Cocoa: Detecting USB devices by Vendor ID

Question

I'm writing a Foundation tool for Mac and trying to detect when Apple devices are connected and disconnected via USB. I found some help in this post along with the USBPrivateDataSample -- but it seems to only be working if I provide both a vendor ID and a product ID. I'd like to eliminate the product ID and find detect all USB events on Apple devices (vendor ID 1452). Any help here?

Here's my code that doesn't seem to detect any devices:

#include <CoreFoundation/CoreFoundation.h>

#include <IOKit/IOKitLib.h>
#include <IOKit/IOMessage.h>
#include <IOKit/IOCFPlugIn.h>
#include <IOKit/usb/IOUSBLib.h>

#define kMyVendorID 1452

int list_devices(void);

int list_devices(void){
    CFMutableDictionaryRef matchingDict;
    io_iterator_t iter;
    kern_return_t kr;
    io_service_t device;
    CFNumberRef numberRef;
    long usbVendor = kMyVendorID;

    /* set up a matching dictionary for the class */
    matchingDict = IOServiceMatching(kIOUSBDeviceClassName);    // Interested in instances of class
    // IOUSBDevice and its subclasses
    if (matchingDict == NULL) {
        fprintf(stderr, "IOServiceMatching returned NULL.\n");
        return -1;
    }

    // We are interested in all USB devices (as opposed to USB interfaces).  The Common Class Specification
    // tells us that we need to specify the idVendor, idProduct, and bcdDevice fields, or, if we're not interested
    // in particular bcdDevices, just the idVendor and idProduct.  Note that if we were trying to match an 
    // IOUSBInterface, we would need to set more values in the matching dictionary (e.g. idVendor, idProduct, 
    // bInterfaceNumber and bConfigurationValue.

    // Create a CFNumber for the idVendor and set the value in the dictionary
    numberRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &usbVendor);
    CFDictionarySetValue(matchingDict, 
                         CFSTR(kUSBVendorID), 
                         numberRef);
    CFRelease(numberRef);
    numberRef = NULL;    


    /* Now we have a dictionary, get an iterator.*/
    kr = IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, &iter);
    if (kr != KERN_SUCCESS)
        return -1;

    /* iterate */
    while ((device = IOIteratorNext(iter)))
    {
        io_name_t       deviceName;
        CFStringRef     deviceNameAsCFString;   

        /* do something with device, eg. check properties */
        /* ... */
        /* And free the reference taken before continuing to the next item */

        // Get the USB device's name.
        kr = IORegistryEntryGetName(device, deviceName);
        if (KERN_SUCCESS != kr) {
            deviceName[0] = '\0';
        }

        deviceNameAsCFString = CFStringCreateWithCString(kCFAllocatorDefault, deviceName, 
                                                         kCFStringEncodingASCII);

        // Dump our data to stderr just to see what it looks like.
        fprintf(stderr, "deviceName: ");
        CFShow(deviceNameAsCFString);

        IOObjectRelease(device);
    }

    /* Done, release the iterator */
    IOObjectRelease(iter);

    return 1;
}

int main(int argc, char* argv[])
{
    while(1){
        list_devices();
        sleep(1);
    }
    return 0;
}

Of note: If I add a product ID to the matchingDict and plug in such a device it will find the device no problem (without changing the vendor ID). But I can't find it with the vendor ID alone.

Answer 1

To get list of all products that belongs to particular vendor you can use wildcards in product ID field .A sample matching condition is as below:

            long vid = 1452; //Apple vendor ID
        CFNumberRef refVendorId = CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &vid);
        CFDictionarySetValue (matchingDict, CFSTR ("idVendor"), refVendorId);
        CFRelease(refVendorId);
        //all product by same vendor
        CFDictionarySetValue (matchingDict, CFSTR ("idProduct"), CFSTR("*"));

Answer 2

Creating a dictionary filter with only a VID entry should match all PIDs for that vendor. I'd recommend registering for device insertion callbacks instead of polling in your own code. Let the OS handle detection and notify your app asynchronously.

This code works for me:

#import "IOKit/hid/IOHIDManager.h"
#include <IOKit/usb/IOUSBLib.h>

@implementation MyApp

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {

    IOHIDManagerRef HIDManager = IOHIDManagerCreate(kCFAllocatorDefault,
                                                    kIOHIDOptionsTypeNone);
    CFMutableDictionaryRef matchDict = CFDictionaryCreateMutable(
                                                    kCFAllocatorDefault,
                                                    2,
                                                    &kCFTypeDictionaryKeyCallBacks,
                                                    &kCFTypeDictionaryValueCallBacks);
    int vid = 0x1234; // ToDo: Place your VID here
    CFNumberRef vid_num = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &vid);
    CFDictionarySetValue(matchDict, CFSTR(kUSBVendorID), vid_num);
    CFRelease(vid_num);

    IOHIDManagerSetDeviceMatching(HIDManager, matchDict);
    // Here we use the same callback for insertion & removal.
    // Use separate handlers if desired.
    IOHIDManagerRegisterDeviceMatchingCallback(HIDManager, Handle_UsbDetectionCallback, (__bridge void*)self);
    IOHIDManagerRegisterDeviceRemovalCallback(HIDManager, Handle_UsbDetectionCallback, (__bridge void*)self);
    IOHIDManagerScheduleWithRunLoop(HIDManager, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
    IOHIDManagerOpen(HIDManager, kIOHIDOptionsTypeNone);
}

// New USB device specified in the matching dictionary has been added (callback function)
static void Handle_UsbDetectionCallback(void *inContext, IOReturn inResult, void *inSender, IOHIDDeviceRef inIOHIDDeviceRef) {
    //ToDo: Code for dealing with the USB device
}

@end