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.



134
135
136
137
138
139
140
141
142
143
 
# File 'lib/linux_stat/usb.rb', line 134

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.



47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
 
# 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.downcase : ''.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) : {}

    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.



174
175
176
177
 
# File 'lib/linux_stat/usb.rb', line 174

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.



156
157
158
 
# File 'lib/linux_stat/usb.rb', line 156

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) 


163
164
165
166
 
# File 'lib/linux_stat/usb.rb', line 163

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.



190
191
192
193
194
195
 
# File 'lib/linux_stat/usb.rb', line 190

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