Enhancing RepositoryContent Struct for SubmoduleGitURL support in github/repos_contents.go

[ArisBee]

Hello,

A few weeks ago, I came across an issue while running a project built atop go-github. My goal was to iterate over a GitHub Submodule folder, but it became evident that go-github might need to parse more elements from the GitHub API.

I've made an attempt to adjust this, but unfortunately, it didn't work. Here are the error logs:

allstar-756f9ccdb9-c9pzl allstar panic: runtime error: invalid memory address or nil pointer dereference                                                                                                                                                    │
│ allstar-756f9ccdb9-c9pzl allstar [signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x8220f8]                                                                                                                                                    │
│ allstar-756f9ccdb9-c9pzl allstar                                                                                                                                                                                                                            │
│ allstar-756f9ccdb9-c9pzl allstar goroutine 52 [running]:                                                                                                                                                                                                    │
│ allstar-756f9ccdb9-c9pzl allstar github.com/catawiki/go-github/v50/github.(*RepositoryContent).GetContent(0xc000a7b9b0?)                                                                                                                                    │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/go/pkg/mod/github.com/catawiki/go-github/v50@v50.0.0-20230811121342-0605ae2cb9e3/github/repos_contents.go:76 +0x18                                                                                        │
│ allstar-756f9ccdb9-c9pzl allstar github.com/ossf/allstar/pkg/config.fetchConfig({0x1a79890, 0xc0006e45a0}, {0x1a731a0, 0xc000305310}, {0xc0002ec7f1, 0xd}, {0xc0002ec7b8, 0x8}, {0x16d135a, 0xc}, ...)                                                      │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/allstar/pkg/config/config.go:206 +0x331                                                                                                                                                                   │
│ allstar-756f9ccdb9-c9pzl allstar github.com/ossf/allstar/pkg/config.getAppConfigs({0x1a79890, 0xc0006e45a0}, {0x1a731a0, 0xc000305310}, {0xc0002ec7f1, 0xd}, {0xc0002ec7b8, 0x8})                                                                           │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/allstar/pkg/config/config.go:394 +0x3ed                                                                                                                                                                   │
│ allstar-756f9ccdb9-c9pzl allstar github.com/ossf/allstar/pkg/config.isBotEnabled({0x1a79890, 0xc0006e45a0}, {0x1a731a0, 0xc000305310}, {0xc0002ec7f1, 0xd}, {0xc0002ec7b8, 0x8})                                                                            │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/allstar/pkg/config/config.go:343 +0x6b                                                                                                                                                                    │
│ allstar-756f9ccdb9-c9pzl allstar github.com/ossf/allstar/pkg/config.IsBotEnabled({0x1a79890?, 0xc0006e45a0?}, 0x16d06b3?, {0xc0002ec7f1?, 0xc00028ca00?}, {0xc0002ec7b8?, 0xd?})                                                                            │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/allstar/pkg/config/config.go:339 +0x4a                                                                                                                                                                    │
│ allstar-756f9ccdb9-c9pzl allstar github.com/ossf/allstar/pkg/enforce.runPoliciesOnInstRepos({0x1a79890, 0xc0006e45a0}, {0xc0005481c0, 0x7, 0x3?}, 0xc000132180?, {0x0, 0x0})                                                                                │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/allstar/pkg/enforce/enforce.go:188 +0x112                                                                                                                                                                 │
│ allstar-756f9ccdb9-c9pzl allstar github.com/ossf/allstar/pkg/enforce.EnforceAll.func1()                                                                                                                                                                     │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/allstar/pkg/enforce/enforce.go:149 +0x1b7                                                                                                                                                                 │
│ allstar-756f9ccdb9-c9pzl allstar golang.org/x/sync/errgroup.(*Group).Go.func1()                                                                                                                                                                             │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/go/pkg/mod/golang.org/x/sync@v0.2.0/errgroup/errgroup.go:75 +0x64                                                                                                                                         │
│ allstar-756f9ccdb9-c9pzl allstar created by golang.org/x/sync/errgroup.(*Group).Go                                                                                                                                                                          │
│ allstar-756f9ccdb9-c9pzl allstar     /home/user/go/pkg/mod/golang.org/x/sync@v0.2.0/errgroup/errgroup.go:72 +0xa5       

Since I've never coded in Go before, there's a chance I might have missed something essential on my working branch. Do you perhaps have insights or suggestions?

[gmlewis]

@ArisBee - from what I can tell, it looks like you did exactly the right thing... so I'm going to take a look at the upstream usage of go-github to see if there is anything unusual there...

Oh, and welcome to Go! Feel free to make PRs to improve this repo. 😄

[gmlewis]

I believe I found the cause of the panic and commented here:
ossf/allstar#442 (comment)

As for go-github supporting the submodule_git_url field, we welcome PRs (and I'll leave this issue open for that). 😄

[ArisBee]

Thank you for looking into it @gmlewis, if my changes to go-github make sense then I can only focus on the changes in the other project.