svn commit: samba r13092 - in trunk/source: lib nsswitch

[jra at samba.org]

Author: jra
Date: 2006-01-23 22:00:30 +0000 (Mon, 23 Jan 2006)
New Revision: 13092

WebSVN: http://websvn.samba.org/cgi-bin/viewcvs.cgi?view=rev&root=samba&rev=13092

Log:
Add code to remove a race condition when we're fork'ing a new
child and changing message disposition.
Jeremy.

Modified:
   trunk/source/lib/messages.c
   trunk/source/nsswitch/winbindd_dual.c


Changeset:
Modified: trunk/source/lib/messages.c
===================================================================
--- trunk/source/lib/messages.c	2006-01-23 21:57:58 UTC (rev 13091)
+++ trunk/source/lib/messages.c	2006-01-23 22:00:30 UTC (rev 13092)
@@ -604,4 +604,19 @@
 		*n_sent = msg_all.n_sent;
 	return True;
 }
+
+/*
+ * Block and unblock receiving of messages. Allows removal of race conditions
+ * when doing a fork and changing message disposition.
+ */
+
+void message_block(void)
+{
+	BlockSignals(True, SIGUSR1);
+}
+
+void message_unblock(void)
+{
+	BlockSignals(False, SIGUSR1);
+}
 /** @} **/

Modified: trunk/source/nsswitch/winbindd_dual.c
===================================================================
--- trunk/source/nsswitch/winbindd_dual.c	2006-01-23 21:57:58 UTC (rev 13091)
+++ trunk/source/nsswitch/winbindd_dual.c	2006-01-23 22:00:30 UTC (rev 13092)
@@ -557,10 +557,15 @@
 	ZERO_STRUCT(state);
 	state.pid = getpid();
 
+	/* Ensure we don't process messages whilst we're
+	   changing the disposition for the child. */
+	message_block();
+
 	child->pid = sys_fork();
 
 	if (child->pid == -1) {
 		DEBUG(0, ("Could not fork: %s\n", strerror(errno)));
+		message_unblock();
 		return False;
 	}
 
@@ -573,6 +578,8 @@
 		child->event.flags = 0;
 		child->requests = NULL;
 		add_fd_event(&child->event);
+		/* We're ok with online/offline messages now. */
+		message_unblock();
 		return True;
 	}
 
@@ -600,6 +607,9 @@
 	message_deregister(MSG_WINBIND_OFFLINE);
 	message_deregister(MSG_WINBIND_ONLINE);
 
+	/* The child is ok with online/offline messages now. */
+	message_unblock();
+
 	child->mem_ctx = talloc_init("child_mem_ctx");
 	if (child->mem_ctx == NULL) {
 		return False;