c++ - Open a device by name using libftdi or libusb -

i using libftdi multiple ftdi devices program running on ubuntu 14.04. have udev rule detects devices based on custom manufacturer string , gives them symlink in dev directory. similar /dev/my-device. use libftdi open device using string instead of pid/vid/serial number.

i did not see capability available in libftdi checked libusb , didn't see functionality either.

you try this:

static int usbgetdescriptorstring(usb_dev_handle *dev, int index, int langid, char *buf, int buflen) {     char buffer[256];     int rval, i;      // make standard request get_descriptor, type string , given index      // (e.g. dev->iproduct)     rval = usb_control_msg(dev,         usb_type_standard | usb_recip_device | usb_endpoint_in,         usb_req_get_descriptor, (usb_dt_string << 8) + index, langid,         buffer, sizeof(buffer), 1000);      if (rval < 0) // error         return rval;      // rval should bytes read, buffer[0] contains actual response size     if ((unsigned char)buffer[0] < rval)         rval = (unsigned char)buffer[0]; // string shorter bytes read      if (buffer[1] != usb_dt_string) // second byte data type         return 0; // invalid return type                    // we're dealing utf-16le here actual chars half of rval,                   // , index 0 doesn't count     rval /= 2;      /* lossy conversion iso latin1 */     (i = 1; < rval && < buflen; i++) {         if (buffer[2 * + 1] == 0)             buf[i - 1] = buffer[2 * i];         else             buf[i - 1] = '?'; /* outside of iso latin1 range */     }     buf[i - 1] = 0;      return - 1; }  static usb_dev_handle * usbopendevice(int vendor, char *vendorname, int product, char *productname) {     struct usb_bus *bus;     struct usb_device *dev;     char devvendor[256], devproduct[256];      usb_dev_handle * handle = null;      usb_init();     usb_find_busses();     usb_find_devices();      (bus = usb_get_busses(); bus; bus = bus->next) {         (dev = bus->devices; dev; dev = dev->next) {             if (dev->descriptor.idvendor != vendor ||                 dev->descriptor.idproduct != product)                 continue;              /* need open device in order query strings */             if (!(handle = usb_open(dev))) {                 fprintf(stderr, "warning: cannot open usb device: %sn",                     usb_strerror());                 continue;             }              /* vendor name */             if (usbgetdescriptorstring(handle, dev->descriptor.imanufacturer, 0x0409, devvendor, sizeof(devvendor)) < 0) {                 fprintf(stderr,                     "warning: cannot query manufacturer device: %sn",                     usb_strerror());                 usb_close(handle);                 continue;             }              /* product name */             if (usbgetdescriptorstring(handle, dev->descriptor.iproduct, 0x0409, devproduct, sizeof(devvendor)) < 0) {                 fprintf(stderr,                     "warning: cannot query product device: %sn",                     usb_strerror());                 usb_close(handle);                 continue;             }              if (strcmp(devvendor, vendorname) == 0 &&                 strcmp(devproduct, productname) == 0)                 return handle;             else                 usb_close(handle);         }     }      return null; }