libusb & PATH_MAX

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Hello,

A lot of packages depend on libusb, and more and more do.  It seems to
me illusory to try to make them all include [!hurd-i386] conditionals,
it'd be easier to just manage to compile libusb, even if it's only to
always report that no device is available.

Now the problem is that PATH_MAX appears in libusb's usb.h...:

struct usb_device {
  struct usb_device *next, *prev;

  char filename[PATH_MAX + 1];
  ...

And applications often do use that field, for outputing debugging
message apparently.  I can see several solutions:

- patch libusb into not having the field. Completely safe option, but
  quite a few applications won't build, notably some that are big
  blockers like pcsc-lite.
- patch libusb into using a char *filename instead. Applications might
  have been using sizeof(dev->filename) and get wrongly compiled.
- like in libusb-win32, patch libusb into defining a LIBUSB_PATH_MAX
  constant to some arbitrary value and use that instead.  Some
  applications might still be using the PATH_MAX constant, but we do not
  define it anyway, so it should be safe.
- just wait for libusb-1.0 that has a PATH_MAX-free interface. That's
  not for tomorrow, as the interface is very different from the legacy
  libusb and thus applications will have to be fixed one by one.

What do people think?  I believe the 3rd solution uploaded to
debian-ports could be a safe interim clearing the way for porting.

Samuel