s4-messaging: fixed the removal of messaging sockets in child tasks

when a child task exits we were firing a destructor on any inherited
messaging contexts, which could trigger a removal of the parents
message socket and messaging database entry.

This adds a new auto_remove flag to imessaging_init(), and exposes the
cleanup code for use by the stream service.

Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>

Autobuild-User: Andrew Tridgell <tridge@samba.org>
Autobuild-Date: Fri Jul 22 08:09:06 CEST 2011 on sn-devel-104

5 files changed, 33 insertions, 22 deletions

diff --git a/source4/lib/messaging/messaging.c b/source4/lib/messaging/messaging.c
index 484f22b2ee..ccc60032a6 100644
--- a/source4/lib/messaging/messaging.c
+++ b/source4/lib/messaging/messaging.c
@@ -541,10 +541,11 @@ NTSTATUS imessaging_send_ptr(struct imessaging_context *msg, struct server_id se
 
 
 /*
-  destroy the messaging context
+  remove our messaging socket and database entry
 */
-static int imessaging_destructor(struct imessaging_context *msg)
+int imessaging_cleanup(struct imessaging_context *msg)
 {
+	DEBUG(5,("imessaging: cleaning up %s\n", msg->path));
 	unlink(msg->path);
 	while (msg->names && msg->names[0]) {
 		irpc_remove_name(msg, msg->names[0]);
@@ -554,11 +555,17 @@ static int imessaging_destructor(struct imessaging_context *msg)
 
 /*
   create the listening socket and setup the dispatcher
+
+  use temporary=true when you want a destructor to remove the
+  associated messaging socket and database entry on talloc free. Don't
+  use this in processes that may fork and a child may talloc free this
+  memory
 */
 struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
-					 const char *dir,
-					 struct server_id server_id, 
-					 struct tevent_context *ev)
+					   const char *dir,
+					   struct server_id server_id,
+					   struct tevent_context *ev,
+					   bool auto_remove)
 {
 	struct imessaging_context *msg;
 	NTSTATUS status;
@@ -622,7 +629,9 @@ struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
 				       EVENT_FD_READ, imessaging_handler, msg);
 	tevent_fd_set_auto_close(msg->event.fde);
 
-	talloc_set_destructor(msg, imessaging_destructor);
+	if (auto_remove) {
+		talloc_set_destructor(msg, imessaging_cleanup);
+	}
 	
 	imessaging_register(msg, NULL, MSG_PING, ping_message);
 	imessaging_register(msg, NULL, MSG_IRPC, irpc_handler);
@@ -641,7 +650,7 @@ struct imessaging_context *imessaging_client_init(TALLOC_CTX *mem_ctx,
 	struct server_id id;
 	ZERO_STRUCT(id);
 	id.pid = random() % 0x10000000;
-	return imessaging_init(mem_ctx, dir, id, ev);
+	return imessaging_init(mem_ctx, dir, id, ev, true);
 }
 /*
   a list of registered irpc server functions
diff --git a/source4/lib/messaging/messaging.h b/source4/lib/messaging/messaging.h
index eb8a8abc79..e51590fe74 100644
--- a/source4/lib/messaging/messaging.h
+++ b/source4/lib/messaging/messaging.h
@@ -54,9 +54,11 @@ NTSTATUS imessaging_register(struct imessaging_context *msg, void *private_data,
 NTSTATUS imessaging_register_tmp(struct imessaging_context *msg, void *private_data,
 				msg_callback_t fn, uint32_t *msg_type);
 struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
-					 const char *dir,
-					 struct server_id server_id,
-					 struct tevent_context *ev);
+					   const char *dir,
+					   struct server_id server_id,
+					   struct tevent_context *ev,
+					   bool auto_remove);
+int imessaging_cleanup(struct imessaging_context *msg);
 struct imessaging_context *imessaging_client_init(TALLOC_CTX *mem_ctx,
 					 const char *dir,
 					 struct tevent_context *ev);
diff --git a/source4/lib/messaging/pymessaging.c b/source4/lib/messaging/pymessaging.c
index cafd45beae..4f90db59f2 100644
--- a/source4/lib/messaging/pymessaging.c
+++ b/source4/lib/messaging/pymessaging.c
@@ -96,13 +96,13 @@ static PyObject *py_imessaging_connect(PyTypeObject *self, PyObject *args, PyObj
 			return NULL;
 
 		ret->msg_ctx = imessaging_init(ret->mem_ctx,
-					    imessaging_path,
-					    server_id,
-					    ev);
+					       imessaging_path,
+					       server_id,
+					       ev, true);
 	} else {
 		ret->msg_ctx = imessaging_client_init(ret->mem_ctx,
-					    imessaging_path,
-					    ev);
+						      imessaging_path,
+						      ev);
 	}
 
 	if (ret->msg_ctx == NULL) {
diff --git a/source4/lib/messaging/tests/irpc.c b/source4/lib/messaging/tests/irpc.c
index cfa2bcb91e..554a7efa99 100644
--- a/source4/lib/messaging/tests/irpc.c
+++ b/source4/lib/messaging/tests/irpc.c
@@ -249,14 +249,14 @@ static bool irpc_setup(struct torture_context *tctx, void **_data)
 		       imessaging_init(tctx,
 				      lpcfg_imessaging_path(tctx, tctx->lp_ctx),
 				      cluster_id(0, MSG_ID1),
-				      data->ev),
+				      data->ev, true),
 		       "Failed to init first messaging context");
 
 	torture_assert(tctx, data->msg_ctx2 = 
 		       imessaging_init(tctx,
 				      lpcfg_imessaging_path(tctx, tctx->lp_ctx),
 				      cluster_id(0, MSG_ID2), 
-				      data->ev),
+				      data->ev, true),
 		       "Failed to init second messaging context");
 
 	/* register the server side function */
diff --git a/source4/lib/messaging/tests/messaging.c b/source4/lib/messaging/tests/messaging.c
index 38c34fc52e..c5d37953d0 100644
--- a/source4/lib/messaging/tests/messaging.c
+++ b/source4/lib/messaging/tests/messaging.c
@@ -72,8 +72,8 @@ static bool test_ping_speed(struct torture_context *tctx)
 	ev = tctx->ev;
 
 	msg_server_ctx = imessaging_init(tctx,
-					lpcfg_imessaging_path(tctx, tctx->lp_ctx), cluster_id(0, 1),
-					ev);
+					 lpcfg_imessaging_path(tctx, tctx->lp_ctx), cluster_id(0, 1),
+					 ev, true);
 	
 	torture_assert(tctx, msg_server_ctx != NULL, "Failed to init ping messaging context");
 		
@@ -81,9 +81,9 @@ static bool test_ping_speed(struct torture_context *tctx)
 	imessaging_register_tmp(msg_server_ctx, tctx, exit_message, &msg_exit);
 
 	msg_client_ctx = imessaging_init(tctx,
-					lpcfg_imessaging_path(tctx, tctx->lp_ctx),
-					cluster_id(0, 2), 
-					ev);
+					 lpcfg_imessaging_path(tctx, tctx->lp_ctx),
+					 cluster_id(0, 2),
+					 ev, true);
 
 	torture_assert(tctx, msg_client_ctx != NULL, 
 		       "msg_client_ctx imessaging_init() failed");