Fix Assert failure in XMLTABLE parser

In an XMLTABLE expression, columns can be marked NOT NULL, and the
parser internally fabricates an option named "is_not_null" to
represent this.  However, the parser also allows users to specify
arbitrary option names.  This creates a conflict: a user can
explicitly use "is_not_null" as an option name and assign it a
non-Boolean value, which violates internal assumptions and triggers an
assertion failure.

To fix, this patch checks whether a user-supplied name collides with
the internally reserved option name and raises an error if so.
Additionally, the internal name is renamed to "__pg__is_not_null" to
further reduce the risk of collision with user-defined names.

Reported-by: Евгений Горбанев <[email protected]>
Author: Richard Guo <[email protected]>
Reviewed-by: Alvaro Herrera <[email protected]>
Discussion: https://postgr.es/m/6bac9886-65bf-4cec-96bd-e304159f28db@basealt.ru
Backpatch-through: 15

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 08e2195fa48a4e7bf30ed4a73487f35a4a8a8356..f230c5ff9e76c31cca55ff621e7fa20b125ab6d4 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -14048,7 +14048,7 @@ xmltable_column_el:
                                         parser_errposition(defel->location)));
                            fc->colexpr = defel->arg;
                        }
-                       else if (strcmp(defel->defname, "is_not_null") == 0)
+                       else if (strcmp(defel->defname, "__pg__is_not_null") == 0)
                        {
                            if (nullability_seen)
                                ereport(ERROR,
@@ -14091,13 +14091,20 @@ xmltable_column_option_list:
 
 xmltable_column_option_el:
            IDENT b_expr
-               { $$ = makeDefElem($1, $2, @1); }
+               {
+                   if (strcmp($1, "__pg__is_not_null") == 0)
+                       ereport(ERROR,
+                               (errcode(ERRCODE_SYNTAX_ERROR),
+                                errmsg("option name \"%s\" cannot be used in XMLTABLE", $1),
+                                parser_errposition(@1)));
+                   $$ = makeDefElem($1, $2, @1);
+               }
            | DEFAULT b_expr
                { $$ = makeDefElem("default", $2, @1); }
            | NOT NULL_P
-               { $$ = makeDefElem("is_not_null", (Node *) makeBoolean(true), @1); }
+               { $$ = makeDefElem("__pg__is_not_null", (Node *) makeBoolean(true), @1); }
            | NULL_P
-               { $$ = makeDefElem("is_not_null", (Node *) makeBoolean(false), @1); }
+               { $$ = makeDefElem("__pg__is_not_null", (Node *) makeBoolean(false), @1); }
            | PATH b_expr
                { $$ = makeDefElem("path", $2, @1); }
        ;

diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out
index 868479997d8acb4deef656d690b938e9466893a0..21677b609a6ca242282c4d91d73829e54d5f520d 100644 (file)
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -1373,6 +1373,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 ERROR:  XMLTABLE function has 1 columns available but 2 columns specified
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+ERROR:  option name "__pg__is_not_null" cannot be used in XMLTABLE
+LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
+                                                             ^
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'

diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out
index 4e8f65de0416b625ae2a9e1ded4ff2772e578a52..852444cb0527b8c609694c29c472ffced724b71e 100644 (file)
--- a/src/test/regress/expected/xml_1.out
+++ b/src/test/regress/expected/xml_1.out
@@ -1047,6 +1047,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 ERROR:  XMLTABLE function has 1 columns available but 2 columns specified
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+ERROR:  option name "__pg__is_not_null" cannot be used in XMLTABLE
+LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
+                                                             ^
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'

diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out
index 4e71cd4f26638eb8f57cd3ae7f13396506d4eeaf..e35fc58f098ecdc079b6a11cce38e2c5729c48de 100644 (file)
--- a/src/test/regress/expected/xml_2.out
+++ b/src/test/regress/expected/xml_2.out
@@ -1359,6 +1359,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 ERROR:  XMLTABLE function has 1 columns available but 2 columns specified
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+ERROR:  option name "__pg__is_not_null" cannot be used in XMLTABLE
+LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
+                                                             ^
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'

diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql
index 4c3520ce8980f71fddefbfd42ac29b1ac4b96b82..0ea4f508837cf660972e7351fa95371b47088e6f 100644 (file)
--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -435,6 +435,8 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'