Source code for can.util

Utilities and configuration file parsing.

import functools
import warnings
from typing import Any, Callable, cast, Dict, Iterable, Tuple, Optional, Union
from time import time, perf_counter, get_clock_info
import json
import os
import os.path
import platform
import re
import logging
from configparser import ConfigParser

import can
from .interfaces import VALID_INTERFACES
from . import typechecking
from .exceptions import CanInterfaceNotImplementedError

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: Optional[typechecking.AcceptedIOType] = None, section: str = "default" ) -> Dict[str, str]: """ 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() # make sure to not transform the entries such that capitalization is preserved config.optionxform = lambda entry: entry # type: ignore 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: Optional[str] = None) -> Dict[str, str]: """ 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 = f"_{context}" if context else "" can_config_key = f"CAN_CONFIG{context_suffix}" config: Dict[str, str] = json.loads(os.environ.get(can_config_key, "{}")) for key, val in mapper.items(): config_option = os.environ.get(val + context_suffix, None) if config_option: config[key] = config_option return config
[docs]def load_config( path: Optional[typechecking.AcceptedIOType] = None, config: Optional[Dict[str, Any]] = None, context: Optional[str] = None, ) -> typechecking.BusConfig: """ 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: CanInterfaceNotImplementedError if the ``interface`` name 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 = cast( Iterable[Union[Dict[str, Any], Callable[[Any], Dict[str, Any]]]], [ 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] bus_config = _create_bus_config(config) can.log.debug("can config: %s", bus_config) return bus_config
def _create_bus_config(config: Dict[str, Any]) -> typechecking.BusConfig: """Validates some config values, performs compatibility mappings and creates specific structures (e.g. for bit timings). :param config: The raw config as specified by the user :return: A config that can be used by a :class:`~can.BusABC` :raises NotImplementedError: if the ``interface`` is unknown """ # 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 CanInterfaceNotImplementedError( f'Unknown interface type "{config["interface"]}"' ) if "bitrate" in config: config["bitrate"] = int(config["bitrate"]) if "fd" in config: config["fd"] = config["fd"] not in ("0", "False", "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(str(config[key]), base=0) del config[key] if timing_conf: timing_conf["bitrate"] = config["bitrate"] config["timing"] = can.BitTiming(**timing_conf) return cast(typechecking.BusConfig, config)
[docs]def set_logging_level(level_name: str) -> None: """Set the logging level for the `"can"` logger. :param level_name: One of: `'critical'`, `'error'`, `'warning'`, `'info'`, `'debug'`, `'subdebug'`, or the value `None` (=default). Defaults to `'debug'`. """ 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 %s", level_name)
[docs]def len2dlc(length: int) -> int: """Calculate the DLC from data length. :param length: Length in number of bytes (0-64) :returns: DLC (0-15) """ 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: int) -> int: """Calculate the data length from DLC. :param dlc: DLC (0-15) :returns: Data length in number of bytes (0-64) """ return CAN_FD_DLC[dlc] if dlc <= 15 else 64
[docs]def channel2int(channel: Optional[typechecking.Channel]) -> Optional[int]: """Try to convert the channel to an integer. :param channel: Channel string (e.g. `"can0"`, `"CAN1"`) or an integer :returns: Channel integer or ``None`` if unsuccessful """ if isinstance(channel, int): return channel if isinstance(channel, str): match = re.match(r".*(\d+)$", channel) if match: return int( return None
[docs]def deprecated_args_alias(**aliases): """Allows to rename/deprecate a function kwarg(s) and optionally have the deprecated kwarg(s) set as alias(es) Example: @deprecated_args_alias(oldArg="new_arg", anotherOldArg="another_new_arg") def library_function(new_arg, another_new_arg): pass @deprecated_args_alias(oldArg="new_arg", obsoleteOldArg=None) def library_function(new_arg): pass """ def deco(f): @functools.wraps(f) def wrapper(*args, **kwargs): _rename_kwargs(f.__name__, kwargs, aliases) return f(*args, **kwargs) return wrapper return deco
def _rename_kwargs( func_name: str, kwargs: Dict[str, str], aliases: Dict[str, str] ) -> None: """Helper function for `deprecated_args_alias`""" for alias, new in aliases.items(): if alias in kwargs: value = kwargs.pop(alias) if new is not None: warnings.warn(f"{alias} is deprecated; use {new}", DeprecationWarning) if new in kwargs: raise TypeError( f"{func_name} received both {alias} (deprecated) and {new}" ) kwargs[new] = value else: warnings.warn(f"{alias} is deprecated", DeprecationWarning)
[docs]def time_perfcounter_correlation() -> Tuple[float, float]: """Get the `perf_counter` value nearest to when time.time() is updated Computed if the default timer used by `time.time` on this platform has a resolution higher than 10μs, otherwise the current time and perf_counter is directly returned. This was chosen as typical timer resolution on Linux/macOS is ~1μs, and the Windows platform can vary from ~500μs to 10ms. Note this value is based on when `time.time()` is observed to update from Python, it is not directly returned by the operating system. :returns: (t, performance_counter) time.time value and time.perf_counter value when the time.time is updated """ # use this if the resolution is higher than 10us if get_clock_info("time").resolution > 1e-5: t0 = time() while True: t1, performance_counter = time(), perf_counter() if t1 != t0: break else: return time(), perf_counter() return t1, performance_counter
if __name__ == "__main__": print("Searching for configuration named:") print("\n".join(CONFIG_FILES)) print() print("Settings:") print(load_config())