c - Why Does `libusb_bulk_transfer' Return 0? -


i using libusb-1.0. when call:

    int rc = libusb_bulk_transfer(handle_,                                   ep_in_addr,                                   (unsigned char *)buf_,                                   64,                                   &read_,                                   0);

it returns rc = 0 (no error) , read_ = 0 (zero number of bytes received). have specified infinite timeout (last argument), isn't `libusb_bulk_transfer' supposed block until have data?

sometimes, returns rc = 0 (no error) , read_ == 0 (zero number of bytes received).

a bulk endpoint can send packets zero bytes of data, called 0 packets. not error condition.


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