GTK# stackoverflow mac

[mfkl]

Hello,

When porting LibVLCSharp to GTK#, I encounter a native crash when the mouse cursor touches the VideoView on GTK Mac. It appears to be a stackoverflow in one of your gtk patches.

Steps to Reproduce

1. Clone GTK# / Xamarin.Forms.Gtk implementations (reloaded) videolan/libvlcsharp#20
2. Build the Samples/LibVLCSharp.GTK.Sample on mac
3. Run it and when the video starts, hover over it with the cursor

Current Behavior

Application crash with

Stack overflow in unmanaged: IP: 0x107261f69, fault addr: 0x7ffeec73eff8
Stack overflow: IP: 0x107261f69, fault addr: 0x7ffeec735ff8
Stacktrace:
  at <unknown> <0xffffffff>
  at Gtk.Application.Run () [0x00001] in /Users/builder/jenkins/workspace/build-package-osx-mono/2018-02/external/bockbuild/builds/gtk-sharp-None/gtk/Application.cs:145
  <...>
  at LibVLCSharp.GTK.Sample.Program.Main () [0x0009d] in /Users/Martz/Projects/LibVLCSharp/Samples/LibVLCSharp.GTK.Sample/Program.cs:35
  at (wrapper runtime-invoke) object.runtime_invoke_void (object,intptr,intptr,intptr) [0x0004d] in <71f4e3d7d65e42b0a699d02e59766d3c>:0

Repro with lldb attached gives

(lldb) c
Process 2937 resuming
Process 2937 stopped
* thread #1, name = 'tid_307', queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=2, address=0x7ffee869ffc8)
    frame #0: 0x000000010b061e59 libgdk-quartz-2.0.0.dylib`find_nsview_at_pos + 41
libgdk-quartz-2.0.0.dylib`find_nsview_at_pos:
->  0x10b061e59 <+41>: callq  0x10b0784da               ; symbol stub for: objc_msgSend
    0x10b061e5e <+46>: movq   0x5c03b(%rip), %rsi       ; "count"
    0x10b061e65 <+53>: movq   %rax, %rdi
    0x10b061e68 <+56>: callq  0x10b0784da               ; symbol stub for: objc_msgSend
Target 0: (mono) stopped.

Expected Behavior

Application does not crash.

On which platforms did you notice this

[x] macOS

Version Used:

Mono JIT compiler version 5.16.0.221 (2018-06/b63e5378e38 Mon Nov 19 18:08:09 EST 2018)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
TLS: normal
SIGSEGV: altstack
Notification: kqueue
Architecture: amd64
Disabled: none
Misc: softdebug
Interpreter: yes
LLVM: yes(3.6.0svn-mono-release_60/0b3cb8ac12c)
GC: sgen (concurrent by default)

Stacktrace

Full backtrace https://gist.github.com/mfkl/921581898e21e0c85ffdff0d31eebd0d

Patch introduced in mono/bockbuild#66

/cc @jeremyVignelles

[Therzok]

@bratsche ^

[Therzok]

I think the patch got reverted and we went back to the initial behaviour of stack overflow.

[bratsche]

Yes that patch is reverted for now.

[jeremyVignelles]

Do we have any workarounds? what can we do then? any ETA for a fix?

This bug is annoying for us because we don't have any LibVLCSharp.Forms implementation that can work on mac.

[jeremyVignelles]

ping? We would really like to release a version of LibVLCSharp for GTK# that works on all 3 platforms...