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[PATCH v2] rebase --update-refs: avoid unintended ref deletion

From
Victoria Dye <vdye@github.com>
Date
Nov 7, 2022, 17:47 UTC
Message-ID
<20221107174752.91186-1-vdye@github.com>
In-Reply-To
<20221104165735.68899-1-vdye@github.com>

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.

To fix this, delete the 'update-refs' state file when 'refs_to_oids' is empty. Additionally, add a tests covering "all update-ref lines removed" cases.

Reported-by: herr.kaste <herr.kaste@gmail.com>
Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Helped-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Victoria Dye <vdye@github.com>
---
Changes since v1:
- Modified approach to handling empty 'refs_to_oids' from "optional force write
  empty file" to "always unlink"
- Added/updated tests
 sequencer.c                   |   9 ++-
 t/t3404-rebase-interactive.sh | 107 ++++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+), 3 deletions(-)
diff --git a/sequencer.c b/sequencer.c
index e658df7e8ff..798a9702961 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4130,11 +4130,14 @@ static int write_update_refs_state(struct string_list *refs_to_oids)
 	struct string_list_item *item;
 	char *path;

-	if (!refs_to_oids->nr)
-		return 0;
-
 	path = rebase_path_update_refs(the_repository->gitdir);

+	if (!refs_to_oids->nr) {
+		if (unlink(path) && errno != ENOENT)
+			result = error_errno(_("could not unlink: %s"), path);
+		goto cleanup;
+	}
+
 	if (safe_create_leading_directories(path)) {
 		result = error(_("unable to create leading directories of %s"),
 			       path);
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 4f5abb5ad25..462cefd25df 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1964,6 +1964,113 @@ test_expect_success 'respect user edits to update-ref steps' '
 	test_cmp_rev HEAD refs/heads/no-conflict-branch
 '

+test_expect_success '--update-refs: all update-ref lines 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 &&
+
+	test_commit test-refs-not-removed &&
+	git commit --amend --fixup first &&
+
+	git rev-parse first second third tip no-conflict-branch >expect-oids &&
+
+	(
+		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
+	) &&
+
+	# Ensure refs are not deleted and their OIDs have not changed
+	git rev-parse first second third tip no-conflict-branch >actual-oids &&
+	test_cmp expect-oids actual-oids
+'
+
+test_expect_success '--update-refs: all update-ref lines removed, then some re-added' '
+	git checkout -b test-refs-not-removed2 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 &&
+
+	test_commit test-refs-not-removed2 &&
+	git commit --amend --fixup first &&
+
+	git rev-parse first second third >expect-oids &&
+
+	(
+		set_cat_todo_editor &&
+		test_must_fail git rebase -i \
+			--autosquash --update-refs \
+			base >todo.raw &&
+		sed -e "/^update-ref/d" <todo.raw >todo
+	) &&
+
+	# Add a break to the end of the todo so we can edit later
+	echo "break" >>todo &&
+
+	(
+		set_replace_editor todo &&
+		git rebase -i --autosquash --update-refs base &&
+		echo "update-ref refs/heads/tip" >todo &&
+		git rebase --edit-todo &&
+		git rebase --continue
+	) &&
+
+	# Ensure first/second/third are unchanged, but tip is updated
+	git rev-parse first second third >actual-oids &&
+	test_cmp expect-oids actual-oids &&
+	test_cmp_rev HEAD tip
+'
+
+test_expect_success '--update-refs: --edit-todo with no update-ref lines' '
+	git checkout -b test-refs-not-removed3 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 &&
+
+	test_commit test-refs-not-removed3 &&
+	git commit --amend --fixup first &&
+
+	git rev-parse first second third tip no-conflict-branch >expect-oids &&
+
+	(
+		set_cat_todo_editor &&
+		test_must_fail git rebase -i \
+			--autosquash --update-refs \
+			base >todo.raw &&
+		sed -e "/^update-ref/d" <todo.raw >todo
+	) &&
+
+	# Add a break to the beginning of the todo so we can resume with no
+	# update-ref lines
+	echo "break" >todo.new &&
+	cat todo >>todo.new &&
+
+	(
+		set_replace_editor todo.new &&
+		git rebase -i --autosquash --update-refs base &&
+
+		# Make no changes when editing so update-refs is still empty
+		cat todo >todo.new &&
+		git rebase --edit-todo &&
+		git rebase --continue
+	) &&
+
+	# Ensure refs are not deleted and their OIDs have not changed
+	git rev-parse first second third tip no-conflict-branch >actual-oids &&
+	test_cmp expect-oids actual-oids
+'
+
 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
Previous: Derrick StoleeNext: Taylor Blau
Message 14 of 17 in “rebase -i --update-refs can lead to deletion of branches”
  1. herr.kasteOct 20, 2022
  2. Erik Cervin EdinOct 20, 2022
  3. Phillip WoodNov 3, 2022
  4. herr.kasteNov 3, 2022
  5. Erik Cervin EdinNov 3, 2022
  6. Victoria DyeNov 4, 2022
  7. Phillip WoodNov 4, 2022
  8. Victoria DyeNov 4, 2022
  9. rebase --update-refs: avoid unintended ref deletionVictoria Dye, Nov 4, 2022
  10. Taylor BlauNov 4, 2022
  11. Phillip WoodNov 4, 2022
  12. Phillip WoodNov 4, 2022
  13. Derrick StoleeNov 7, 2022
  14. rebase --update-refs: avoid unintended ref deletionVictoria Dye, Nov 7, 2022
  15. Taylor BlauNov 7, 2022
  16. Derrick StoleeNov 7, 2022
  17. Phillip WoodNov 8, 2022

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