Source code for can.util

# coding: utf-8

Utilities and configuration file parsing.

import json
import os
import os.path
import platform
import re
import logging
from configparser import ConfigParser

import can
from can.interfaces import VALID_INTERFACES

log = logging.getLogger("can.util")

# List of valid data lengths for a CAN FD message
CAN_FD_DLC = [0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 20, 24, 32, 48, 64]

REQUIRED_KEYS = ["interface", "channel"]

CONFIG_FILES = ["~/can.conf"]

if platform.system() == "Linux":
    CONFIG_FILES.extend(["/etc/can.conf", "~/.can", "~/.canrc"])
elif platform.system() == "Windows" or platform.python_implementation() == "IronPython":
    CONFIG_FILES.extend(["can.ini", os.path.join(os.getenv("APPDATA", ""), "can.ini")])

[docs]def load_file_config(path=None, section="default"): """ Loads configuration from file with following content:: [default] interface = socketcan channel = can0 :param path: path to config file. If not specified, several sensible default locations are tried depending on platform. :param section: name of the section to read configuration from. """ config = ConfigParser() if path is None:[os.path.expanduser(path) for path in CONFIG_FILES]) else: _config = {} if config.has_section(section): _config.update(dict((key, val) for key, val in config.items(section))) return _config
[docs]def load_environment_config(context=None): """ Loads config dict from environmental variables (if set): * CAN_INTERFACE * CAN_CHANNEL * CAN_BITRATE * CAN_CONFIG if context is supplied, "_{context}" is appended to the environment variable name we will look at. For example if context="ABC": * CAN_INTERFACE_ABC * CAN_CHANNEL_ABC * CAN_BITRATE_ABC * CAN_CONFIG_ABC """ mapper = { "interface": "CAN_INTERFACE", "channel": "CAN_CHANNEL", "bitrate": "CAN_BITRATE", } context_suffix = "_{}".format(context) if context else "" config = {} can_config_key = "CAN_CONFIG" + context_suffix if can_config_key in os.environ: config = json.loads(os.environ.get(can_config_key)) for key, val in mapper.items(): if val in os.environ: config[key] = os.environ.get(val + context_suffix) return config
[docs]def load_config(path=None, config=None, context=None): """ Returns a dict with configuration details which is loaded from (in this order): - config - can.rc - Environment variables CAN_INTERFACE, CAN_CHANNEL, CAN_BITRATE - Config files ``/etc/can.conf`` or ``~/.can`` or ``~/.canrc`` where the latter may add or replace values of the former. Interface can be any of the strings from ``can.VALID_INTERFACES`` for example: kvaser, socketcan, pcan, usb2can, ixxat, nican, virtual. .. note:: The key ``bustype`` is copied to ``interface`` if that one is missing and does never appear in the result. :param path: Optional path to config file. :param config: A dict which may set the 'interface', and/or the 'channel', or neither. It may set other values that are passed through. :param context: Extra 'context' pass to config sources. This can be use to section other than 'default' in the configuration file. :return: A config dictionary that should contain 'interface' & 'channel':: { 'interface': 'python-can backend interface to use', 'channel': 'default channel to use', # possibly more } Note ``None`` will be used if all the options are exhausted without finding a value. All unused values are passed from ``config`` over to this. :raises: NotImplementedError if the ``interface`` isn't recognized """ # start with an empty dict to apply filtering to all sources given_config = config or {} config = {} # use the given dict for default values config_sources = [ given_config, can.rc, lambda _context: load_environment_config( # pylint: disable=unnecessary-lambda _context ), lambda _context: load_environment_config(), lambda _context: load_file_config(path, _context), lambda _context: load_file_config(path), ] # Slightly complex here to only search for the file config if required for cfg in config_sources: if callable(cfg): cfg = cfg(context) # remove legacy operator (and copy to interface if not already present) if "bustype" in cfg: if "interface" not in cfg or not cfg["interface"]: cfg["interface"] = cfg["bustype"] del cfg["bustype"] # copy all new parameters for key in cfg: if key not in config: config[key] = cfg[key] # substitute None for all values not found for key in REQUIRED_KEYS: if key not in config: config[key] = None if config["interface"] not in VALID_INTERFACES: raise NotImplementedError( "Invalid CAN Bus Type - {}".format(config["interface"]) ) if "bitrate" in config: config["bitrate"] = int(config["bitrate"]) if "fd" in config: config["fd"] = config["fd"] not in ("0", "False", "false") if "data_bitrate" in config: config["data_bitrate"] = int(config["data_bitrate"]) # Create bit timing configuration if given timing_conf = {} for key in ( "f_clock", "brp", "tseg1", "tseg2", "sjw", "nof_samples", "btr0", "btr1", ): if key in config: timing_conf[key] = int(config[key], base=0) del config[key] if timing_conf: timing_conf["bitrate"] = config.get("bitrate") config["timing"] = can.BitTiming(**timing_conf) can.log.debug("can config: {}".format(config)) return config
[docs]def set_logging_level(level_name=None): """Set the logging level for the "can" logger. Expects one of: 'critical', 'error', 'warning', 'info', 'debug', 'subdebug' """ can_logger = logging.getLogger("can") try: can_logger.setLevel(getattr(logging, level_name.upper())) except AttributeError: can_logger.setLevel(logging.DEBUG) log.debug("Logging set to {}".format(level_name))
[docs]def len2dlc(length): """Calculate the DLC from data length. :param int length: Length in number of bytes (0-64) :returns: DLC (0-15) :rtype: int """ if length <= 8: return length for dlc, nof_bytes in enumerate(CAN_FD_DLC): if nof_bytes >= length: return dlc return 15
[docs]def dlc2len(dlc): """Calculate the data length from DLC. :param int dlc: DLC (0-15) :returns: Data length in number of bytes (0-64) :rtype: int """ return CAN_FD_DLC[dlc] if dlc <= 15 else 64
[docs]def channel2int(channel): """Try to convert the channel to an integer. :param channel: Channel string (e.g. can0, CAN1) or integer :returns: Channel integer or `None` if unsuccessful :rtype: int """ if channel is None: return None if isinstance(channel, int): return channel # String and byte objects have a lower() method if hasattr(channel, "lower"): match = re.match(r".*(\d+)$", channel) if match: return int( return None
if __name__ == "__main__": print("Searching for configuration named:") print("\n".join(CONFIG_FILES)) print() print("Settings:") print(load_config())