Add support for VixDiskLib_PrepareForAccess.

We should tell Vsphere we are opening disks e.g. call
VixDiskLib_PrepareForAccess() before opening and VixDiskLib_EndAccess()
after closing.

From the include file:

This function is used to notify the host of the virtual machine that the
disks of the virtual machine will be opened. The host disables
operations on the virtual machine that may be adversely affected
if they are performed while the disks are open by a third party
application.

vadp_dumper/bareos_vadp_dumper.cpp

@@ -87,6 +87,8 @@
 #define BAREOSMAGIC 0x12122012
 #define PROTOCOL_VERSION 1
 
+#define BAREOS_VADPDUMPER_IDENTITY "BareosVADPDumper"
+
 /*
  * Generic identification structure, 128 bytes with padding.
  * This includes a protocol version.
@@ -357,16 +359,35 @@ static inline void cleanup_vixdisklib()
  */
 static void cleanup(int sig)
 {
+   VixError err;
+
    if (info) {
       VixDiskLib_FreeInfo(info);
    }
 
+   if (diskHandle) {
+      VixDiskLib_Close(diskHandle);
+      diskHandle = NULL;
+   }
+
    if (connection) {
       VixDiskLib_Disconnect(connection);
       if (cleanup_on_disconnect) {
          cleanup_vixdisklib();
       }
    }
+
+   if (!local_vmdk) {
+      err = VixDiskLib_EndAccess(&cnxParams, BAREOS_VADPDUMPER_IDENTITY);
+      if (VIX_FAILED(err)) {
+         char *error_txt;
+
+         error_txt = VixDiskLib_GetErrorText(err, NULL);
+         fprintf(stderr, "Failed to End Access: %s [%d]\n", error_txt, err);
+         VixDiskLib_FreeErrorText(error_txt);
+      }
+   }
+
    cleanup_cnxParams();
 
    VixDiskLib_Exit();
@@ -477,9 +498,20 @@ static inline void do_vixdisklib_connect(const char *key, json_t *connect_params
          }
          snapshot_moref = json_string_value(object);
       }
+
+      if (!local_vmdk) {
+         err = VixDiskLib_PrepareForAccess(&cnxParams, BAREOS_VADPDUMPER_IDENTITY);
+         if (VIX_FAILED(err)) {
+            char *error_txt;
+
+            error_txt = VixDiskLib_GetErrorText(err, NULL);
+            fprintf(stderr, "Failed to Prepare For Access: %s [%d]\n", error_txt, err);
+            VixDiskLib_FreeErrorText(error_txt);
+         }
+      }
    }
-   err = VixDiskLib_ConnectEx(&cnxParams, (readonly) ? TRUE : FALSE, snapshot_moref, vixdisklib_config, &connection);
 
+   err = VixDiskLib_ConnectEx(&cnxParams, (readonly) ? TRUE : FALSE, snapshot_moref, vixdisklib_config, &connection);
    if (VIX_FAILED(err)) {
       char *error_txt;
 
@@ -494,10 +526,6 @@ static inline void do_vixdisklib_connect(const char *key, json_t *connect_params
 bail_out:
    if (!succeeded) {
       cleanup(1);
-   } else if (!cleanup_on_disconnect) {
-      if (!local_vmdk) {
-         cleanup_cnxParams();
-      }
    }
 }
 
@@ -1113,6 +1141,7 @@ static inline bool process_cbt(const char *key, json_t *cbt)
 bail_out:
    if (diskHandle) {
       VixDiskLib_Close(diskHandle);
+      diskHandle = NULL;
    }
 
    return retval;
@@ -1236,6 +1265,7 @@ static inline bool process_restore_stream(bool validate_only, json_t *value)
 bail_out:
    if (diskHandle) {
       VixDiskLib_Close(diskHandle);
+      diskHandle = NULL;
    }
 
    return retval;