pymeds/FSStorage.py

#!/usr/bin/env python
# Copyright 2006 John-Mark Gurney <gurney_j@resnet.uoregon.edu>
#
# $Id$
#

import FileDIDL
import errno
import itertools
import os
import sets
import stat

from DIDLLite import StorageFolder, Item, VideoItem, AudioItem, TextItem, ImageItem, Resource
from twisted.web import static
from twisted.python import log

__all__ = [ 'registerklassfun', 'FSObject', 'FSItem', 'FSVideoItem',
		'FSAudioItem', 'FSTextItem', 'FSImageItem', 'mimetoklass',
		'FSDirectory',
	]

mimedict = static.loadMimeTypes()

klassfuns = []

def registerklassfun(fun):
	klassfuns.append(fun)

def statcmp(a, b, cmpattrs = [ 'st_ino', 'st_dev', 'st_size', 'st_mtime', ]):
	if a is None or b is None:
		return False

	for i in cmpattrs:
		if getattr(a, i) != getattr(b, i):
			return False
	return True

class FSObject(object):
	def __init__(self, path):
		self.FSpath = path
		self.pstat = None

	def checkUpdate(self):
		# need to handle no such file or directory
		# push it up? but still need to handle disappearing
		try:
			nstat = os.stat(self.FSpath)
			if statcmp(self.pstat, nstat):
				return self

			self.pstat = nstat
			self.doUpdate()
		except OSError, x:
			log.msg('os.stat, OSError: %s' % x)
			if x.errno in (errno.ENOENT, errno.ENOTDIR, errno.EPERM, ):
				# We can't access it anymore, delete it
				self.cd.delItem(self.id)
				return None
			else:
				raise x

		return self

	def doUpdate(self):
		raise NotImplementedError

class FSItem(FSObject, Item):
	def __init__(self, *args, **kwargs):
		FSObject.__init__(self, kwargs['path'])
		del kwargs['path']
		mimetype = kwargs['mimetype']
		del kwargs['mimetype']
		kwargs['content'] = static.File(self.FSpath)
		Item.__init__(self, *args, **kwargs)
		self.url = '%s/%s' % (self.cd.urlbase, self.id)
		self.mimetype = mimetype

	def doUpdate(self):
		self.res = Resource(self.url, 'http-get:*:%s:*' % self.mimetype)
		self.res.size = os.path.getsize(self.FSpath)
		Item.doUpdate(self)

def defFS(path, fobj):
	if os.path.isdir(path):
		# new dir
		return FSDirectory, { 'path': path }
	elif os.path.isfile(path):
		# new file - fall through to below
		pass
	else:
		log.msg('skipping (not dir or reg): %s' % path)
		return None, None

	klass, mt = FileDIDL.buildClassMT(FSItem, path)

	return klass, { 'path': path, 'mimetype': mt }

def dofileadd(cd, parent, path, name):
	klass = None
	fsname = os.path.join(path, name)
	try:
		fobj = open(fsname)
	except:
		fobj = None
	for i in itertools.chain(klassfuns, ( defFS, )):
		try:
			try:
				fobj.seek(0)	# incase the call expects a clean file
			except:
				pass

			klass, kwargs = i(fsname, fobj)
			if klass is not None:
				break
		except:
			#import traceback
			#traceback.print_exc(file=log.logfile)
			pass

	if klass is None:
		return

	log.msg('matched:', os.path.join(path, name), `i`, `klass`)
	return cd.addItem(parent, klass, name, **kwargs)

class FSDirectory(FSObject, StorageFolder):
	def __init__(self, *args, **kwargs):
		path = kwargs['path']
		del kwargs['path']
		StorageFolder.__init__(self, *args, **kwargs)
		FSObject.__init__(self, path)

		# mapping from path to objectID
		self.pathObjmap = {}

	def doUpdate(self):
		# We need to rescan this dir, and see if our children has
		# changed any.
		children = sets.Set(os.listdir(self.FSpath))
		for i in self.pathObjmap.keys():
			if i not in children:
				# delete
				self.cd.delItem(self.pathObjmap[i])
				del self.pathObjmap[i]

		for i in children:
			if i in self.pathObjmap:
				continue

			# new object
			nf = dofileadd(self.cd, self.id, self.FSpath, i)

			if nf is not None:
				self.pathObjmap[i] = nf

		# sort our children
		self.sort(lambda x, y: cmp(x.title, y.title))

		# Pass up to handle UpdateID
		StorageFolder.doUpdate(self)