feat(remote): add basic --remote support

This is starting from @geekodour's work at
https://github.com/neovim/neovim/pull/8326

runtime/lua/vim/_editor.lua

@@ -636,6 +636,78 @@ function vim.pretty_print(...)
   return ...
 end
 
+local function __rpcrequest(...)
+  return vim.api.nvim_call_function("rpcrequest", {...})
+end
+
+function vim._cs_remote(rcid, args)
+
+  local f_silent = false
+  local f_wait = false
+  local f_tab = false
+  local should_exit = true
+  local command = 'edit '
+
+  local subcmd = string.sub(args[1],10)
+
+  if subcmd == '' then
+    -- no flags to set
+  elseif subcmd == 'tab' then
+    f_tab = true
+  elseif subcmd == 'silent' then
+    f_silent = true
+  elseif subcmd == 'wait' then
+    f_wait = true
+  elseif subcmd == 'wait-silent' then
+    f_wait = true
+    f_silent = true
+  elseif subcmd == 'tab-wait' then
+    f_tab = true
+    f_wait = true
+  elseif subcmd == 'tab-silent' then
+    f_tab = true
+    f_silent = true
+  elseif subcmd == 'tab-wait-silent' then
+    f_tab = true
+    f_wait = true
+    f_silent = true
+  elseif subcmd == 'send' then
+    __rpcrequest(rcid, 'nvim_input', args[2])
+    return { should_exit = should_exit, tabbed = f_tab, files = 0 }
+    -- should we show warning if --server doesn't exist in --send and --expr?
+  elseif subcmd == 'expr' then
+    local res = __rpcrequest(rcid, 'vim_eval', args[2])
+    print(res)
+    return { should_exit = should_exit, tabbed = f_tab, files = 0 }
+  else
+    print('--remote subcommand not found')
+  end
+
+  table.remove(args,1)
+
+  if not f_silent and rcid == 0 then
+    print('Remote server does not exist.')
+  end
+
+  if f_silent and rcid == 0 then
+    print('Remote server does not exist. starting new server')
+    should_exit = false
+  end
+
+  if f_tab then command = 'tabedit ' end
+
+  if rcid ~= 0 then
+    for _, key in ipairs(args) do
+      __rpcrequest(rcid, 'nvim_command', command .. key)
+    end
+  end
+
+  return {
+    should_exit = should_exit,
+    tabbed = f_tab,
+    files = table.getn(args)
+  }
+end
 
 require('vim._meta')
 

src/nvim/api/vim.c

@@ -1997,7 +1997,7 @@ Array nvim_get_proc_children(Integer pid, Error *err)
     DLOG("fallback to vim._os_proc_children()");
     Array a = ARRAY_DICT_INIT;
     ADD(a, INTEGER_OBJ(pid));
-    String s = cstr_to_string("return vim._os_proc_children(select(1, ...))");
+    String s = cstr_to_string("return vim._os_proc_children(select(...))");
     Object o = nlua_exec(s, a, err);
     api_free_string(s);
     api_free_array(a);

src/nvim/main.c

@@ -268,6 +268,10 @@ int main(int argc, char **argv)
   }
 
   server_init(params.listen_addr);
+  if (params.remote) {
+    handle_remote_client(&params, params.remote,
+                         params.server_addr, argc, argv);
+  }
 
   if (GARGCOUNT > 0) {
     fname = get_fname(&params, cwd);
@@ -803,6 +807,67 @@ static void init_locale(void)
 }
 #endif
 
+/// Handle remote subcommands
+static void handle_remote_client(mparm_T *params, int remote_args,
+                                 char *server_addr, int argc, char **argv)
+{
+    Object rvobj = OBJECT_INIT;
+    rvobj.data.dictionary = (Dictionary)ARRAY_DICT_INIT;
+    rvobj.type = kObjectTypeDictionary;
+    CallbackReader on_data = CALLBACK_READER_INIT;
+    const char *error = NULL;
+    uint64_t rc_id = server_addr == NULL ? 0 : channel_connect(false,
+                     server_addr, true, on_data, 50, &error);
+
+    Boolean should_exit = true;
+    Boolean tabbed;
+    int files;
+
+    int t_argc = remote_args;
+    Array args = ARRAY_DICT_INIT;
+    String arg_s;
+    for (; t_argc < argc; t_argc++) {
+      arg_s = cstr_to_string(argv[t_argc]);
+      ADD(args, STRING_OBJ(arg_s));
+    }
+
+    Error err = ERROR_INIT;
+    Array a = ARRAY_DICT_INIT;
+    ADD(a, INTEGER_OBJ((int)rc_id));
+    ADD(a, ARRAY_OBJ(args));
+    String s = cstr_to_string("return vim._cs_remote(...)");
+    Object o = executor_exec_lua_api(s, a, &err);
+    api_free_string(s);
+    api_free_array(a);
+
+    if (o.type == kObjectTypeDictionary) {
+      rvobj.data.dictionary = o.data.dictionary;
+    } else if (!ERROR_SET(&err)) {
+      api_set_error(&err, kErrorTypeException,
+                    "Function returned unexpected value");
+    }
+
+    for (size_t i = 0; i < rvobj.data.dictionary.size ; i++) {
+      if (strcmp(rvobj.data.dictionary.items[i].key.data, "tabbed") == 0) {
+        // should we check items[i].value.type here?
+        tabbed = rvobj.data.dictionary.items[i].value.data.boolean;
+      } else if (strcmp(rvobj.data.dictionary.items[i].key.data, "should_exit") == 0) {
+        should_exit = rvobj.data.dictionary.items[i].value.data.boolean;
+      } else if (strcmp(rvobj.data.dictionary.items[i].key.data, "files") == 0) {
+        files = (int)rvobj.data.dictionary.items[i].value.data.integer;
+      }
+    }
+
+    if (should_exit) {
+      mch_exit(0);
+    } else {
+      if (tabbed) {
+        params->window_count = files;
+        params->window_layout = WIN_TABS;
+      }
+    }
+}
+
 /// Decides whether text (as opposed to commands) will be read from stdin.
 /// @see EDIT_STDIN
 static bool edit_stdin(bool explicit, mparm_T *parmp)
@@ -868,6 +933,8 @@ static void command_line_scan(mparm_T *parmp)
         // "--version" give version message
         // "--noplugin[s]" skip plugins
         // "--cmd <cmd>" execute cmd before vimrc
+        // "--remote" execute commands remotey on a server
+        // "--server" name of vim server to send remote commands to
         if (STRICMP(argv[0] + argv_idx, "help") == 0) {
           usage();
           os_exit(0);
@@ -906,6 +973,11 @@ static void command_line_scan(mparm_T *parmp)
           argv_idx += 6;
         } else if (STRNICMP(argv[0] + argv_idx, "literal", 7) == 0) {
           // Do nothing: file args are always literal. #7679
+        } else if (STRNICMP(argv[0] + argv_idx, "remote", 6) == 0) {
+          parmp->remote = parmp->argc - argc;
+        } else if (STRNICMP(argv[0] + argv_idx, "server", 6) == 0) {
+          want_argument = true;
+          argv_idx += 6;
         } else if (STRNICMP(argv[0] + argv_idx, "noplugin", 8) == 0) {
           p_lpl = false;
         } else if (STRNICMP(argv[0] + argv_idx, "cmd", 3) == 0) {
@@ -1137,6 +1209,9 @@ static void command_line_scan(mparm_T *parmp)
           } else if (strequal(argv[-1], "--listen")) {
             // "--listen {address}"
             parmp->listen_addr = argv[0];
+          } else if (strequal(argv[-1], "--server")) {
+            // "--server {address}"
+            parmp->server_addr = argv[0];
           }
           // "--startuptime <file>" already handled
           break;
@@ -1291,6 +1366,8 @@ static void init_params(mparm_T *paramp, int argc, char **argv)
   paramp->use_debug_break_level = -1;
   paramp->window_count = -1;
   paramp->listen_addr = NULL;
+  paramp->server_addr = NULL;
+  paramp->remote = 0;
 }
 
 /// Initialize global startuptime file if "--startuptime" passed as an argument.
@@ -2041,6 +2118,8 @@ static void usage(void)
   mch_msg(_("  --headless            Don't start a user interface\n"));
   mch_msg(_("  --listen <address>    Serve RPC API from this address\n"));
   mch_msg(_("  --noplugin            Don't load plugins\n"));
+  mch_msg(_("  --remote[-subcommand] Execute commands remotely on a server\n"));
+  mch_msg(_("  --server <address>    Specify RPC server to send commands to\n"));
   mch_msg(_("  --startuptime <file>  Write startup timing messages to <file>\n"));
   mch_msg(_("\nSee \":help startup-options\" for all options.\n"));
 }

src/nvim/main.h

@@ -39,6 +39,8 @@ typedef struct {
   int diff_mode;                        // start with 'diff' set
 
   char *listen_addr;                    // --listen {address}
+  int remote;                           // --remote-[subcmd] {file1} {file2}
+  char *server_addr;                    // --server {address}
 } mparm_T;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS