Segfaults on Ubuntu Xenial

[Space-Ed]

libasound2 & libasound2-dev installed

$ ruby --version
ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-linux]

$ amidi -l
Dir Device    Name
IO  hw:2,0    Virtual Raw MIDI (16 subdevices)
IO  hw:2,1    Virtual Raw MIDI (16 subdevices)
IO  hw:2,2    Virtual Raw MIDI (16 subdevices)
IO  hw:2,3    Virtual Raw MIDI (16 subdevices)

Gemfile

gem "alsa-rawmidi"

alsa-midi.rb

require "alsa-rawmidi"
AlsaRawMIDI::Device.all

$ ruby alsa-midi.rb
alsa-rawmidi/api.rb:407: [BUG] Segmentation fault at 0xffffffff9bf5a098

[lucasluitjes]

I have the exact same problem, same libraries, ruby version 2.5.1, fresh ubuntu install. My C is really rusty, but if there's anything I can do to help resolve this, please let me know.

Details below:

$ ruby -e "require 'unimidi' ; UniMIDI::Input.gets"

Select a MIDI input...
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/api.rb:407: [BUG] Segmentation fault at 0xffffffffe3328e48
ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux]

-- Control frame information -----------------------------------------------
c:0019 p:---- s:0096 e:000095 CFUNC  :snd_ctl_rawmidi_next_device
c:0018 p:0036 s:0090 e:000089 BLOCK  /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/api.rb:407 [FINISH]
c:0017 p:---- s:0085 e:000084 CFUNC  :select
c:0016 p:0025 s:0081 e:000080 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/api.rb:405
c:0015 p:0015 s:0075 e:000074 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/soundcard.rb:31
c:0014 p:0022 s:0070 e:000069 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/soundcard.rb:14 [FINISH]
c:0013 p:---- s:0065 e:000064 CFUNC  :new
c:0012 p:0064 s:0060 e:000056 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/soundcard.rb:23
c:0011 p:0013 s:0052 e:000051 BLOCK  /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/device.rb:45 [FINISH]
c:0010 p:---- s:0047 e:000046 CFUNC  :times
c:0009 p:0021 s:0043 e:000042 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/device.rb:44
c:0008 p:0018 s:0037 e:000036 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/device.rb:25
c:0007 p:0015 s:0033 e:000032 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/adapter/alsa-rawmidi.rb:16
c:0006 p:0018 s:0029 e:000028 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/loader.rb:20
c:0005 p:0012 s:0022 e:000021 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/input.rb:17
c:0004 p:0004 s:0018 e:000017 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/device.rb:19
c:0003 p:0048 s:0014 e:000013 METHOD /home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/device.rb:41
c:0002 p:0019 s:0006 e:000005 EVAL   -e:1 [FINISH]
c:0001 p:0000 s:0003 E:000ca0 (none) [FINISH]

-- Ruby level backtrace information ----------------------------------------
-e:1:in `<main>'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/device.rb:41:in `gets'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/device.rb:19:in `list'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/input.rb:17:in `all'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/loader.rb:20:in `devices'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/unimidi-0.4.8/lib/unimidi/adapter/alsa-rawmidi.rb:16:in `inputs'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/device.rb:25:in `all_by_type'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/device.rb:44:in `get_devices'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/device.rb:44:in `times'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/device.rb:45:in `block in get_devices'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/soundcard.rb:23:in `find'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/soundcard.rb:23:in `new'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/soundcard.rb:14:in `initialize'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/soundcard.rb:31:in `populate_subdevices'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/api.rb:405:in `get_device_ids'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/api.rb:405:in `select'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/api.rb:407:in `block in get_device_ids'
/home/lucas/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/alsa-rawmidi-0.3.2/lib/alsa-rawmidi/api.rb:407:in `snd_ctl_rawmidi_next_device'

[arirusso]

What does your RawMIDI setup look like?

Some info here that might be helpful

[lucasluitjes]

Edited: premature posting, formatting fixes

$ aconnect -i
client 0: 'System' [type=kernel]
    0 'Timer           '
    1 'Announce        '
client 14: 'Midi Through' [type=kernel]
    0 'Midi Through Port-0'
client 20: 'USB2MIDI' [type=kernel]
    0 'USB2MIDI MIDI 1 '
$ amidi -l
Dir Device    Name
IO  hw:1,0,0  USB2MIDI MIDI 1

I tested roughly the same script using python/mido/rtmidi, so it doesn't look like the hardware is the problem.

[arirusso]

I think the issue is that you need a RawMIDI device listed there. This should be handled better by the gem as to not segfault. See this guide and let me know if that helps. Unfortunately, I don't have an Ubuntu computer handy to try this all on, but I should in August

[lucasluitjes]

Using that guide I do see my rawmidi device in there, the USB2MIDI hardware device. In case it helps, all that's connected is a FCB1010 control surface, just an input device, not a synth or other output.

The same USB2MIDI + FCB1010 setup works well with alsa-rawmidi on ubuntu 14, by the way. Thanks for looking into it so far!

$ cat /proc/asound/cards
 0 [PCH            ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0xdc220000 irq 129
 1 [USB2MIDI       ]: USB-Audio - USB2MIDI
                      Alesis INC. USB2MIDI at usb-0000:00:14.0-7, full speed
$ cat /proc/asound/devices 
  1:        : sequencer
  2: [ 0]   : control
  3: [ 0- 0]: digital audio playback
  4: [ 0- 0]: digital audio capture
  5: [ 0- 3]: digital audio playback
  6: [ 0- 7]: digital audio playback
  7: [ 0- 8]: digital audio playback
  8: [ 0- 9]: digital audio playback
  9: [ 0-10]: digital audio playback
 10: [ 0- 0]: hardware dependent
 11: [ 0- 2]: hardware dependent
 12: [ 1]   : control
 13: [ 1- 0]: raw midi
 33:        : timer

[fukuchi]

Hi,

Here's a quick-and-dirty hack to avoid the segmentation fault:

--- ./api.rb	2019-02-15 16:50:37.218105977 +0900
+++ /tmp/api.rb	2019-02-15 16:50:30.766584839 +0900
@@ -330,9 +330,9 @@
       # @param [Proc] block
       # @return [Integer]
       def open(id, &block)
-        handle_pointer = FFI::MemoryPointer.new(FFI.type_size(:int))
+        handle_pointer = FFI::MemoryPointer.new(FFI.type_size(:ulong))
         yield(handle_pointer)
-        handle_pointer.read_int
+        handle_pointer.read_ulong
       end
 
     end
@@ -424,9 +424,9 @@
       # @param [Integer] soundcard_id
       # @return [Integer]
       def get_handle(soundcard_id)
-        handle_pointer = FFI::MemoryPointer.new(FFI.type_size(:int))
+        handle_pointer = FFI::MemoryPointer.new(FFI.type_size(:ulong))
         API.snd_ctl_open(handle_pointer, get_name(soundcard_id), 0)
-        handle_pointer.read_int
+        handle_pointer.read_ulong
       end
 
     end

This works with Ubuntu 18.04 as far as I tested.

While I'm not familiar with the implementation of Ruby's FFI, I found that the problem behind this issue is that the latest alsa-rawmidi uses 'int' to store the address value.

The patch above may have a problem on 32-bit environment and/or old Linux distributions because probably they uses 32-bit runtimes instead 64-bit.

[chrisbrasington]

Thank you @fukuchi, that ulong patch was exactly what I needed to communicate with my USBMIDI device!

[NoraCodes]

@arirusso I'm also getting this error, on Ubuntu 20.04; any chance you could apply this patch and update the package?

[dromer]

This patch also works for me! (debian buster amd64)

Would be great to not have to hack this in manually.

[najati]

Fantastic. This patch unstuck me on Raspbian. Is it not applied because it's waiting for a PR?