Add locking for long runs

.gitignore

@@ -1 +1,2 @@
 .venv
+*~

tivomirror.py

@@ -13,6 +13,7 @@ import http.cookiejar
 import datetime
 import getopt
 import errno
+import fcntl
 import functools
 import logging
 import logging.handlers
@@ -30,11 +31,13 @@ import urllib.request, urllib.error, urllib.parse
 import xml.dom.minidom
 import yaml
 
+from contextlib import contextmanager
 from io import TextIOWrapper
 
 
 class Config:
 	config = '~/.tivo/config.yaml'
+	lockfile = config + '.lock'
 	cookies = "cookies.txt"
 	gig = 1024.0 * 1024 * 1024
 	headers = requests.utils.default_headers()
@@ -382,6 +385,16 @@ class FdLogger(threading.Thread):
 			self.logger.exception("")
 
 
+@contextmanager
+def exclusive():
+	with open(os.path.expanduser(config.lockfile), 'w') as f:
+		try:
+			fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
+		except BlockingIOError as e:
+			raise TivoException('another tivomirror instance is already running')
+		yield 'locked'
+		fcntl.lockf(f, fcntl.LOCK_UN)
+
 @timeout(43200)
 def download_item(item, mak, target):
 	global config
@@ -524,6 +537,7 @@ def mirror(toc, downloaddb, one=False):
 			(config.targetdir, avail / config.gig, config.minfree / config.gig))
 		sys.exit(1)
 
+	with exclusive() as lock:
 		items = toc.getItems()
 		logger.info("*** {} shows listed".format(len(items)))
 		for item in items:
@@ -537,6 +551,7 @@ def mirror(toc, downloaddb, one=False):
 
 
 def download_episode(toc, downloaddb, episode):
+	with exclusive() as lock:
 		items = toc.getItems()
 		options = {}
 		for item in items:
@@ -549,6 +564,7 @@ def download_episode(toc, downloaddb, episode):
 
 
 def printtoc(toc, downloaddb):
+	with exclusive() as lock:
 		items = toc.getItems()
 		print("*** {} shows listed".format(len(items)))
 		shows = {}