Based on the docs I came up with this code

require "libusb"

usb = LIBUSB::Context.new

device = usb.devices(:idVendor => 0x16d0, :idProduct => 0x0753).first

raise "device not found" if device.nil?

device.open_interface(0) do |handle|
  handle.control_transfer({
    :bmRequestType => LIBUSB::ENDPOINT_IN|LIBUSB::REQUEST_TYPE_CLASS|LIBUSB::RECIPIENT_INTERFACE,
    :bRequest => 0x01,
    :wIndex => 0,
    :wValue => 0,
    :dataIn => 1,
    :timeout => 0
  }) do |result|
    puts "result #{result}"
  end
end

but it never returns. Does the libusb gem require eventmachine? or what am I doing wrong?

I'm working on a little driver to set key colors and actuation heights on a Realforce RGB keyboard, but am seeing inconsistent results, which I'm sure is something I'm missing, but I cannot figure out what it is.

Most of the time when I run the code below, it fails with LIBUSB::ERROR_IO, and does not make it far enough to be seen by Wireshark. I see the same behavior whether running as root or normal user, and with both Ruby 2.3.3 and 2.4.1.

It fails far more often than it works, but when it gets into a working state, it stays that way until I unplug and replug the device.

Is there anything obvious I'm missing here? It's clear from various searches that getting devices into the correct state for reading and writing is something that others struggle with as well.

system uname (Ubuntu 17.04):

Linux vatican 4.10.0-26-generic #30-Ubuntu SMP Tue Jun 27 09:30:12 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

the code:

require 'libusb'
require 'pry'

VENDOR_ID = 0x0853
PRODUCT_ID = 0x013a
#ENDPOINT = 0x04
data = "\xaa\xaa\x62\x00\x04\x00\xff\x00\x00".force_encoding(Encoding::BINARY)

usb = LIBUSB::Context.new
usb.debug = 10

devices = usb.devices(idVendor: VENDOR_ID, idProduct: PRODUCT_ID)
device = devices.first

raise 'No device found' unless device

begin
  endpoint_in = device.endpoints.find { |ep| !(ep.bEndpointAddress & LIBUSB::ENDPOINT_IN).zero? }
  endpoint_out = device.endpoints.find { |ep| (ep.bEndpointAddress & LIBUSB::ENDPOINT_IN).zero? }
  # binding.pry

  h = device.open
  h.auto_detach_kernel_driver = true
  h.claim_interface(0)
  h.clear_halt endpoint_in
  response = h.interrupt_transfer(
    endpoint: endpoint_out,
    dataOut: data,
    timeout: 10000
  )

  p response
ensure
  h.release_interface(0)
  h.close
end

When it fails:

libusb: debug [libusb_get_device_list]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_config_descriptor] index 0
libusb: debug [libusb_get_config_descriptor] index 0
libusb: debug [libusb_open] open 1.47
libusb: debug [usbi_add_pollfd] add fd 14 events 4
libusb: debug [libusb_claim_interface] interface 0
libusb: debug [libusb_clear_halt] endpoint 81
libusb: debug [libusb_alloc_transfer] transfer 0x55d35fc5d7e0
libusb: debug [libusb_submit_transfer] transfer 0x55d35fc5d7e0
libusb: debug [add_to_flying_list] arm timerfd for timeout in 10000ms (first in line)
libusb: debug [submit_bulk_transfer] need 1 urbs for new transfer with length 9
libusb: error [submit_bulk_transfer] submiturb failed error -1 errno=16
libusb: debug [submit_bulk_transfer] first URB failed, easy peasy
libusb: debug [disarm_timerfd]
libusb: debug [libusb_release_interface] interface 0
libusb: debug [libusb_close]
libusb: debug [usbi_remove_pollfd] remove fd 14
/home/mpd/.rvm/gems/ruby-2.3.3/gems/libusb-0.6.2-x86_64-linux/lib/libusb/constants.rb:62:in `raise_error': LIBUSB::ERROR_IO in libusb_submit_transfer (LIBUSB::ERROR_IO)
        from /home/mpd/.rvm/gems/ruby-2.3.3/gems/libusb-0.6.2-x86_64-linux/lib/libusb/transfer.rb:202:in `submit!'
        from /home/mpd/.rvm/gems/ruby-2.3.3/gems/libusb-0.6.2-x86_64-linux/lib/libusb/transfer.rb:229:in `submit_and_wait'
        from /home/mpd/.rvm/gems/ruby-2.3.3/gems/libusb-0.6.2-x86_64-linux/lib/libusb/dev_handle.rb:544:in `submit_transfer'
        from /home/mpd/.rvm/gems/ruby-2.3.3/gems/libusb-0.6.2-x86_64-linux/lib/libusb/dev_handle.rb:465:in `interrupt_transfer'
        from usb.rb:35:in `<main>'
libusb: debug [libusb_free_transfer] transfer 0x55d35fc5d7e0

When it works:

libusb: debug [libusb_get_device_list]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_device_descriptor]
libusb: debug [libusb_get_config_descriptor] index 0
libusb: debug [libusb_get_config_descriptor] index 0
libusb: debug [libusb_open] open 1.43
libusb: debug [usbi_add_pollfd] add fd 14 events 4
libusb: debug [libusb_claim_interface] interface 0
libusb: debug [libusb_clear_halt] endpoint 81
libusb: debug [libusb_alloc_transfer] transfer 0x563855794c20
libusb: debug [libusb_submit_transfer] transfer 0x563855794c20
libusb: debug [add_to_flying_list] arm timerfd for timeout in 10000ms (first in line)
libusb: debug [submit_bulk_transfer] need 1 urbs for new transfer with length 9
libusb: debug [libusb_handle_events_timeout_completed] doing our own event handling
libusb: debug [handle_events] poll fds modified, reallocating
libusb: debug [handle_events] poll() 3 fds with timeout in 60000ms
libusb: debug [handle_events] poll() returned 1
libusb: debug [reap_for_handle] urb type=1 status=0 transferred=9
libusb: debug [handle_bulk_completion] handling completion status 0 of bulk urb 1/1
libusb: debug [handle_bulk_completion] last URB in transfer --> complete!
libusb: debug [disarm_timerfd]
libusb: debug [usbi_handle_transfer_completion] transfer 0x563855794c20 has callback 0x7f3bdb7b5000
libusb: debug [libusb_release_interface] interface 0
libusb: debug [libusb_close]
libusb: debug [usbi_remove_pollfd] remove fd 14
libusb: debug [libusb_free_transfer] transfer 0x563855794c20

Full lsusb output for this device:

Bus 001 Device 016: ID 0853:013a Topre Corporation 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.01
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0         8
  idVendor           0x0853 Topre Corporation
  idProduct          0x013a 
  bcdDevice            0.01
  iManufacturer           1 Topre
  iProduct                2 BackLightKB
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           91
    bNumInterfaces          3
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xa0
      (Bus Powered)
      Remote Wakeup
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      1 Boot Interface Subclass
      bInterfaceProtocol      1 Keyboard
      iInterface              3 (error)
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.11
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      65
         Report Descriptors: 
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      0 No Subclass
      bInterfaceProtocol      0 None
      iInterface              4 (error)
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.11
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength     119
         Report Descriptors: 
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0020  1x 32 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      0 No Subclass
      bInterfaceProtocol      0 None
      iInterface              0 
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.11
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      34
         Report Descriptors: 
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x04  EP 4 OUT
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               1
Device Status:     0x0000
  (Bus Powered)

FreeBSD as a system version of libusb (/usr/lib/libusb.so):

The libusb library contains interfaces for directly managing a usb device. The current implementation supports v1.0 of the libusb API.

whenever I try to claim an interface on my OSX machine I get the above error. Below is an irb log showing the problem. Any idea whats wrong? TIA.

 > usb = LIBUSB::Context.new
 => #<LIBUSB::Context:0x007fcb428cb080 @ctx=#<FFI::Pointer address=0x007fcb4228a7a0>> 
> device = usb.devices(:idVendor => 0x1294, :idProduct =>0x1320).first
 => #<LIBUSB::Device 250/6 1294:1320 MAIL MAIL ? (HID (00,00))> 
> handle = device.open_interface(0)
LIBUSB::ERROR_ACCESS: LIBUSB::ERROR_ACCESS in libusb_claim_interface
    from /Users/perrynfowler/.rvm/gems/ruby-1.9.3-p286/gems/libusb-0.2.2/lib/libusb/constants.rb:46:in `raise_error'
    from /Users/perrynfowler/.rvm/gems/ruby-1.9.3-p286/gems/libusb-0.2.2/lib/libusb/dev_handle.rb:76:in `claim_interface'
    from /Users/perrynfowler/.rvm/gems/ruby-1.9.3-p286/gems/libusb-0.2.2/lib/libusb/device.rb:77:in `block in open_interface'
    from /Users/perrynfowler/.rvm/gems/ruby-1.9.3-p286/gems/libusb-0.2.2/lib/libusb/device.rb:62:in `open'
    from /Users/perrynfowler/.rvm/gems/ruby-1.9.3-p286/gems/libusb-0.2.2/lib/libusb/device.rb:76:in `open_interface'
    from (irb):5
    from /Users/perrynfowler/.rvm/rubies/ruby-1.9.3-p286/bin/irb:16:in `<main>'

I can see the transfer method "Interrupt" if I do:

device.interfaces[9].endpoints[0].inspect
=> #<LIBUSB::Endpoint 10 IN  Interrupt>

However I can't seem to get this "Interrupt" string any other way other than inspect.

The inspect source is figuring quite a lot of very useful stuff like transfer_type, synchronization_type and usage_type but this info cannot be accessed any other way but parsing the inspect string, why is this?

Can we please have transport_type, synchronization_type and usage_type methods that return a string like "Interrupt"?

Here is the method in question that can be found in /lib/libusb/endpoint.rb

def inspect
  endpoint_address = self.bEndpointAddress
  num = endpoint_address & 0b00001111
  inout = (endpoint_address & 0b10000000) == 0 ? "OUT" : "IN "
  bits = self.bmAttributes
  transfer_type = %w[Control Isochronous Bulk Interrupt][0b11 & bits]
  type = [transfer_type]
  if transfer_type == 'Isochronous'
    synchronization_type = %w[NoSynchronization Asynchronous Adaptive Synchronous][(0b1100 & bits) >> 2]
    usage_type = %w[Data Feedback ImplicitFeedback ?][(0b110000 & bits) >> 4]
    type << synchronization_type << usage_type
  end
  "\#<#{self.class} #{num} #{inout} #{type.join(" ")}>"
end

Hi, I have this problem under osx lion: I've installed ffi and libusb gem:

port install libusb
gem install ffi
gem install libusb

When I run this code

require 'libusb'

I've this error:

/Users/pioz/.rvm/gems/ruby-1.9.3-p0/gems/libusb-0.1.3/lib/libusb.rb:24:in `<module:Call>': uninitialized constant LIBUSB::Call::FFI (NameError)
from /Users/pioz/.rvm/gems/ruby-1.9.3-p0/gems/libusb-0.1.3/lib/libusb.rb:23:in `<module:LIBUSB>'
from /Users/pioz/.rvm/gems/ruby-1.9.3-p0/gems/libusb-0.1.3/lib/libusb.rb:20:in `<top (required)>'
from /Users/pioz/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:59:in `require'
from /Users/pioz/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:59:in `rescue in require'
from /Users/pioz/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
from main.rb:1:in `<main>'

Ruby version 1.9.3, libusb version 1.0.9, libusb gem version 0.1.3, ffi gem version 1.0.11.

Any idea?

Code sample:

#!/usr/bin/env ruby
require 'libusb'
require 'libusb/eventmachine'

context = LIBUSB::Context.new

EventMachine.run do
  context.eventmachine_register

  puts "Started!"
end

Error in the console after plugging in / out a usb device:

Starter!
HOTPLUG_EVENT_DEVICE_ARRIVED: #<LIBUSB::Device 20/9 04b8:0e04 EPSON TM-T801FV 535739460006190000 (Printer (01,02))>
/Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libusb-0.5.1/lib/libusb/context.rb:394:in `block in on_hotplug_event': hotplug event handler must return :finish or :repeat (ArgumentError)
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libusb-0.5.1/lib/libusb/context.rb:192:in `libusb_handle_events_timeout_completed'
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libusb-0.5.1/lib/libusb/context.rb:192:in `handle_events'
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libusb-0.5.1/lib/libusb/eventmachine.rb:97:in `block in eventmachine_add_pollfd'
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libusb-0.5.1/lib/libusb/eventmachine.rb:79:in `block in need_handle_events'
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libusb-0.5.1/lib/libusb/eventmachine.rb:78:in `each'
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libusb-0.5.1/lib/libusb/eventmachine.rb:78:in `need_handle_events'
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/eventmachine-1.2.0.1/lib/eventmachine.rb:194:in `run_machine'
    from /Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/eventmachine-1.2.0.1/lib/eventmachine.rb:194:in `run'
    from app/main.rb:22:in `<main>'

I am attempting to port the code from this blog post to ruby and libusb. It can be found here. I seem to be running into TRANSFER_TIMED_OUT on the first interrupt_read on line 28. Unfortunately, the error does not contain transferred so I think there's nothing to read. Since the C code from the blog post seems to work properly I assume either I am doing something wrong (likely) or there's a bug in ruby-libusb. Any thoughts or suggestions?

Asked by Simone per Email:

I'm trying to use the 'libusb' gem in Ruby under Windows 7. I can connect to the device but when I try to send the command to the device I get the following error:

C:\>ruby rubyusb2.rb
C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/libusb-0.6.2-x86-mingw32/li
b/libusb/transfer.rb:76:in `buffer=': undefined method `bytesize' for 131072:Fix
num (NoMethodError)
        from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/libusb-0.6.2-x
86-mingw32/lib/libusb/dev_handle.rb:460:in `interrupt_transfer'
        from rubyusb2.rb:18:in `<main>'

This is my code:

require "libusb"

usb = LIBUSB::Context.new
device = usb.devices(idVendor: 0x0452, idProduct: 0xFFFF).first

handle = device.open

begin
  handle.claim_interface(0)
rescue LIBUSB::ERROR_BUSY
  handle.detach_kernel_driver(0)
  handle.claim_interface(0)
end

handle.interrupt_transfer(endpoint: 0x02, dataOut: 0x020000)

handle.close

If I enter a string (es. "02") instead of a hexadecimal parameter in the :dataOut parameter, there are no problems. There is a way to send directly data in hex using the parameter: dataOut?

Thanks for making edits to the LIBUSB library. Our design project would be of the question without it.

I realize this stems from an issue in FFI. Any ideas how to fix this?

I try to store a LIBUSB::Context object in the Rack::Session while using Sinatra. I can store the object in the Rack Session fine, but when I bring it back down, I get this error.

https://twitter.com/#!/westonplatter/status/180213943380348928/photo/1 TypeError at /session no _dump_data is defined for class FFI::Pointer file: cookie.rb location: dump line: 60

https://github.com/ffi/ffi/blob/master/lib/ffi/pointer.rb

Any help is appreciated.

Rich Morin asked per mail:

First, thanks for writing and supporting libusb.  Using it, I was able to detect and characterize a iKKEGOL 10633 three-pedal USB Foot Switch which I recently purchased.

I've been thinking about building a "smart" USB switch, based on a RasPi 3B.  Basically, it would act as a programmable crossbar switch, allowing any device to talk to any computer.  For example, it might let a braille display be used by several computers, controlled by a foot switch.

My naive question has to do with things like plug gender, protocol roles, etc.  Is there a relatively easy way (in hardware and software) for a computer to act as a USB device?

Hey there Lars,

Right now the samep code shows this:

usb = LIBUSB::Context.new
device = usb.devices(idVendor: 0x04b4, idProduct: 0x8613).first

I don't know how to obtain these 0x04b4 entries.

When I do this I get "nil" value.

Is there some way to obtain a list of all ids currently plugged in? I have an USB stick plugged in.

Not sure how to get the vendor id.

Could the example show this for when you insert a new USB device, how to find out the ID and then use that to query content, or auto-mount at a later time? Right now this is an obstacle as I don't know how to get the vendor id as such. Perhaps the example can be extended to find out the IDs somehow. Thanks.

When calling #control_transfer with :dataIn the returned string as an extra 8 bytes (due to CONTROL_SETUP_SIZE ?) Tested the same query in C using libusb_control_transfer, I've got the right result

I sniffed communication between software on Windows and a sonometer. Now I want to mimic it on Linux. Software sends URB_INTERRUPT out to endpoint 2, with some capture data that probably means "give me current state". Then there is another URB_INTERRUPT in, to endpoint 1. And this interruption has capture data with current state I need. I tried to mimic it and I failed. I described it on stackoverflow. If you have a second I would be greatfull for help.

https://stackoverflow.com/questions/56360704/i-cannot-mimic-sniffed-urb-interruption-using-libusb-for-ruby

When running this simple script

require "libusb"

usb = LIBUSB::Context.new

device = usb.devices(idVendor: 0x0100, idProduct: 0x0001).first

device.open do |dev|
  if dev.kernel_driver_active?(0)
    dev.detach_kernel_driver(0)
  end
  dev.claim_interface(0) {}
end

puts 'exiting'

to access my Generic HID device (a custom AVR ATMEGA32U4), in 20% of the cases I'm getting a segfault:

exiting
segfault-demo.rb: [BUG] Segmentation fault at 0x00007f9bff0be7ef
ruby 2.4.5p335 (2018-10-18) [x86_64-linux]

-- Control frame information -----------------------------------------------
c:0001 p:0000 s:0003 E:001710 (none) [FINISH]


-- Machine register context ------------------------------------------------
 RIP: 0x00007f9bff0be7ef RBP: 0x00007f9bff0aced0 RSP: 0x00007f9bff0acec0
 RAX: 0x0000000000000001 RBX: 0x00000000ffffffff RCX: 0x00007f9c07708501
 RDX: 0x00000000ffffffff RDI: 0x0000000000000000 RSI: 0x0000000000000002
  R8: 0x0000000000000000  R9: 0x00007f9bff0ad700 R10: 0x00007f9bff0ad9d0
 R11: 0x0000000000000000 R12: 0x00007ffd3f7dad4e R13: 0x00007ffd3f7dad4f
 R14: 0x00007f9bff0ad700 R15: 0x00007f9c08afd000 EFL: 0x0000000000010206

-- C level backtrace information -------------------------------------------
/nix/store/n8i8zc2max1cq7nz50lwrry2w6i3gfgi-ruby-2.4.5/lib/libruby.so.2.4(rb_vm_bugreport+0x769) [0x7f9c085e93d9]
/nix/store/n8i8zc2max1cq7nz50lwrry2w6i3gfgi-ruby-2.4.5/lib/libruby.so.2.4 [0x7f9c084685d4]
/nix/store/n8i8zc2max1cq7nz50lwrry2w6i3gfgi-ruby-2.4.5/lib/libruby.so.2.4 [0x7f9c0855d02e]
/nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libpthread.so.0 [0x7f9c081b6f10]
/nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libgcc_s.so.1(__getf2+0x3f) [0x7f9bff0be7ef]
/nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libpthread.so.0 [0x7f9c081ac5a7]
/nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libc.so.6(clone+0x3f) [0x7f9c0771222f]

(Full diagnostic output)

The error doesn't happen when using libusb in a similar way via C or Python. Note that the error appears while exiting, after the last code statement. The error disappears when running sleep 0.01 before exiting. (But not sleep 0.001, which seems to be a too short sleep duration). Besides this error, other features of this library, like transfers, are properly functioning.

Environment:

Tested Ruby versions: 2.5.3p105, 2.4.5p335
ffi (1.10.0)
libusb (0.6.4)
Linux 4.14.83 (NixOS)

Let me know if's there's anything more I can do to help debugging this.

Hello there,

Firstly, apologies if this is not the appropriate forum for implementation questions. I'm trying to use the library to create a ruby translation of the following C++ library:

void UsbDownloader::run()
{
    bool hasError = true;
#ifndef USB_READ_DUMP
    libusb_device_handle* handle = 0;

    do { // Error loop
        int r;

        // Open USB device
        handle = libusb_open_device_with_vid_pid(ctx, BSM_VID, BSM_PID);
        if (!handle) {
            qCritical() << "Failed to open the device";
            break;
        }
        qDebug() << "USB device opened";

        // Detach kernel driver
        if (libusb_kernel_driver_active(handle, USB_INTERFACE_IN)) {
            qDebug() << "Detaching kernel driver...";
            r = libusb_detach_kernel_driver(handle, USB_INTERFACE_IN);
            if (r < 0) {
                qCritical() << "libusb_detach_kernel_driver error" << r;
                break;
            }
            qDebug() << "Kernel driver detached";
        }

        // Claim interface
        qDebug() << "Claiming interface...";
        r = libusb_claim_interface(handle, USB_INTERFACE_IN);
        if (r < 0) {
            qCritical() << "usb_claim_interface error" << r;
            break;
        }
        qDebug() << "Interface claimed";

        // Prepare to receive data
        qDebug() << "Register for interrupt data";
        libusb_transfer *transfer_receive = libusb_alloc_transfer(0);
        unsigned char buffer_receive[8];
        UsbDownloaderData usb_data;
#ifdef USB_WRITE_DUMP
        usb_data.dump.setFileName(USB_WRITE_DUMP);
        usb_data.dump.open(QIODevice::WriteOnly | QIODevice::Truncate);
#endif
        libusb_fill_interrupt_transfer(transfer_receive, handle, LIBUSB_ENDPOINT_IN | USB_INTERFACE_OUT, buffer_receive, sizeof(buffer_receive), cb_in, &usb_data, 30000);
        r = libusb_submit_transfer(transfer_receive);
        if (r < 0) {
            qCritical() << "libusb_submit_transfer error" << r;
            break;
        }

        // Prepare to send request
        qDebug() << "Send control request";
        libusb_transfer *transfer_send = libusb_alloc_transfer(0);
        unsigned char buffer_send[LIBUSB_CONTROL_SETUP_SIZE + USB_CTRL_DATA_LEN] __attribute__ ((aligned (2)));
        libusb_fill_control_setup(buffer_send, LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE, USB_CTRL_REQUEST, USB_CTRL_VALUE, 0, USB_CTRL_DATA_LEN);
        buffer_send[LIBUSB_CONTROL_SETUP_SIZE] = USB_CTRL_DATA_FIRST;
        memset(buffer_send + LIBUSB_CONTROL_SETUP_SIZE + 1, 0, USB_CTRL_DATA_LEN - 1);
        libusb_fill_control_transfer(transfer_send, handle, buffer_send, cb_out, 0, 3000);
        r = libusb_submit_transfer(transfer_send);
        if (r < 0) {
            qCritical() << "libusb_submit_transfer error" << r;
            break;
        }

        // Wait for completion
        while (!usb_data.completed) {
            r = libusb_handle_events_completed(ctx, 0);
            emit progress(100 * usb_data.data.size() / USB_EXPECTED_LEN);
            if (r < 0)
                break;
        }

#ifdef USB_WRITE_DUMP
        if (usb_data.dump.isOpen())
            usb_data.dump.close();
#endif

        // Emit completion signal
        if (usb_data.completed) {
            emit completed(usb_data.data);
            hasError = false;
        }
    } while(false);

    // Close USB device
    if (handle) {
        libusb_release_interface(handle, USB_INTERFACE_IN);
        qDebug() << "Released interface";
        libusb_close(handle);
        handle = 0;
        qDebug() << "Closed USB device";
    }
#else
    do { // Error loop
        QFile usb_data_file(USB_READ_DUMP);
        if (!usb_data_file.open(QIODevice::ReadOnly | QIODevice::Text)) {
            qCritical() << "Failed to open" << USB_READ_DUMP;
            break;
        }

        UsbDownloaderData usb_data;
#ifdef USB_WRITE_DUMP
        usb_data.dump.setFileName(USB_WRITE_DUMP);
        usb_data.dump.open(QIODevice::WriteOnly | QIODevice::Truncate);
#endif

        while (!usb_data_file.atEnd()) {
            char buff[20];
            qint64 s = usb_data_file.readLine(buff, 20);
            if (s < 16 || s > 17)
                break;

            if (s == 17 && buff[16] != '\n')
                break;

            libusb_transfer t;
            unsigned char b[8];
            bool ok;
            t.buffer = b;
            t.actual_length = 8;
            t.status = LIBUSB_TRANSFER_ERROR; // ignored as error, to avoid resubmit
            t.user_data = &usb_data;
            for(int i = 0; i < 8; ++i) {
                b[i] = (unsigned char) QString("%1%2").arg(buff[i * 2]).arg(buff[i * 2 + 1]).toUShort(&ok, 16);
                if (!ok)
                    break;
            }
            if (!ok)
                break;

            cb_in(&t);
            emit progress(100 * usb_data.data.size() / USB_EXPECTED_LEN);
        }

#ifdef USB_WRITE_DUMP
        if (usb_data.dump.isOpen())
            usb_data.dump.close();
#endif

        if (usb_data_file.atEnd()) {
            emit completed(usb_data.data);
            hasError = false;
        }

        usb_data_file.close();
    } while(false);
#endif
    // Emit error signal
    if (hasError)
        emit error();
}

I understand that I need to initiate a control_transfer to set up the transfer, and then use interrupt_transfer for the passing of data from my device. My current implementation looks something like this:

usb = LIBUSB::Context.new
@device = usb.devices(idVendor: BSM_VID, idProduct: BSM_PID).first
@device.open do |device|
	# setup interrupt transfer (ready to receive)
	device.claim_interface(0) do |handle|
		handle.control_transfer(
			bmRequestType: 0x21,
			bRequest: USB_CTRL_REQUEST,
			wValue: USB_CTRL_VALUE,
			wIndex: 0x000,
			dataOut: '\x10\x00\x00\x00\x00\x00\x00\x00'
		) do |result|
			puts "control_transfer result: #{result}"
		end

		handle.interrupt_transfer(
			endpoint: @device.endpoints.first,
			dataIn: 8
		)
	end
end

This yields a TRANSFER_STALL in the control_transfer block and raises error TRANSFER_TIMED_OUT (LIBUSB::ERROR_TIMEOUT).

I'm hoping someone might be able to shed some light on how to correctly use the control_transfer and interrupt_transfer methods of LIBUSB::DevHandle in tandem?

Really appreciate the help!