mudpy/data.py

   1 """Data interface functions for the mudpy engine."""
   2
   3 # Copyright (c) 2004-2017 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 Data:
  16
  17     """A file containing universe elements and their facets."""
  18
  19     def __init__(self,
  20                  source,
  21                  universe,
  22                  flags=None,
  23                  relative=None,
  24                  ):
  25         self.source = source
  26         self.universe = universe
  27         if flags is None:
  28             self.flags = []
  29         else:
  30             self.flags = flags[:]
  31         self.relative = relative
  32         self.load()
  33
  34     def load(self):
  35         """Read a file, create elements and poplulate facets accordingly."""
  36         self.modified = False
  37         self.source = find_file(
  38                 self.source, relative=self.relative, universe=self.universe)
  39         try:
  40             self.data = yaml.safe_load(open(self.source))
  41         except FileNotFoundError:
  42             # it's normal if the file is one which doesn't exist yet
  43             self.data = {}
  44             log_entry = ("File %s is unavailable." % self.source, 6)
  45             try:
  46                 mudpy.misc.log(*log_entry)
  47             except NameError:
  48                 # happens when we're not far enough along in the init process
  49                 self.universe.setup_loglines.append(log_entry)
  50         if not hasattr(self.universe, "files"):
  51             self.universe.files = {}
  52         self.universe.files[self.source] = self
  53         includes = []
  54         for node in list(self.data):
  55             if node == "_load":
  56                 for included in self.data["_load"]:
  57                     included = find_file(
  58                         included,
  59                         relative=self.source,
  60                         universe=self.universe)
  61                     if included not in includes:
  62                         includes.append(included)
  63                 continue
  64             if node.startswith("_"):
  65                 continue
  66             facet_pos = node.rfind(".") + 1
  67             prefix = node[:facet_pos].strip(".")
  68             try:
  69                 element = self.universe.contents[prefix]
  70             except KeyError:
  71                 element = mudpy.misc.Element(prefix, self.universe, self)
  72             element.set(node[facet_pos:], self.data[node])
  73             if prefix.startswith("mudpy.movement."):
  74                 self.universe.directions.add(
  75                     prefix[prefix.rfind(".") + 1:])
  76         for include_file in includes:
  77             if not os.path.isabs(include_file):
  78                 include_file = find_file(
  79                     include_file,
  80                     relative=self.source,
  81                     universe=self.universe
  82                 )
  83             if (include_file not in self.universe.files or not
  84                     self.universe.files[include_file].is_writeable()):
  85                 Data(include_file, self.universe)
  86
  87     def save(self):
  88         """Write the data, if necessary."""
  89         normal_umask = 0o0022
  90         private_umask = 0o0077
  91         private_file_mode = 0o0600
  92
  93         # when modified, writeable and has content or the file exists
  94         if self.modified and self.is_writeable() and (
  95            self.data or os.path.exists(self.source)
  96            ):
  97
  98             # make parent directories if necessary
  99             if not os.path.exists(os.path.dirname(self.source)):
 100                 old_umask = os.umask(normal_umask)
 101                 os.makedirs(os.path.dirname(self.source))
 102                 os.umask(old_umask)
 103
 104             # backup the file
 105             if "mudpy.limit" in self.universe.contents:
 106                 max_count = self.universe.contents["mudpy.limit"].get(
 107                     "backups", 0)
 108             else:
 109                 max_count = 0
 110             if os.path.exists(self.source) and max_count:
 111                 backups = []
 112                 for candidate in os.listdir(os.path.dirname(self.source)):
 113                     if re.match(
 114                        os.path.basename(self.source) +
 115                        r"""\.\d+$""", candidate
 116                        ):
 117                         backups.append(int(candidate.split(".")[-1]))
 118                 backups.sort()
 119                 backups.reverse()
 120                 for old_backup in backups:
 121                     if old_backup >= max_count - 1:
 122                         os.remove(self.source + "." + str(old_backup))
 123                     elif not os.path.exists(
 124                         self.source + "." + str(old_backup + 1)
 125                     ):
 126                         os.rename(
 127                             self.source + "." + str(old_backup),
 128                             self.source + "." + str(old_backup + 1)
 129                         )
 130                 if not os.path.exists(self.source + ".0"):
 131                     os.rename(self.source, self.source + ".0")
 132
 133             # our data file
 134             if "private" in self.flags:
 135                 old_umask = os.umask(private_umask)
 136                 file_descriptor = open(self.source, "w")
 137                 if oct(stat.S_IMODE(os.stat(
 138                         self.source)[stat.ST_MODE])) != private_file_mode:
 139                     # if it's marked private, chmod it appropriately
 140                     os.chmod(self.source, private_file_mode)
 141             else:
 142                 old_umask = os.umask(normal_umask)
 143                 file_descriptor = open(self.source, "w")
 144             os.umask(old_umask)
 145
 146             # write and close the file
 147             yaml.safe_dump(self.data, allow_unicode=True,
 148                            default_flow_style=False, stream=file_descriptor)
 149             file_descriptor.close()
 150
 151             # unset the modified flag
 152             self.modified = False
 153
 154     def is_writeable(self):
 155         """Returns True if the _lock is False."""
 156         try:
 157             return not self.data.get("_lock", False)
 158         except KeyError:
 159             return True
 160
 161
 162 def find_file(
 163     file_name=None,
 164     category=None,
 165     prefix=None,
 166     relative=None,
 167     search=None,
 168     stash=None,
 169     universe=None
 170 ):
 171     """Return an absolute file path based on configuration."""
 172
 173     # this is all unnecessary if it's already absolute
 174     if file_name and os.path.isabs(file_name):
 175         return os.path.realpath(file_name)
 176
 177     # if a universe was provided, try to get some defaults from there
 178     if universe:
 179
 180         if hasattr(
 181                 universe, "contents") and "mudpy.filing" in universe.contents:
 182             filing = universe.contents["mudpy.filing"]
 183             if not prefix:
 184                 prefix = filing.get("prefix")
 185             if not search:
 186                 search = filing.get("search")
 187             if not stash:
 188                 stash = filing.get("stash")
 189
 190         # if there's only one file loaded, try to work around a chicken<egg
 191         elif hasattr(universe, "files") and len(
 192             universe.files
 193         ) == 1 and not universe.files[
 194                 list(universe.files.keys())[0]].is_writeable():
 195             data_file = universe.files[list(universe.files.keys())[0]].data
 196
 197             # try for a fallback default directory
 198             if not stash:
 199                 stash = data_file.get(".mudpy.filing.stash", "")
 200
 201             # try for a fallback root path
 202             if not prefix:
 203                 prefix = data_file.get(".mudpy.filing.prefix", "")
 204
 205             # try for a fallback search path
 206             if not search:
 207                 search = data_file.get(".mudpy.filing.search", "")
 208
 209         # another fallback root path, this time from the universe startdir
 210         if hasattr(universe, "startdir"):
 211             if not prefix:
 212                 prefix = universe.startdir
 213             elif not os.path.isabs(prefix):
 214                 prefix = os.path.join(universe.startdir, prefix)
 215
 216     # when no root path is specified, assume the current working directory
 217     if (not prefix or prefix == ".") and hasattr(universe, "startdir"):
 218         prefix = universe.startdir
 219
 220     # make sure it's absolute
 221     prefix = os.path.realpath(prefix)
 222
 223     # if there's no search path, just use the root path and etc
 224     if not search:
 225         search = [prefix, "etc"]
 226
 227     # work on a copy of the search path, to avoid modifying the caller's
 228     else:
 229         search = search[:]
 230
 231     # if there's no default path, use the last component of the search path
 232     if not stash:
 233         stash = search[-1]
 234
 235     # if an existing file or directory reference was supplied, prepend it
 236     if relative:
 237         if os.path.isdir(relative):
 238             search = [relative] + search
 239         else:
 240             search = [os.path.dirname(relative)] + search
 241
 242     # make the search path entries absolute and throw away any dupes
 243     clean_search = []
 244     for each_path in search:
 245         if not os.path.isabs(each_path):
 246             each_path = os.path.realpath(os.path.join(prefix, each_path))
 247         if each_path not in clean_search:
 248             clean_search.append(each_path)
 249
 250     # start hunting for the file now
 251     for each_path in clean_search:
 252
 253         # construct the candidate path
 254         candidate = os.path.join(each_path, file_name)
 255
 256         # if the file exists and is readable, we're done
 257         if os.path.isfile(candidate):
 258             file_name = os.path.realpath(candidate)
 259             break
 260
 261         # if the path is a directory, look for an __init__ file
 262         if os.path.isdir(candidate):
 263             file_name = os.path.realpath(
 264                     os.path.join(candidate, "__init__.yaml"))
 265             break
 266
 267     # it didn't exist after all, so use the default path instead
 268     if not os.path.isabs(file_name):
 269         file_name = os.path.join(stash, file_name)
 270     if not os.path.isabs(file_name):
 271         file_name = os.path.join(prefix, file_name)
 272
 273     # and normalize it last thing before returning
 274     file_name = os.path.realpath(file_name)
 275     return file_name