Re: [PATCH] rebase --update-refs: avoid unintended ref deletion
- From
- Phillip Wood <phillip.wood123@gmail.com>
- Date
- Nov 4, 2022, 20:12 UTC
- Message-ID
- <6c022318-afc0-2ad7-b29c-ccb87f2f2e94@dunelm.org.uk>
- In-Reply-To
- <20221104165735.68899-1-vdye@github.com>
Hi Victoria
On 04/11/2022 16:57, Victoria Dye wrote:
Show 11 quoted lines
> In b3b1a21d1a5 (sequencer: rewrite update-refs as user edits todo list, > 2022-07-19), the 'todo_list_filter_update_refs()' step was added to handle > the removal of 'update-ref' lines from a 'rebase-todo'. Specifically, it > removes potential ref updates from the "update refs state" if a ref does not > have a corresponding 'update-ref' line. > > However, because 'write_update_refs_state()' will not update the state if > the 'refs_to_oids' list was empty, removing *all* 'update-ref' lines will > result in the state remaining unchanged from how it was initialized (with > all refs' "after" OID being null). Then, when the ref update is applied, all > refs will be updated to null and consequently deleted.
Thanks for taking the time to track down the cause of this bug and fix it.
Show 10 quoted lines
> To fix this, add a 'force_if_empty' flag to allow writing the update refs > state even if 'refs_to_oids' is empty. The three usages of > 'write_update_refs_state()' are updated as follows: > > - in 'todo_list_filter_update_refs()': force_if_empty is 1 because update > ref entries are removed here. This setting fixes the ref deletion issue. > - in 'do_update_ref()': force_if_empty is 0, since this method only modifies > (does not add or delete) ref update entries. > - in 'todo_list_add_update_ref_commands()': force_if_empty is 0, since this > method strictly adds ref update entries.
I think not writing the list if it is empty is just an optimization to avoid creating an empty file. I wonder if it would be simpler to unlink() any existing file if write_update_refs_state() is called with an empty list rather than adding the force flag.
> Additionally, add a test covering the "all update-ref lines removed" case.
That's great
Best Wishes
Phillip
Show 110 quoted lines
> Reported-by: herr.kaste <herr.kaste@gmail.com>
> Signed-off-by: Victoria Dye <vdye@github.com>
> ---
> This fixes the issue reported in [1]. I initially misinterpreted the root
> cause (thought that 'todo_list_filter_update_refs()' was only applied in the
> case of '--edit-todo'). After looking into it a bit more, it appears that
> the actual failure case is much narrower, occurring only when *all*
> 'update-ref' lines were deleted from the 'rebase-todo'.
>
> Thanks!
> - Victoria
>
> [1] https://lore.kernel.org/git/CAFzd1+5F4zqQ1CNeY2xaaf0r__JmE4ECiBt5h5OdiJHbaE78VA@mail.gmail.com/
>
> sequencer.c | 15 ++++++++++-----
> t/t3404-rebase-interactive.sh | 24 ++++++++++++++++++++++++
> 2 files changed, 34 insertions(+), 5 deletions(-)
>
> diff --git a/sequencer.c b/sequencer.c
> index e658df7e8ff..4d99a4fd6ca 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4122,7 +4122,7 @@ static int do_merge(struct repository *r,
> return ret;
> }
>
> -static int write_update_refs_state(struct string_list *refs_to_oids)
> +static int write_update_refs_state(struct string_list *refs_to_oids, int force_if_empty)
> {
> int result = 0;
> struct lock_file lock = LOCK_INIT;
> @@ -4130,7 +4130,12 @@ static int write_update_refs_state(struct string_list *refs_to_oids)
> struct string_list_item *item;
> char *path;
>
> - if (!refs_to_oids->nr)
> + /*
> + * If 'force' is specified, we want to write the updated refs even if
> + * the list is empty. This is only needed for callers that may have
> + * deleted items from 'refs_to_oids'.
> + */
> + if (!refs_to_oids->nr && !force_if_empty)
> return 0;
>
> path = rebase_path_update_refs(the_repository->gitdir);
> @@ -4260,7 +4265,7 @@ void todo_list_filter_update_refs(struct repository *r,
> }
>
> if (updated)
> - write_update_refs_state(&update_refs);
> + write_update_refs_state(&update_refs, 1);
> string_list_clear(&update_refs, 1);
> }
>
> @@ -4281,7 +4286,7 @@ static int do_update_ref(struct repository *r, const char *refname)
> }
> }
>
> - write_update_refs_state(&list);
> + write_update_refs_state(&list, 0);
> string_list_clear(&list, 1);
> return 0;
> }
> @@ -6015,7 +6020,7 @@ static int todo_list_add_update_ref_commands(struct todo_list *todo_list)
> }
> }
>
> - res = write_update_refs_state(&ctx.refs_to_oids);
> + res = write_update_refs_state(&ctx.refs_to_oids, 0);
>
> string_list_clear(&ctx.refs_to_oids, 1);
>
> diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
> index 4f5abb5ad25..e7d3721ece8 100755
> --- a/t/t3404-rebase-interactive.sh
> +++ b/t/t3404-rebase-interactive.sh
> @@ -1964,6 +1964,30 @@ test_expect_success 'respect user edits to update-ref steps' '
> test_cmp_rev HEAD refs/heads/no-conflict-branch
> '
>
> +test_expect_success '--update-refs: do not delete refs if all update-ref are removed' '
> + git checkout -b test-refs-not-removed no-conflict-branch &&
> + git branch -f base HEAD~4 &&
> + git branch -f first HEAD~3 &&
> + git branch -f second HEAD~3 &&
> + git branch -f third HEAD~1 &&
> + git branch -f tip &&
> + (
> + set_cat_todo_editor &&
> + test_must_fail git rebase -i --update-refs base >todo.raw &&
> + sed -e "/^update-ref/d" <todo.raw >todo
> + ) &&
> + (
> + set_replace_editor todo &&
> + git rebase -i --update-refs base
> + ) &&
> +
> + test_cmp_rev HEAD~3 refs/heads/first &&
> + test_cmp_rev HEAD~3 refs/heads/second &&
> + test_cmp_rev HEAD~1 refs/heads/third &&
> + test_cmp_rev HEAD refs/heads/tip &&
> + test_cmp_rev HEAD refs/heads/no-conflict-branch
> +'
> +
> test_expect_success '--update-refs: check failed ref update' '
> git checkout -B update-refs-error no-conflict-branch &&
> git branch -f base HEAD~4 &&
> --
> 2.38.0
>