moonraker: add initial source

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

moonraker/plugins/shell_command.py

@@ -0,0 +1,88 @@
+# linux shell command execution utility
+#
+# Copyright (C) 2020  Eric Callahan <arksine.code@gmail.com>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+import os
+import shlex
+import subprocess
+import logging
+import tornado
+from tornado import gen
+from tornado.ioloop import IOLoop
+
+class ShellCommand:
+    def __init__(self, cmd, callback=None):
+        self.io_loop = IOLoop.current()
+        self.name = cmd
+        self.output_cb = callback
+        cmd = os.path.expanduser(cmd)
+        self.command = shlex.split(cmd)
+        self.partial_output = b""
+
+    def _process_output(self, fd, events):
+        if events & IOLoop.ERROR:
+            return
+        try:
+            data = os.read(fd, 4096)
+        except Exception:
+            return
+        data = self.partial_output + data
+        if b'\n' not in data:
+            self.partial_output = data
+            return
+        elif data[-1] != b'\n':
+            split = data.rfind(b'\n') + 1
+            self.partial_output = data[split:]
+            data = data[:split]
+        try:
+            self.output_cb(data)
+        except Exception:
+            logging.exception("Error writing command output")
+
+    async def run(self, timeout=2., verbose=True):
+        if not timeout or self.output_cb is None:
+            # Fire and forget commands cannot be verbose as we can't
+            # clean up after the process terminates
+            verbose = False
+        try:
+            proc = subprocess.Popen(
+                self.command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+        except Exception:
+            logging.exception(
+                "shell_command: Command {%s} failed" % (self.name))
+            return
+        if verbose:
+            fd = proc.stdout.fileno()
+            self.io_loop.add_handler(
+                fd, self._process_output, IOLoop.READ | IOLoop.ERROR)
+        elif not timeout:
+            # fire and forget, return from execution
+            return
+        sleeptime = 0
+        complete = False
+        while sleeptime < timeout:
+            await gen.sleep(.05)
+            sleeptime += .05
+            if proc.poll() is not None:
+                complete = True
+                break
+        if not complete:
+            proc.terminate()
+        if verbose:
+            if self.partial_output:
+                self.output_cb(self.partial_output)
+                self.partial_output = b""
+            if complete:
+                msg = "Command {%s} finished\n" % (self.name)
+            else:
+                msg = "Command {%s} timed out" % (self.name)
+                logging.info("shell_command: " + msg)
+            self.io_loop.remove_handler(fd)
+
+class ShellCommandFactory:
+    def build_shell_command(self, cmd, callback):
+        return ShellCommand(cmd, callback)
+
+def load_plugin(server):
+    return ShellCommandFactory()