Neaten up our choices of SQLSTATEs for XML-related errors.

When our XML-handling modules were first written, the SQL standard
lacked any error codes that were particularly intended for XML
error conditions.  Unsurprisingly, this led to some rather random
choices of errcodes in those modules.  Now the standard has a whole
SQLSTATE class, "Class 10 - XQuery Error", with a reasonably large
selection of relevant-looking errcodes.

In this patch I've chosen one fairly generic code defined by the
standard, 10608 = invalid_argument_for_xquery, and used it where
it seemed appropriate.  I've also made an effort to replace
ERRCODE_INTERNAL_ERROR everywhere it was not clearly reporting
a coding problem; in particular, many of the existing uses look
like they can fairly be reported as ERRCODE_OUT_OF_MEMORY.

It might be interesting to try to map libxml2's error codes into
the standard's new collection, but I've not undertaken that here.

Discussion: https://postgr.es/m/417250.1726341268@sss.pgh.pa.us

4 files changed, 27 insertions, 21 deletions

diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c
index 0fdf735fafe..ef78aa00c88 100644
--- a/contrib/xml2/xpath.c
+++ b/contrib/xml2/xpath.c
@@ -388,7 +388,7 @@ pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
 			/* compile the path */
 			comppath = xmlXPathCtxtCompile(workspace->ctxt, xpath);
 			if (comppath == NULL)
-				xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+				xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 							"XPath Syntax Error");
 
 			/* Now evaluate the path expression. */
@@ -652,7 +652,7 @@ xpath_table(PG_FUNCTION_ARGS)
 						comppath = xmlXPathCtxtCompile(ctxt, xpaths[j]);
 						if (comppath == NULL)
 							xml_ereport(xmlerrcxt, ERROR,
-										ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+										ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 										"XPath Syntax Error");
 
 						/* Now evaluate the path expression. */
diff --git a/contrib/xml2/xslt_proc.c b/contrib/xml2/xslt_proc.c
index f30a3a42c03..e761ca5cb5f 100644
--- a/contrib/xml2/xslt_proc.c
+++ b/contrib/xml2/xslt_proc.c
@@ -90,7 +90,7 @@ xslt_process(PG_FUNCTION_ARGS)
 								XML_PARSE_NOENT);
 
 		if (doctree == NULL)
-			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_XML_DOCUMENT,
 						"error parsing XML document");
 
 		/* Same for stylesheet */
@@ -99,14 +99,14 @@ xslt_process(PG_FUNCTION_ARGS)
 							  XML_PARSE_NOENT);
 
 		if (ssdoc == NULL)
-			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_XML_DOCUMENT,
 						"error parsing stylesheet as XML document");
 
 		/* After this call we need not free ssdoc separately */
 		stylesheet = xsltParseStylesheetDoc(ssdoc);
 
 		if (stylesheet == NULL)
-			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 						"failed to parse stylesheet");
 
 		xslt_ctxt = xsltNewTransformContext(stylesheet, doctree);
@@ -141,7 +141,7 @@ xslt_process(PG_FUNCTION_ARGS)
 										  NULL, NULL, xslt_ctxt);
 
 		if (restree == NULL)
-			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
+			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 						"failed to apply stylesheet");
 
 		resstat = xsltSaveResultToString(&resstr, &reslen, restree, stylesheet);
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 41b1a5c6b0b..040a8962639 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -344,7 +344,7 @@ xml_out_internal(xmltype *x, pg_enc target_encoding)
 	}
 
 	ereport(WARNING,
-			errcode(ERRCODE_INTERNAL_ERROR),
+			errcode(ERRCODE_DATA_CORRUPTED),
 			errmsg_internal("could not parse XML declaration in stored value"),
 			errdetail_for_xml_code(res_code));
 #endif
@@ -742,7 +742,7 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
 		{
 			/* If it's a document, saving is easy. */
 			if (xmlSaveDoc(ctxt, doc) == -1 || xmlerrcxt->err_occurred)
-				xml_ereport(xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+				xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
 							"could not save document to xmlBuffer");
 		}
 		else if (content_nodes != NULL)
@@ -785,7 +785,7 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
 					if (xmlSaveTree(ctxt, newline) == -1 || xmlerrcxt->err_occurred)
 					{
 						xmlFreeNode(newline);
-						xml_ereport(xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+						xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
 									"could not save newline to xmlBuffer");
 					}
 				}
@@ -793,7 +793,7 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
 				if (xmlSaveTree(ctxt, node) == -1 || xmlerrcxt->err_occurred)
 				{
 					xmlFreeNode(newline);
-					xml_ereport(xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+					xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
 								"could not save content to xmlBuffer");
 				}
 			}
@@ -1004,7 +1004,7 @@ xmlpi(const char *target, text *arg, bool arg_is_null, bool *result_is_null)
 
 	if (pg_strcasecmp(target, "xml") == 0)
 		ereport(ERROR,
-				(errcode(ERRCODE_SYNTAX_ERROR), /* really */
+				(errcode(ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION),
 				 errmsg("invalid XML processing instruction"),
 				 errdetail("XML processing instruction target name cannot be \"%s\".", target)));
 
@@ -4383,7 +4383,7 @@ xpath_internal(text *xpath_expr_text, xmltype *data, ArrayType *namespaces,
 	xpath_len = VARSIZE_ANY_EXHDR(xpath_expr_text);
 	if (xpath_len == 0)
 		ereport(ERROR,
-				(errcode(ERRCODE_DATA_EXCEPTION),
+				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_XQUERY),
 				 errmsg("empty XPath expression")));
 
 	string = pg_xmlCharStrndup(datastr, len);
@@ -4456,7 +4456,7 @@ xpath_internal(text *xpath_expr_text, xmltype *data, ArrayType *namespaces,
 		 */
 		xpathcomp = xmlXPathCtxtCompile(xpathctx, xpath_expr);
 		if (xpathcomp == NULL || xmlerrcxt->err_occurred)
-			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 						"invalid XPath expression");
 
 		/*
@@ -4468,7 +4468,7 @@ xpath_internal(text *xpath_expr_text, xmltype *data, ArrayType *namespaces,
 		 */
 		xpathobj = xmlXPathCompiledEval(xpathcomp, xpathctx);
 		if (xpathobj == NULL || xmlerrcxt->err_occurred)
-			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 						"could not create XPath object");
 
 		/*
@@ -4798,7 +4798,7 @@ XmlTableSetNamespace(TableFuncScanState *state, const char *name, const char *ur
 	if (xmlXPathRegisterNs(xtCxt->xpathcxt,
 						   pg_xmlCharStrndup(name, strlen(name)),
 						   pg_xmlCharStrndup(uri, strlen(uri))))
-		xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_DATA_EXCEPTION,
+		xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 					"could not set XML namespace");
 #else
 	NO_XML_SUPPORT();
@@ -4820,7 +4820,7 @@ XmlTableSetRowFilter(TableFuncScanState *state, const char *path)
 
 	if (*path == '\0')
 		ereport(ERROR,
-				(errcode(ERRCODE_DATA_EXCEPTION),
+				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_XQUERY),
 				 errmsg("row path filter must not be empty string")));
 
 	xstr = pg_xmlCharStrndup(path, strlen(path));
@@ -4830,7 +4830,7 @@ XmlTableSetRowFilter(TableFuncScanState *state, const char *path)
 
 	xtCxt->xpathcomp = xmlXPathCtxtCompile(xtCxt->xpathcxt, xstr);
 	if (xtCxt->xpathcomp == NULL || xtCxt->xmlerrcxt->err_occurred)
-		xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_SYNTAX_ERROR,
+		xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 					"invalid XPath expression");
 #else
 	NO_XML_SUPPORT();
@@ -4854,7 +4854,7 @@ XmlTableSetColumnFilter(TableFuncScanState *state, const char *path, int colnum)
 
 	if (*path == '\0')
 		ereport(ERROR,
-				(errcode(ERRCODE_DATA_EXCEPTION),
+				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_XQUERY),
 				 errmsg("column path filter must not be empty string")));
 
 	xstr = pg_xmlCharStrndup(path, strlen(path));
@@ -4864,7 +4864,7 @@ XmlTableSetColumnFilter(TableFuncScanState *state, const char *path, int colnum)
 
 	xtCxt->xpathscomp[colnum] = xmlXPathCtxtCompile(xtCxt->xpathcxt, xstr);
 	if (xtCxt->xpathscomp[colnum] == NULL || xtCxt->xmlerrcxt->err_occurred)
-		xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_DATA_EXCEPTION,
+		xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 					"invalid XPath expression");
 #else
 	NO_XML_SUPPORT();
@@ -4891,7 +4891,7 @@ XmlTableFetchRow(TableFuncScanState *state)
 	{
 		xtCxt->xpathobj = xmlXPathCompiledEval(xtCxt->xpathcomp, xtCxt->xpathcxt);
 		if (xtCxt->xpathobj == NULL || xtCxt->xmlerrcxt->err_occurred)
-			xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+			xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 						"could not create XPath object");
 
 		xtCxt->row_count = 0;
@@ -4955,7 +4955,7 @@ XmlTableGetValue(TableFuncScanState *state, int colnum,
 		/* Evaluate column path */
 		xpathobj = xmlXPathCompiledEval(xtCxt->xpathscomp[colnum], xtCxt->xpathcxt);
 		if (xpathobj == NULL || xtCxt->xmlerrcxt->err_occurred)
-			xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+			xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INVALID_ARGUMENT_FOR_XQUERY,
 						"could not create XPath object");
 
 		/*
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
index b43a24d4bcd..97d91eb1e9e 100644
--- a/src/backend/utils/errcodes.txt
+++ b/src/backend/utils/errcodes.txt
@@ -141,6 +141,12 @@ Section: Class 0Z - Diagnostics Exception
 0Z000    E    ERRCODE_DIAGNOSTICS_EXCEPTION                                  diagnostics_exception
 0Z002    E    ERRCODE_STACKED_DIAGNOSTICS_ACCESSED_WITHOUT_ACTIVE_HANDLER    stacked_diagnostics_accessed_without_active_handler
 
+Section: Class 10 - XQuery Error
+
+# recent SQL versions define quite a few codes in this class, but for now
+# we are only using this generic one
+10608    E    ERRCODE_INVALID_ARGUMENT_FOR_XQUERY                            invalid_argument_for_xquery
+
 Section: Class 20 - Case Not Found
 
 20000    E    ERRCODE_CASE_NOT_FOUND                                         case_not_found