certmaster/config.py

   1 # This program is free software; you can redistribute it and/or modify
   2 # it under the terms of the GNU General Public License as published by
   3 # the Free Software Foundation; either version 2 of the License, or
   4 # (at your option) any later version.
   5 #
   6 # This program is distributed in the hope that it will be useful,
   7 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 # GNU Library General Public License for more details.
  10 #
  11 # You should have received a copy of the GNU General Public License
  12 # along with this program; if not, write to the Free Software
  13 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14 # Copyright 2002 Duke University
  15 # filched from yum  - menno smits wrote this - he rocks
  16
  17
  18 import os
  19 import sys
  20 import warnings
  21 import copy
  22 import urlparse
  23 from ConfigParser import NoSectionError, NoOptionError, ConfigParser
  24 from ConfigParser import ParsingError
  25 import exceptions
  26
  27 CONFIG_FILE = "/etc/certmaster/certmaster.conf"
  28
  29 class ConfigError(exceptions.Exception):
  30     def __init__(self, value=None):
  31         exceptions.Exception.__init__(self)
  32         self.value = value
  33     def __str__(self):
  34         return "%s" %(self.value,)
  35
  36
  37 class Option(object):
  38     '''
  39     This class handles a single Yum configuration file option. Create
  40     subclasses for each type of supported configuration option.
  41
  42     Python descriptor foo (__get__ and __set__) is used to make option
  43     definition easy and consise.
  44     '''
  45
  46     def __init__(self, default=None):
  47         self._setattrname()
  48         self.inherit = False
  49         self.default = default
  50
  51     def _setattrname(self):
  52         '''Calculate the internal attribute name used to store option state in
  53         configuration instances.
  54         '''
  55         self._attrname = '__opt%d' % id(self)
  56
  57     def __get__(self, obj, objtype):
  58         '''Called when the option is read (via the descriptor protocol).
  59
  60         @param obj: The configuration instance to modify.
  61         @param objtype: The type of the config instance (not used).
  62         @return: The parsed option value or the default value if the value
  63             wasn't set in the configuration file.
  64         '''
  65         if obj is None:
  66             return self
  67
  68         return getattr(obj, self._attrname, None)
  69
  70     def __set__(self, obj, value):
  71         '''Called when the option is set (via the descriptor protocol).
  72
  73         @param obj: The configuration instance to modify.
  74         @param value: The value to set the option to.
  75         @return: Nothing.
  76         '''
  77         # Only try to parse if its a string
  78         if isinstance(value, basestring):
  79             try:
  80                 value = self.parse(value)
  81             except ValueError, e:
  82                 # Add the field name onto the error
  83                 raise ValueError('Error parsing %r: %s' % (value, str(e)))
  84
  85         setattr(obj, self._attrname, value)
  86
  87     def setup(self, obj, name):
  88         '''Initialise the option for a config instance.
  89         This must be called before the option can be set or retrieved.
  90
  91         @param obj: BaseConfig (or subclass) instance.
  92         @param name: Name of the option.
  93         '''
  94         setattr(obj, self._attrname, copy.copy(self.default))
  95
  96     def clone(self):
  97         '''Return a safe copy of this Option instance
  98         '''
  99         new = copy.copy(self)
 100         new._setattrname()
 101         return new
 102
 103     def parse(self, s):
 104         '''Parse the string value to the Option's native value.
 105
 106         @param s: Raw string value to parse.
 107         @return: Validated native value.
 108
 109         Will raise ValueError if there was a problem parsing the string.
 110         Subclasses should override this.
 111         '''
 112         return s
 113
 114     def tostring(self, value):
 115         '''Convert the Option's native value to a string value.
 116
 117         @param value: Native option value.
 118         @return: String representation of input.
 119
 120         This does the opposite of the parse() method above.
 121         Subclasses should override this.
 122         '''
 123         return str(value)
 124
 125
 126 def Inherit(option_obj):
 127     '''Clone an Option instance for the purposes of inheritance. The returned
 128     instance has all the same properties as the input Option and shares items
 129     such as the default value. Use this to avoid redefinition of reused
 130     options.
 131
 132     @param option_obj: Option instance to inherit.
 133     @return: New Option instance inherited from the input.
 134     '''
 135     new_option = option_obj.clone()
 136     new_option.inherit = True
 137     return new_option
 138
 139
 140 class ListOption(Option):
 141
 142     def __init__(self, default=None):
 143         if default is None:
 144             default = []
 145         super(ListOption, self).__init__(default)
 146
 147     def parse(self, s):
 148         """Converts a string from the config file to a workable list
 149
 150         Commas and spaces are used as separators for the list
 151         """
 152         # we need to allow for the '\n[whitespace]' continuation - easier
 153         # to sub the \n with a space and then read the lines
 154         s = s.replace('\n', ' ')
 155         s = s.replace(',', ' ')
 156         return s.split()
 157
 158     def tostring(self, value):
 159         return '\n '.join(value)
 160
 161
 162 class UrlOption(Option):
 163     '''
 164     This option handles lists of URLs with validation of the URL scheme.
 165     '''
 166
 167     def __init__(self, default=None, schemes=('http', 'ftp', 'file', 'https'),
 168             allow_none=False):
 169         super(UrlOption, self).__init__(default)
 170         self.schemes = schemes
 171         self.allow_none = allow_none
 172
 173     def parse(self, url):
 174         url = url.strip()
 175
 176         # Handle the "_none_" special case
 177         if url.lower() == '_none_':
 178             if self.allow_none:
 179                 return None
 180             else:
 181                 raise ValueError('"_none_" is not a valid value')
 182
 183         # Check that scheme is valid
 184         (s,b,p,q,f,o) = urlparse.urlparse(url)
 185         if s not in self.schemes:
 186             raise ValueError('URL must be %s not "%s"' % (self._schemelist(), s))
 187
 188         return url
 189
 190     def _schemelist(self):
 191         '''Return a user friendly list of the allowed schemes
 192         '''
 193         if len(self.schemes) < 1:
 194             return 'empty'
 195         elif len(self.schemes) == 1:
 196             return self.schemes[0]
 197         else:
 198             return '%s or %s' % (', '.join(self.schemes[:-1]), self.schemes[-1])
 199
 200
 201 class UrlListOption(ListOption):
 202     '''
 203     Option for handling lists of URLs with validation of the URL scheme.
 204     '''
 205
 206     def __init__(self, default=None, schemes=('http', 'ftp', 'file', 'https')):
 207         super(UrlListOption, self).__init__(default)
 208
 209         # Hold a UrlOption instance to assist with parsing
 210         self._urloption = UrlOption(schemes=schemes)
 211
 212     def parse(self, s):
 213         out = []
 214         for url in super(UrlListOption, self).parse(s):
 215             out.append(self._urloption.parse(url))
 216         return out
 217
 218
 219 class IntOption(Option):
 220     def parse(self, s):
 221         try:
 222             return int(s)
 223         except (ValueError, TypeError), e:
 224             raise ValueError('invalid integer value')
 225
 226
 227 class BoolOption(Option):
 228     def parse(self, s):
 229         s = s.lower()
 230         if s in ('0', 'no', 'false'):
 231             return False
 232         elif s in ('1', 'yes', 'true'):
 233             return True
 234         else:
 235             raise ValueError('invalid boolean value')
 236
 237     def tostring(self, value):
 238         if value:
 239             return "1"
 240         else:
 241             return "0"
 242
 243
 244 class FloatOption(Option):
 245     def parse(self, s):
 246         try:
 247             return float(s.strip())
 248         except (ValueError, TypeError):
 249             raise ValueError('invalid float value')
 250
 251
 252 class SelectionOption(Option):
 253     '''Handles string values where only specific values are allowed
 254     '''
 255     def __init__(self, default=None, allowed=()):
 256         super(SelectionOption, self).__init__(default)
 257         self._allowed = allowed
 258
 259     def parse(self, s):
 260         if s not in self._allowed:
 261             raise ValueError('"%s" is not an allowed value' % s)
 262         return s
 263
 264 class BytesOption(Option):
 265
 266     # Multipliers for unit symbols
 267     MULTS = {
 268         'k': 1024,
 269         'm': 1024*1024,
 270         'g': 1024*1024*1024,
 271     }
 272
 273     def parse(self, s):
 274         """Parse a friendly bandwidth option to bytes
 275
 276         The input should be a string containing a (possibly floating point)
 277         number followed by an optional single character unit. Valid units are
 278         'k', 'M', 'G'. Case is ignored.
 279
 280         Valid inputs: 100, 123M, 45.6k, 12.4G, 100K, 786.3, 0
 281         Invalid inputs: -10, -0.1, 45.6L, 123Mb
 282
 283         Return value will always be an integer
 284
 285         1k = 1024 bytes.
 286
 287         ValueError will be raised if the option couldn't be parsed.
 288         """
 289         if len(s) < 1:
 290             raise ValueError("no value specified")
 291
 292         if s[-1].isalpha():
 293             n = s[:-1]
 294             unit = s[-1].lower()
 295             mult = self.MULTS.get(unit, None)
 296             if not mult:
 297                 raise ValueError("unknown unit '%s'" % unit)
 298         else:
 299             n = s
 300             mult = 1
 301
 302         try:
 303             n = float(n)
 304         except ValueError:
 305             raise ValueError("couldn't convert '%s' to number" % n)
 306
 307         if n < 0:
 308             raise ValueError("bytes value may not be negative")
 309
 310         return int(n * mult)
 311
 312
 313 class ThrottleOption(BytesOption):
 314
 315     def parse(self, s):
 316         """Get a throttle option.
 317
 318         Input may either be a percentage or a "friendly bandwidth value" as
 319         accepted by the BytesOption.
 320
 321         Valid inputs: 100, 50%, 80.5%, 123M, 45.6k, 12.4G, 100K, 786.0, 0
 322         Invalid inputs: 100.1%, -4%, -500
 323
 324         Return value will be a int if a bandwidth value was specified or a
 325         float if a percentage was given.
 326
 327         ValueError will be raised if input couldn't be parsed.
 328         """
 329         if len(s) < 1:
 330             raise ValueError("no value specified")
 331
 332         if s[-1] == '%':
 333             n = s[:-1]
 334             try:
 335                 n = float(n)
 336             except ValueError:
 337                 raise ValueError("couldn't convert '%s' to number" % n)
 338             if n < 0 or n > 100:
 339                 raise ValueError("percentage is out of range")
 340             return n / 100.0
 341         else:
 342             return BytesOption.parse(self, s)
 343
 344
 345 class BaseConfig(object):
 346     '''
 347     Base class for storing configuration definitions. Subclass when creating
 348     your own definitons.
 349     '''
 350
 351     def __init__(self):
 352         self._section = None
 353
 354         for name in self.iterkeys():
 355             option = self.optionobj(name)
 356             option.setup(self, name)
 357
 358     def __str__(self):
 359         out = []
 360         out.append('[%s]' % self._section)
 361         for name, value in self.iteritems():
 362             out.append('%s: %r' % (name, value))
 363         return '\n'.join(out)
 364
 365     def populate(self, parser, section, parent=None):
 366         '''Set option values from a INI file section.
 367
 368         @param parser: ConfParser instance (or subclass)
 369         @param section: INI file section to read use.
 370         @param parent: Optional parent BaseConfig (or subclass) instance to use
 371             when doing option value inheritance.
 372         '''
 373         self.cfg = parser
 374         self._section = section
 375
 376         for name in self.iterkeys():
 377             option = self.optionobj(name)
 378             value = None
 379             try:
 380                 value = parser.get(section, name)
 381             except (NoSectionError, NoOptionError):
 382                 # No matching option in this section, try inheriting
 383                 if parent and option.inherit:
 384                     value = getattr(parent, name)
 385
 386             if value is not None:
 387                 setattr(self, name, value)
 388
 389     def optionobj(cls, name):
 390         '''Return the Option instance for the given name
 391         '''
 392         obj = getattr(cls, name, None)
 393         if isinstance(obj, Option):
 394             return obj
 395         else:
 396             raise KeyError
 397     optionobj = classmethod(optionobj)
 398
 399     def isoption(cls, name):
 400         '''Return True if the given name refers to a defined option
 401         '''
 402         try:
 403             cls.optionobj(name)
 404             return True
 405         except KeyError:
 406             return False
 407     isoption = classmethod(isoption)
 408
 409     def iterkeys(self):
 410         '''Yield the names of all defined options in the instance.
 411         '''
 412         for name, item in self.iteritems():
 413             yield name
 414
 415     def iteritems(self):
 416         '''Yield (name, value) pairs for every option in the instance.
 417
 418         The value returned is the parsed, validated option value.
 419         '''
 420         # Use dir() so that we see inherited options too
 421         for name in dir(self):
 422             if self.isoption(name):
 423                 yield (name, getattr(self, name))
 424
 425     def write(self, fileobj, section=None, always=()):
 426         '''Write out the configuration to a file-like object
 427
 428         @param fileobj: File-like object to write to
 429         @param section: Section name to use. If not-specified the section name
 430             used during parsing will be used.
 431         @param always: A sequence of option names to always write out.
 432             Options not listed here will only be written out if they are at
 433             non-default values. Set to None to dump out all options.
 434         '''
 435         # Write section heading
 436         if section is None:
 437             if self._section is None:
 438                 raise ValueError("not populated, don't know section")
 439             section = self._section
 440
 441         # Updated the ConfigParser with the changed values
 442         cfgOptions = self.cfg.options(section)
 443         for name,value in self.iteritems():
 444             option = self.optionobj(name)
 445             if always is None or name in always or option.default != value or name in cfgOptions :
 446                 self.cfg.set(section,name, option.tostring(value))
 447         # write the updated ConfigParser to the fileobj.
 448         self.cfg.write(fileobj)
 449
 450     def getConfigOption(self, option, default=None):
 451         warnings.warn('getConfigOption() will go away in a future version of Yum.\n'
 452                 'Please access option values as attributes or using getattr().',
 453                 DeprecationWarning)
 454         if hasattr(self, option):
 455             return getattr(self, option)
 456         return default
 457
 458     def setConfigOption(self, option, value):
 459         warnings.warn('setConfigOption() will go away in a future version of Yum.\n'
 460                 'Please set option values as attributes or using setattr().',
 461                 DeprecationWarning)
 462         if hasattr(self, option):
 463             setattr(self, option, value)
 464         else:
 465             raise ConfigError, 'No such option %s' % option
 466
 467
 468 def read_config(config_file, BaseConfigDerived):
 469     confparser = ConfigParser()
 470     opts = BaseConfigDerived()
 471     if os.path.exists(config_file):
 472         try:
 473             confparser.read(config_file)
 474         except ParsingError, e:
 475             print >> sys.stderr, "Error reading config file: %s" % e
 476             sys.exit(1)
 477     opts.populate(confparser, 'main')
 478     return opts