#!/usr/bin/env python3
"""
Utilities and configuration file parsing.
"""
from __future__ import absolute_import
import can
from can.interfaces import VALID_INTERFACES
try:
from configparser import ConfigParser
except ImportError:
from ConfigParser import SafeConfigParser as ConfigParser
import os
import os.path
import sys
import platform
import re
import logging
log = logging.getLogger('can.util')
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):
"""
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.
"""
config = ConfigParser()
if path is None:
config.read([os.path.expanduser(path) for path in CONFIG_FILES])
else:
config.read(path)
if not config.has_section('default'):
return {}
return dict(
(key, val)
for key, val in config.items('default')
)
[docs]def load_environment_config():
"""
Loads config dict from environmental variables (if set):
* CAN_INTERFACE
* CAN_CHANNEL
* CAN_BITRATE
"""
mapper = {
'interface': 'CAN_INTERFACE',
'channel': 'CAN_CHANNEL',
'bitrate': 'CAN_BITRATE',
}
return dict(
(key, os.environ.get(val))
for key, val in mapper.items()
if val in os.environ
)
[docs]def load_config(path=None, config=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::
If you pass ``"socketcan"`` this automatically selects between the
native and ctypes version.
:param path:
Optional path to config file.
:param config:
A dict which may set the 'interface', and/or the 'channel', or neither.
:return:
A config dictionary that should contain 'interface' & 'channel'::
{
'interface': 'python-can backend interface to use',
'channel': 'default channel to use',
}
Note ``None`` will be used if all the options are exhausted without
finding a value.
"""
if config is None:
config = {}
system_config = {}
configs = [
config,
can.rc,
load_environment_config,
lambda: load_file_config(path)
]
# Slightly complex here to only search for the file config if required
for cfg in configs:
if callable(cfg):
cfg = cfg()
for key in cfg:
if key not in system_config and cfg[key] is not None:
system_config[key] = cfg[key]
# substitute None for all values not found
for key in REQUIRED_KEYS:
if key not in system_config:
system_config[key] = None
if system_config['interface'] == 'socketcan':
system_config['interface'] = choose_socketcan_implementation()
if system_config['interface'] not in VALID_INTERFACES:
raise NotImplementedError('Invalid CAN Bus Type - {}'.format(system_config['interface']))
if 'bitrate' in system_config:
system_config['bitrate'] = int(system_config['bitrate'])
can.log.debug("can config: {}".format(system_config))
return system_config
[docs]def choose_socketcan_implementation():
"""Set the best version of SocketCAN for this system.
:param config: The can.rc configuration dictionary
:raises Exception: If the system doesn't support SocketCAN
"""
# Check OS: SocketCAN is available only under Linux
if not sys.platform.startswith('linux'):
msg = 'SocketCAN not available under {}'.format(
sys.platform)
raise Exception(msg)
else:
# Check release: SocketCAN was added to Linux 2.6.25
rel_string = platform.release()
m = re.match(r'\d+\.\d+\.\d', rel_string)
if m is None:
msg = 'Bad linux release {}'.format(rel_string)
raise Exception(msg)
rel_num = [int(i) for i in rel_string[:m.end()].split('.')]
if (rel_num >= [2, 6, 25]):
# Check Python version: SocketCAN was added in 3.3
return 'socketcan_native' if sys.version_info >= (3, 3) else 'socketcan_ctypes'
else:
msg = 'SocketCAN not available under Linux {}'.format(
rel_string)
raise Exception(msg)
[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))
if __name__ == "__main__":
print("Searching for configuration named:")
print("\n".join(CONFIG_FILES))
print("Settings:")
print(load_config())