Bug #16171518 - LOAD XML DOES NOT HANDLE EMPTY ELEMENTS

DESCRIPTION
===========
Inability of mysql LOAD XML command to handle empty XML
tags i.e. <row><tag/></row>. Also the behaviour is wrong
and (different than above) when there is a space in empty
tag i.e. <row><tag /></row>

ANALYSIS
========
In read_xml() the case where we encounter a close tag ('/')
we're decreasing the 'level' blindly which is wrong.
Actually when its an without-space-empty-tag (succeeding
char is '>'), we need to skip the decrement. In other words
whenever we hit a close tag ('/'), decrease the 'level'
only when (i) It's not an (without space) empty tag i.e.
<tag/> or, (ii) It is of format <row col="val" .../>

FIX
===
The switch case for '/' is modified. We've removed the
blind decrement of 'level'. We do it only when its not an
without-space-empty-tag. Also we are setting 'in_tag' to
false to let program know that we're done reading current
tag (required in the case of format <row col="val" .../>)

mysql-test/r/loadxml.result

@@ -93,3 +93,30 @@ a	b
 216	!&bb b;
 3	!b3
 DROP TABLE t1;
+#
+# Bug#16171518 LOAD XML DOES NOT HANDLE EMPTY ELEMENTS
+#
+CREATE TABLE t1 (col1 VARCHAR(3), col2 VARCHAR(3), col3 VARCHAR(3), col4 VARCHAR(4));
+LOAD XML INFILE '../../std_data/bug16171518_1.dat' INTO TABLE t1;
+SELECT * FROM t1 ORDER BY col1, col2, col3, col4;
+col1	col2	col3	col4
+0bc	def	ghi	jkl
+1no	NULL	pqr	stu
+2BC	DEF	GHI	JKL
+3NO	NULL	PQR	STU
+4bc	def	ghi	jkl
+5no	pqr	stu	vwx
+6BC	DEF	NULL	JKL
+7NO	PQR	STU	VWX
+8bc	def	ghi	NULL
+9kl	NULL	mno	pqr
+ABC	DEF	NULL	JKL
+MNO	NULL	STU	VWX
+DROP TABLE t1;
+CREATE TABLE t1 (col1 VARCHAR(3), col2 VARCHAR(3), col3 INTEGER);
+LOAD XML INFILE '../../std_data/bug16171518_2.dat' INTO TABLE t1;
+SELECT * FROM t1 ORDER BY col1, col2, col3;
+col1	col2	col3
+ABC	DEF	NULL
+GHI	NULL	123
+DROP TABLE t1;

mysql-test/std_data/bug16171518_1.dat

+<test_rows>
+  <row>
+    <col1>0bc</col1>
+    <col2>def</col2>
+    <col3>ghi</col3>
+    <col4>jkl</col4>
+  </row>
+  <row>
+    <col1>1no</col1>
+    <col2/>
+    <col3>pqr</col3>
+    <col4>stu</col4>
+  </row>
+
+  <row>
+    <col1>2BC</col1>
+    <col2>DEF</col2>
+    <col3>GHI</col3>
+    <col4>JKL</col4>
+  </row>
+  <row>
+    <col1>3NO</col1>
+    <col2 />
+    <col3>PQR</col3>
+    <col4>STU</col4>
+  </row>
+
+  <row col1="4bc" col2="def" col3="ghi" col4="jkl"/>
+  <row col1="5no"   col2="pqr"   col3="stu"   col4="vwx"   />
+
+  <row>
+    <field name='col1'>6BC</field>
+    <field name='col2'>DEF</field>
+    <field name='col3'></field>
+    <field name='col4'>JKL</field>
+  </row>
+  <row>
+    <field name='col1'>7NO</field>
+    <field name='col2'>PQR</field>
+    <field name='col3'>STU</field>
+    <field name='col4'>VWX</field>
+  </row>
+
+  <row>
+    <col1>8bc</col1>
+    <col2>def</col2>
+    <col3>ghi</col3>
+    <col4 />
+  </row>
+  <row>
+    <col1>9kl</col1>
+    <col2/>
+    <col3>mno</col3>
+    <col4>pqr</col4>
+  </row>
+
+  <row col1="ABC" col2="DEF" col3="" col4="JKL"/>
+  <row col1="MNO" col2="" col3="STU" col4="VWX"/>
+</test_rows>

mysql-test/std_data/bug16171518_2.dat

+<test_rows>
+  <row>
+    <col1>ABC</col1>
+    <col2>DEF</col2>
+    <col3 />
+  </row>
+  <row>
+    <col1>GHI</col1>
+    <col2 />
+    <col3>123</col3>
+  </row>
+</test_rows>

mysql-test/t/loadxml.test

@@ -116,3 +116,17 @@ LOAD XML INFILE '../../std_data/loadxml.dat' INTO TABLE t1
 ROWS IDENTIFIED BY '<row>' (a,@b) SET b=concat('!',@b);
 SELECT * FROM t1 ORDER BY a;
 DROP TABLE t1;
+
+
+--echo #
+--echo # Bug#16171518 LOAD XML DOES NOT HANDLE EMPTY ELEMENTS
+--echo #
+CREATE TABLE t1 (col1 VARCHAR(3), col2 VARCHAR(3), col3 VARCHAR(3), col4 VARCHAR(4));
+LOAD XML INFILE '../../std_data/bug16171518_1.dat' INTO TABLE t1;
+SELECT * FROM t1 ORDER BY col1, col2, col3, col4;
+DROP TABLE t1;
+
+CREATE TABLE t1 (col1 VARCHAR(3), col2 VARCHAR(3), col3 INTEGER);
+LOAD XML INFILE '../../std_data/bug16171518_2.dat' INTO TABLE t1;
+SELECT * FROM t1 ORDER BY col1, col2, col3;
+DROP TABLE t1;

sql/sql_load.cc

 /*
-   Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1987,8 +1987,15 @@ int READ_INFO::read_xml()
       break;
       
     case '/': /* close tag */
-      level--;
       chr= my_tospace(GET);
+      /* Decrease the 'level' only when (i) It's not an */
+      /* (without space) empty tag i.e. <tag/> or, (ii) */
+      /* It is of format <row col="val" .../>           */
+      if(chr != '>' || in_tag)
+      {
+        level--;
+        in_tag= false;
+      }
       if(chr != '>')   /* if this is an empty tag <tag   /> */
         tag.length(0); /* we should keep tag value          */
       while(chr != '>' && chr != my_b_EOF)