Promptly close the netcmd_semaphore handle after use

If more than one openvpn processes are running and one aborts
without releasing the semaphore, subsequent processes fail to get
a lock for the semaphore. This may be avoided by not keeping open
handles to the semaphore so that Windows can destroy it when no
open handles remain.

See also: http://article.gmane.org/gmane.network.openvpn.devel/11913

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1465871689-13533-1-git-send-email-selva.nair@gmail.com>
URL: http://article.gmane.org/gmane.network.openvpn.devel/11919
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 6aa4c9091300f62fae0bf7a9198de0edd2d8b7c7)

diff --git a/src/openvpn/win32.c b/src/openvpn/win32.c
index e17cca1efeb586424c32e2e95f5078e96573313c..4f2df14bb057e44b9d91c4839240460bd6b78e6b 100644 (file)
--- a/src/openvpn/win32.c
+++ b/src/openvpn/win32.c
@@ -119,7 +119,6 @@ init_win32 (void)
     }
   window_title_clear (&window_title);
   win32_signal_clear (&win32_signal);
-  netcmd_semaphore_init ();
 }
 
 void
@@ -765,6 +764,10 @@ void
 netcmd_semaphore_lock (void)
 {
   const int timeout_seconds = 600;
+
+  if (!netcmd_semaphore.hand)
+    netcmd_semaphore_init ();
+
   if (!semaphore_lock (&netcmd_semaphore, timeout_seconds * 1000))
     msg (M_FATAL, "Cannot lock net command semaphore"); 
 }
@@ -773,6 +776,8 @@ void
 netcmd_semaphore_release (void)
 {
   semaphore_release (&netcmd_semaphore);
+  /* netcmd_semaphore has max count of 1 - safe to close after release */
+  semaphore_close (&netcmd_semaphore);
 }
 
 /*