Make _strptime escape regex syntax in format string to prevent use in internal regex.

brettcannon · brettcannon · commit 1e91d8eb0306 · 2003-04-19T04:00:56.000Z
diff --git a/Lib/_strptime.py b/Lib/_strptime.py
@@ -373,8 +373,17 @@ def sorter(a, b):
         return '%s)' % regex
 
     def pattern(self, format):
-        """Return re pattern for the format string."""
+        """Return re pattern for the format string.
+        
+        Need to make sure that any characters that might be interpreted as
+        regex syntax is escaped.
+        
+        """
         processed_format = ''
+        # The sub() call escapes all characters that might be misconstrued
+        # as regex syntax.
+        regex_chars = re_compile(r"([\\.^$*+?{}\[\]|])")
+        format = regex_chars.sub(r"\\\1", format)
         whitespace_replacement = re_compile('\s+')
         format = whitespace_replacement.sub('\s*', format)
         while format.find('%') != -1:
diff --git a/Lib/test/test_strptime.py b/Lib/test/test_strptime.py
@@ -168,6 +168,14 @@ def test_pattern(self):
                         "did not find 'd' directive pattern string '%s'" %
                          pattern_string)
 
+    def test_pattern_escaping(self):
+        # Make sure any characters in the format string that might be taken as
+        # regex syntax is escaped.
+        pattern_string = self.time_re.pattern("\d+")
+        self.failUnless(r"\\d\+" in pattern_string,
+                        "%s does not have re characters escaped properly" %
+                        pattern_string)
+
     def test_compile(self):
         # Check that compiled regex is correct
         found = self.time_re.compile(r"%A").match(self.locale_time.f_weekday[6])
@@ -201,6 +209,12 @@ def test_blankpattern(self):
         self.failUnless(_strptime.TimeRE(test_locale).pattern("%Z") == '',
                         "with timezone == ('',''), TimeRE().pattern('%Z') != ''")
 
+    def test_matching_with_escapes(self):
+        # Make sure a format that requires escaping of characters works
+        compiled_re = self.time_re.compile("\w+ %m")
+        found = compiled_re.match("\w+ 10")
+        self.failUnless(found, "Escaping failed of format '\w+ 10'")
+
 class StrptimeTests(unittest.TestCase):
     """Tests for _strptime.strptime."""
 
