Unique hardware ID in Mac OS X

For C/C++:

#include <IOKit/IOKitLib.h>

void get_platform_uuid(char * buf, int bufSize) {
    io_registry_entry_t ioRegistryRoot = IORegistryEntryFromPath(kIOMasterPortDefault, "IOService:/");
    CFStringRef uuidCf = (CFStringRef) IORegistryEntryCreateCFProperty(ioRegistryRoot, CFSTR(kIOPlatformUUIDKey), kCFAllocatorDefault, 0);
    IOObjectRelease(ioRegistryRoot);
    CFStringGetCString(uuidCf, buf, bufSize, kCFStringEncodingMacRoman);
    CFRelease(uuidCf);    
}