From 9bf24768664be6faf79333e1d4d6d14a0d33587b Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 25 Oct 2019 15:22:40 -0400 Subject: [PATCH] Avoid failure when selecting a namespace node in XMLTABLE. It appears that libxml2 doesn't bother to set the "children" field of an XML_NAMESPACE_DECL node to null; that field just contains garbage. In v10 and v11, this can result in a crash in XMLTABLE(). The rewrite done in commit 251cf2e27 fixed this, somewhat accidentally, in v12. We're not going to back-patch 251cf2e27, however. The case apparently doesn't have wide use, so rather than risk introducing other problems, just add a safety check to throw an error. Even though no bug manifests in v12/HEAD, add the relevant test case there too, to prevent future regressions. Chapman Flack (per private report) --- src/backend/utils/adt/xml.c | 7 ++++++- src/test/regress/expected/xml.out | 4 ++++ src/test/regress/expected/xml_1.out | 8 ++++++++ src/test/regress/expected/xml_2.out | 4 ++++ src/test/regress/sql/xml.sql | 4 ++++ 5 files changed, 26 insertions(+), 1 deletion(-) diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c index 3a857bb0260..a456dca458d 100644 --- a/src/backend/utils/adt/xml.c +++ b/src/backend/utils/adt/xml.c @@ -4608,6 +4608,12 @@ XmlTableGetValue(TableFuncScanState *state, int colnum, xmlChar *str; xmlNodePtr node; + node = xpathobj->nodesetval->nodeTab[0]; + if (node->type == XML_NAMESPACE_DECL) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("XMLTABLE cannot cast a namespace node to a non-XML result type"))); + /* * Most nodes (elements and even attributes) store their data * in children nodes. If they don't have children nodes, it @@ -4615,7 +4621,6 @@ XmlTableGetValue(TableFuncScanState *state, int colnum, * CDATA sections are an exception: they don't have children * but have content in the Text/CDATA node itself. */ - node = xpathobj->nodesetval->nodeTab[0]; if (node->type != XML_CDATA_SECTION_NODE && node->type != XML_TEXT_NODE) node = node->xmlChildrenNode; diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out index 61fe3b44034..d887a314815 100644 --- a/src/test/regress/expected/xml.out +++ b/src/test/regress/expected/xml.out @@ -1167,6 +1167,10 @@ SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'), PASSING '10' COLUMNS a int PATH 'a'); ERROR: DEFAULT namespace is not supported +SELECT * FROM XMLTABLE('/' + PASSING '' + COLUMNS a text PATH 'foo/namespace::node()'); +ERROR: XMLTABLE cannot cast a namespace node to a non-XML result type -- used in prepare statements PREPARE pp AS SELECT xmltable.* diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out index c20caea08af..9f2b0904f67 100644 --- a/src/test/regress/expected/xml_1.out +++ b/src/test/regress/expected/xml_1.out @@ -1042,6 +1042,14 @@ LINE 3: PASSING '' + COLUMNS a text PATH 'foo/namespace::node()'); +ERROR: unsupported XML feature +LINE 2: PASSING '' + ^ +DETAIL: This functionality requires the server to be built with libxml support. +HINT: You need to rebuild PostgreSQL using --with-libxml. -- used in prepare statements PREPARE pp AS SELECT xmltable.* diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out index 1e763acb444..f11eebfd911 100644 --- a/src/test/regress/expected/xml_2.out +++ b/src/test/regress/expected/xml_2.out @@ -1147,6 +1147,10 @@ SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'), PASSING '10' COLUMNS a int PATH 'a'); ERROR: DEFAULT namespace is not supported +SELECT * FROM XMLTABLE('/' + PASSING '' + COLUMNS a text PATH 'foo/namespace::node()'); +ERROR: XMLTABLE cannot cast a namespace node to a non-XML result type -- used in prepare statements PREPARE pp AS SELECT xmltable.* diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql index e5eb0110e25..f7f5edc7171 100644 --- a/src/test/regress/sql/xml.sql +++ b/src/test/regress/sql/xml.sql @@ -401,6 +401,10 @@ SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'), PASSING '10' COLUMNS a int PATH 'a'); +SELECT * FROM XMLTABLE('/' + PASSING '' + COLUMNS a text PATH 'foo/namespace::node()'); + -- used in prepare statements PREPARE pp AS SELECT xmltable.*