Linux: Handle failure to read active configuration during enumeration

diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index bdd7e1d..058b736 100644 (file)
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -646,7 +646,8 @@ static int usbfs_get_active_config(struct libusb_device *dev, int fd)
                if (errno == ENODEV)
                        return LIBUSB_ERROR_NO_DEVICE;
 
-               usbi_err(DEVICE_CTX(dev),
+               /* we hit this error path frequently with buggy devices :( */
+               usbi_warn(DEVICE_CTX(dev),
                        "get_configuration failed ret=%d errno=%d", r, errno);
                return LIBUSB_ERROR_IO;
        }
@@ -716,7 +717,13 @@ static int initialize_device(struct libusb_device *dev, uint8_t busnum,
                                "determine active configuration descriptor", path);
                } else {
                        active_config = usbfs_get_active_config(dev, fd);
-                       if (active_config < 0) {
+                       if (active_config == LIBUSB_ERROR_IO) {
+                               /* buggy devices sometimes fail to report their active config.
+                                * assume unconfigured and continue the probing */
+                               usbi_warn(DEVICE_CTX(dev), "couldn't query active "
+                                       "configuration, assumung unconfigured");
+                               device_configured = 0;
+                       } else if (active_config < 0) {
                                close(fd);
                                return active_config;
                        } else if (active_config == 0) {
@@ -725,7 +732,7 @@ static int initialize_device(struct libusb_device *dev, uint8_t busnum,
                                 * not support buggy devices in these circumstances.
                                 * stick to the specs: a configuration value of 0 means
                                 * unconfigured. */
-                               usbi_dbg("assuming unconfigured device");
+                               usbi_dbg("active cfg 0? assuming unconfigured device");
                                device_configured = 0;
                        }
                }