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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2023-09-18 14:27:47 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2023-09-18 14:27:47 -0400 |
| commit | ec693a3f304cf91c717c0fe07abcd4185952fde5 (patch) | |
| tree | 628eabb3608d04514c134567d31aaab0b7d59e87 | |
| parent | 53630f12d39b9c5d98abb7bae4818715306422ed (diff) | |
| download | postgresql-ec693a3f304cf91c717c0fe07abcd4185952fde5.tar.gz postgresql-ec693a3f304cf91c717c0fe07abcd4185952fde5.zip | |
Don't crash if cursor_to_xmlschema is used on a non-data-returning Portal.
cursor_to_xmlschema() assumed that any Portal must have a tupDesc,
which is not so. Add a defensive check.
It's plausible that this mistake occurred because of the rather
poorly chosen name of the lookup function SPI_cursor_find(),
which in such cases is returning something that isn't very much
like a cursor. Add some documentation to try to forestall future
errors of the same ilk.
Report and patch by Boyu Yang (docs changes by me). Back-patch
to all supported branches.
Discussion: https://postgr.es/m/dd343010-c637-434c-a8cb-418f53bda3b8.yangboyu.yby@alibaba-inc.com
| -rw-r--r-- | doc/src/sgml/spi.sgml | 13 | ||||
| -rw-r--r-- | src/backend/utils/adt/xml.c | 4 |
2 files changed, 17 insertions, 0 deletions
diff --git a/doc/src/sgml/spi.sgml b/doc/src/sgml/spi.sgml index 16c3ab71e85..47f4b5b4317 100644 --- a/doc/src/sgml/spi.sgml +++ b/doc/src/sgml/spi.sgml @@ -2727,6 +2727,19 @@ Portal SPI_cursor_find(const char * <parameter>name</parameter>) <symbol>NULL</symbol> if none was found </para> </refsect1> + + <refsect1> + <title>Notes</title> + + <para> + Beware that this function can return a <type>Portal</type> object + that does not have cursor-like properties; for example it might not + return tuples. If you simply pass the <type>Portal</type> pointer + to other SPI functions, they can defend themselves against such + cases, but caution is appropriate when directly inspecting + the <type>Portal</type>. + </para> + </refsect1> </refentry> <!-- *********************************************** --> diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c index 866d0d649a4..2300c7ebf34 100644 --- a/src/backend/utils/adt/xml.c +++ b/src/backend/utils/adt/xml.c @@ -3012,6 +3012,10 @@ cursor_to_xmlschema(PG_FUNCTION_ARGS) ereport(ERROR, (errcode(ERRCODE_UNDEFINED_CURSOR), errmsg("cursor \"%s\" does not exist", name))); + if (portal->tupDesc == NULL) + ereport(ERROR, + (errcode(ERRCODE_INVALID_CURSOR_STATE), + errmsg("portal \"%s\" does not return tuples", name))); xmlschema = _SPI_strdup(map_sql_table_to_xmlschema(portal->tupDesc, InvalidOid, nulls, |