MacOS: When extracting buslocation Unique ID is expected to be exactly 18 chars long

[naali]

Not sure if it's just me and my luck, but at least for me MacOS 13.1 (Ventura) seems to give Unique IDs with a length of 17 chars... This causes buslocation detection to fail so devices can't be recognized from each other if you happen to have multiple similar cameras connected.

I made a quick & dirty patch to platformcontext.mm that extracts buslocation from 17 char Unique IDs and it seems to work. Maybe the Unique ID should be handled by dropping pid & vid and then using the rest of it as the buslocation? That way the Unique ID lenght woudln't matter...

Other solution that might work (if the id is < 18 chars) is to zeropad the beginning till it is long enough. It will get converted from string to uint32_t so trailing zeros wouldn't matter.

I assume that the Unique ID is stored as an actual number value at some point and the leading zeros are cut off when converting it to string. At least on my case this could be the reason:

ioreg -p IOUSB -l -w 0 | grep Global | grep class
      +-o Global Shutter Camera@02140000  <class IOUSBHostDevice, id 0x1001f0d11, registered, matched, active, busy 0 (18 ms), retain 35>
      +-o Global Shutter Camera@02110000  <class IOUSBHostDevice, id 0x1001f0d2a, registered, matched, active, busy 0 (19 ms), retain 35>

Enough with the speculations, here's the quick & dirty patch :)

        } else if (device.uniqueID.length == 17) {
            std::string locStdStr = std::string(device.uniqueID.UTF8String);

            // sanity check for PID and VID to make sure the unique ID is indeed
            // in the format we expect..
            char pidStr[5];
            char vidStr[5];
            snprintf(pidStr, sizeof(pidStr), "%04x", deviceInfo->m_pid);
            snprintf(vidStr, sizeof(vidStr), "%04x", deviceInfo->m_vid);

            if ((locStdStr.substr(9,4) == std::string(vidStr)) &&
                (locStdStr.substr(13,4) == std::string(pidStr)))
            {
                // format seems to be correct
                NSString *hexString = [device.uniqueID substringWithRange:NSMakeRange(2,7)];
                NSScanner *scanner = [NSScanner scannerWithString:hexString];
                [scanner scanHexInt:&(deviceInfo->m_busLocation)];

                LOG(LOG_DEBUG, "Location : %08X\n", deviceInfo->m_busLocation);
                [scanner dealloc];
                [hexString dealloc];
            }
            else
            {
                LOG(LOG_DEBUG, "VID/PID mismatch!\n");
                LOG(LOG_DEBUG, "Extracted VID %s\n", locStdStr.substr(10,4).c_str());
                LOG(LOG_DEBUG, "Extracted PID %s\n", locStdStr.substr(14,4).c_str());
            }
        }