v6-0002-error-safe-for-casting-character-to-other-types-per-pg_ca.patch

From 4d0fc95b1fc9690b7a631b98d3d0f392a2a293bd Mon Sep 17 00:00:00 2001
From: jian he <jian.universality@gmail.com>
Date: Sat, 9 Aug 2025 17:49:04 +0800
Subject: [PATCH v6 02/18] error safe for casting character to other types per
 pg_cast

select castsource::regtype, casttarget::regtype, castfunc,
castcontext,castmethod, pp.prosrc, pp.proname from pg_cast pc join pg_proc pp on
pp.oid = pc.castfunc and pc.castfunc > 0
and castsource::regtype ='character'::regtype
order by castsource::regtype;

 castsource |    casttarget     | castfunc | castcontext | castmethod |   prosrc    | proname
------------+-------------------+----------+-------------+------------+-------------+---------
 character  | text              |      401 | i           | f          | rtrim1      | text
 character  | character varying |      401 | i           | f          | rtrim1      | text
 character  | "char"            |      944 | a           | f          | text_char   | char
 character  | name              |      409 | i           | f          | bpchar_name | name
 character  | xml               |     2896 | e           | f          | texttoxml   | xml
 character  | character         |      668 | i           | f          | bpchar      | bpchar
(6 rows)

only texttoxml, bpchar(PG_FUNCTION_ARGS) need take care of error handling.
other already error safe.
---
 src/backend/executor/execExprInterp.c |  2 +-
 src/backend/utils/adt/varchar.c       |  2 +-
 src/backend/utils/adt/xml.c           | 12 ++++++++----
 src/include/utils/xml.h               |  2 +-
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 0e1a74976f7..67f4e00eac4 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -4542,7 +4542,7 @@ ExecEvalXmlExpr(ExprState *state, ExprEvalStep *op)
 
 				*op->resvalue = PointerGetDatum(xmlparse(data,
 														 xexpr->xmloption,
-														 preserve_whitespace));
+														 preserve_whitespace, NULL));
 				*op->resnull = false;
 			}
 			break;
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 3f40c9da1a0..5cb5c8c46f9 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -307,7 +307,7 @@ bpchar(PG_FUNCTION_ARGS)
 		{
 			for (i = maxmblen; i < len; i++)
 				if (s[i] != ' ')
-					ereport(ERROR,
+					ereturn(fcinfo->context, (Datum) 0,
 							(errcode(ERRCODE_STRING_DATA_RIGHT_TRUNCATION),
 							 errmsg("value too long for type character(%d)",
 									maxlen)));
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 182e8f75db7..1d423e0f9a3 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -660,7 +660,7 @@ texttoxml(PG_FUNCTION_ARGS)
 {
 	text	   *data = PG_GETARG_TEXT_PP(0);
 
-	PG_RETURN_XML_P(xmlparse(data, xmloption, true));
+	PG_RETURN_XML_P(xmlparse(data, xmloption, true, fcinfo->context));
 }
 
 
@@ -1029,14 +1029,18 @@ xmlelement(XmlExpr *xexpr,
 
 
 xmltype *
-xmlparse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace)
+xmlparse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace, Node *escontext)
 {
 #ifdef USE_LIBXML
 	xmlDocPtr	doc;
 
 	doc = xml_parse(data, xmloption_arg, preserve_whitespace,
-					GetDatabaseEncoding(), NULL, NULL, NULL);
-	xmlFreeDoc(doc);
+					GetDatabaseEncoding(), NULL, NULL, escontext);
+	if (doc)
+		xmlFreeDoc(doc);
+
+	if (SOFT_ERROR_OCCURRED(escontext))
+		return NULL;
 
 	return (xmltype *) data;
 #else
diff --git a/src/include/utils/xml.h b/src/include/utils/xml.h
index 0d7a816b9f9..b3d3f11fac4 100644
--- a/src/include/utils/xml.h
+++ b/src/include/utils/xml.h
@@ -73,7 +73,7 @@ extern xmltype *xmlconcat(List *args);
 extern xmltype *xmlelement(XmlExpr *xexpr,
 						   Datum *named_argvalue, bool *named_argnull,
 						   Datum *argvalue, bool *argnull);
-extern xmltype *xmlparse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace);
+extern xmltype *xmlparse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace, Node *escontext);
 extern xmltype *xmlpi(const char *target, text *arg, bool arg_is_null, bool *result_is_null);
 extern xmltype *xmlroot(xmltype *data, text *version, int standalone);
 extern bool xml_is_document(xmltype *arg);
-- 
2.34.1