Improve udev installation

Add command line function to install udev rule,
and tell user where to find the file if they
want to install it manually.

Author: bessman

99-pslab.rules pslab/99-pslab.rules

@@ -15,13 +15,17 @@
 import argparse
 import csv
 import json
+import platform
+import os.path
+import shutil
 import sys
 import time
 from itertools import zip_longest
 from typing import List, Tuple
 
 import numpy as np
 
+import pslab
 import pslab.protocol as CP
 from pslab.instrument.logic_analyzer import LogicAnalyzer
 from pslab.instrument.oscilloscope import Oscilloscope
@@ -224,6 +228,10 @@ def main(args: argparse.Namespace):
     args : :class:`argparse.Namespace`
         Parsed arguments.
     """
+    if args.function == "install":
+        install(args)
+        return
+
     handler = SerialHandler(port=args.port)
 
     if args.function == "collect":
@@ -456,4 +464,55 @@ def cmdline(args: List[str] = None):
     add_collect_args(subparser)
     add_wave_args(subparser)
     add_pwm_args(subparser)
+    add_install_args(subparser)
     main(parser.parse_args(args))
+
+
+def install(args: argparse.Namespace):
+    """Install udev rule on Linux.
+
+    Parameters
+    ----------
+    args : :class:`argparse.Namespace`
+        Parsed arguments.
+    """
+    if not platform.system() == "Linux":
+        print(f"Installation not required on {platform.system()}.")
+        return
+    else:
+        try:
+            SerialHandler.check_udev()
+        except OSError:
+            _install()
+            return
+
+        if args.force:
+            _install()
+            return
+
+        print("udev rule already installed.")
+
+
+def _install():
+    udev_rules = os.path.join(pslab.__path__[0], "99-pslab.rules")
+    target = "/etc/udev/rules.d/99-pslab.rules"
+    shutil.copyfile(udev_rules, target)
+    return
+
+
+def add_install_args(subparser: argparse._SubParsersAction):
+    """Add arguments for install function to ArgumentParser.
+
+    Parameters
+    ----------
+    subparser : :class:`argparse._SubParsersAction`
+        SubParser to add other arguments related to install function.
+    """
+    install = subparser.add_parser("install")
+    install.add_argument(
+        "-f",
+        "--force",
+        action="store_true",
+        default=False,
+        help="Overwrite existing udev rules.",
+    )

pslab/cli.py

@@ -18,6 +18,7 @@
 import serial
 from serial.tools import list_ports
 
+import pslab
 import pslab.protocol as CP
 
 logger = logging.getLogger(__name__)
@@ -79,7 +80,7 @@ def __init__(
         baudrate: int = 1000000,
         timeout: float = 1.0,
     ):
-        self._check_udev()
+        self.check_udev()
         self.version = ""
         self._log = b""
         self._logging = False
@@ -98,7 +99,8 @@ def __init__(
         self.connected = self.interface.is_open
 
     @staticmethod
-    def _check_udev():
+    def check_udev():
+        """Check if udev rule is installed on Linux."""
         if platform.system() == "Linux":
             udev_paths = [
                 "/run/udev/rules.d/",
@@ -110,11 +112,11 @@ def _check_udev():
                 if os.path.isfile(udev_rules):
                     break
             else:
-                e = (
+                raise OSError(
                     "A udev rule must be installed to access the PSLab. "
-                    + "Please copy 99-pslab.rules to /etc/udev/rules.d/."
+                    "Please run 'pslab install' as root, or copy "
+                    f"{pslab.__path__[0]}/99-pslab.rules to {udev_paths[1]}."
                 )
-                raise OSError(e)
 
     @staticmethod
     def _list_ports() -> List[str]:
@@ -401,7 +403,8 @@ def __init__(
         super().__init__(port, baudrate, timeout)
 
     @staticmethod
-    def _check_udev():
+    def check_udev():
+        """See :meth:`SerialHandler.check_udev`."""
         pass
 
     def connect(

pslab/serial_handler.py

@@ -30,7 +30,7 @@ def mock_serial(mocker):
 
 @pytest.fixture
 def mock_handler(mocker, mock_serial, mock_list_ports):
-    mocker.patch("pslab.serial_handler.SerialHandler._check_udev")
+    mocker.patch("pslab.serial_handler.SerialHandler.check_udev")
     mock_list_ports.grep.return_value = mock_ListPortInfo()
     return SerialHandler()
 
@@ -47,21 +47,21 @@ def test_detect(mocker, mock_serial, mock_list_ports):
 
 def test_connect_scan_port(mocker, mock_serial, mock_list_ports):
     mock_list_ports.grep.return_value = mock_ListPortInfo()
-    mocker.patch("pslab.serial_handler.SerialHandler._check_udev")
+    mocker.patch("pslab.serial_handler.SerialHandler.check_udev")
     SerialHandler()
     mock_serial().open.assert_called()
 
 
 def test_connect_scan_failure(mocker, mock_serial, mock_list_ports):
     mock_list_ports.grep.return_value = mock_ListPortInfo(found=False)
-    mocker.patch("pslab.serial_handler.SerialHandler._check_udev")
+    mocker.patch("pslab.serial_handler.SerialHandler.check_udev")
     with pytest.raises(SerialException):
         SerialHandler()
 
 
 def test_connect_multiple_connected(mocker, mock_serial, mock_list_ports):
     mock_list_ports.grep.return_value = mock_ListPortInfo(multiple=True)
-    mocker.patch("pslab.serial_handler.SerialHandler._check_udev")
+    mocker.patch("pslab.serial_handler.SerialHandler.check_udev")
     with pytest.raises(RuntimeError):
         SerialHandler()