Needs better error reporting

[hadess]

$ sudo cat /sys/kernel/debug/hid/0005:3820:0009.0008/rdesc | head -n1 | xxd -r -p | jhbuild run hidrd-convert -i natv -o xml
Failed to read input item at offset 86:
invalid item encountered

Not much that I can do with that though. I'll try adding some better error reporting in lib/item/any.c, see where it fails.

[hadess]

The output of head -n1 in the above command:
8bitdo-native.txt

[spbnick]

Hi hadess, which version of hidrd are you using?

[hadess]

That was with git master and the attached file.

[hadess]

main_tag = hidrd_item_main_get_tag(item);

It failed with "main_tag = 0"

Not sure if that means it couldn't parse the main tag, or some other failure.

[hadess]

I'll note that the above rdesc was parsed by the Linux kernel without a problem, so it's very likely to be a valid descriptor.

[hadess]

http://eleccelerator.com/usbdescreqparser/ parses the above descriptor as:

0x05, 0x01,        // Usage Page (Generic Desktop Ctrls)
0x09, 0x05,        // Usage (Game Pad)
0xA1, 0x01,        // Collection (Application)
0x85, 0x03,        //   Report ID (3)
0x05, 0x01,        //   Usage Page (Generic Desktop Ctrls)
0x15, 0x00,        //   Logical Minimum (0)
0x25, 0x07,        //   Logical Maximum (7)
0x46, 0x3B, 0x01,  //   Physical Maximum (315)
0x95, 0x01,        //   Report Count (1)
0x75, 0x04,        //   Report Size (4)
0x65, 0x14,        //   Unit (System: English Rotation, Length: Centimeter)
0x09, 0x39,        //   Usage (Hat switch)
0x81, 0x42,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,Null State)
0x75, 0x01,        //   Report Size (1)
0x95, 0x04,        //   Report Count (4)
0x81, 0x01,        //   Input (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
0x15, 0x00,        //   Logical Minimum (0)
0x26, 0xFF, 0x00,  //   Logical Maximum (255)
0x09, 0x30,        //   Usage (X)
0x09, 0x31,        //   Usage (Y)
0x09, 0x32,        //   Usage (Z)
0x09, 0x35,        //   Usage (Rz)
0x95, 0x04,        //   Report Count (4)
0x75, 0x08,        //   Report Size (8)
0x81, 0x02,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
0x05, 0x02,        //   Usage Page (Sim Ctrls)
0x15, 0x00,        //   Logical Minimum (0)
0x26, 0xFF, 0x00,  //   Logical Maximum (255)
0x09, 0xC4,        //   Usage (Accelerator)
0x09, 0xC5,        //   Usage (Brake)
0x95, 0x02,        //   Report Count (2)
0x75, 0x08,        //   Report Size (8)
0x81, 0x02,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
0x05, 0x09,        //   Usage Page (Button)
0x19, 0x01,        //   Usage Minimum (0x01)
0x29, 0x10,        //   Usage Maximum (0x10)
0x15, 0x00,        //   Logical Minimum (0)
0x25, 0x01,        //   Logical Maximum (1)
0x75, 0x01,        //   Report Size (1)
0x95, 0x10,        //   Report Count (16)
0x81, 0x02,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
0xC0,              // End Collection
0x00,              // Unknown (bTag: 0x00, bType: 0x00)

// 87 bytes

And removing the trailing "00" fixes the parsing by hidrd. That's where the 0 was coming from :)

[spbnick]

Thank you for the investigation, @hadess
Indeed, a descriptor with trailing zero would be an invalid descriptor.
However, hidrd needs to be modified to be more resilient and to produce better error messages.
I personally don't have much time for that at the moment, but I would of course welcome patches working towards that.

[hadess]

Doesn't seem to bother Windows, Linux, iOS or Android, FWIW.

[spbnick]

@hadess Yes, that's why hidrd needs to be improved. Nevertheless the descriptor is invalid.