mudpy/data.py

   1 """Data interface functions for the mudpy engine."""
   2
   3 # Copyright (c) 2004-2018 Jeremy Stanley <fungi@yuggoth.org>. Permission
   4 # to use, copy, modify, and distribute this software is granted under
   5 # terms provided in the LICENSE file distributed with this software.
   6
   7 import os
   8 import re
   9 import stat
  10
  11 import mudpy
  12 import yaml
  13
  14
  15 class _IBSEmitter(yaml.emitter.Emitter):
  16
  17     """Override the default YAML Emitter to indent block sequences."""
  18
  19     def expect_block_sequence(self):
  20         """Match the expectations of the ``yamllint`` style checker."""
  21
  22         # TODO(fungi) Get an option for this implemented upstream in
  23         # the pyyaml library
  24         self.increase_indent(flow=False, indentless=False)
  25         self.state = self.expect_first_block_sequence_item
  26
  27
  28 class _IBSDumper(yaml.SafeDumper, _IBSEmitter):
  29
  30     """Use our _IBSEmitter instead of the default implementation."""
  31
  32     pass
  33
  34
  35 class Data:
  36
  37     """A file containing universe elements and their facets."""
  38
  39     def __init__(self,
  40                  source,
  41                  universe,
  42                  flags=None,
  43                  relative=None,
  44                  ):
  45         self.source = source
  46         self.universe = universe
  47         if flags is None:
  48             self.flags = []
  49         else:
  50             self.flags = flags[:]
  51         self.relative = relative
  52         self.load()
  53
  54     def load(self):
  55         """Read a file, create elements and poplulate facets accordingly."""
  56         self.modified = False
  57         self.source = find_file(
  58                 self.source, relative=self.relative, universe=self.universe)
  59         try:
  60             self.data = yaml.safe_load(open(self.source))
  61             log_entry = ("Loaded file %s into memory." % self.source, 5)
  62         except FileNotFoundError:
  63             # it's normal if the file is one which doesn't exist yet
  64             self.data = {}
  65             log_entry = ("File %s is unavailable." % self.source, 6)
  66         try:
  67             mudpy.misc.log(*log_entry)
  68         except NameError:
  69             # happens when we're not far enough along in the init process
  70             self.universe.setup_loglines.append(log_entry)
  71         if not hasattr(self.universe, "files"):
  72             self.universe.files = {}
  73         self.universe.files[self.source] = self
  74         includes = []
  75         for node in list(self.data):
  76             if node == "_load":
  77                 for included in self.data["_load"]:
  78                     included = find_file(
  79                         included,
  80                         relative=self.source,
  81                         universe=self.universe)
  82                     if included not in includes:
  83                         includes.append(included)
  84                 continue
  85             if node.startswith("_"):
  86                 continue
  87             facet_pos = node.rfind(".") + 1
  88             prefix = node[:facet_pos].strip(".")
  89             try:
  90                 element = self.universe.contents[prefix]
  91             except KeyError:
  92                 element = mudpy.misc.Element(prefix, self.universe, self)
  93             element.set(node[facet_pos:], self.data[node])
  94             if prefix.startswith("mudpy.movement."):
  95                 self.universe.directions.add(
  96                     prefix[prefix.rfind(".") + 1:])
  97         for include_file in includes:
  98             if not os.path.isabs(include_file):
  99                 include_file = find_file(
 100                     include_file,
 101                     relative=self.source,
 102                     universe=self.universe
 103                 )
 104             if (include_file not in self.universe.files or not
 105                     self.universe.files[include_file].is_writeable()):
 106                 Data(include_file, self.universe)
 107
 108     def save(self):
 109         """Write the data, if necessary."""
 110         normal_umask = 0o0022
 111         private_umask = 0o0077
 112         private_file_mode = 0o0600
 113
 114         # when modified, writeable and has content or the file exists
 115         if self.modified and self.is_writeable() and (
 116            self.data or os.path.exists(self.source)
 117            ):
 118
 119             # make parent directories if necessary
 120             if not os.path.exists(os.path.dirname(self.source)):
 121                 old_umask = os.umask(normal_umask)
 122                 os.makedirs(os.path.dirname(self.source))
 123                 os.umask(old_umask)
 124
 125             # backup the file
 126             if "mudpy.limit" in self.universe.contents:
 127                 max_count = self.universe.contents["mudpy.limit"].get(
 128                     "backups", 0)
 129             else:
 130                 max_count = 0
 131             if os.path.exists(self.source) and max_count:
 132                 backups = []
 133                 for candidate in os.listdir(os.path.dirname(self.source)):
 134                     if re.match(
 135                        os.path.basename(self.source) +
 136                        r"""\.\d+$""", candidate
 137                        ):
 138                         backups.append(int(candidate.split(".")[-1]))
 139                 backups.sort()
 140                 backups.reverse()
 141                 for old_backup in backups:
 142                     if old_backup >= max_count - 1:
 143                         os.remove(self.source + "." + str(old_backup))
 144                     elif not os.path.exists(
 145                         self.source + "." + str(old_backup + 1)
 146                     ):
 147                         os.rename(
 148                             self.source + "." + str(old_backup),
 149                             self.source + "." + str(old_backup + 1)
 150                         )
 151                 if not os.path.exists(self.source + ".0"):
 152                     os.rename(self.source, self.source + ".0")
 153
 154             # our data file
 155             if "private" in self.flags:
 156                 old_umask = os.umask(private_umask)
 157                 file_descriptor = open(self.source, "w")
 158                 if oct(stat.S_IMODE(os.stat(
 159                         self.source)[stat.ST_MODE])) != private_file_mode:
 160                     # if it's marked private, chmod it appropriately
 161                     os.chmod(self.source, private_file_mode)
 162             else:
 163                 old_umask = os.umask(normal_umask)
 164                 file_descriptor = open(self.source, "w")
 165             os.umask(old_umask)
 166
 167             # write and close the file
 168             yaml.dump(self.data, Dumper=_IBSDumper, allow_unicode=True,
 169                       default_flow_style=False, explicit_start=True, indent=4,
 170                       stream=file_descriptor)
 171             file_descriptor.close()
 172
 173             # unset the modified flag
 174             self.modified = False
 175
 176     def is_writeable(self):
 177         """Returns True if the _lock is False."""
 178         try:
 179             return not self.data.get("_lock", False)
 180         except KeyError:
 181             return True
 182
 183
 184 def find_file(
 185     file_name=None,
 186     group=None,
 187     prefix=None,
 188     relative=None,
 189     search=None,
 190     stash=None,
 191     universe=None
 192 ):
 193     """Return an absolute file path based on configuration."""
 194
 195     # this is all unnecessary if it's already absolute
 196     if file_name and os.path.isabs(file_name):
 197         return os.path.realpath(file_name)
 198
 199     # if a universe was provided, try to get some defaults from there
 200     if universe:
 201
 202         if hasattr(
 203                 universe, "contents") and "mudpy.filing" in universe.contents:
 204             filing = universe.contents["mudpy.filing"]
 205             if not prefix:
 206                 prefix = filing.get("prefix")
 207             if not search:
 208                 search = filing.get("search")
 209             if not stash:
 210                 stash = filing.get("stash")
 211
 212         # if there's only one file loaded, try to work around a chicken<egg
 213         elif hasattr(universe, "files") and len(
 214             universe.files
 215         ) == 1 and not universe.files[
 216                 list(universe.files.keys())[0]].is_writeable():
 217             data_file = universe.files[list(universe.files.keys())[0]].data
 218
 219             # try for a fallback default directory
 220             if not stash:
 221                 stash = data_file.get(".mudpy.filing.stash", "")
 222
 223             # try for a fallback root path
 224             if not prefix:
 225                 prefix = data_file.get(".mudpy.filing.prefix", "")
 226
 227             # try for a fallback search path
 228             if not search:
 229                 search = data_file.get(".mudpy.filing.search", "")
 230
 231         # another fallback root path, this time from the universe startdir
 232         if hasattr(universe, "startdir"):
 233             if not prefix:
 234                 prefix = universe.startdir
 235             elif not os.path.isabs(prefix):
 236                 prefix = os.path.join(universe.startdir, prefix)
 237
 238     # when no root path is specified, assume the current working directory
 239     if (not prefix or prefix == ".") and hasattr(universe, "startdir"):
 240         prefix = universe.startdir
 241
 242     # make sure it's absolute
 243     prefix = os.path.realpath(prefix)
 244
 245     # if there's no search path, just use the root path and etc
 246     if not search:
 247         search = [prefix, "etc"]
 248
 249     # work on a copy of the search path, to avoid modifying the caller's
 250     else:
 251         search = search[:]
 252
 253     # if there's no default path, use the last component of the search path
 254     if not stash:
 255         stash = search[-1]
 256
 257     # if an existing file or directory reference was supplied, prepend it
 258     if relative:
 259         if os.path.isdir(relative):
 260             search = [relative] + search
 261         else:
 262             search = [os.path.dirname(relative)] + search
 263
 264     # make the search path entries absolute and throw away any dupes
 265     clean_search = []
 266     for each_path in search:
 267         if not os.path.isabs(each_path):
 268             each_path = os.path.realpath(os.path.join(prefix, each_path))
 269         if each_path not in clean_search:
 270             clean_search.append(each_path)
 271
 272     # start hunting for the file now
 273     for each_path in clean_search:
 274
 275         # construct the candidate path
 276         candidate = os.path.join(each_path, file_name)
 277
 278         # if the file exists and is readable, we're done
 279         if os.path.isfile(candidate):
 280             file_name = os.path.realpath(candidate)
 281             break
 282
 283         # if the path is a directory, look for an __init__ file
 284         if os.path.isdir(candidate):
 285             file_name = os.path.realpath(
 286                     os.path.join(candidate, "__init__.yaml"))
 287             break
 288
 289     # it didn't exist after all, so use the default path instead
 290     if not os.path.isabs(file_name):
 291         file_name = os.path.join(stash, file_name)
 292     if not os.path.isabs(file_name):
 293         file_name = os.path.join(prefix, file_name)
 294
 295     # and normalize it last thing before returning
 296     file_name = os.path.realpath(file_name)
 297     return file_name