fix: add NULL argument handling for PUT and PUT_LINE

Handle NULL arguments in ora_dbms_output_put and ora_dbms_output_put_line
by treating NULL as empty string, matching Oracle's behavior.

- Check PG_ARGISNULL(0) before calling PG_GETARG_TEXT_PP
- Treat NULL as empty string (appends nothing for PUT, empty line for PUT_LINE)
- Add regression tests for NULL handling in both functions

Author: rophy

contrib/ivorysql_ora/src/builtin_functions/dbms_output.c

@@ -307,19 +307,25 @@ ora_dbms_output_disable(PG_FUNCTION_ARGS)
  *
  * Output a line to the buffer (with newline).
  * If there's pending PUT text, append it first (Oracle behavior).
+ * Oracle behavior: NULL is treated as empty string.
  */
 Datum
 ora_dbms_output_put_line(PG_FUNCTION_ARGS)
 {
-	text	   *line_text;
 	char	   *line_str;
 
 	/* Silently discard if buffer not enabled (Oracle behavior) */
 	if (output_buffer == NULL || !output_buffer->enabled)
 		PG_RETURN_VOID();
 
-	line_text = PG_GETARG_TEXT_PP(0);
-	line_str = text_to_cstring(line_text);
+	/* Handle NULL argument - treat as empty string (Oracle behavior) */
+	if (PG_ARGISNULL(0))
+		line_str = "";
+	else
+	{
+		text	   *line_text = PG_GETARG_TEXT_PP(0);
+		line_str = text_to_cstring(line_text);
+	}
 
 	/* If there's pending PUT text, append it first (Oracle behavior) */
 	if (output_buffer->current_line->len > 0)
@@ -342,19 +348,25 @@ ora_dbms_output_put_line(PG_FUNCTION_ARGS)
  *
  * Output text without newline (accumulates in current_line).
  * Oracle behavior: not retrievable until NEW_LINE or PUT_LINE is called.
+ * Oracle behavior: NULL is treated as empty string (appends nothing).
  */
 Datum
 ora_dbms_output_put(PG_FUNCTION_ARGS)
 {
-	text	   *text_arg;
 	char	   *str;
 
 	/* Silently discard if buffer not enabled */
 	if (output_buffer == NULL || !output_buffer->enabled)
 		PG_RETURN_VOID();
 
-	text_arg = PG_GETARG_TEXT_PP(0);
-	str = text_to_cstring(text_arg);
+	/* Handle NULL argument - treat as empty string (Oracle behavior) */
+	if (PG_ARGISNULL(0))
+		str = "";
+	else
+	{
+		text	   *text_arg = PG_GETARG_TEXT_PP(0);
+		str = text_to_cstring(text_arg);
+	}
 
 	/* Accumulate in current_line without creating a line yet */
 	appendStringInfoString(output_buffer->current_line, str);

src/pl/plisql/src/expected/plisql_dbms_output.out

@@ -16,6 +16,11 @@ CALL dbms_output.put_line(NULL);
 CALL dbms_output.put('First part');
 CALL dbms_output.put(' second part');
 CALL dbms_output.new_line();
+-- Test PUT with NULL (should append nothing)
+CALL dbms_output.put('Before NULL');
+CALL dbms_output.put(NULL);
+CALL dbms_output.put(' - After NULL');
+CALL dbms_output.new_line();
 -- Test multiple PUT calls
 CALL dbms_output.put('Line');
 CALL dbms_output.put(' with');

src/pl/plisql/src/sql/plisql_dbms_output.sql

@@ -22,6 +22,12 @@ CALL dbms_output.put('First part');
 CALL dbms_output.put(' second part');
 CALL dbms_output.new_line();
 
+-- Test PUT with NULL (should append nothing)
+CALL dbms_output.put('Before NULL');
+CALL dbms_output.put(NULL);
+CALL dbms_output.put(' - After NULL');
+CALL dbms_output.new_line();
+
 -- Test multiple PUT calls
 CALL dbms_output.put('Line');
 CALL dbms_output.put(' with');