terom@5: """
terom@5:     Mount filesystems.
terom@5: """
terom@5: 
terom@69: from pvl.backup.invoke import invoke, optargs, command
terom@5: 
terom@5: import contextlib
terom@33: import os, os.path
terom@5: import logging
terom@33: import tempfile
terom@5: 
terom@5: log = logging.getLogger('pvl.backup.mount')
terom@5: 
terom@5: 
terom@5: class MountError (Exception) :
terom@5:     pass
terom@5: 
terom@5: class Mount (object) :
terom@5:     """
terom@5:         Trivial filesystem mounting
terom@5:     """
terom@5: 
terom@5:     MOUNT   = '/bin/mount'
terom@5:     UMOUNT  = '/bin/umount'
terom@5: 
terom@5: 
terom@69:     def __init__ (self, dev, mnt, readonly=False, sudo=None) :
terom@5:         """
terom@5:             dev         - device path
terom@5:             mnt         - mount path
terom@5:             readonly    - mount readonly
terom@69:             sudo        - invoke sudo
terom@5:         """
terom@5: 
terom@5:         self.dev = dev
terom@5:         self.mnt = mnt
terom@5:         self.readonly = readonly
terom@69:         self.sudo = sudo
terom@5: 
terom@5:     @property
terom@5:     def path (self) :
terom@5:         return self.mnt
terom@5: 
terom@5:     def options (self) :
terom@5:         """
terom@5:             Mount options as a comma-separated string.
terom@5:         """
terom@5: 
terom@5:         options = [
terom@5:                 ('ro' if self.readonly else None),
terom@5:         ]
terom@5: 
terom@5:         return ','.join(option for option in options if option)
terom@5: 
terom@5:     def open (self) :
terom@5:         """
terom@5:             Mount
terom@5:         """
terom@5: 
terom@5:         # check
terom@5:         if not os.path.isdir(self.mnt) :
terom@5:             raise MountError("Mountpoint is not a directory: {mnt}".format(mnt=self.mnt))
terom@5: 
terom@78:         if self.is_mounted() :
terom@5:             raise MountError("Mountpoint is already mounted: {mnt}".format(mnt=self.mnt))
terom@5: 
terom@5:         if not os.path.exists(self.dev) :
terom@5:             raise MountError("Device does not exist: {dev}".format(dev=self.dev))
terom@5: 
terom@5:         # mount
terom@69:         invoke(self.MOUNT, optargs(self.dev, self.mnt, options=self.options()), sudo=self.sudo)
terom@5: 
terom@78:     def is_mounted (self) :
terom@78:         """
terom@78:             Test if the given mountpoint is mounted.
terom@78:         """
terom@78:         
terom@78:         # workaround http://bugs.python.org/issue2466
terom@78:         if os.path.exists(self.mnt) and not os.path.exists(os.path.join(self.mnt, '.')) :
terom@78:             # this is a sign of a mountpoint that we do not have access to
terom@78:             return True
terom@78: 
terom@78:         return os.path.ismount(self.mnt)
terom@78: 
terom@5:     def close (self) :
terom@5:         """
terom@5:             Un-mount
terom@5:         """
terom@5: 
terom@5:         # check
terom@78:         if not self.is_mounted() :
terom@5:             raise MountError("Mountpoint is not mounted: {mnt}".format(mnt=self.mnt))
terom@5: 
terom@5:         # umount
terom@69:         invoke(self.UMOUNT, optargs(self.mnt), sudo=self.sudo)
terom@5: 
terom@10:     def __repr__ (self) :
terom@10:         return "Mount(dev={dev}, mnt={mnt})".format(
terom@10:                 dev     = repr(self.dev),
terom@10:                 mnt     = repr(self.mnt),
terom@10:         )
terom@10: 
terom@10:     def __str__ (self) :
terom@10:         return self.mnt
terom@10: 
terom@5: @contextlib.contextmanager
terom@33: def mount (dev, mnt=None, name_hint='tmp', **kwargs) :
terom@5:     """
terom@5:         Use a temporary mount:
terom@5: 
terom@33:         with mount('/dev/...', readonly=True) as mount:
terom@5:             ...
terom@33: 
terom@33:         Mounts at the given mountpoint path, or a tempdir
terom@5:     """
terom@5: 
terom@33:     if mnt is None :
terom@33:         mnt = tmpdir = tempfile.mkdtemp(suffix='.mnt', prefix=name_hint)
terom@5: 
terom@33:         log.debug("using tmp mnt: %s", tmpdir)
terom@5: 
terom@33:     else :
terom@33:         tmpdir = None
terom@33:         
terom@33:     log.debug("mount: %s -> %s", dev, mnt)
terom@33: 
terom@33:     # with tempdir
terom@5:     try :
terom@33:         mount = Mount(dev, mnt, **kwargs)
terom@33: 
terom@33:         # open
terom@33:         log.debug("open: %s", mount)
terom@33:         mount.open()
terom@33: 
terom@33:         try :
terom@33:             log.debug("got: %s", mount)
terom@33:             yield mount
terom@33: 
terom@33:         finally:
terom@33:             # cleanup
terom@33:             log.debug("cleanup: %s", mount)
terom@78: 
terom@78:             try :
terom@78:                 mount.close()
terom@78: 
terom@78:             except Exception as ex :
terom@78:                 log.warning("cleanup: %s: %s", mount, ex)
terom@5: 
terom@5:     finally:
terom@33:         if tmpdir :
terom@33:             # cleanup
terom@33:             log.debug("cleanup tmp mnt: %s", tmpdir)
terom@33:             os.rmdir(tmpdir)
terom@5: