From: Phillip Wood Date: Fri, 04 Nov 2022 20:12:23 GMT Subject: Re: [PATCH] rebase --update-refs: avoid unintended ref deletion 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: > 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. > 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 > Reported-by: herr.kaste > Signed-off-by: Victoria Dye > --- > 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 > + ) && > + ( > + 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 >