Source Code for Module ganeti.storage.filestorage

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  3   
  4  # Copyright (C) 2013 Google Inc. 
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 29   
 30   
 31  """File storage functions. 
 32   
 33  """ 
 34   
 35  import logging 
 36  import os 
 37   
 38  from ganeti import compat 
 39  from ganeti import constants 
 40  from ganeti import errors 
 41  from ganeti import pathutils 
 42  from ganeti import utils 
 43   
 44   
 45 -def GetFileStorageSpaceInfo(path): 
 46    """Retrieves the free and total space of the device where the file is 
 47       located. 
 48   
 49       @type path: string 
 50       @param path: Path of the file whose embracing device's capacity is 
 51         reported. 
 52       @return: a dictionary containing 'vg_size' and 'vg_free' given in MebiBytes 
 53   
 54    """ 
 55    try: 
 56      result = os.statvfs(path) 
 57      free = (result.f_frsize * result.f_bavail) / (1024 * 1024) 
 58      size = (result.f_frsize * result.f_blocks) / (1024 * 1024) 
 59      return {"type": constants.ST_FILE, 
 60              "name": path, 
 61              "storage_size": size, 
 62              "storage_free": free} 
 63    except OSError, e: 
 64      raise errors.CommandError("Failed to retrieve file system information about" 
 65                                " path: %s - %s" % (path, e.strerror)) 
 66   
 67   
 68 -def _GetForbiddenFileStoragePaths(): 
 69    """Builds a list of path prefixes which shouldn't be used for file storage. 
 70   
 71    @rtype: frozenset 
 72   
 73    """ 
 74    paths = set([ 
 75      "/boot", 
 76      "/dev", 
 77      "/etc", 
 78      "/home", 
 79      "/proc", 
 80      "/root", 
 81      "/sys", 
 82      ]) 
 83   
 84    for prefix in ["", "/usr", "/usr/local"]: 
 85      paths.update(map(lambda s: "%s/%s" % (prefix, s), 
 86                       ["bin", "lib", "lib32", "lib64", "sbin"])) 
 87   
 88    return compat.UniqueFrozenset(map(os.path.normpath, paths)) 
 89   
 90   
 91 -def _ComputeWrongFileStoragePaths(paths, 
 92                                    _forbidden=_GetForbiddenFileStoragePaths()): 
 93    """Cross-checks a list of paths for prefixes considered bad. 
 94   
 95    Some paths, e.g. "/bin", should not be used for file storage. 
 96   
 97    @type paths: list 
 98    @param paths: List of paths to be checked 
 99    @rtype: list 
100    @return: Sorted list of paths for which the user should be warned 
101   
102    """ 
103    def _Check(path): 
104      return (not os.path.isabs(path) or 
105              path in _forbidden or 
106              filter(lambda p: utils.IsBelowDir(p, path), _forbidden)) 
107   
108    return utils.NiceSort(filter(_Check, map(os.path.normpath, paths))) 
109   
110   
111 -def ComputeWrongFileStoragePaths(_filename=pathutils.FILE_STORAGE_PATHS_FILE): 
112    """Returns a list of file storage paths whose prefix is considered bad. 
113   
114    See L{_ComputeWrongFileStoragePaths}. 
115   
116    """ 
117    return _ComputeWrongFileStoragePaths(_LoadAllowedFileStoragePaths(_filename)) 
118   
119   
120 -def _CheckFileStoragePath(path, allowed, exact_match_ok=False): 
121    """Checks if a path is in a list of allowed paths for file storage. 
122   
123    @type path: string 
124    @param path: Path to check 
125    @type allowed: list 
126    @param allowed: List of allowed paths 
127    @type exact_match_ok: bool 
128    @param exact_match_ok: whether or not it is okay when the path is exactly 
129        equal to an allowed path and not a subdir of it 
130    @raise errors.FileStoragePathError: If the path is not allowed 
131   
132    """ 
133    if not os.path.isabs(path): 
134      raise errors.FileStoragePathError("File storage path must be absolute," 
135                                        " got '%s'" % path) 
136   
137    for i in allowed: 
138      if not os.path.isabs(i): 
139        logging.info("Ignoring relative path '%s' for file storage", i) 
140        continue 
141   
142      if exact_match_ok: 
143        if os.path.normpath(i) == os.path.normpath(path): 
144          break 
145   
146      if utils.IsBelowDir(i, path): 
147        break 
148    else: 
149      raise errors.FileStoragePathError("Path '%s' is not acceptable for file" 
150                                        " storage" % path) 
151   
152   
153 -def _LoadAllowedFileStoragePaths(filename): 
154    """Loads file containing allowed file storage paths. 
155   
156    @rtype: list 
157    @return: List of allowed paths (can be an empty list) 
158   
159    """ 
160    try: 
161      contents = utils.ReadFile(filename) 
162    except EnvironmentError: 
163      return [] 
164    else: 
165      return utils.FilterEmptyLinesAndComments(contents) 
166   
167   
168 -def CheckFileStoragePathAcceptance( 
169      path, _filename=pathutils.FILE_STORAGE_PATHS_FILE, 
170      exact_match_ok=False): 
171    """Checks if a path is allowed for file storage. 
172   
173    @type path: string 
174    @param path: Path to check 
175    @raise errors.FileStoragePathError: If the path is not allowed 
176   
177    """ 
178    allowed = _LoadAllowedFileStoragePaths(_filename) 
179    if not allowed: 
180      raise errors.FileStoragePathError("No paths are valid or path file '%s'" 
181                                        " was not accessible." % _filename) 
182   
183    if _ComputeWrongFileStoragePaths([path]): 
184      raise errors.FileStoragePathError("Path '%s' uses a forbidden prefix" % 
185                                        path) 
186   
187    _CheckFileStoragePath(path, allowed, exact_match_ok=exact_match_ok) 
188   
189   
190 -def _CheckFileStoragePathExistance(path): 
191    """Checks whether the given path is usable on the file system. 
192   
193    This checks wether the path is existing, a directory and writable. 
194   
195    @type path: string 
196    @param path: path to check 
197   
198    """ 
199    if not os.path.isdir(path): 
200      raise errors.FileStoragePathError("Path '%s' does not exist or is not a" 
201                                        " directory." % path) 
202    if not os.access(path, os.W_OK): 
203      raise errors.FileStoragePathError("Path '%s' is not writable" % path) 
204   
205   
206 -def CheckFileStoragePath( 
207      path, _allowed_paths_file=pathutils.FILE_STORAGE_PATHS_FILE): 
208    """Checks whether the path exists and is acceptable to use. 
209   
210    Can be used for any file-based storage, for example shared-file storage. 
211   
212    @type path: string 
213    @param path: path to check 
214    @rtype: string 
215    @returns: error message if the path is not ready to use 
216   
217    """ 
218    try: 
219      CheckFileStoragePathAcceptance(path, _filename=_allowed_paths_file, 
220                                     exact_match_ok=True) 
221    except errors.FileStoragePathError as e: 
222      return str(e) 
223    if not os.path.isdir(path): 
224      return "Path '%s' is not existing or not a directory." % path 
225    if not os.access(path, os.W_OK): 
226      return "Path '%s' is not writable" % path 
227