Remote file kitten: Integrate with the ssh kitten

docs/changelog.rst

@@ -49,6 +49,10 @@ Detailed list of changes
 
 - Fix a regression in the previous release that caused mouse move events to be incorrectly reported as drag events even when a button is not pressed (:iss:`4992`)
 
+- remote file kitten: Integrate with the ssh kitten for improved performance
+  and robustness. Re-uses the control master connection of the ssh kitten to
+  avoid round-trip latency.
+
 - Fix tab selection when closing a new tab not correct in some scenarios (:iss:`4987`)
 
 - A new action :ac:`open_url` to open the specified URL (:pull:`5004`)

docs/kittens/remote_file.rst

@@ -27,13 +27,16 @@ supports hyperlinks.
 .. versionadded:: 0.19.0
 
 .. note::
-   Nested SSH sessions are not supported. The kitten will always try to copy
+   For best results, use this kitten with the :doc:`ssh kitten <./ssh>`.
-   remote files from the first SSH host. This is because there is no way for
+   Otherwise, nested SSH sessions are not supported. The kitten will always try to copy
+   remote files from the first SSH host. This is because, without the ssh
+   kitten, there is no way for
    |kitty| to detect and follow a nested SSH session robustly. Use the
    :doc:`transfer` kitten for such situations.
 
 .. note::
-   If you have not setup automatic password-less SSH access, then, when editing
+   If you have not setup automatic password-less SSH access, and are not using
+   the ssh kitten, then, when editing
    starts you will be asked to enter your password just once, thereafter the SSH
    connection will be re-used.
 

kittens/remote_file/main.py

@@ -27,6 +27,9 @@ from ..tui.operations import (
 from ..tui.utils import get_key_press
 
 
+is_ssh_kitten_sentinel = '!#*&$#($ssh-kitten)(##$'
+
+
 def key(x: str) -> str:
     return styled(x, bold=True, fg='green')
 
@@ -53,10 +56,9 @@ The data used to connect over ssh.
 
 
 def show_error(msg: str) -> None:
-    print(styled(msg, fg='red'))
+    print(styled(msg, fg='red'), file=sys.stderr)
     print()
-    print('Press any key to quit')
+    print('Press any key to quit', flush=True)
-    sys.stdout.flush()
     with raw_mode():
         while True:
             try:
@@ -112,10 +114,20 @@ class ControlMaster:
         self.remote_path = remote_path
         self.dest = dest
         self.tdir = ''
+        self.last_error_log = ''
         self.cmd_prefix = cmd = [
             conn_data.binary, '-o', f'ControlPath=~/.ssh/kitty-master-{os.getpid()}-%r@%h:%p',
             '-o', 'TCPKeepAlive=yes', '-o', 'ControlPersist=yes'
         ]
+        self.is_ssh_kitten = conn_data.binary is is_ssh_kitten_sentinel
+        if self.is_ssh_kitten:
+            del cmd[:]
+            self.batch_cmd_prefix = cmd
+            sk_cmdline = json.loads(conn_data.identity_file)
+            while '-t' in sk_cmdline:
+                sk_cmdline.remove('-t')
+            cmd.extend(sk_cmdline[:-2])
+        else:
             if conn_data.port:
                 cmd.extend(['-p', str(conn_data.port)])
             if conn_data.identity_file:
@@ -130,6 +142,7 @@ class ControlMaster:
             raise Exception(f'The ssh command: {shlex.join(cmd)} failed with exit code {p.returncode} and output: {out}')
 
     def __enter__(self) -> 'ControlMaster':
+        if not self.is_ssh_kitten:
             self.check_call(
                 self.cmd_prefix + ['-o', 'ControlMaster=auto', '-fN', self.conn_data.hostname])
             self.check_call(
@@ -140,6 +153,7 @@ class ControlMaster:
         return self
 
     def __exit__(self, *a: Any) -> None:
+        if not self.is_ssh_kitten:
             subprocess.Popen(
                 self.batch_cmd_prefix + ['-O', 'exit', self.conn_data.hostname],
                 stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL
@@ -149,12 +163,16 @@ class ControlMaster:
 
     @property
     def is_alive(self) -> bool:
+        if self.is_ssh_kitten:
+            return True
         return subprocess.Popen(
             self.batch_cmd_prefix + ['-O', 'check', self.conn_data.hostname],
             stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL
         ).wait() == 0
 
     def check_hostname_matches(self) -> bool:
+        if self.is_ssh_kitten:
+            return True
         cp = subprocess.run(self.batch_cmd_prefix + [self.conn_data.hostname, 'hostname', '-f'], stdout=subprocess.PIPE,
                             stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL)
         if cp.returncode == 0:
@@ -181,21 +199,35 @@ class ControlMaster:
                 return response == 'y'
         return True
 
+    def show_error(self, msg: str) -> None:
+        if self.last_error_log:
+            print(self.last_error_log, file=sys.stderr)
+            self.last_error_log = ''
+        show_error(msg)
+
     def download(self) -> bool:
+        cmdline = self.batch_cmd_prefix + [self.conn_data.hostname, 'cat', self.remote_path]
         with open(self.dest, 'wb') as f:
-            return subprocess.run(
+            cp = subprocess.run(cmdline, stdout=f, stderr=subprocess.PIPE, stdin=subprocess.DEVNULL)
-                self.batch_cmd_prefix + [self.conn_data.hostname, 'cat', self.remote_path],
+            if cp.returncode != 0:
-                stdout=f, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL
+                self.last_error_log = f'The command: {shlex.join(cmdline)} failed\n' + cp.stderr.decode()
-            ).returncode == 0
+                return False
+        return True
 
     def upload(self, suppress_output: bool = True) -> bool:
         cmd_prefix = self.cmd_prefix if suppress_output else self.batch_cmd_prefix
         cmd = cmd_prefix + [self.conn_data.hostname, 'cat', '>', self.remote_path]
         if not suppress_output:
-            print(' '.join(map(shlex.quote, cmd)))
+            print(shlex.join(cmd))
-        redirect = subprocess.DEVNULL if suppress_output else None
         with open(self.dest, 'rb') as f:
-            return subprocess.run(cmd, stdout=redirect, stderr=redirect, stdin=f).returncode == 0
+            if suppress_output:
+                cp = subprocess.run(cmd, stdin=f, capture_output=True)
+                if cp.returncode == 0:
+                    return True
+                self.last_error_log = f'The command: {shlex.join(cmd)} failed\n' + cp.stdout.decode()
+            else:
+                return subprocess.run(cmd, stdin=f).returncode == 0
+        return False
 
 
 Result = Optional[str]
@@ -278,11 +310,15 @@ def save_as(conn_data: SSHConnectionData, remote_path: str, cli_opts: RemoteFile
     with ControlMaster(conn_data, remote_path, cli_opts, dest=dest) as master:
         if master.check_hostname_matches():
             if not master.download():
-                show_error('Failed to copy file from remote machine')
+                master.show_error('Failed to copy file from remote machine')
 
 
 def handle_action(action: str, cli_opts: RemoteFileCLIOptions) -> Result:
-    conn_data = SSHConnectionData(*json.loads(cli_opts.ssh_connection_data or ''))
+    cli_data = json.loads(cli_opts.ssh_connection_data or '')
+    if cli_data and cli_data[0] == is_ssh_kitten_sentinel:
+        conn_data = SSHConnectionData(is_ssh_kitten_sentinel, cli_data[-1], -1, identity_file=json.dumps(cli_data[1:]))
+    else:
+        conn_data = SSHConnectionData(*cli_data)
     remote_path = cli_opts.path or ''
     if action == 'open':
         print('Opening', cli_opts.path, 'from', cli_opts.hostname)
@@ -291,7 +327,7 @@ def handle_action(action: str, cli_opts: RemoteFileCLIOptions) -> Result:
             if master.check_hostname_matches():
                 if master.download():
                     return dest
-                show_error('Failed to copy file from remote machine')
+                master.show_error('Failed to copy file from remote machine')
     elif action == 'edit':
         print('Editing', cli_opts.path, 'from', cli_opts.hostname)
         editor = get_editor()
@@ -299,7 +335,7 @@ def handle_action(action: str, cli_opts: RemoteFileCLIOptions) -> Result:
             if not master.check_hostname_matches():
                 return None
             if not master.download():
-                show_error(f'Failed to download {remote_path}')
+                master.show_error(f'Failed to download {remote_path}')
                 return None
             mtime = os.path.getmtime(master.dest)
             print(reset_terminal(), end='', flush=True)
@@ -314,9 +350,9 @@ def handle_action(action: str, cli_opts: RemoteFileCLIOptions) -> Result:
             print(reset_terminal(), end='', flush=True)
             if master.is_alive:
                 if not master.upload(suppress_output=False):
-                    show_error(f'Failed to upload {remote_path}')
+                    master.show_error(f'Failed to upload {remote_path}')
             else:
-                show_error(f'Failed to upload {remote_path}, SSH master process died')
+                master.show_error(f'Failed to upload {remote_path}, SSH master process died')
     elif action == 'save':
         print('Saving', cli_opts.path, 'from', cli_opts.hostname)
         save_as(conn_data, remote_path, cli_opts)

kitty/window.py

@@ -829,7 +829,16 @@ class Window:
             set_clipboard_string(url)
 
     def handle_remote_file(self, netloc: str, remote_path: str) -> None:
+        from .utils import SSHConnectionData
         from kittens.ssh.main import get_connection_data
+        from kittens.remote_file.main import is_ssh_kitten_sentinel
+        args = self.ssh_kitten_cmdline()
+        conn_data: Union[None, List[str], SSHConnectionData] = None
+        if args:
+            ssh_cmdline = sorted(self.child.foreground_processes, key=lambda p: p['pid'])[-1]['cmdline'] or ['']
+            idx = ssh_cmdline.index('--')
+            conn_data = [is_ssh_kitten_sentinel] + list(ssh_cmdline[:idx + 2])
+        else:
             args = self.child.foreground_cmdline
             conn_data = get_connection_data(args, self.child.foreground_cwd or self.child.current_cwd or '')
             if conn_data is None: