<sigh>. listen the EFAULT error is being thrown by this bit of code inside
libusb:
static int reap_for_handle(struct libusb_device_handle *handle)
{
struct usbfs_urb *urb;
int r = ioctl(hpriv->fd, IOCTL_USBFS_REAPURBNDELAY, &urb);
if (r < 0) {
....
Notice how the only address we're passing in is an address on the stack. So
that definitely is not a bad address, that leaves the buffers in which the
kernel code in drivers/usb/core/devio.c: processcompl() will
copy any received data, and those buffers are provided by applications using
libusb, not by libusb itself.
So this very very likely is an application bug. We are not, I repeat NOT going
to add error handling for EFAULT to libusb, that is just crazy. EFAULT is a
syscalls variant of segfaulting it means someone is passing around bad
pointers. Normally a program would immediately segfault then, but if the
pointer gets passed to a syscall you get EFAULT instead. What you're asking
for is the equivalent of adding a signal 11 handler which somehow magically
fixes things to continue running after some application bug.
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