injection_points: Add variant for injection_point_attach()

This new function is able to take in input more data than the existing
injection_point_attach():
- A library name.
- A function name.
- Some private data.

This gives more flexibility for tests so as these would not need to
reinvent a wrapper for InjectionPointAttach() when attaching a callback
from a library other than "injection_points".  injection_point_detach()
can be used with both versions of injection_point_attach().

Author: Rahila Syed <rahilasyed.90@gmail.com>
Reviewed-by: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAH2L28sOG2b_TKkZU51dy+pWJtny1mqDmeFiFoUASGa0X0iiKQ@mail.gmail.com

src/test/modules/injection_points/expected/injection_points.out

@@ -307,7 +307,40 @@ SELECT injection_points_detach('TestConditionLocal1');
  
 (1 row)
 
--- No points should be left around.
+-- Function variant for attach.
+SELECT injection_points_attach(NULL, NULL, NULL, NULL);
+ERROR:  injection point name cannot be NULL
+SELECT injection_points_attach('injection_points', NULL, NULL, NULL);
+ERROR:  injection point library cannot be NULL
+SELECT injection_points_attach('injection_points', 'injection_notice', NULL, NULL);
+ERROR:  injection point function cannot be NULL
+SELECT injection_points_attach('TestInjectionNoticeFunc',
+  'injection_points', 'injection_notice', NULL);
+ injection_points_attach 
+-------------------------
+ 
+(1 row)
+
+SELECT point_name, library, function FROM injection_points_list()
+  ORDER BY point_name COLLATE "C";
+       point_name        |     library      |     function     
+-------------------------+------------------+------------------
+ TestInjectionNoticeFunc | injection_points | injection_notice
+(1 row)
+
+SELECT injection_points_run('TestInjectionNoticeFunc', NULL); -- notice
+NOTICE:  notice triggered for injection point TestInjectionNoticeFunc
+ injection_points_run 
+----------------------
+ 
+(1 row)
+
+SELECT injection_points_detach('TestInjectionNoticeFunc');
+ injection_points_detach 
+-------------------------
+ 
+(1 row)
+
 SELECT point_name, library, function FROM injection_points_list()
   ORDER BY point_name COLLATE "C";
  point_name | library | function 

src/test/modules/injection_points/injection_points--1.0.sql

@@ -14,6 +14,18 @@ RETURNS void
 AS 'MODULE_PATHNAME', 'injection_points_attach'
 LANGUAGE C STRICT PARALLEL UNSAFE;
 
+--
+-- injection_points_attach()
+--
+-- Attaches a function to the given injection point, with library name,
+-- function name and private data.
+--
+CREATE FUNCTION injection_points_attach(IN point_name TEXT,
+    IN library_name TEXT, IN function_name TEXT, IN private_data BYTEA)
+RETURNS void
+AS 'MODULE_PATHNAME', 'injection_points_attach_func'
+LANGUAGE C PARALLEL UNSAFE;
+
 --
 -- injection_points_load()
 --

src/test/modules/injection_points/injection_points.c

@@ -391,6 +391,47 @@ injection_points_attach(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
+/*
+ * SQL function for creating an injection point with library name, function
+ * name and private data.
+ */
+PG_FUNCTION_INFO_V1(injection_points_attach_func);
+Datum
+injection_points_attach_func(PG_FUNCTION_ARGS)
+{
+	char	   *name;
+	char	   *lib_name;
+	char	   *function;
+	bytea	   *private_data = NULL;
+	int			private_data_size = 0;
+
+	if (PG_ARGISNULL(0))
+		elog(ERROR, "injection point name cannot be NULL");
+	if (PG_ARGISNULL(1))
+		elog(ERROR, "injection point library cannot be NULL");
+	if (PG_ARGISNULL(2))
+		elog(ERROR, "injection point function cannot be NULL");
+
+	name = text_to_cstring(PG_GETARG_TEXT_PP(0));
+	lib_name = text_to_cstring(PG_GETARG_TEXT_PP(1));
+	function = text_to_cstring(PG_GETARG_TEXT_PP(2));
+
+	if (!PG_ARGISNULL(3))
+	{
+		private_data = PG_GETARG_BYTEA_PP(3);
+		private_data_size = VARSIZE_ANY_EXHDR(private_data);
+	}
+
+	pgstat_report_inj_fixed(1, 0, 0, 0, 0);
+	if (private_data != NULL)
+		InjectionPointAttach(name, lib_name, function, VARDATA_ANY(private_data),
+							 private_data_size);
+	else
+		InjectionPointAttach(name, lib_name, function, NULL,
+							 0);
+	PG_RETURN_VOID();
+}
+
 /*
  * SQL function for loading an injection point.
  */

src/test/modules/injection_points/sql/injection_points.sql

@@ -88,7 +88,16 @@ SELECT injection_points_detach('TestConditionError');
 SELECT injection_points_attach('TestConditionLocal1', 'error');
 SELECT injection_points_detach('TestConditionLocal1');
 
--- No points should be left around.
+-- Function variant for attach.
+SELECT injection_points_attach(NULL, NULL, NULL, NULL);
+SELECT injection_points_attach('injection_points', NULL, NULL, NULL);
+SELECT injection_points_attach('injection_points', 'injection_notice', NULL, NULL);
+SELECT injection_points_attach('TestInjectionNoticeFunc',
+  'injection_points', 'injection_notice', NULL);
+SELECT point_name, library, function FROM injection_points_list()
+  ORDER BY point_name COLLATE "C";
+SELECT injection_points_run('TestInjectionNoticeFunc', NULL); -- notice
+SELECT injection_points_detach('TestInjectionNoticeFunc');
 SELECT point_name, library, function FROM injection_points_list()
   ORDER BY point_name COLLATE "C";