Retrieve device information in Linux from device file descriptor using c++ -


how can device info including device name device file descriptor?

for example, in skype can see device "/dev/snd/pcmc2d0c" has name: "usb 2.0 camera. usb audio default audio device (default:card=camera)"

how can such device name using c++?

int file = open("/dev/snd/pcmc2d0c", o_rdwr | o_nonblock, 0); if (-1 == file) // check error occurred during opening? {     perror("open");     return -1; } if (-1 == ioctl(file, /* appropriate ioctl value device info? */, /* appropriate structure fill device info? */)) {     perror("ioctl");     return -1; }

there no ioctl values getting device information. in special case it's usb device, has other sources device type information.

you can sysfs file system, mounted @ /sys. there directory /sys/bus/usb/devices/, has symbolic link entries pointing real devices.

on system, there example /sys/bus/usb/devices/3-4. symbolic link leads directory /sys/devices/pci0000:00/0000:00:12.0/usb3/3-4/, has several files identifying device.

idvendor , idproduct contain numbers 045e , 00cb. these numbers, can file /usr/share/misc/usb.ids , find 

... 045e  microsoft corp. ...         00ca  fingerprint reader         00cb  basic optical mouse v2.0         00ce  generic ppc flash device ...

you have similar information hard disk drives, example. /sys/devices/pci0000:00/0000:00:11.0/host0/target0:0:0/0:0:0:0/block/sda/ hard disk , entry device/model in directory contains string toshiba dt01aca1, identifying thoshiba 1tb hard disk drive.


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