diff options
| -rw-r--r-- | libusb/os/linux_usbfs.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c index edf1545..1ed9ad8 100644 --- a/libusb/os/linux_usbfs.c +++ b/libusb/os/linux_usbfs.c @@ -384,6 +384,8 @@ static int op_get_config_descriptor(struct libusb_device *dev, return r; } +/* cache the active config descriptor in memory. a value of -1 means that + * we aren't sure which one is active, so just assume the first one. */ static int cache_active_config(struct libusb_device *dev, int fd, int active_config) { @@ -394,11 +396,15 @@ static int cache_active_config(struct libusb_device *dev, int fd, int idx; int r; - r = usbi_get_config_index_by_value(dev, active_config, &idx); - if (r < 0) - return r; - if (idx == -1) - return LIBUSB_ERROR_NOT_FOUND; + if (active_config == -1) { + idx = 0; + } else { + r = usbi_get_config_index_by_value(dev, active_config, &idx); + if (r < 0) + return r; + if (idx == -1) + return LIBUSB_ERROR_NOT_FOUND; + } r = get_config_descriptor(fd, idx, tmp, sizeof(tmp)); if (r < 0) { |