primitive FFI sample broken on macOS due to import problem

[kakyoism]

Problem

On macOS, running the primitive sample code after proper CMaking the C lib gives the following error

$ !dart
dart primitives.dart
Unhandled exception:
Invalid argument(s): Failed to load dynamic library (dlopen(./primitives_library/libprimtives.dylib, 1): image not found)
#0      _open (dart:ffi-patch/ffi_dynamic_library_patch.dart:10:55)
#1      new DynamicLibrary.open (dart:ffi-patch/ffi_dynamic_library_patch.dart:19:12)
#2      main (file:///Users/kakyo/Desktop/_task/MMT/research/hello-mamguest/hello_dart/primitives/primitives.dart:41:32)
#3      _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:305:19)
#4      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:12)

Fix

$ sdiff -l theirs/ffi/primitives/primitives.dart mine/primitives/primitives.dart | cat -n | grep -v -e '($'
5	import 'dart:ffi';					      |	import 'dart:ffi' as ffi;
41	  final dylib = DynamicLibrary.open(path);		      |	  final dylib = ffi.DynamicLibrary.open(path);

[domesticmouse]

Can you please submit the fix as a pull request?

[domesticmouse]

Also, I'm curious how your change fixes things. Is there two different DynamicLibrary objects in scope?

[dcantir]

@domesticmouse Hi, I got the same problem on my machine, but seems like the issue is using relative paths when trying to import the library (I get this message in the exception: "file system relative paths not allowed in hardened programs").

[dcharkes]

"file system relative paths not allowed in hardened programs"

On MacOS the dylib needs to be in the same or a sub folder of the dart executable. See dart-lang/sdk#38314 (comment). (I'm not sure if you can fix the sample here, as the dart binary is part of the SDK folder and this simples repo is a different repo.)

[dcharkes]

Also, I'm curious how your change fixes things. Is there two different DynamicLibrary objects in scope?

I did a breaking change, I changed those methods to be extension methods. Importing with as does not import the extension methods into the current scope.

[irvifa]

Hi I think the one proposed by @dcantir fix the problem and it's a minor one, can someone help take a look on that? Thanks!