Synnefo » snf-ganeti

import stat

def EnforcePermission(path, mode, uid=-1, gid=-1, must_exist=True,

                      _chmod_fn=os.chmod, _chown_fn=os.chown, _stat_fn=os.stat):

  """Enforces that given path has given permissions.

  @param path: The path to the file

  @param mode: The mode of the file

  @param uid: The uid of the owner of this file

  @param gid: The gid of the owner of this file

  @param must_exist: Specifies if non-existance of path will be an error

  @param _chmod_fn: chmod function to use (unittest only)

  @param _chown_fn: chown function to use (unittest only)

  """

  logging.debug("Checking %s", path)

  try:

    st = _stat_fn(path)

    fmode = stat.S_IMODE(st[stat.ST_MODE])

    if fmode != mode:

      logging.debug("Changing mode of %s from %#o to %#o", path, fmode, mode)

      _chmod_fn(path, mode)

    if max(uid, gid) > -1:

      fuid = st[stat.ST_UID]

      fgid = st[stat.ST_GID]

      if fuid != uid or fgid != gid:

        logging.debug("Changing owner of %s from UID %s/GID %s to"

                      " UID %s/GID %s", path, fuid, fgid, uid, gid)

        _chown_fn(path, uid, gid)

  except EnvironmentError, err:

    if err.errno == errno.ENOENT:

      if must_exist:

        raise errors.GenericError("Path %s should exist, but does not" % path)

    else:

      raise errors.GenericError("Error while changing permissions on %s: %s" %

                                (path, err))

def MakeDirWithPerm(path, mode, uid, gid, _lstat_fn=os.lstat,

                    _mkdir_fn=os.mkdir, _perm_fn=EnforcePermission):

  """Enforces that given path is a dir and has given mode, uid and gid set.

  @param path: The path to the file

  @param mode: The mode of the file

  @param uid: The uid of the owner of this file

  @param gid: The gid of the owner of this file

  @param _lstat_fn: Stat function to use (unittest only)

  @param _mkdir_fn: mkdir function to use (unittest only)

  @param _perm_fn: permission setter function to use (unittest only)

  """

  logging.debug("Checking directory %s", path)

  try:

    # We don't want to follow symlinks

    st = _lstat_fn(path)

  except EnvironmentError, err:

    if err.errno != errno.ENOENT:

      raise errors.GenericError("stat(2) on %s failed: %s" % (path, err))

    _mkdir_fn(path)

  else:

    if not stat.S_ISDIR(st[stat.ST_MODE]):

      raise errors.GenericError(("Path %s is expected to be a directory, but "

                                 "isn't") % path)

  _perm_fn(path, mode, uid=uid, gid=gid)