Do not hold self-references. This then avoids the problem of having to

ensure that we only drop our self-reference exactly once.

To maintain the guarantee that an object won't go out of scope
unexpectedly while one of its event handlers is being called, the
event-calling functions now automatically obtain and drop extra
references.

1 files changed, 9 insertions, 6 deletions

diff --git a/src/core/hw.c b/src/core/hw.c
index 80cac99c..460ec583 100644
--- a/src/core/hw.c
+++ b/src/core/hw.c
@@ -22,7 +22,6 @@ static const char hw_msg[] = "Hello world!\n";
 static void hw_finished ( struct hw *hw, int rc ) {
 	xfer_nullify ( &hw->xfer );
 	xfer_close ( &hw->xfer, rc );
-	ref_put ( &hw->refcnt );
 }
 
 static void hw_xfer_close ( struct xfer_interface *xfer, int rc ) {
@@ -31,13 +30,14 @@ static void hw_xfer_close ( struct xfer_interface *xfer, int rc ) {
 	hw_finished ( hw, rc );
 }
 
-static int hw_xfer_request ( struct xfer_interface *xfer, off_t start __unused,
-			     int whence __unused, size_t len __unused ) {
+static void hw_xfer_request ( struct xfer_interface *xfer,
+			      off_t start __unused, int whence __unused,
+			      size_t len __unused ) {
 	struct hw *hw = container_of ( xfer, struct hw, xfer );
+	int rc;
 
-	xfer_deliver_raw ( xfer, hw_msg, sizeof ( hw_msg ) );
-	hw_finished ( hw, 0 );
-	return 0;
+	rc = xfer_deliver_raw ( xfer, hw_msg, sizeof ( hw_msg ) );
+	hw_finished ( hw, rc );
 }
 
 static struct xfer_interface_operations hw_xfer_operations = {
@@ -52,13 +52,16 @@ static struct xfer_interface_operations hw_xfer_operations = {
 static int hw_open ( struct xfer_interface *xfer, struct uri *uri __unused ) {
 	struct hw *hw;
 
+	/* Allocate and initialise structure */
 	hw = malloc ( sizeof ( *hw ) );
 	if ( ! hw )
 		return -ENOMEM;
 	memset ( hw, 0, sizeof ( *hw ) );
 	xfer_init ( &hw->xfer, &hw_xfer_operations, &hw->refcnt );
 
+	/* Attach parent interface, mortalise self, and return */
 	xfer_plug_plug ( &hw->xfer, xfer );
+	ref_put ( &hw->refcnt );
 	return 0;
 }