From bda5f2b3d9e794193b63fd90aa9e35c67e763717 Mon Sep 17 00:00:00 2001
From: "R. David Murray" <rdmurray@bitdance.com>
Date: Fri, 9 Jul 2010 13:29:33 +0000
Subject: [PATCH] Merged revisions 82732,82734,82738 via svnmerge from
 svn+ssh://pythondev@svn.python.org/python/branches/release27-maint

................
  r82732 | r.david.murray | 2010-07-09 09:16:00 -0400 (Fri, 09 Jul 2010) | 13 lines

  Merged revisions 82730 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/branches/py3k

  'merge' in the sense that this is the same fix by the same author.

  ........
    r82730 | r.david.murray | 2010-07-09 08:23:21 -0400 (Fri, 09 Jul 2010) | 4 lines

    7846: limit fnmatch pattern cache to _MAXCACHE=100 entries.

    Patch by Andrew Clegg.
  ........
................
  r82734 | r.david.murray | 2010-07-09 09:17:45 -0400 (Fri, 09 Jul 2010) | 9 lines

  Merged revisions 82731 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/branches/py3k

  ........
    r82731 | r.david.murray | 2010-07-09 09:14:03 -0400 (Fri, 09 Jul 2010) | 2 lines

    Fix sort order mistake in Misc/ACKS.
  ........
................
  r82738 | r.david.murray | 2010-07-09 09:25:56 -0400 (Fri, 09 Jul 2010) | 2 lines

  Add missing NEWS entry for 7646.
................
---
 Lib/fnmatch.py           |  5 +++++
 Lib/test/test_fnmatch.py | 11 ++++++++++-
 Misc/ACKS                |  1 +
 Misc/NEWS                |  2 ++
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/Lib/fnmatch.py b/Lib/fnmatch.py
index 4c149eb7817..b1c37f59dff 100644
--- a/Lib/fnmatch.py
+++ b/Lib/fnmatch.py
@@ -15,6 +15,7 @@ import re
 __all__ = ["filter", "fnmatch","fnmatchcase","translate"]
 
 _cache = {}
+_MAXCACHE = 100
 
 def fnmatch(name, pat):
     """Test whether FILENAME matches PATTERN.
@@ -44,6 +45,8 @@ def filter(names, pat):
     pat=os.path.normcase(pat)
     if not pat in _cache:
         res = translate(pat)
+        if len(_cache) >= _MAXCACHE:
+            _cache.clear()
         _cache[pat] = re.compile(res)
     match=_cache[pat].match
     if os.path is posixpath:
@@ -66,6 +69,8 @@ def fnmatchcase(name, pat):
 
     if not pat in _cache:
         res = translate(pat)
+        if len(_cache) >= _MAXCACHE:
+            _cache.clear()
         _cache[pat] = re.compile(res)
     return _cache[pat].match(name) is not None
 
diff --git a/Lib/test/test_fnmatch.py b/Lib/test/test_fnmatch.py
index 3a55b85f623..015c580b61f 100644
--- a/Lib/test/test_fnmatch.py
+++ b/Lib/test/test_fnmatch.py
@@ -3,7 +3,7 @@
 from test import test_support
 import unittest
 
-from fnmatch import fnmatch, fnmatchcase
+from fnmatch import fnmatch, fnmatchcase, _MAXCACHE, _cache
 
 
 class FnmatchTestCase(unittest.TestCase):
@@ -49,6 +49,15 @@ class FnmatchTestCase(unittest.TestCase):
         check('AbC', 'abc', 0, fnmatchcase)
         check('abc', 'AbC', 0, fnmatchcase)
 
+    def test_cache_clearing(self):
+        # check that caches do not grow too large
+        # http://bugs.python.org/issue7846
+
+        # string pattern cache
+        for i in range(_MAXCACHE + 1):
+            fnmatch('foo', '?' * i)
+
+        self.assertTrue(len(_cache) <= _MAXCACHE)
 
 def test_main():
     test_support.run_unittest(FnmatchTestCase)
diff --git a/Misc/ACKS b/Misc/ACKS
index 94a22a860ec..b6634a789b7 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -132,6 +132,7 @@ Tom Christiansen
 Vadim Chugunov
 David Cinege
 Mike Clarkson
+Andrew Clegg
 Brad Clements
 Steve Clift
 Nick Coghlan
diff --git a/Misc/NEWS b/Misc/NEWS
index 0efac1b772a..f6f8044ac80 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -81,6 +81,8 @@ C-API
 Library
 -------
 
+- Issue #7646: The fnmatch pattern cache no longer grows without bound.
+
 - Issue #9136: Fix 'dictionary changed size during iteration'
   RuntimeError produced when profiling the decimal module.  This was
   due to a dangerous iteration over 'locals()' in Context.__init__.