/usr/lib/python3/dist-packages/simple_cdd/env.py is in python3-simple-cdd 0.6.5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import sys
import os
import re
import json
import tempfile
try:
# After Python 3.3
from collections.abc import Iterable
except ImportError:
# This has changed in Python 3.3 (why, oh why?), reinforcing the idea that
# the best Python version ever is still 2.7, simply because upstream has
# promised that they won't touch it (and break it) for at least 5 more
# years.
from collections import Iterable
from .utils import shell_quote
import logging
log = logging.getLogger()
class Backtick:
"""
Represent a value obtained by executing a command and reading its standard
output. This allows to use commands as default values for configuration
variables.
"""
def __init__(self, *command):
self.val = command
self.cached_result = None
def __str__(self):
return "$({})".format(" ".join(shell_quote(x) for x in self.val))
def __call__(self):
if self.cached_result is None:
self.cached_result = subprocess.check_output(self.val, universal_newlines=True).strip()
return self.cached_result
class Variable:
"""
Base class for environment variable proxies.
This acts as a glue between the configuration files, the environment,
python, the command line arguments and the scripts that we run.
"""
def __init__(self, name, default=None, cmdline=None, help=None, env=None):
# Name of the variable in the environment
self.name = name
# Default value of the variable, as a python value that will be read or
# evaluated when the variable value is requested and none has been set
self.default = default
# Name(s) of command line arguments to set this variable
if isinstance(cmdline, str):
self.cmdline = [cmdline]
else:
self.cmdline = cmdline
# Documentation for this variable
self.help = help
# Current environment (usually set later)
self.env = env
# Current value, stored as a string ready to be exported in the
# environment
self.current = None
# Set to true when the variable was automatically created and not
# defined in the code
self.automatically_created = False
def __str__(self):
"""
Get the current value as a string
"""
if self.current is None:
# TODO: build a value from the defaults
res = self.default_to_string()
else:
res = self.current
return res
def to_parser(self, parser):
"""
Add an option for this variable to the command line parser
"""
default = self.format_default()
if default == "":
parser.add_argument(*self.cmdline, action="store", dest=self.name, help=self.help)
else:
help = self.help + " (default: {})".format(default)
parser.add_argument(*self.cmdline, action="store", dest=self.name, help=help)
def format_default(self):
"""
Format the default value for showing in documentation and command line
help
"""
return str(self.default)
def default_to_string(self):
"""
Convert the default value to a string
"""
if callable(self.default):
# If 'default' is a python callable, call it and return its result
return str(self.default())
elif self.default is None:
return ""
elif isinstance(self.default, str):
return self.env.format(self.default)
else:
return str(self.default)
def to_python(self):
"""
Return the current value as a python value
"""
# To be overridden
return str(self)
def from_python(self, value):
"""
Set the current value from a python value
"""
# To be overridden
self.current = str(value)
def from_commandline(self, value):
"""
Set the current value from a command line option
"""
if value is None:
return
elif value is True:
self.current = "true"
elif value is False:
self.current = ""
else:
self.current = value.strip()
class BoolVar(Variable):
"""
A proxy for a boolean environment variable. For python it behaves as a
bool, and for the environment it will be "true" for True and "" for False
"""
def to_parser(self, parser):
default = self.format_default()
help = self.help + " (default: {})".format(default)
parser.add_argument(*self.cmdline, action="store_true", dest=self.name, help=help)
def format_default(self):
if isinstance(self.default, bool):
return "true" if self.default else "false"
else:
return super().format_default()
def default_to_string(self):
if isinstance(self.default, bool):
bval = self.default
else:
bval = super().default_to_string() == "true"
return "true" if bval else ""
def to_python(self):
return str(self) == "true"
def from_python(self, value):
self.current = "true" if value else ""
class TextVar(Variable):
"""
A proxy for a string environment variable. For python it behaves as a
str, and for the environment it will be a string.
"""
pass
class PathVar(Variable):
"""
A proxy for a string environment variable that contains a path. For python
it behaves as a str, and for the environment it will be a string. It
supports appending, and default variables in the form of a string, which
will be properly concatenated into a path.
"""
def append(self, value):
if not isinstance(value, str):
raise ValueError("Attempted to append a non-string value to a path")
self.from_python(os.path.join(str(self), value))
def format_default(self):
if isinstance(self.default, str):
return self.default
elif isinstance(self.default, Iterable):
return os.path.join(self.default)
else:
return super().format_default()
def default_to_string(self):
if isinstance(self.default, str):
return self.env.format(self.default)
elif isinstance(self.default, Iterable):
formatted = [self.env.format(x) for x in self.default]
return os.path.join(*formatted)
else:
return super().default_to_string()
class ListVar(Variable):
"""
A proxy for a string environment variable that contains a list of strings.
For python it behaves as a sequence, and for the environment it will be a
space separated string. It supports appending. Command line arguments can
be space or comma separated.
"""
def append(self, value):
cur = self.to_python()
if isinstance(value, str):
cur.append(value)
elif isinstance(value, Iterable):
cur.extend(value)
else:
raise ValueError("Attempted to append a {} value to a list".format(value.__class__))
self.from_python(cur)
def format_default(self):
if isinstance(self.default, str):
return self.default
elif isinstance(self.default, Iterable):
return " ".join(self.default)
else:
return super().format_default()
def default_to_string(self):
if isinstance(self.default, str):
return self.env.format(self.default)
elif isinstance(self.default, Iterable):
return " ".join(self.env.format(x) for x in self.default)
else:
return super().default_to_string()
def to_python(self):
val = str(self)
if val:
return val.split()
else:
return []
def from_python(self, value):
if value:
if isinstance(value, str):
self.current = value
elif isinstance(value, Iterable):
self.current = " ".join(value)
else:
raise ValueError("Attempted to append a {} value to a path".format(value.__class__))
else:
self.current = ""
def from_commandline(self, value):
if isinstance(value, str):
items = re.split(r"\s*,\s*", value.strip())
self.current = " ".join(items)
else:
super().from_commandline(value)
class Environment:
"""
Keep track of environment changes
"""
def __init__(self, variables):
env = {}
for v in variables:
v.env = self
if v.name in env:
raise AssertionError("{} defined twice".format(v.name))
env[v.name] = v
if v.name in os.environ:
v.current = os.environ[v.name]
for name, val in os.environ.items():
if name in env: continue
v = TextVar(name, help="Preexisting environment variable {}".format(name))
env[name] = v
v.automatically_created = True
v.current = val
super().__setattr__("env", env)
super().__setattr__("initial", dict(os.environ))
def parse_commandline(self, args):
"""
Set values from command line arguments
"""
for name, v in self.env.items():
if v.cmdline is None: continue
v.from_commandline(getattr(args, name))
def get(self, name):
"""
Get a value by name, returns the empty string if not found
"""
val = self.env.get(name, None)
if val is None:
return ""
else:
return val.to_python()
def set(self, name, value):
"""
Set a value by name, converting the python value to the type of the variable name.
"""
cur = self.env.get(name, None)
if cur is None:
self.env[name] = cur = TextVar(name, env=self)
cur.automatically_created = True
cur.from_python(value)
def set_from_commandline(self, name, value):
"""
Set a value by name, converting the user string value to the type of the variable name.
"""
cur = self.env.get(name, None)
if cur is None:
self.env[name] = cur = TextVar(name, env=self)
cur.automatically_created = True
cur.from_commandline(value)
def append(self, name, value):
"""
Append elements or sequences to a list
"""
cur = self.env.get(name, None)
if cur is None:
self.env[name] = cur = TextVar(name, env=self)
cur.append(value)
def unset(self, name):
"""
Unset an element
"""
del self.env[name]
def read_config_file(self, pathname):
"""
Source a config file and edit configuration from its environment
"""
log.info("Reading configuration file %s", pathname)
# Write the source wrapper to a temporary file and execute it
with tempfile.NamedTemporaryFile("w+t") as fd:
print("set -a", file=fd)
print(". " + os.path.abspath(pathname), file=fd)
print("exec {} -c 'import os,json,sys;json.dump(dict(os.environ),sys.stdout)'".format(sys.executable), file=fd)
fd.flush()
out = subprocess.check_output(["sh", fd.name]).decode("utf-8")
# Parse its output
if not out.strip(): return
lines = out.split("\n")
# Pass through stdout from the script
for line in lines[:-1]:
print(line)
# Parse the environment set by the script
new_env = json.loads(lines[-1])
# Diff our environment and the script one, to see what was set
for key in new_env.keys() - os.environ.keys():
log.info("%s: new var %s=%s", pathname, key, shell_quote(new_env[key]))
self.set_from_commandline(key, new_env[key])
for key in new_env.keys() & os.environ.keys():
if os.environ[key] == new_env[key]: continue
log.info("%s: changed var %s=%s", pathname, key, shell_quote(new_env[key]))
self.set_from_commandline(key, new_env[key])
def export_iter(self):
"""
Generate a sequence of (name, value, changed) where:
name is the variable name
value is the variable value as a string
changed is a boolean that is True if the value has changed since
the original environmenf at program startup
"""
for name, val in sorted(self.env.items()):
valstr = str(val)
yield name, val, valstr != self.initial.get(name, None)
def export(self):
"""
Export variables for the script
"""
os.environ.clear()
for name, val, changed in self.export_iter():
if changed:
log.info("export %s=%s", name, shell_quote(val))
#else:
# log.info("export %s=%s", name, shell_quote(val))
os.environ[name] = val
def format(self, string, *args, **kw):
"""
Call string.format() including all the known env vars
"""
kwargs = dict(self.env)
kwargs.update(**kw)
return string.format(*args, **kwargs)
def __getattr__(self, name):
"""
Get a value by name, raises exception if not found
"""
val = self.env.get(name, None)
if val is None or val.automatically_created:
raise AttributeError("Environment has no variable '{}'".format(name))
else:
return val.to_python()
def __setattr__(self, name, val):
"""
Get a value by name, raises exception if not found
"""
val = self.env.get(name, None)
if val is None:
super().__setattr__(name, val)
else:
cur.from_python(value)
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