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authorVinay Sajip <vinay_sajip@yahoo.co.uk>2012-04-24 22:33:33 (GMT)
committerVinay Sajip <vinay_sajip@yahoo.co.uk>2012-04-24 22:33:33 (GMT)
commita5798ded26e3ad67946b7d8150a8e13b0075fbf8 (patch)
tree508e1844c0372f19b7bcdbf22d9aeb7de1635ca6 /Lib/logging
parent5438ed1572f5e379cac8b85ed2226101a1bfcacc (diff)
parent66b8b08752a2e30cbbbd12295247df050d534c4b (diff)
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Issue #14632: Updated WatchedFileHandler to deal with race condition. Thanks to John Mulligan for the problem report and patch.
Diffstat (limited to 'Lib/logging')
-rw-r--r--Lib/logging/handlers.py49
1 files changed, 30 insertions, 19 deletions
diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index 9c63797..7a97c80 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -23,7 +23,7 @@ Copyright (C) 2001-2012 Vinay Sajip. All Rights Reserved.
To use, simply 'import logging.handlers' and log away!
"""
-import logging, socket, os, pickle, struct, time, re
+import errno, logging, socket, os, pickle, struct, time, re
from codecs import BOM_UTF8
from stat import ST_DEV, ST_INO, ST_MTIME
import queue
@@ -419,11 +419,13 @@ class WatchedFileHandler(logging.FileHandler):
"""
def __init__(self, filename, mode='a', encoding=None, delay=False):
logging.FileHandler.__init__(self, filename, mode, encoding, delay)
- if not os.path.exists(self.baseFilename):
- self.dev, self.ino = -1, -1
- else:
- stat = os.stat(self.baseFilename)
- self.dev, self.ino = stat[ST_DEV], stat[ST_INO]
+ self.dev, self.ino = -1, -1
+ self._statstream()
+
+ def _statstream(self):
+ if self.stream:
+ sres = os.fstat(self.stream.fileno())
+ self.dev, self.ino = sres[ST_DEV], sres[ST_INO]
def emit(self, record):
"""
@@ -433,21 +435,30 @@ class WatchedFileHandler(logging.FileHandler):
has, close the old stream and reopen the file to get the
current stream.
"""
- if not os.path.exists(self.baseFilename):
- stat = None
- changed = True
- else:
- stat = os.stat(self.baseFilename)
- changed = (stat[ST_DEV] != self.dev) or (stat[ST_INO] != self.ino)
- if changed and self.stream is not None:
- self.stream.flush()
- self.stream.close()
- self.stream = self._open()
- if stat is None:
- stat = os.stat(self.baseFilename)
- self.dev, self.ino = stat[ST_DEV], stat[ST_INO]
+ # Reduce the chance of race conditions by stat'ing by path only
+ # once and then fstat'ing our new fd if we opened a new log stream.
+ # See issue #14632: Thanks to John Mulligan for the problem report
+ # and patch.
+ try:
+ # stat the file by path, checking for existence
+ sres = os.stat(self.baseFilename)
+ except OSError as err:
+ if err.errno == errno.ENOENT:
+ sres = None
+ else:
+ raise
+ # compare file system stat with that of our stream file handle
+ if not sres or sres[ST_DEV] != self.dev or sres[ST_INO] != self.ino:
+ if self.stream is not None:
+ # we have an open file handle, clean it up
+ self.stream.flush()
+ self.stream.close()
+ # open a new file handle and get new stat info from that fd
+ self.stream = self._open()
+ self._statstream()
logging.FileHandler.emit(self, record)
+
class SocketHandler(logging.Handler):
"""
A handler class which writes logging records, in pickle format, to