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.


Comments

Post a Comment

Popular posts from this blog

Why does Ruby on Rails generate add a blank line to the end of a file? -

running rails generate controller foo home results in: class foocontroller < application controller def home end end (there's nothing on line in actual file, blank line) is there purpose blank line? it's common use newline indicate end of line, last line. many editors (like vi, use) add in newline silently. consensus text files (especially in unix world) should end in newline, , there have been problems historically if wasn't present. why should text files end newline? the tool used count lines in file "wc" counts newlines in file, without trailing newline show 3 instead of 4. it improves readability of templates used in generator. consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb to remove trailing newline, template have last line of: end<% end -%> instead of: end <% end -%> that seems less readable me. the discussion below refers ...
Read more

keyboard - Smiles and long press feature in Android -

i've created android keyboard. how add features inserting smilies, , using long keypresses display symbols? to create long-press behavior allows select several options pop-up menu, follow guide (specifically pop-up menu section): http://developer.android.com/guide/topics/ui/menus.html smileys (also known emoticons) combination of keys, understood programs , parsed same way. have do, when clicks smiley face on keyboard, simulate pressing of key combination matching emoticon. example, when clicks smiley, should simulate key presses ':' , ')' :). here's list of emoticons: http://en.wikipedia.org/wiki/list_of_emoticons
Read more

node.js - Bad Request - node js ajax post -

i'm using express 3.0 , node v0.11.0. have button submits form , i'm using ajax post data json object node server. client code is: $('#contact').submit(function(e) { console.log('submit called'); var formdata = json.stringify($('form').serializeobject()); console.log(formdata); $.ajax({ url: "http://localhost:3000/savedata/", type: "post", datatype: 'json', data: {objectdata: formdata}, contenttype: "application/json", complete: function() { console.log('process complete'); }, success: function(data) { console.log('process sucess'); }, error: function() { console.log('process error'); }, }); return false; }); then on server: var express = require('express'); var app = express(); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyparser());...
Read more