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Commit 6661030

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Richard Guo
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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 <gorbanyoves@basealt.ru> Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Alvaro Herrera <alvherre@kurilemu.de> Discussion: https://postgr.es/m/6bac9886-65bf-4cec-96bd-e304159f28db@basealt.ru Backpatch-through: 15
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+25
-4
lines changed

5 files changed

+25
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‎src/backend/parser/gram.y

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -13820,7 +13820,7 @@ xmltable_column_el:
1382013820
parser_errposition(defel->location)));
1382113821
fc->colexpr = defel->arg;
1382213822
}
13823-
else if (strcmp(defel->defname, "is_not_null") == 0)
13823+
else if (strcmp(defel->defname, "__pg__is_not_null") == 0)
1382413824
{
1382513825
if (nullability_seen)
1382613826
ereport(ERROR,
@@ -13863,13 +13863,20 @@ xmltable_column_option_list:
1386313863

1386413864
xmltable_column_option_el:
1386513865
IDENT b_expr
13866-
{ $$ = makeDefElem($1, $2, @1); }
13866+
{
13867+
if (strcmp($1, "__pg__is_not_null") == 0)
13868+
ereport(ERROR,
13869+
(errcode(ERRCODE_SYNTAX_ERROR),
13870+
errmsg("option name \"%s\" cannot be used in XMLTABLE", $1),
13871+
parser_errposition(@1)));
13872+
$$ = makeDefElem($1, $2, @1);
13873+
}
1386713874
| DEFAULT b_expr
1386813875
{ $$ = makeDefElem("default", $2, @1); }
1386913876
| NOT NULL_P
13870-
{ $$ = makeDefElem("is_not_null", (Node *) makeBoolean(true), @1); }
13877+
{ $$ = makeDefElem("__pg__is_not_null", (Node *) makeBoolean(true), @1); }
1387113878
| NULL_P
13872-
{ $$ = makeDefElem("is_not_null", (Node *) makeBoolean(false), @1); }
13879+
{ $$ = makeDefElem("__pg__is_not_null", (Node *) makeBoolean(false), @1); }
1387313880
;
1387413881

1387513882
xml_namespace_list:

‎src/test/regress/expected/xml.out

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1139,6 +1139,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
11391139
-- errors
11401140
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
11411141
ERROR: XMLTABLE function has 1 columns available but 2 columns specified
1142+
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
1143+
ERROR: option name "__pg__is_not_null" cannot be used in XMLTABLE
1144+
LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
1145+
^
11421146
-- XMLNAMESPACES tests
11431147
SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
11441148
'/zz:rows/zz:row'

‎src/test/regress/expected/xml_1.out

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -876,6 +876,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
876876
-- errors
877877
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
878878
ERROR: XMLTABLE function has 1 columns available but 2 columns specified
879+
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
880+
ERROR: option name "__pg__is_not_null" cannot be used in XMLTABLE
881+
LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
882+
^
879883
-- XMLNAMESPACES tests
880884
SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
881885
'/zz:rows/zz:row'

‎src/test/regress/expected/xml_2.out

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1125,6 +1125,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
11251125
-- errors
11261126
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
11271127
ERROR: XMLTABLE function has 1 columns available but 2 columns specified
1128+
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
1129+
ERROR: option name "__pg__is_not_null" cannot be used in XMLTABLE
1130+
LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
1131+
^
11281132
-- XMLNAMESPACES tests
11291133
SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
11301134
'/zz:rows/zz:row'

‎src/test/regress/sql/xml.sql

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -387,6 +387,8 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
387387
-- errors
388388
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
389389

390+
SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
391+
390392
-- XMLNAMESPACES tests
391393
SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
392394
'/zz:rows/zz:row'

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