Windows: Try alternative methods to query port number

This commit is similar to #634 but I think it offers a better approach. The commit adds two more methods for querying the port number, in addition to the existing SPDRP_ADDRESS method, which may not actually return the port number when using USB drivers other than the Microsoft driver.

The first method uses SPDRP_LOCATION_INFORMATION, which may return a port in a format similar to "Port_#0002.Hub_#000D".

The second method uses SPDRP_LOCATION_PATHS, which returns the device location in a format similar to "PCIROOT(B2)#PCI(0300)#PCI(0000)#USBROOT(0)#USB(1)#USB(2)#USBMI(3)", where the port number is the number within the last "#USB()" token.

If both methods fail, SPDRP_ADDRESS is still used as a fallback.

Closes #867

Signed-off-by: Nathan Hjelm <hjelmn@google.com>

diff --git a/libusb/os/windows_winusb.c b/libusb/os/windows_winusb.c
index 877a2ab..e1e599c 100644 (file)
--- a/libusb/os/windows_winusb.c
+++ b/libusb/os/windows_winusb.c
@@ -1223,6 +1223,47 @@ static int init_device(struct libusb_device *dev, struct libusb_device *parent_d
        return LIBUSB_SUCCESS;
 }
 
+static bool get_dev_port_number(HDEVINFO dev_info, SP_DEVINFO_DATA *dev_info_data, DWORD *port_nr)
+{
+       char buffer[MAX_KEY_LENGTH];
+       DWORD size;
+
+       // First try SPDRP_LOCATION_INFORMATION, which returns a REG_SZ. The string *may* have a format
+       // similar to "Port_#0002.Hub_#000D", in which case we can extract the port number. However, we
+       // cannot extract the port if the returned string does not follow this format.
+       if (pSetupDiGetDeviceRegistryPropertyA(dev_info, dev_info_data, SPDRP_LOCATION_INFORMATION,
+                       NULL, (PBYTE)buffer, sizeof(buffer), NULL)) {
+               // Check for the required format.
+               if (strncmp(buffer, "Port_#", 6) == 0) {
+                       *port_nr = atoi(buffer + 6);
+                       return true;
+               }
+       }
+
+       // Next try SPDRP_LOCATION_PATHS, which returns a REG_MULTI_SZ (but we only examine the first
+       // string in it). Each path has a format similar to,
+       // "PCIROOT(B2)#PCI(0300)#PCI(0000)#USBROOT(0)#USB(1)#USB(2)#USBMI(3)", and the port number is
+       // the number within the last "USB(x)" token.
+       if (pSetupDiGetDeviceRegistryPropertyA(dev_info, dev_info_data, SPDRP_LOCATION_PATHS,
+                       NULL, (PBYTE)buffer, sizeof(buffer), NULL)) {
+               // Find the last "#USB(x)" substring
+               for (char *token = strrchr(buffer, '#'); token != NULL; token = strrchr(buffer, '#')) {
+                       if (strncmp(token, "#USB(", 5) == 0) {
+                               *port_nr = atoi(token + 5);
+                               return true;
+                       }
+                       // Shorten the string and try again.
+                       *token = '\0';
+               }
+       }
+
+       // Lastly, try SPDRP_ADDRESS, which returns a REG_DWORD. The address *may* be the port number,
+       // which is true for the Microsoft driver but may not be true for other drivers. However, we
+       // have no other options here but to accept what it returns.
+       return pSetupDiGetDeviceRegistryPropertyA(dev_info, dev_info_data, SPDRP_ADDRESS,
+                       NULL, (PBYTE)port_nr, sizeof(*port_nr), &size) && (size == sizeof(*port_nr));
+}
+
 static int enumerate_hcd_root_hub(struct libusb_context *ctx, const char *dev_id,
        uint8_t bus_number, DEVINST devinst)
 {
@@ -1747,10 +1788,8 @@ static int winusb_get_device_list(struct libusb_context *ctx, struct discovered_
                                r = enumerate_hcd_root_hub(ctx, dev_id, (uint8_t)(i + 1), dev_info_data.DevInst);
                                break;
                        case GEN_PASS:
-                               // The SPDRP_ADDRESS for USB devices is the device port number on the hub
                                port_nr = 0;
-                               if (!pSetupDiGetDeviceRegistryPropertyA(*dev_info, &dev_info_data, SPDRP_ADDRESS,
-                                               NULL, (PBYTE)&port_nr, sizeof(port_nr), &size) || (size != sizeof(port_nr)))
+                               if (!get_dev_port_number(*dev_info, &dev_info_data, &port_nr))
                                        usbi_warn(ctx, "could not retrieve port number for device '%s': %s", dev_id, windows_error_str(0));
                                r = init_device(dev, parent_dev, (uint8_t)port_nr, dev_info_data.DevInst);
                                if (r == LIBUSB_SUCCESS) {

diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 53d05fe..6524fe2 100644 (file)
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11621
+#define LIBUSB_NANO 11622