From 4baa2602af289b4f44913c77e8badf41399e4f7a Mon Sep 17 00:00:00 2001
From: Diana Clarke <diana.joan.clarke@gmail.com>
Date: Wed, 31 Aug 2016 14:55:43 -0400
Subject: [PATCH] Revert error packet parsing changes

Revert the changes made in commit 02910b7 to the mysql error packet
parsing, as it didn't take the CLIENT_PROTOCOL_41 case into account.

It appears that the non-CLIENT_PROTOCOL_41 case was off by one as well
(sliced data on 4 vs 3).

I also added two new tests to cover those cases.

See: https://dev.mysql.com/doc/internals/en/packet-ERR_Packet.html
---
 pymysql/err.py            |  7 ++++++-
 pymysql/tests/__init__.py |  1 +
 pymysql/tests/test_err.py | 21 +++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 pymysql/tests/test_err.py

diff --git a/pymysql/err.py b/pymysql/err.py
index 70beb33c..24862632 100644
--- a/pymysql/err.py
+++ b/pymysql/err.py
@@ -97,6 +97,11 @@ def _map_error(exc, *errors):
 
 def raise_mysql_exception(data):
     errno = struct.unpack('<h', data[1:3])[0]
-    errval = data[4:].decode('utf-8', 'replace')
+    is_41 = data[3:4] == b"#"
+    if is_41:
+        # client protocol 4.1
+        errval = data[9:].decode('utf-8', 'replace')
+    else:
+        errval = data[3:].decode('utf-8', 'replace')
     errorclass = error_map.get(errno, InternalError)
     raise errorclass(errno, errval)
diff --git a/pymysql/tests/__init__.py b/pymysql/tests/__init__.py
index 8fd6363e..a9f5a4bf 100644
--- a/pymysql/tests/__init__.py
+++ b/pymysql/tests/__init__.py
@@ -5,6 +5,7 @@
 from pymysql.tests.test_connection import *
 from pymysql.tests.test_converters import *
 from pymysql.tests.test_cursor import *
+from pymysql.tests.test_err import *
 from pymysql.tests.test_issues import *
 from pymysql.tests.test_load_local import *
 from pymysql.tests.test_nextset import *
diff --git a/pymysql/tests/test_err.py b/pymysql/tests/test_err.py
new file mode 100644
index 00000000..3468d1b1
--- /dev/null
+++ b/pymysql/tests/test_err.py
@@ -0,0 +1,21 @@
+import unittest2
+
+from pymysql import err
+
+
+__all__ = ["TestRaiseException"]
+
+
+class TestRaiseException(unittest2.TestCase):
+
+    def test_raise_mysql_exception(self):
+        data = b"\xff\x15\x04Access denied"
+        with self.assertRaises(err.OperationalError) as cm:
+            err.raise_mysql_exception(data)
+        self.assertEqual(cm.exception.args, (1045, 'Access denied'))
+
+    def test_raise_mysql_exception_client_protocol_41(self):
+        data = b"\xff\x15\x04#28000Access denied"
+        with self.assertRaises(err.OperationalError) as cm:
+            err.raise_mysql_exception(data)
+        self.assertEqual(cm.exception.args, (1045, 'Access denied'))