv.org/en/latest/stream.html#c.uv_read_start.
+    //
+    // We don't need to do anything with the RBuffer because the next call
+    // to `alloc_cb` will return the same unused pointer(`rbuffer_produced`
+    // won't be called)
+    if (cnt == UV_ENOBUFS || cnt == 0) {
+      return;
+    } else if (cnt == UV_EOF && uvstream->type == UV_TTY) {
+      // The TTY driver might signal TTY without closing the stream
+      invoke_read_cb(stream, 0, true);
+    } else {
+      DLOG("Closing Stream (%p): %s (%s)", stream,
            uv_err_name((int)cnt), os_strerror((int)cnt));
       // Read error or EOF, either way stop the stream and invoke the callback
       // with eof == true
@@ -130,6 +130,7 @@ static void read_cb(uv_stream_t *uvstream, ssize_t cnt, const uv_buf_t *buf)
 
   // at this point we're sure that cnt is positive, no error occurred
   size_t nread = (size_t)cnt;
+  stream->num_bytes += nread;
   // Data was already written, so all we need is to update 'wpos' to reflect
   // the space actually used in the buffer.
   rbuffer_produced(stream->buffer, nread);
@@ -187,6 +188,7 @@ static void read_event(void **argv)
   if (stream->read_cb) {
     size_t count = (uintptr_t)argv[1];
     bool eof = (uintptr_t)argv[2];
+    stream->did_eof = eof;
     stream->read_cb(stream, stream->buffer, count, stream->cb_data, eof);
   }
   stream->pending_reqs--;
diff --git a/src/nvim/event/stream.h b/src/nvim/event/stream.h
index 70a708ff4d..e713323f5c 100644
--- a/src/nvim/event/stream.h
+++ b/src/nvim/event/stream.h
@@ -14,10 +14,7 @@ typedef struct stream Stream;
 ///
 /// @param stream The Stream instance
 /// @param rbuffer The associated RBuffer instance
-/// @param count Number of bytes to read. This must be respected if keeping
-///              the order of events is a requirement. This is because events
-///              may be queued and only processed later when more data is copied
-///              into to the buffer, so one read may starve another.
+/// @param count Number of bytes that was read.
 /// @param data User-defined data
 /// @param eof If the stream reached EOF.
 typedef void (*stream_read_cb)(Stream *stream, RBuffer *buf, size_t count,
@@ -34,6 +31,7 @@ typedef void (*stream_close_cb)(Stream *stream, void *data);
 
 struct stream {
   bool closed;
+  bool did_eof;
   union {
     uv_pipe_t pipe;
     uv_tcp_t tcp;
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index c639dbcf83..d21cfe7ab6 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -1080,6 +1080,8 @@ EXTERN char_u e_jobtblfull[] INIT(= N_("E901: Job table is full"));
 EXTERN char_u e_jobspawn[] INIT(= N_(
     "E903: Process failed to start: %s: \"%s\""));
 EXTERN char_u e_channotpty[] INIT(= N_("E904: channel is not a pty"));
+EXTERN char_u e_stdiochan2[] INIT(= N_(
+    "E905: Couldn't open stdio channel: %s"));
 EXTERN char_u e_libcall[] INIT(= N_("E364: Library call failed for \"%s()\""));
 EXTERN char_u e_mkdir[] INIT(= N_("E739: Cannot create directory %s: %s"));
 EXTERN char_u e_markinval[] INIT(= N_("E19: Mark has invalid line number"));
@@ -1190,9 +1192,13 @@ EXTERN char *ignoredp;
 
 // If a msgpack-rpc channel should be started over stdin/stdout
 EXTERN bool embedded_mode INIT(= false);
+// Dont try to start an user interface
+// or read/write to stdio (unless embedding)
+EXTERN bool headless_mode INIT(= false);
 
 /// next free id for a job or rpc channel
-EXTERN uint64_t next_chan_id INIT(= 1);
+/// 1 is reserved for stdio channel
+EXTERN uint64_t next_chan_id INIT(= 2);
 
 /// Used to track the status of external functions.
 /// Currently only used for iconv().
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 93afe11f3a..9059644fc0 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -103,7 +103,6 @@ typedef struct {
   bool input_isatty;                    // stdin is a terminal
   bool output_isatty;                   // stdout is a terminal
   bool err_isatty;                      // stderr is a terminal
-  bool headless;                        // Do not start the builtin UI.
   int no_swap_file;                     // "-n" argument used
   int use_debug_break_level;
   int window_count;                     /* number of windows to use */
@@ -299,7 +298,7 @@ int main(int argc, char **argv)
   cmdline_row = (int)(Rows - p_ch);
   msg_row = cmdline_row;
   screenalloc(false);           /* allocate screen buffers */
-  set_init_2(params.headless);
+  set_init_2(headless_mode);
   TIME_MSG("inits 2");
 
   msg_scroll = TRUE;
@@ -311,7 +310,7 @@ int main(int argc, char **argv)
   /* Set the break level after the terminal is initialized. */
   debug_break_level = params.use_debug_break_level;
 
-  bool reading_input = !params.headless && (params.input_isatty
+  bool reading_input = !headless_mode && (params.input_isatty
       || params.output_isatty || params.err_isatty);
 
   if (reading_input) {
@@ -448,7 +447,7 @@ int main(int argc, char **argv)
     wait_return(TRUE);
   }
 
-  if (!params.headless) {
+  if (!headless_mode) {
     // Stop reading from input stream, the UI layer will take over now.
     input_stop();
     ui_builtin_start();
@@ -809,11 +808,14 @@ static void command_line_scan(mparm_T *parmp)
             }
             mch_exit(0);
           } else if (STRICMP(argv[0] + argv_idx, "headless") == 0) {
-            parmp->headless = true;
+            headless_mode = true;
           } else if (STRICMP(argv[0] + argv_idx, "embed") == 0) {
             embedded_mode = true;
-            parmp->headless = true;
-            channel_from_stdio();
+            headless_mode = true;
+            const char *err;
+            if (!channel_from_stdio(true, CALLBACK_READER_INIT, &err)) {
+              abort();
+            }
           } else if (STRNICMP(argv[0] + argv_idx, "literal", 7) == 0) {
 #if !defined(UNIX)
             parmp->literal = TRUE;
@@ -1216,7 +1218,6 @@ static void init_params(mparm_T *paramp, int argc, char **argv)
   memset(paramp, 0, sizeof(*paramp));
   paramp->argc = argc;
   paramp->argv = argv;
-  paramp->headless = false;
   paramp->want_full_screen = true;
   paramp->use_debug_break_level = -1;
   paramp->window_count = -1;
@@ -1387,7 +1388,7 @@ static void handle_tag(char_u *tagname)
 // When starting in Ex mode and commands come from a file, set Silent mode.
 static void check_tty(mparm_T *parmp)
 {
-  if (parmp->headless) {
+  if (headless_mode) {
     return;
   }
 
diff --git a/src/nvim/msgpack_rpc/channel.c b/src/nvim/msgpack_rpc/channel.c
index 42b1f63830..56af4fa791 100644
--- a/src/nvim/msgpack_rpc/channel.c
+++ b/src/nvim/msgpack_rpc/channel.c
@@ -13,7 +13,6 @@
 #include "nvim/api/ui.h"
 #include "nvim/channel.h"
 #include "nvim/msgpack_rpc/channel.h"
-#include "nvim/msgpack_rpc/server.h"
 #include "nvim/event/loop.h"
 #include "nvim/event/libuv_process.h"
 #include "nvim/event/rstream.h"
@@ -30,12 +29,9 @@
 #include "nvim/map.h"
 #include "nvim/log.h"
 #include "nvim/misc1.h"
-#include "nvim/path.h"
 #include "nvim/lib/kvec.h"
 #include "nvim/os/input.h"
 
-#define CHANNEL_BUFFER_SIZE 0xffff
-
 #if MIN_LOG_LEVEL > DEBUG_LOG_LEVEL
 #define log_client_msg(...)
 #define log_server_msg(...)
@@ -66,57 +62,18 @@ void rpc_start(Channel *channel)
   rpc->next_request_id = 1;
   kv_init(rpc->call_stack);
 
-  Stream *in = channel_instream(channel);
-  Stream *out = channel_outstream(channel);
-
-  DLOG("rpc ch %" PRIu64 " in-stream=%p out-stream=%p", channel->id, in, out);
-
-  wstream_init(in, 0);
-  rstream_init(out, CHANNEL_BUFFER_SIZE);
-  rstream_start(out, receive_msgpack, channel);
-}
-
-/// Creates an API channel from a tcp/pipe socket connection
-///
-/// @param watcher The SocketWatcher ready to accept the connection
-void channel_from_connection(SocketWatcher *watcher)
-{
-  Channel *channel = channel_alloc(kChannelStreamSocket);
-  socket_watcher_accept(watcher, &channel->stream.socket);
-  channel_incref(channel);  // close channel only after the stream is closed
-  channel->stream.socket.internal_close_cb = close_cb;
-  channel->stream.socket.internal_data = channel;
-  rpc_start(channel);
-}
-
-/// TODO: move to eval.c, also support bytes
-uint64_t channel_connect(bool tcp, const char *address,
-                         int timeout, const char **error)
-{
-  if (!tcp) {
-    char *path = fix_fname(address);
-    if (server_owns_pipe_address(path)) {
-      // avoid deadlock
-      xfree(path);
-      return channel_create_internal();
-    }
-    xfree(path);
-  }
+  if (channel->streamtype != kChannelStreamInternal) {
+    Stream *out = channel_outstream(channel);
+#if MIN_LOG_LEVEL <= DEBUG_LOG_LEVEL
+    Stream *in = channel_instream(channel);
+    DLOG("rpc ch %" PRIu64 " in-stream=%p out-stream=%p", channel->id, in, out);
+#endif
 
-  Channel *channel = channel_alloc(kChannelStreamSocket);
-  if (!socket_connect(&main_loop, &channel->stream.socket,
-                      tcp, address, timeout, error)) {
-    channel_decref(channel);
-    return 0;
+    rstream_start(out, receive_msgpack, channel);
   }
-
-  channel_incref(channel);  // close channel only after the stream is closed
-  channel->stream.socket.internal_close_cb = close_cb;
-  channel->stream.socket.internal_data = channel;
-  rpc_start(channel);
-  return channel->id;
 }
 
+
 static Channel *find_rpc_channel(uint64_t id)
 {
   Channel *chan = find_channel(id);
@@ -263,29 +220,6 @@ bool channel_close(uint64_t id)
   return true;
 }
 
-/// Creates an API channel from stdin/stdout. This is used when embedding
-/// Neovim
-void channel_from_stdio(void)
-{
-  Channel *channel = channel_alloc(kChannelStreamStdio);
-  channel_incref(channel);  // stdio channels are only closed on exit
-  // read stream
-  rstream_init_fd(&main_loop, &channel->stream.stdio.in, 0, CHANNEL_BUFFER_SIZE);
-  wstream_init_fd(&main_loop, &channel->stream.stdio.out, 1, 0);
-
-  rpc_start(channel);
-}
-
-/// Creates a loopback channel. This is used to avoid deadlock
-/// when an instance connects to its own named pipe.
-uint64_t channel_create_internal(void)
-{
-  Channel *channel = channel_alloc(kChannelStreamInternal);
-  channel_incref(channel);  // internal channel lives until process exit
-  rpc_start(channel);
-  return channel->id;
-}
-
 void channel_process_exit(uint64_t id, int status)
 {
   Channel *channel = pmap_get(uint64_t)(channels, id);
@@ -663,11 +597,6 @@ void rpc_free(Channel *channel)
   kv_destroy(channel->rpc.call_stack);
 }
 
-static void close_cb(Stream *stream, void *data)
-{
-  channel_decref(data);
-}
-
 static bool is_rpc_response(msgpack_object *obj)
 {
   return obj->type == MSGPACK_OBJECT_ARRAY
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index f54fe412ba..ec2ebb9d19 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -227,18 +227,15 @@ static int do_os_system(char **argv,
     return -1;
   }
 
-  // We want to deal with stream events as fast a possible while queueing
-  // process events, so reset everything to NULL. It prevents closing the
+  // Note: unlike process events, stream events are not queued, as we want to
+  // deal with stream events as fast a possible.  It prevents closing the
   // streams while there's still data in the OS buffer (due to the process
   // exiting before all data is read).
   if (input != NULL) {
-    proc->in.events = NULL;
     wstream_init(&proc->in, 0);
   }
-  proc->out.events = NULL;
   rstream_init(&proc->out, 0);
   rstream_start(&proc->out, data_cb, &buf);
-  proc->err.events = NULL;
   rstream_init(&proc->err, 0);
   rstream_start(&proc->err, data_cb, &buf);
 
diff --git a/src/nvim/rbuffer.c b/src/nvim/rbuffer.c
index 18d453cbe9..df9394fbb2 100644
--- a/src/nvim/rbuffer.c
+++ b/src/nvim/rbuffer.c
@@ -121,7 +121,7 @@ char *rbuffer_read_ptr(RBuffer *buf, size_t *read_count) FUNC_ATTR_NONNULL_ALL
 {
   if (!buf->size) {
     *read_count = 0;
-    return NULL;
+    return buf->read_ptr;
   }
 
   if (buf->read_ptr < buf->write_ptr) {