Merge two copies of tuple-building code in pltcl.c.

Make pltcl_trigger_handler() construct modified tuples using
pltcl_build_tuple_result(), rather than its own copy of essentially
the same logic.  This results in slightly different message wording for
the error cases, and in one case a different SQLSTATE, but it seems
unlikely that any existing applications are depending on any of those
details.

While at it, fix a typo in commit 26abb50c: pltcl_build_tuple_result was
applying encoding conversion in the wrong direction.  That would be a
back-patchable bug fix, except the code hasn't shipped yet.

Jim Nasby, reviewed by me

Discussion: https://postgr.es/m/d2c6425a-d9e0-f034-f774-4a872c234d89@BlueTreble.com

src/pl/tcl/pltcl.c

@@ -202,6 +202,9 @@ typedef struct pltcl_call_state
 	/* Call info struct, or NULL in a trigger */
 	FunctionCallInfo fcinfo;
 
+	/* Trigger data, if we're in a normal (not event) trigger; else NULL */
+	TriggerData *trigdata;
+
 	/* Function we're executing (NULL if not yet identified) */
 	pltcl_proc_desc *prodesc;
 
@@ -1000,8 +1003,8 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS, pltcl_call_state *call_state,
 	const char *result;
 	int			result_Objc;
 	Tcl_Obj   **result_Objv;
-	Datum	   *values;
-	bool	   *nulls;
+
+	call_state->trigdata = trigdata;
 
 	/* Connect to SPI manager */
 	if (SPI_connect() != SPI_OK_CONNECT)
@@ -1018,7 +1021,7 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS, pltcl_call_state *call_state,
 
 	interp = prodesc->interp_desc->interp;
 
-	tupdesc = trigdata->tg_relation->rd_att;
+	tupdesc = RelationGetDescr(trigdata->tg_relation);
 
 	/************************************************************
 	 * Create the tcl command to call the internal
@@ -1219,69 +1222,9 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS, pltcl_call_state *call_state,
 				 errmsg("could not split return value from trigger: %s",
 						utf_u2e(Tcl_GetStringResult(interp)))));
 
-	if (result_Objc % 2 != 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-		 errmsg("trigger's return list must have even number of elements")));
-
-	values = (Datum *) palloc0(tupdesc->natts * sizeof(Datum));
-	nulls = (bool *) palloc(tupdesc->natts * sizeof(bool));
-	memset(nulls, true, tupdesc->natts * sizeof(bool));
-
-	for (i = 0; i < result_Objc; i += 2)
-	{
-		char	   *ret_name = utf_u2e(Tcl_GetString(result_Objv[i]));
-		char	   *ret_value = utf_u2e(Tcl_GetString(result_Objv[i + 1]));
-		int			attnum;
-		Oid			typinput;
-		Oid			typioparam;
-		FmgrInfo	finfo;
-
-		/************************************************************
-		 * Get the attribute number
-		 *
-		 * We silently ignore ".tupno", if it's present but doesn't match
-		 * any actual output column.  This allows direct use of a row
-		 * returned by pltcl_set_tuple_values().
-		 ************************************************************/
-		attnum = SPI_fnumber(tupdesc, ret_name);
-		if (attnum == SPI_ERROR_NOATTRIBUTE)
-		{
-			if (strcmp(ret_name, ".tupno") == 0)
-				continue;
-			ereport(ERROR,
-					(errcode(ERRCODE_UNDEFINED_COLUMN),
-					 errmsg("unrecognized attribute \"%s\"",
-							ret_name)));
-		}
-		if (attnum <= 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					 errmsg("cannot set system attribute \"%s\"",
-							ret_name)));
-
-		/************************************************************
-		 * Lookup the attribute type's input function
-		 ************************************************************/
-		getTypeInputInfo(tupdesc->attrs[attnum - 1]->atttypid,
-						 &typinput, &typioparam);
-		fmgr_info(typinput, &finfo);
-
-		/************************************************************
-		 * Set the attribute to NOT NULL and convert the contents
-		 ************************************************************/
-		values[attnum - 1] = InputFunctionCall(&finfo,
-											   ret_value,
-											   typioparam,
-									  tupdesc->attrs[attnum - 1]->atttypmod);
-		nulls[attnum - 1] = false;
-	}
-
-	/* Build the modified tuple to return */
-	rettup = heap_form_tuple(tupdesc, values, nulls);
-
-	pfree(values);
-	pfree(nulls);
+	/* Convert function result to tuple */
+	rettup = pltcl_build_tuple_result(interp, result_Objv, result_Objc,
+									  call_state);
 
 	return rettup;
 }
@@ -3014,6 +2957,8 @@ pltcl_build_tuple_argument(HeapTuple tuple, TupleDesc tupdesc)
  * pltcl_build_tuple_result() - Build a tuple of function's result rowtype
  *				  from a Tcl list of column names and values
  *
+ * In a trigger function, we build a tuple of the trigger table's rowtype.
+ *
  * Note: this function leaks memory.  Even if we made it clean up its own
  * mess, there's no way to prevent the datatype input functions it calls
  * from leaking.  Run it in a short-lived context, unless we're about to
@@ -3023,24 +2968,44 @@ static HeapTuple
 pltcl_build_tuple_result(Tcl_Interp *interp, Tcl_Obj **kvObjv, int kvObjc,
 						 pltcl_call_state *call_state)
 {
+	TupleDesc	tupdesc;
+	AttInMetadata *attinmeta;
 	char	  **values;
 	int			i;
 
+	if (call_state->ret_tupdesc)
+	{
+		tupdesc = call_state->ret_tupdesc;
+		attinmeta = call_state->attinmeta;
+	}
+	else if (call_state->trigdata)
+	{
+		tupdesc = RelationGetDescr(call_state->trigdata->tg_relation);
+		attinmeta = TupleDescGetAttInMetadata(tupdesc);
+	}
+	else
+	{
+		elog(ERROR, "PL/Tcl function does not return a tuple");
+		tupdesc = NULL;			/* keep compiler quiet */
+		attinmeta = NULL;
+	}
+
+	values = (char **) palloc0(tupdesc->natts * sizeof(char *));
+
 	if (kvObjc % 2 != 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 		errmsg("column name/value list must have even number of elements")));
 
-	values = (char **) palloc0(call_state->ret_tupdesc->natts * sizeof(char *));
-
 	for (i = 0; i < kvObjc; i += 2)
 	{
-		char	   *fieldName = utf_e2u(Tcl_GetString(kvObjv[i]));
-		int			attn = SPI_fnumber(call_state->ret_tupdesc, fieldName);
+		char	   *fieldName = utf_u2e(Tcl_GetString(kvObjv[i]));
+		int			attn = SPI_fnumber(tupdesc, fieldName);
 
 		/*
-		 * As in pltcl_trigger_handler, silently ignore ".tupno" if it's in
-		 * the list but doesn't match any column name.
+		 * We silently ignore ".tupno", if it's present but doesn't match any
+		 * actual output column.  This allows direct use of a row returned by
+		 * pltcl_set_tuple_values().
 		 */
 		if (attn == SPI_ERROR_NOATTRIBUTE)
 		{
@@ -3058,10 +3023,10 @@ pltcl_build_tuple_result(Tcl_Interp *interp, Tcl_Obj **kvObjv, int kvObjc,
 					 errmsg("cannot set system attribute \"%s\"",
 							fieldName)));
 
-		values[attn - 1] = utf_e2u(Tcl_GetString(kvObjv[i + 1]));
+		values[attn - 1] = utf_u2e(Tcl_GetString(kvObjv[i + 1]));
 	}
 
-	return BuildTupleFromCStrings(call_state->attinmeta, values);
+	return BuildTupleFromCStrings(attinmeta, values);
 }
 
 /**********************************************************************