Bug#18201: XML: ExtractValue works even if the xml

fragment is not well-formed xml

Problem:
- ExtractValue silently returned NULL if a wrong XML value is passed.
- In some cases "unexpected END-OF-INPUT" error was not detected, and
  a non-NULL result could be returned for a bad XML value.

Fix:
- Adding warning messages, to make user aware why NULL was returned.
- Missing "unexpected END-OF-INPUT" error is reported now.


mysql-test/r/xml.result:
  - Fixing XML systax error in old test
  - Adding test cases.
mysql-test/t/xml.test:
  - Fixing XML systax error in old test
  - Adding test cases.
sql/item_xmlfunc.cc:
  Produce warning in case of XML systax error,
  instead of silentrly returning NULL.
strings/xml.c:
  - Making error messages better looking and clearer:
  It is important because now they're seen in SHOW WARNINGS
  (previously they were used only for debugging purposes).
  - Adding "unexpected END-OF-INPUT" error if after scanning
    closing tag for the root element some input is left
    (previously this error was ignored in a mistake).

1 files changed, 12 insertions, 1 deletions

diff --git a/mysql-test/t/xml.test b/mysql-test/t/xml.test
index 8ed623883b6..af509a2f45e 100644
--- a/mysql-test/t/xml.test
+++ b/mysql-test/t/xml.test
@@ -53,7 +53,7 @@ SELECT extractValue(@xml,'/a//@x');
 SELECT extractValue(@xml,'/a//@x[1]');
 SELECT extractValue(@xml,'/a//@x[2]');
 
-SET @xml='<a><b>b1</b><b>b2</b><c><b>c1b1</b><b>c1b2</b></c><c><b>c2b1</c></b>/a>';
+SET @xml='<a><b>b1</b><b>b2</b><c><b>c1b1</b><b>c1b2</b></c><c><b>c2b1</c></b></a>';
 SELECT extractValue(@xml,'//b[1]');
 SELECT extractValue(@xml,'/descendant::b[1]');
 
@@ -285,6 +285,17 @@ select extractvalue('<a>Jack</a>' collate latin1_bin,'/a[contains(../a,"j")]');
 select ExtractValue('<tag1><![CDATA[test]]></tag1>','/tag1');
 
 #
+# Bug#18201: XML: ExtractValue works even if the xml fragment
+# is not well-formed xml
+#
+select extractValue('<a>a','/a');
+select extractValue('<a>a<','/a');
+select extractValue('<a>a</','/a');
+select extractValue('<a>a</a','/a');
+select extractValue('<a>a</a></b>','/a');
+select extractValue('<a b=>a</a>','/a');
+
+#
 # Bug #18171 XML: ExtractValue: the XPath position()
 # function crashes the server!
 #