Issue #20331: Fixed possible FD leaks in various modules:

SimpleHTTPServer, imghdr, mailcap, mimetypes, xml.etree.

Lib/SimpleHTTPServer.py

@@ -43,7 +43,9 @@ class SimpleHTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
         """Serve a GET request."""
         f = self.send_head()
         if f:
+            try:
                 self.copyfile(f, self.wfile)
+            finally:
                 f.close()
 
     def do_HEAD(self):
@@ -88,6 +90,7 @@ class SimpleHTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
         except IOError:
             self.send_error(404, "File not found")
             return None
+        try:
             self.send_response(200)
             self.send_header("Content-type", ctype)
             fs = os.fstat(f.fileno())
@@ -95,6 +98,9 @@ class SimpleHTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
             self.send_header("Last-Modified", self.date_time_string(fs.st_mtime))
             self.end_headers()
             return f
+        except:
+            f.close()
+            raise
 
     def list_directory(self, path):
         """Helper to produce a directory listing (absent index.html).

Lib/imghdr.py

@@ -7,6 +7,8 @@ __all__ = ["what"]
 #-------------------------#
 
 def what(file, h=None):
+    f = None
+    try:
         if h is None:
             if isinstance(file, basestring):
                 f = open(file, 'rb')
@@ -15,10 +17,6 @@ def what(file, h=None):
                 location = file.tell()
                 h = file.read(32)
                 file.seek(location)
-            f = None
-    else:
-        f = None
-    try:
         for tf in tests:
             res = tf(h, f)
             if res:

Lib/mailcap.py

@@ -22,8 +22,8 @@ def getcaps():
             fp = open(mailcap, 'r')
         except IOError:
             continue
+        with fp:
             morecaps = readmailcapfile(fp)
-        fp.close()
         for key, value in morecaps.iteritems():
             if not key in caps:
                 caps[key] = value

Lib/mimetypes.py

@@ -373,6 +373,7 @@ def read_mime_types(file):
         f = open(file)
     except IOError:
         return None
+    with f:
         db = MimeTypes()
         db.readfp(f, True)
         return db.types_map[True]

Lib/xml/etree/ElementInclude.py

@@ -75,14 +75,13 @@ class FatalIncludeError(SyntaxError):
 # @throws IOError If the loader fails to load the resource.
 
 def default_loader(href, parse, encoding=None):
-    file = open(href)
+    with open(href) as file:
         if parse == "xml":
             data = ElementTree.parse(file).getroot()
         else:
             data = file.read()
             if encoding:
                 data = data.decode(encoding)
-    file.close()
     return data
 
 ##