[Spice-devel] [USBCLERK PATCH] get_dev_info: ignore devices with no "install_state" information

[Uri Lublin]

It may happen (not sure how) that a single device appears
twice in the list of USB devices. Only one entry has information
for the currently installed device/driver.

If that happens, currently we just pick the first one, which
may be an invalid entry that says a nont-WinUSB (e.g. USBSTOR)
is the driver installed, and WinUSB driver removal fails
(saying it's already not installed).

Experiments show that for such an invalid entry, getting "install_state"
property fails.

This patch makes get_dev_info ignore devices with no "install_state"
and pick up the right entry (e.g. with WinUSB driver when driver
removal is requested).
---

I'm not sure why I have not seen this before.
I encountered that problem when running spice-client on a WinXP VM,
and trying to usbredir a USB storage device. Upon stopping usbredir
of the device the WinUSB driver removal by usbclerk failed.
Maybe changes in qemu-kvm USB emulation caused this, maybe
something else.

---
 usbclerk.cpp |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/usbclerk.cpp b/usbclerk.cpp
index 7df11f5..170ff99 100644
--- a/usbclerk.cpp
+++ b/usbclerk.cpp
@@ -616,12 +616,17 @@ bool USBClerk::get_dev_info(HDEVINFO devs, int vid, int pid, SP_DEVINFO_DATA *de
     TCHAR dev_id[MAX_DEVICE_ID_LEN];
     TCHAR service_name[MAX_DEVICE_PROP_LEN];
     bool dev_found = false;
+    DWORD state_install;
 
     _sntprintf(dev_prefix, MAX_DEVICE_ID_LEN, TEXT("USB\\VID_%04X&PID_%04X\\"), vid, pid);
     dev_info->cbSize = sizeof(*dev_info);
     for (DWORD dev_index = 0; SetupDiEnumDeviceInfo(devs, dev_index, dev_info); dev_index++) {
         if (SetupDiGetDeviceInstanceId(devs, dev_info, dev_id, MAX_DEVICE_ID_LEN, NULL) &&
-                (dev_found = !!wcsstr(dev_id, dev_prefix))) {
+            wcsstr(dev_id, dev_prefix) &&
+            SetupDiGetDeviceRegistryProperty(devs, dev_info, SPDRP_INSTALL_STATE, NULL,
+                                             (PBYTE)&state_install, sizeof(state_install),
+                                             NULL)) {
+            dev_found = true;
             break;
         }
     }
-- 
1.7.1