Issue #16250: Fix the invocations of URLError which had misplaced filename attribute for exception

Lib/test/test_urllib.py

@@ -270,8 +270,36 @@ Content-Type: text/html; charset=iso-8859-1
 
     def test_missing_localfile(self):
         # Test for #10836
-        with self.assertRaises(urllib.error.URLError):
+        with self.assertRaises(urllib.error.URLError) as e:
             urlopen('file://localhost/a/file/which/doesnot/exists.py')
+        self.assertTrue(e.exception.filename)
+        self.assertTrue(e.exception.reason)
+
+    def test_file_notexists(self):
+        fd, tmp_file = tempfile.mkstemp()
+        tmp_fileurl = 'file://' + tmp_file
+
+        self.assertTrue(os.path.exists(tmp_file))
+        self.assertTrue(urlopen(tmp_fileurl))
+
+        os.unlink(tmp_file)
+        self.assertFalse(os.path.exists(tmp_file))
+        with self.assertRaises(urllib.error.URLError):
+            urlopen(tmp_fileurl)
+
+    def test_ftp_nohost(self):
+        test_ftp_url = 'ftp:///path'
+        with self.assertRaises(urllib.error.URLError) as e:
+            urlopen(test_ftp_url)
+        self.assertFalse(e.exception.filename)
+        self.assertTrue(e.exception.reason)
+
+    def test_ftp_nonexisting(self):
+        with self.assertRaises(urllib.error.URLError) as e:
+            urlopen('ftp://localhost/a/file/which/doesnot/exists.py')
+        self.assertFalse(e.exception.filename)
+        self.assertTrue(e.exception.reason)
+
 
     def test_userpass_inurl(self):
         self.fakehttp(b"HTTP/1.0 200 OK\r\n\r\nHello!")
@@ -305,7 +333,7 @@ Content-Type: text/html; charset=iso-8859-1
 
     def test_URLopener_deprecation(self):
         with support.check_warnings(('',DeprecationWarning)):
-            warn = urllib.request.URLopener()
+            urllib.request.URLopener()
 
 class urlretrieve_FileTests(unittest.TestCase):
     """Test urllib.urlretrieve() on local files"""

Lib/urllib/request.py

@@ -1419,9 +1419,9 @@ class FileHandler(BaseHandler):
                 else:
                     origurl = 'file://' + filename
                 return addinfourl(open(localfile, 'rb'), headers, origurl)
-        except OSError as msg:
+        except OSError as exp:
             # users shouldn't expect OSErrors coming from urlopen()
-            raise URLError(msg)
+            raise URLError(exp)
         raise URLError('file not on local host')
 
 def _safe_gethostbyname(host):
@@ -1480,8 +1480,8 @@ class FTPHandler(BaseHandler):
                 headers += "Content-length: %d\n" % retrlen
             headers = email.message_from_string(headers)
             return addinfourl(fp, headers, req.full_url)
-        except ftplib.all_errors as msg:
-            exc = URLError('ftp error: %s' % msg)
+        except ftplib.all_errors as exp:
+            exc = URLError('ftp error: %r' % exp)
             raise exc.with_traceback(sys.exc_info()[2])
 
     def connect_ftp(self, user, passwd, host, port, dirs, timeout):
@@ -1876,7 +1876,7 @@ class URLopener:
     def open_file(self, url):
         """Use local file or FTP depending on form of URL."""
         if not isinstance(url, str):
-            raise URLError('file error', 'proxy support for file protocol currently not implemented')
+            raise URLError('file error: proxy support for file protocol currently not implemented')
         if url[:2] == '//' and url[2:3] != '/' and url[2:12].lower() != 'localhost/':
             raise ValueError("file:// scheme is supported only on localhost")
         else:
@@ -1912,15 +1912,15 @@ class URLopener:
             elif file[:2] == './':
                 raise ValueError("local file url may start with / or file:. Unknown url of type: %s" % url)
             return addinfourl(open(localname, 'rb'), headers, urlfile)
-        raise URLError('local file error', 'not on local host')
+        raise URLError('local file error: not on local host')
 
     def open_ftp(self, url):
         """Use FTP protocol."""
         if not isinstance(url, str):
-            raise URLError('ftp error', 'proxy support for ftp protocol currently not implemented')
+            raise URLError('ftp error: proxy support for ftp protocol currently not implemented')
         import mimetypes
         host, path = splithost(url)
-        if not host: raise URLError('ftp error', 'no host given')
+        if not host: raise URLError('ftp error: no host given')
         host, port = splitport(host)
         user, host = splituser(host)
         if user: user, passwd = splitpasswd(user)
@@ -1969,13 +1969,13 @@ class URLopener:
                 headers += "Content-Length: %d\n" % retrlen
             headers = email.message_from_string(headers)
             return addinfourl(fp, headers, "ftp:" + url)
-        except ftperrors() as msg:
-            raise URLError('ftp error', msg).with_traceback(sys.exc_info()[2])
+        except ftperrors() as exp:
+            raise URLError('ftp error %r' % exp).with_traceback(sys.exc_info()[2])
 
     def open_data(self, url, data=None):
         """Use "data" URL."""
         if not isinstance(url, str):
-            raise URLError('data error', 'proxy support for data protocol currently not implemented')
+            raise URLError('data error: proxy support for data protocol currently not implemented')
         # ignore POSTed data
         #
         # syntax of data URLs:
@@ -2304,7 +2304,7 @@ class ftpwrapper:
                 conn, retrlen = self.ftp.ntransfercmd(cmd)
             except ftplib.error_perm as reason:
                 if str(reason)[:3] != '550':
-                    raise URLError('ftp error', reason).with_traceback(
+                    raise URLError('ftp error: %d' % reason).with_traceback(
                         sys.exc_info()[2])
         if not conn:
             # Set transfer mode to ASCII!
@@ -2316,7 +2316,7 @@ class ftpwrapper:
                     try:
                         self.ftp.cwd(file)
                     except ftplib.error_perm as reason:
-                        raise URLError('ftp error', reason) from reason
+                        raise URLError('ftp error: %d' % reason) from reason
                 finally:
                     self.ftp.cwd(pwd)
                 cmd = 'LIST ' + file

Misc/NEWS

@@ -59,6 +59,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #16250: Fix the invocations of URLError which had misplaced filename
+  attribute for exception.
+
 - Issue #10836: Fix exception raised when file not found in urlretrieve
   Initial patch by Ezio Melotti.