Setting up Xcode to debug C Extension

Whaat · May 20, 2022, 4:19pm

After a long time away from using Xcode to work with C extensions, I am trying to get the debugging environment to work so that I can set breakpoints in Xcode and step through the cpp code while a SketchUp extension is executing it.

Is there a tutorial or documentation somewhere that describes the setup for this? I have done it before a long time ago but can’t remember the steps for configuring everything.

DanRathbun · May 21, 2022, 2:51am

ReadMe files:

github.com

SketchUp/ruby-c-extension-examples/blob/main/macOS.md

# macOS Notes

## Useful commands

### Check the architecture of a binary

```
$ file SUEX_HelloWorld.bundle 
SUEX_HelloWorld.bundle: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit bundle x86_64] [arm64:Mach-O 64-bit bundle arm64]
SUEX_HelloWorld.bundle (for architecture x86_64):	Mach-O 64-bit bundle x86_64
SUEX_HelloWorld.bundle (for architecture arm64):	Mach-O 64-bit bundle arm64
```

### Check the deployment target

It appear that x86_64 and arm64 binaries doesn't report the same way.

```
$ otool -arch x86_64 -l SUEX_HelloWorld.bundle | grep -A 5 LC_VERSION_MIN_MACOSX
      cmd LC_VERSION_MIN_MACOSX

This file has been truncated. show original

Example XCode project file(s) …

Additional tidbits on the SDK intro page …

SketchUp C API: SketchUp C API

tt_su · May 25, 2022, 9:22am

In you Scheme configuration you set the Application to launch (pick your SketchUp version)

You need to ensure that SketchUp loads your Ruby C Extension from the build dir so breakpoints work. This might clash with your “normal” logic to load the Ruby C Extension. For this I often use startup args to modify where the extension loads the binary.

I don’t have a ready screenshot for Xcode, but it’d be similar to this VSCode setup:

github.com

SketchUp/sketchup-live-c-api/blob/60548c603dde2470a79d3af1e8e1e7ed9eef1759/.vscode/launch.json#L54-L60

      
        
            "program": "/Applications/SketchUp ${input:sketchupVersion}/SketchUp.app/Contents/MacOS/SketchUp",
            "args": [
              "-RubyStartup",
              "${workspaceFolder}/cext/scripts/debug.rb",
              "-RubyStartupArg",
              "Id=LiveCAPI;Config=${input:buildType};Path=${workspaceRoot}/ruby"
            ],

github.com

SketchUp/sketchup-live-c-api/blob/60548c603dde2470a79d3af1e8e1e7ed9eef1759/ruby/live-c-api/main.rb#L8-L27

      
        
            # Load guard for the Ruby C Extension, allowing the binary to be loaded
            # from the build directory.
            #
            # Parse startup args:
            # "Config=${input:buildType};Path=${workspaceRoot}/ruby"
            args = (ARGV[0] || '').split(';')
            args = args.map { |arg| arg.split('=') }.to_h
            if args['Id'] == 'LiveCAPI'
              # This means the Ruby C Extension will be loaded via the
              # <project_dir>/cext/scripts/debug.rb helper for purposes of debugging.
              puts "#{self.name} C Extension deferred loading for debugging..."
            elsif defined?(CEXT_VERSION)
              # This means the Ruby C Extension has already been loaded by other means.
              puts "#{self.name} C Extension already loaded"
            else
              # This binary is not checked in. Use CMake to "install" it to this
              # location before running/packaging the SketchUp extension.
              # (VSCode) `<Command Palette>` » CMake: Install
              require 'live-c-api/cext/2.5/example'
            end

This kind of setup has let me quickly jump into debugging my Ruby C extensions in VS/VSCode/Xcode without having to manually copy any files or modify source once it’s all setup.

tt_su · May 31, 2022, 1:30pm

A post was split to a new topic: Debugging on macOS