SIGSEV during git town propose

[FirelightFlagboy]

Steps to reproduce

N/A

Command output

Handle unfinished command: continue

[parsec-v2-main-program] git merge --no-edit main
Already up to date.

[parsec-v2-main-program] git push -u origin parsec-v2-main-program
Enumerating objects: 9, done.
Counting objects: 100% (9/9), done.
Delta compression using up to 16 threads
Compressing objects: 100% (5/5), done.
Writing objects: 100% (5/5), 727 bytes | 727.00 KiB/s, done.
Total 5 (delta 2), reused 0 (delta 0), pack-reused 0 (from 0)
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
remote: 
remote: Create a pull request for 'parsec-v2-main-program' on GitHub by visiting:
remote:      https://github.com/FirelightFlagboy/parsec-cloud-nix/pull/new/parsec-v2-main-program
remote: 
To github.com:FirelightFlagboy/parsec-cloud-nix.git
 * [new branch]      parsec-v2-main-program -> parsec-v2-main-program
branch 'parsec-v2-main-program' set up to track 'origin/parsec-v2-main-program'.

[parsec-v2-main-program] git stash pop
On branch parsec-v2-main-program
Your branch is up to date with 'origin/parsec-v2-main-program'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   packages/v3/native-build.nix

no changes added to commit (use "git add" and/or "git commit -a")
Dropped refs/stash@{0} (d0a2f5e5ef981c79574a76fe10bd18636d5cc08f)
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x6b0b60]

goroutine 1 [running]:
github.com/git-town/git-town/v14/src/vm/opcodes.(*CreateProposal).Run(0xc0002844f8, {{0x0, 0x0}, 0xc000420020, 0xc0001eb8c0, 0xc000382290, 0xc0003822a0, 0xc000149440, 0xc0003b2260})
        github.com/git-town/git-town/v14/src/vm/opcodes/create_proposal.go:23 +0x80
github.com/git-town/git-town/v14/src/vm/interpreter/full.Execute({0xc00020ec18, {0x0, 0x0}, 0xc000420020, 0x0, {{0xc000150734, 0x16}, {0xc000259180, 0x3, 0x4}}, ...})
        github.com/git-town/git-town/v14/src/vm/interpreter/full/execute.go:27 +0x2a3
github.com/git-town/git-town/v14/src/validate.continueRunstate(0xc00016ab40, {{0x0, 0x0}, {0xc000150734, 0x16}, {0x12a8860, 0x0, 0x0}, 0x0, {{0xc000150734, ...}, ...}, ...})
        github.com/git-town/git-town/v14/src/validate/handle_unfinished_state.go:100 +0x1f8
github.com/git-town/git-town/v14/src/validate.HandleUnfinishedState({{0x0, 0x0}, {0xc000150734, 0x16}, {0x12a8860, 0x0, 0x0}, 0x0, {{0xc000150734, 0x16}, ...}, ...})
        github.com/git-town/git-town/v14/src/validate/handle_unfinished_state.go:48 +0x4c8
github.com/git-town/git-town/v14/src/execute.LoadRepoSnapshot({0xc00020ec18, {0x12a8860, 0x0, 0x0}, 0x1, 0x1, 0xc0001eb9b0, {0x0, 0x0, 0x0, ...}, ...})
        github.com/git-town/git-town/v14/src/execute/load_repo_snapshot.go:23 +0x285
github.com/git-town/git-town/v14/src/cmd.determineProposeConfig(0xc0001eb9b0, 0x0, 0x0)
        github.com/git-town/git-town/v14/src/cmd/propose.go:119 +0x1b8
github.com/git-town/git-town/v14/src/cmd.executePropose(0x0, 0x0)
        github.com/git-town/git-town/v14/src/cmd/propose.go:67 +0xa6
github.com/git-town/git-town/v14/src/cmd.proposeCommand.func1(0xc000200008, {0x12a8860?, 0x4?, 0xc62e33?})
        github.com/git-town/git-town/v14/src/cmd/propose.go:47 +0x45
github.com/spf13/cobra.(*Command).execute(0xc000200008, {0x12a8860, 0x0, 0x0})
        github.com/spf13/cobra@v1.8.0/command.go:983 +0xaca
github.com/spf13/cobra.(*Command).ExecuteC(0xc0001da308)
        github.com/spf13/cobra@v1.8.0/command.go:1115 +0x3ff
github.com/spf13/cobra.(*Command).Execute(...)
        github.com/spf13/cobra@v1.8.0/command.go:1039
github.com/git-town/git-town/v14/src/cmd.Execute()
        github.com/git-town/git-town/v14/src/cmd/core.go:37 +0x619
main.main()
        github.com/git-town/git-town/v14/main.go:18 +0x1e

Additional information

If I redo git town propose and choose to continue the previous operation, it also result in SIGSEV

Handle unfinished command: continue

[parsec-v2-main-program] git merge --no-edit main
Already up to date.

[parsec-v2-main-program] git push -u origin parsec-v2-main-program
branch 'parsec-v2-main-program' set up to track 'origin/parsec-v2-main-program'.
Everything up-to-date
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x6b0b60]

goroutine 1 [running]:
github.com/git-town/git-town/v14/src/vm/opcodes.(*CreateProposal).Run(0xc00012d9b0, {{0x0, 0x0}, 0xc0003b6020, 0xc0001181b0, 0xc000054cd0, 0xc000054ce0, 0xc0001301e0, 0xc0000256c0})
        github.com/git-town/git-town/v14/src/vm/opcodes/create_proposal.go:23 +0x80
github.com/git-town/git-town/v14/src/vm/interpreter/full.Execute({0xc00014a018, {0x0, 0x0}, 0xc0003b6020, 0x1, {{0xc000114459, 0x16}, {0xc000123b80, 0x3, 0x4}}, ...})
        github.com/git-town/git-town/v14/src/vm/interpreter/full/execute.go:27 +0x2a3
github.com/git-town/git-town/v14/src/validate.continueRunstate(0xc000146360, {{0x0, 0x0}, {0xc000114459, 0x16}, {0x12a8860, 0x0, 0x0}, 0x1, {{0xc000114459, ...}, ...}, ...})
        github.com/git-town/git-town/v14/src/validate/handle_unfinished_state.go:100 +0x1f8
github.com/git-town/git-town/v14/src/validate.HandleUnfinishedState({{0x0, 0x0}, {0xc000114459, 0x16}, {0x12a8860, 0x0, 0x0}, 0x1, {{0xc000114459, 0x16}, ...}, ...})
        github.com/git-town/git-town/v14/src/validate/handle_unfinished_state.go:48 +0x4c8
github.com/git-town/git-town/v14/src/execute.LoadRepoSnapshot({0xc00014a018, {0x12a8860, 0x0, 0x0}, 0x1, 0x1, 0xc0001182a0, {0x0, 0x1, 0x0, ...}, ...})
        github.com/git-town/git-town/v14/src/execute/load_repo_snapshot.go:23 +0x285
github.com/git-town/git-town/v14/src/cmd.determineProposeConfig(0xc0001182a0, 0x0, 0x0)
        github.com/git-town/git-town/v14/src/cmd/propose.go:119 +0x1b8
github.com/git-town/git-town/v14/src/cmd.executePropose(0x0, 0x0)
        github.com/git-town/git-town/v14/src/cmd/propose.go:67 +0xa6
github.com/git-town/git-town/v14/src/cmd.proposeCommand.func1(0xc0001fe008, {0x12a8860?, 0x4?, 0xc62e33?})
        github.com/git-town/git-town/v14/src/cmd/propose.go:47 +0x45
github.com/spf13/cobra.(*Command).execute(0xc0001fe008, {0x12a8860, 0x0, 0x0})
        github.com/spf13/cobra@v1.8.0/command.go:983 +0xaca
github.com/spf13/cobra.(*Command).ExecuteC(0xc0001e2308)
        github.com/spf13/cobra@v1.8.0/command.go:1115 +0x3ff
github.com/spf13/cobra.(*Command).Execute(...)
        github.com/spf13/cobra@v1.8.0/command.go:1039
github.com/git-town/git-town/v14/src/cmd.Execute()
        github.com/git-town/git-town/v14/src/cmd/core.go:37 +0x619
main.main()
        github.com/git-town/git-town/v14/main.go:18 +0x1e

The first git town propose that fail (not because of a SIGSEV):

I found the deprecated local setting "git-town.main-branch-name".
I am upgrading this setting to the new format "git-town.main-branch".

I found the deprecated local setting "git-town.perennial-branch-names".
I am upgrading this setting to the new format "git-town.perennial-branches".

[parsec-v2-main-program] git fetch --prune --tags
Selected parent branch for "parsec-v2-main-program": main

[parsec-v2-main-program] git add -A

[parsec-v2-main-program] git stash
Saved working directory and index state WIP on parsec-v2-main-program: 69505f0 Add `meta.mainProgram` for parsec-v2

[parsec-v2-main-program] git checkout main
Switched to branch 'main'
Your branch is ahead of 'origin/main' by 1 commit.
  (use "git push" to publish your local commits)

[main] git rebase origin/main
Current branch main is up to date.

[main] git push
Enumerating objects: 9, done.
Counting objects: 100% (9/9), done.
Delta compression using up to 16 threads
Compressing objects: 100% (5/5), done.
Writing objects: 100% (5/5), 727 bytes | 727.00 KiB/s, done.
Total 5 (delta 2), reused 0 (delta 0), pack-reused 0 (from 0)
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
remote: error: GH013: Repository rule violations found for refs/heads/main.
remote: Review all repository rules at http://github.com/FirelightFlagboy/parsec-cloud-nix/rules?ref=refs%2Fheads%2Fmain
remote: 
remote: - 2 of 2 required status checks are expected.
remote: 
remote: - Changes must be made through a pull request.
remote: 
To github.com:FirelightFlagboy/parsec-cloud-nix.git
 ! [remote rejected] main -> main (push declined due to repository rule violations)
error: failed to push some refs to 'github.com:FirelightFlagboy/parsec-cloud-nix.git'


Error: exit status 1

To continue after having resolved conflicts, run "git town continue".
To go back to where you started, run "git town undo".

[FirelightFlagboy]

The segfault come from that line:

git-town/src/vm/opcodes/create_proposal.go

Line 23 in 69c416c

prURL, err := args.Connector.NewProposalURL(self.Branch, parentBranch)

From the following line:

github.com/git-town/git-town/v14/src/vm/opcodes.(*CreateProposal).Run(0xc00012d9b0, {{0x0, 0x0}, 0xc0003b6020, 0xc0001181b0, 0xc000054cd0, 0xc000054ce0, 0xc0001301e0, 0xc0000256c0})

I assume the seconds arguments passed to CreateProposal.Run (shared.RunArgs) contains some null value (indicated by {0x0, 0x0})

From the definition of the struct RunArgs:

git-town/src/vm/shared/runargs.go

Lines 11 to 19 in 69c416c

	type RunArgs struct {
	Connector hostingdomain.Connector
	DialogTestInputs *components.TestInputs
	Lineage configdomain.Lineage
	PrependOpcodes func(...Opcode)
	RegisterUndoablePerennialCommit func(gitdomain.SHA)
	Runner *git.ProdRunner
	UpdateInitialBranchLocalSHA func(gitdomain.LocalBranchName, gitdomain.SHA) error
	}

It's likely that RunArgs.Connector is null (since it's the first element of the struct)

[kevgo]

Thanks for submitting this detailed report! Yes, that's probably a null value blowing up in production 🤔. I'm in the middle of introducing Go's equivalent of the Rust Option for all nullable values to get rid of this problem once and for all.

[kevgo]

@FirelightFlagboy v14.2.2 ships the fix for this. Please report when this problem still occurs. Thanks!