Respect the fact, that the driver can return NULL-pointer, instead of a string having 0 characters!
(makes third-party drivers compatibility better)

Modified: trunk/reactos/ntoskrnl/io/pnpmgr.c

--- trunk/reactos/ntoskrnl/io/pnpmgr.c	2005-12-08 09:51:24 UTC (rev 19962)
+++ trunk/reactos/ntoskrnl/io/pnpmgr.c	2005-12-08 10:30:08 UTC (rev 19963)
@@ -1586,10 +1586,11 @@

       {
          /* Add information from parent bus device to InstancePath */
          wcscat(InstancePath, ParentIdPrefix.Buffer);

-         if (*(PWSTR)IoStatusBlock.Information)

+         if (IoStatusBlock.Information && *(PWSTR)IoStatusBlock.Information)

             wcscat(InstancePath, L"&");
       }

-      wcscat(InstancePath, (PWSTR)IoStatusBlock.Information);

+      if (IoStatusBlock.Information)
+         wcscat(InstancePath, (PWSTR)IoStatusBlock.Information);

 
       /*
        * FIXME: Check for valid characters, if there is invalid characters
@@ -1701,7 +1702,7 @@

       &IoStatusBlock,
       IRP_MN_QUERY_ID,
       &Stack);

-   if (NT_SUCCESS(Status))

+   if (NT_SUCCESS(Status) && IoStatusBlock.Information)

    {
       /*
       * FIXME: Check for valid characters, if there is invalid characters
@@ -1730,7 +1731,7 @@

          (TotalLength + 1) * sizeof(WCHAR));
       if (!NT_SUCCESS(Status))
       {

-         DPRINT1("ZwSetValueKey() failed (Status %lx)\n", Status);

+         DPRINT1("ZwSetValueKey() failed (Status %lx) or no Compatible ID returned\n", Status);

       }
    }
    else
@@ -1748,10 +1749,13 @@

       &IoStatusBlock,
       IRP_MN_QUERY_DEVICE_TEXT,
       &Stack);

-   if (NT_SUCCESS(Status))

+   /* This key is mandatory, so even if the Irp fails, we still write it */
+   RtlInitUnicodeString(&ValueName, L"DeviceDesc");
+   if (ZwQueryValueKey(InstanceKey, &ValueName, KeyValueBasicInformation, NULL, 0, &RequiredLength) == STATUS_OBJECT_NAME_NOT_FOUND)

    {

-      RtlInitUnicodeString(&ValueName, L"DeviceDesc");
-      if (ZwQueryValueKey(InstanceKey, &ValueName, KeyValueBasicInformation, NULL, 0, &RequiredLength) == STATUS_OBJECT_NAME_NOT_FOUND)

+      if (NT_SUCCESS(IoStatusBlock.Status) &&
+         IoStatusBlock.Information &&
+         (*(PWSTR)IoStatusBlock.Information != 0))

       {
          /* This key is overriden when a driver is installed. Don't write the
           * new description if another one already exists */
@@ -1762,15 +1766,26 @@

                                 (PVOID)IoStatusBlock.Information,
                                 (wcslen((PWSTR)IoStatusBlock.Information) + 1) * sizeof(WCHAR));
       }

-      if (!NT_SUCCESS(Status))

+      else

       {

-         DPRINT1("ZwSetValueKey() failed (Status 0x%lx)\n", Status);

+         UNICODE_STRING DeviceDesc;
+         RtlInitUnicodeString(&DeviceDesc, L"Unknown Device");
+         DPRINT("Driver didn't return DeviceDesc (Status %x), so place unknown device there\n", Status);
+
+         Status = ZwSetValueKey(InstanceKey,
+            &ValueName,
+            0,
+            REG_SZ,
+            &DeviceDesc,
+            (wcslen((PWSTR)&DeviceDesc) + 1) * sizeof(WCHAR));
+
+         if (!NT_SUCCESS(Status))
+         {
+            DPRINT1("ZwSetValueKey() failed (Status 0x%lx)\n", Status);
+         }
+

       }
    }

-   else
-   {
-      DPRINT("IopInitiatePnpIrp() failed (Status %x)\n", Status);
-   }

 
    DPRINT("Sending IRP_MN_QUERY_DEVICE_TEXT.DeviceTextLocation to device stack\n");
 
@@ -1781,7 +1796,7 @@

       &IoStatusBlock,
       IRP_MN_QUERY_DEVICE_TEXT,
       &Stack);

-   if (NT_SUCCESS(Status))

+   if (NT_SUCCESS(Status) && IoStatusBlock.Information)

    {
       DPRINT("LocationInformation: %S\n", (PWSTR)IoStatusBlock.Information);
       RtlInitUnicodeString(&ValueName, L"LocationInformation");
@@ -1798,7 +1813,7 @@

    }
    else
    {

-      DPRINT("IopInitiatePnpIrp() failed (Status %x)\n", Status);

+      DPRINT("IopInitiatePnpIrp() failed (Status %x) or IoStatusBlock.Information=NULL\n", Status);

    }
 
    DPRINT("Sending IRP_MN_QUERY_BUS_INFORMATION to device stack\n");
@@ -1808,7 +1823,7 @@

       &IoStatusBlock,
       IRP_MN_QUERY_BUS_INFORMATION,
       NULL);

-   if (NT_SUCCESS(Status))

+   if (NT_SUCCESS(Status) && IoStatusBlock.Information)

    {
       PPNP_BUS_INFORMATION BusInformation =
          (PPNP_BUS_INFORMATION)IoStatusBlock.Information;
@@ -1820,7 +1835,7 @@

    }
    else
    {

-      DPRINT("IopInitiatePnpIrp() failed (Status %x)\n", Status);

+      DPRINT("IopInitiatePnpIrp() failed (Status %x) or IoStatusBlock.Information=NULL\n", Status);

 
       DeviceNode->ChildBusNumber = 0xFFFFFFF0;
       DeviceNode->ChildInterfaceType = InterfaceTypeUndefined;
@@ -1834,7 +1849,7 @@

       &IoStatusBlock,
       IRP_MN_QUERY_RESOURCES,
       NULL);

-   if (NT_SUCCESS(Status))

+   if (NT_SUCCESS(Status) && IoStatusBlock.Information)

    {
       DeviceNode->BootResources =
          (PCM_RESOURCE_LIST)IoStatusBlock.Information;