Cannot load unsigned dylibs on macOS with dart:ffi or native extensions

[mit-mit]

Now that the Dart SDK is signed (i.e. dart is signed), we don't seem to be able to load unsigned dylibs anymore:

Unhandled exception:
Invalid argument(s): Failed to load dynamic library (dlopen(osdialog.dylib, 1): no suitable image found.  Did find:
	osdialog.dylib: code signature in (osdialog.dylib) not valid for use in process using Library Validation: mapped file has no cdhash, completely unsigned? Code has to be at least ad-hoc signed.)
#0      _open (dart:ffi-patch/ffi_dynamic_library_patch.dart:10:55)
#1      new DynamicLibrary.open (dart:ffi-patch/ffi_dynamic_library_patch.dart:17:12)
#2      main (file:///Users/mit/dev/playground/dart/ffi/osdialog/os.dart:11:36)
#3      _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:305:19)
#4      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:12)
| ~/dev/playground/dart/ffi/osdialog @ mit-macbookpro3 (mit)

[aab29]

We're running into this issue with the game engine we're developing. 👾 After upgrading to 2.5, we can no longer run the tests for our engine because they need to load dylibs. We've tried signing the dylibs, but we can't figure out a way to sign them such that dart can interface with them. ✍️ 🙅‍♂

[mit-mit]

@aab29 are you using ffi? Which operating system?

If on macOS, did you try signing the library?

[mit-mit]

If macOS, can you try the following workaround:

1. Make sure you have the codesign tool in your terminal
2. Locate the main dart binary
3. Run codesign --remove-signature <path to dart binary>
4. Run tests again

You might want to take a backup copy of the dart command first, or re-install dart when done.

[aab29]

Hi @mit-mit ! Thanks for your speedy, helpful response! I'm sorry my reply is so delayed. We've been busy over here. 🤓 ⌨️

No--we are not using ffi. The error message we were getting was similar to the one I found here, but I'm afraid I missed that detail before I commented. We're still using the old native extensions system to interface with our dylibs. 💾 Let me know if you'd like me to create a separate issue or anything.

We're currently running Dart 2.5.2, and we're hitting the same error messages we hit under Dart 2.5.0. 🎯 We are indeed running MacOS. For now we're running Mojave (10.14.6), but we're hoping to upgrade to Catalina soon. 🔜 🆙

The workaround you suggested (removing the signature on the main dart binary) works fine! Thank you! 🙌 For the moment we're happy with this, but obviously it's not ideal in the long run.

We don't have much experience dealing with code signing, so apologies if we're not doing something obvious. 🤔 From what we can tell, it seems like we should now be codesigning our own dynamic libraries, but if we sign them with our own credentials, it's not possible to interface with the dart binary (signed with a different team identifier). ✍️ I suppose we could build and sign our own dart binary, but that is still much more involved than we'd like for this use case. 💁‍♂

Please let me know if there's any other information we can provide that might be helpful! ℹ️

[keertip]

@mit-mit , folks are going to run into this with doing the ffi tutorial. Has there been any progress? Ran into this with -dev.8.2 installed using brew.

[dcharkes]

Conceptually speaking it makes sense that a signed Dart binary can only load signed (third party) shared libraries.

For now, unsigned binaries can load unsigned (and probably signed) third party libraries. However, future MacOS versions will likely disallow that.

I think the path forward would be to include in our tutorial how to sign your own custom made library on MacOS Catalina.

cc @mkustermann