Module: LinuxStat::USB

Defined in:
lib/linux_stat/usb.rb

Class Method Summary collapse

Class Method Details

.count ⇒ Object Also known as: count_devices

Opens /sys/bus/usb/devices, and counts the total number of devices connected to the USB interface. The return type is an integer.

It checks for devices with vendor and product id file. If there’s no such file, it will not count them as a USB device.

It could be also an integrated hub or a webcam, as well as external hotpluggable devices like printer, USB storage devices, USB mouse, USB keyboard, USB joypad etc.

But if the information isn’t available, it will return nil.



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# File 'lib/linux_stat/usb.rb', line 135

def count
	@@sys_usb_readable ||= File.readable?('/sys/bus/usb/devices/')
	return nil unless @@sys_usb_readable

	Dir['/sys/bus/usb/devices/*/'.freeze].count { |x|
		id_vendor_file = File.join(x, 'idVendor'.freeze)
		id_product_file = File.join(x, 'idProduct'.freeze)
		File.readable?(id_vendor_file) && File.readable?(id_product_file)
	}
end

.devices_stat(hwdata: true) ⇒ Object

devices_stat(hwdata: true)

Returns details about the devices found in /sys/bus/usb/devices/

The return value is an Array of multiple Hashes. If there’s no info available, it will rather return an empty Array.

On Android Termux for example, it can not list the directories because they are not readable the the regular user.

It can have information like:

path, id, vendor id, product id, manufacturer, serial, bus number, dev number, b_max_power, b_max_packet_size, etc.

An example of the returned sample from a test machine is:

LinuxStat::USB.devices_stat

=> [{:path=>"/sys/bus/usb/devices/1-1.2/", :id=>"04d9:1203", :vendor_id=>"04d9", :product_id=>"1203", :bus_num=>1, :dev_num=>4, :hwdata=>{:vendor=>"Holtek Semiconductor, Inc.", :product=>"Keyboard"}, :authorized=>true, :b_max_power=>"100mA", :b_max_packet_size0=>8}

Right, it’s an array of Hashes.

It also takes one option. The hwdata, which is true by default.

Information about usb devices is found inside /usr/share/hwdata/usb.ids

The data contains the vendor and the product.

If the option is enabled, it will try look at /usr/share/hwdata/usb.ids

But the file will be read only once. The consecutive calls to this method won’t open the hwdata all the times.

But if there’s no hwdata, the Hash returned by this method will not contain hwdata key.

The data is only populated if it’s available. For example, if there’s no manufacturer available for the product, the returned Hash will not contain the information about the manufacturer.

Also note that if there’s no info available or no USB devices, it will return an empty Hash.



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# File 'lib/linux_stat/usb.rb', line 47

def devices_stat(hwdata: true)
	@@sys_usb_readable ||= File.readable?('/sys/bus/usb/devices/')
	return [] unless @@sys_usb_readable

	Dir['/sys/bus/usb/devices/*/'.freeze].sort!.map! { |x|
		id_vendor_file = File.join(x, 'idVendor'.freeze)
		next unless File.readable?(id_vendor_file)
		id_vendor = IO.read(id_vendor_file).strip

		id_product_file = File.join(x, 'idProduct'.freeze)
		next unless File.readable?(id_vendor_file)
		id_product = IO.read(id_product_file).strip

		bus_num_file = File.join(x, 'busnum'.freeze)
		bus_num = File.readable?(bus_num_file) ? IO.read(bus_num_file).strip : ''.freeze

		dev_num_file = File.join(x, 'devnum'.freeze)
		dev_num = File.readable?(dev_num_file) ? IO.read(dev_num_file).strip : ''.freeze

		serial_file = File.join(x, 'serial'.freeze)
		serial = File.readable?(serial_file) ? IO.read(serial_file).strip : ''.freeze

		product_file = File.join(x, 'product'.freeze)
		product = File.readable?(product_file) ? IO.read(product_file).strip : ''.freeze

		manufacturer_file = File.join(x, 'manufacturer'.freeze)
		manufacturer = File.readable?(manufacturer_file) ? IO.read(manufacturer_file).strip : ''.freeze

		removable_file = File.join(x, 'removable'.freeze)
		removable = File.readable?(removable_file) ? IO.read(removable_file).strip : ''.freeze

		authorized_file = File.join(x, 'authorized'.freeze)
		authorized = File.readable?(authorized_file) ? IO.read(authorized_file).to_i : ''.freeze

		b_max_power_file = File.join(x, 'bMaxPower'.freeze)
		b_max_power = File.readable?(b_max_power_file) ? IO.read(b_max_power_file).strip : ''.freeze

		b_max_packet_size0_file = File.join(x, 'bMaxPacketSize0'.freeze)
		b_max_packet_size0 = File.readable?(b_max_packet_size0_file) ? IO.read(b_max_packet_size0_file).to_i : ''.freeze

		query = hwdata ? query_hwdata(id_vendor, id_product) : {}

		removable.downcase!
		is_removable = if removable == 'removable'.freeze
			true
		elsif removable == 'unknown'.freeze
			nil
		else
			false
		end

		ret = {
			path: x, id: "#{id_vendor}:#{id_product}",
			vendor_id: id_vendor, product_id: id_product
		}

		ret.merge!(bus_num: bus_num.to_i) unless bus_num.empty?
		ret.merge!(dev_num: dev_num.to_i) unless dev_num.empty?

		ret.merge!(serial: serial) unless serial.empty?

		ret.merge!(hwdata: query) unless query.empty?
		ret.merge!(product: product) unless product.empty?
		ret.merge!(manufacturer: manufacturer) unless manufacturer.empty?

		ret.merge!(removable: is_removable) unless is_removable.nil?
		ret.merge!(authorized: authorized == 1)

		ret.merge!(b_max_power: b_max_power) unless b_max_power.empty?
		ret.merge!(b_max_packet_size0: b_max_packet_size0) if b_max_packet_size0

		ret
	}.tap(&:compact!)
end

.hwdata_file ⇒ Object

Returns the hwdata_file as string.

If hwdata_file isn’t set, it will return an empty frozen string.

Once it’s set, it can’t be changed.



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# File 'lib/linux_stat/usb.rb', line 175

def hwdata_file
	@@hwdata_file ||= nil
	@@hwdata_file ? @@hwdata_file : ''.freeze
end

.hwdata_file=(file) ⇒ Object

hwdata_file = file

Lets you set the hwdata_file about usb.ids.

The hwdata file about usb.ids contains vendor name and product name information about devices. This is then mapped by the other methods that utilizes hwdata/usb.ids.

Do note that this method is intended to run only once, at the beginning. If you use any other method that utilizes hwdata/usb.ids, before calling this method, this method will not work.



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# File 'lib/linux_stat/usb.rb', line 157

def hwdata_file=(file)
	@@hwdata_file ||= file.freeze
end

.hwdata_file_set? ⇒ Boolean

Checks if hwdata_file is already initialized or not. Once it’s initialized, calling hwdata_file = ‘something/usb.ids’ is futile.

Returns:

  • (Boolean) 


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# File 'lib/linux_stat/usb.rb', line 164

def hwdata_file_set?
	@@hwdata_file ||= nil
	!!@@hwdata_file
end

.initialize_hwdata ⇒ Object

Initializes hwdata

hwdata can take upto 0.1 to 0.2 seconds to get initialized.

Calling this method will load hwdata for future use.

Once it’s initialized, hwdata_file can’t be changed.

If this method initializes hwdata, it will return true Othewise this method will return false.



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# File 'lib/linux_stat/usb.rb', line 191

def initialize_hwdata
	@@hwdata ||= nil
	init = !@@hwdata
	hwdata
	init
end