lib audit_logging: add _WARN_UNUSED_RESULT_

Have the compiler issue a warning when the return code from the API is
ignored.

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

Autobuild-User(master): Gary Lockyer <gary@samba.org>
Autobuild-Date(master): Wed Jul 25 09:28:31 CEST 2018 on sn-devel-144

2 files changed, 66 insertions, 47 deletions

diff --git a/lib/audit_logging/audit_logging.h b/lib/audit_logging/audit_logging.h
index 84738d2bb93..4203743f315 100644
--- a/lib/audit_logging/audit_logging.h
+++ b/lib/audit_logging/audit_logging.h
@@ -21,8 +21,9 @@
 #include <talloc.h>
 #include "lib/messaging/irpc.h"
 #include "lib/tsocket/tsocket.h"
+#include "lib/util/attr.h"
 
-char* audit_get_timestamp(TALLOC_CTX *frame);
+_WARN_UNUSED_RESULT_ char *audit_get_timestamp(TALLOC_CTX *frame);
 void audit_log_human_text(const char *prefix,
 			  const char *message,
 			  int debug_class,
@@ -50,43 +51,48 @@ void audit_message_send(struct imessaging_context *msg_ctx,
 			const char *server_name,
 			uint32_t message_type,
 			struct json_object *message);
-struct json_object json_new_object(void);
-struct json_object json_new_array(void);
+_WARN_UNUSED_RESULT_ struct json_object json_new_object(void);
+_WARN_UNUSED_RESULT_ struct json_object json_new_array(void);
 void json_free(struct json_object *object);
 void json_assert_is_array(struct json_object *array);
-bool json_is_invalid(struct json_object *object);
+_WARN_UNUSED_RESULT_ bool json_is_invalid(struct json_object *object);
 
-int json_add_int(struct json_object *object, const char *name, const int value);
-int json_add_bool(struct json_object *object,
-		  const char *name,
-		  const bool value);
-int json_add_string(struct json_object *object,
-		    const char *name,
-		    const char *value);
-int json_add_object(struct json_object *object,
-		    const char *name,
-		    struct json_object *value);
-int json_add_stringn(struct json_object *object,
-		     const char *name,
-		     const char *value,
-		     const size_t len);
-int json_add_version(struct json_object *object, int major, int minor);
-int json_add_timestamp(struct json_object *object);
-int json_add_address(struct json_object *object,
-		     const char *name,
-		     const struct tsocket_address *address);
-int json_add_sid(struct json_object *object,
-		 const char *name,
-		 const struct dom_sid *sid);
-int json_add_guid(struct json_object *object,
-		  const char *name,
-		  const struct GUID *guid);
+_WARN_UNUSED_RESULT_ int json_add_int(struct json_object *object,
+				      const char *name,
+				      const int value);
+_WARN_UNUSED_RESULT_ int json_add_bool(struct json_object *object,
+				       const char *name,
+				       const bool value);
+_WARN_UNUSED_RESULT_ int json_add_string(struct json_object *object,
+					 const char *name,
+					 const char *value);
+_WARN_UNUSED_RESULT_ int json_add_object(struct json_object *object,
+					 const char *name,
+					 struct json_object *value);
+_WARN_UNUSED_RESULT_ int json_add_stringn(struct json_object *object,
+					  const char *name,
+					  const char *value,
+					  const size_t len);
+_WARN_UNUSED_RESULT_ int json_add_version(struct json_object *object,
+					  int major,
+					  int minor);
+_WARN_UNUSED_RESULT_ int json_add_timestamp(struct json_object *object);
+_WARN_UNUSED_RESULT_ int json_add_address(
+    struct json_object *object,
+    const char *name,
+    const struct tsocket_address *address);
+_WARN_UNUSED_RESULT_ int json_add_sid(struct json_object *object,
+				      const char *name,
+				      const struct dom_sid *sid);
+_WARN_UNUSED_RESULT_ int json_add_guid(struct json_object *object,
+				       const char *name,
+				       const struct GUID *guid);
 
-struct json_object json_get_array(struct json_object *object,
-				  const char* name);
-struct json_object json_get_object(struct json_object *object,
-				   const char* name);
-char *json_to_string(TALLOC_CTX *mem_ctx,
-		     struct json_object *object);
+_WARN_UNUSED_RESULT_ struct json_object json_get_array(
+    struct json_object *object, const char *name);
+_WARN_UNUSED_RESULT_ struct json_object json_get_object(
+    struct json_object *object, const char *name);
+_WARN_UNUSED_RESULT_ char *json_to_string(TALLOC_CTX *mem_ctx,
+					  struct json_object *object);
 #endif
 #endif
diff --git a/lib/audit_logging/tests/audit_logging_test.c b/lib/audit_logging/tests/audit_logging_test.c
index 07c52eada39..acd2a4f697f 100644
--- a/lib/audit_logging/tests/audit_logging_test.c
+++ b/lib/audit_logging/tests/audit_logging_test.c
@@ -604,6 +604,7 @@ static void test_json_to_string(void **state)
 {
 	struct json_object object;
 	char *s = NULL;
+	int rc;
 
 	TALLOC_CTX *ctx = talloc_new(NULL);
 
@@ -613,7 +614,8 @@ static void test_json_to_string(void **state)
 	assert_string_equal("{}", s);
 	TALLOC_FREE(s);
 
-	json_add_string(&object, "name", "value");
+	rc = json_add_string(&object, "name", "value");
+	assert_int_equal(0, rc);
 	s = json_to_string(ctx, &object);
 	assert_string_equal("{\"name\": \"value\"}", s);
 	TALLOC_FREE(s);
@@ -641,6 +643,7 @@ static void test_json_get_array(void **state)
 	json_t *o = NULL;
 	struct json_object o1;
 	struct json_object o2;
+	int rc;
 
 	object = json_new_object();
 
@@ -651,9 +654,12 @@ static void test_json_get_array(void **state)
 	json_free(&array);
 
 	o1 = json_new_object();
-	json_add_string(&o1, "value", "value-one");
-	json_add_object(&stored_array, NULL, &o1);
-	json_add_object(&object, "stored_array", &stored_array);
+	rc = json_add_string(&o1, "value", "value-one");
+	assert_int_equal(0, rc);
+	rc = json_add_object(&stored_array, NULL, &o1);
+	assert_int_equal(0, rc);
+	rc = json_add_object(&object, "stored_array", &stored_array);
+	assert_int_equal(0, rc);
 
 	array = json_get_array(&object, "stored_array");
 	assert_true(array.valid);
@@ -679,11 +685,14 @@ static void test_json_get_array(void **state)
 	array = json_get_array(&object, "stored_array");
 	assert_true(json_is_array(array.root));
 	o2 = json_new_object();
-	json_add_string(&o2, "value", "value-two");
+	rc = json_add_string(&o2, "value", "value-two");
+	assert_int_equal(0, rc);
 	assert_true(o2.valid);
-	json_add_object(&array, NULL, &o2);
+	rc = json_add_object(&array, NULL, &o2);
+	assert_int_equal(0, rc);
 	assert_true(json_is_array(array.root));
-	json_add_object(&object, "stored_array", &array);
+	rc = json_add_object(&object, "stored_array", &array);
+	assert_int_equal(0, rc);
 	assert_true(json_is_array(array.root));
 
 	array = json_get_array(&object, "stored_array");
@@ -728,6 +737,7 @@ static void test_json_get_object(void **state)
 	struct json_object o2;
 	struct json_object o3;
 	json_t *value = NULL;
+	int rc;
 
 	object = json_new_object();
 
@@ -738,8 +748,10 @@ static void test_json_get_object(void **state)
 	json_free(&o1);
 
 	o1 = json_new_object();
-	json_add_string(&o1, "value", "value-one");
-	json_add_object(&object, "stored_object", &o1);
+	rc = json_add_string(&o1, "value", "value-one");
+	assert_int_equal(0, rc);
+	rc = json_add_object(&object, "stored_object", &o1);
+	assert_int_equal(0, rc);
 
 	o2 = json_get_object(&object, "stored_object");
 	assert_true(o2.valid);
@@ -752,9 +764,10 @@ static void test_json_get_object(void **state)
 
 	assert_string_equal("value-one", json_string_value(value));
 
-	json_add_string(&o2, "value", "value-two");
-	json_add_object(&object, "stored_object", &o2);
-
+	rc = json_add_string(&o2, "value", "value-two");
+	assert_int_equal(0, rc);
+	rc = json_add_object(&object, "stored_object", &o2);
+	assert_int_equal(0, rc);
 
 	o3 = json_get_object(&object, "stored_object");
 	assert_true(o3.valid);