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[PATCH 07/11] commit: avoid race when creating orphan commits

From
Michael Haggerty <mhagger@alum.mit.edu>
Date
Feb 8, 2015, 16:14 UTC
Message-ID
<1423412045-15616-8-git-send-email-mhagger@alum.mit.edu>
In-Reply-To
<1423412045-15616-1-git-send-email-mhagger@alum.mit.edu>

If, during the initial check, HEAD doesn't point at anything, then we should make sure that it *still* doesn't point at anything when we are ready to update the reference. Otherwise, another process might commit while we are working (e.g., while we are waiting for the user to edit the commit message) and we will silently overwrite it.

This fixes a failing test in t7516.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 builtin/commit.c        | 2 +-
 t/t7516-commit-races.sh | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/builtin/commit.c b/builtin/commit.c
index 5654abd..c566e32 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1772,7 +1772,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 	if (!transaction ||
 	    ref_transaction_update(transaction, "HEAD", sha1,
 				   current_head
-				   ? current_head->object.sha1 : NULL,
+				   ? current_head->object.sha1 : null_sha1,
 				   0, sb.buf, &err) ||
 	    ref_transaction_commit(transaction, &err)) {
 		rollback_index_files();
diff --git a/t/t7516-commit-races.sh b/t/t7516-commit-races.sh
index 5efa351..17a139e 100755
--- a/t/t7516-commit-races.sh
+++ b/t/t7516-commit-races.sh
@@ -17,7 +17,7 @@ test_expect_success 'set up editor' '
 	chmod +x editor
 '
 
-test_expect_failure 'race to create orphan commit' '
+test_expect_success 'race to create orphan commit' '
 	test_must_fail env EDITOR=./editor git commit --allow-empty &&
 	git show -s --pretty=format:%s >subject &&
 	grep -q hare subject &&
-- 
2.1.4
Previous: Junio C HamanoNext: Stefan Beller
Message 19 of 35 in “Allow reference values to be checked in a transaction”
  1. 00/11 Allow reference values to be checked in a transactionMichael Haggerty, Feb 8, 2015
  2. 01/11 refs: move REF_DELETING to refs.cMichael Haggerty, Feb 8, 2015
  3. Stefan BellerFeb 9, 2015
  4. 02/11 refs: remove the gap in the REF_* constant valuesMichael Haggerty, Feb 8, 2015
  5. Stefan BellerFeb 9, 2015
  6. 03/11 struct ref_update: move "have_old" into "flags"Michael Haggerty, Feb 8, 2015
  7. 04/11 ref_transaction_update(): remove "have_old" parameterMichael Haggerty, Feb 8, 2015
  8. Stefan BellerFeb 9, 2015
  9. Michael HaggertyFeb 11, 2015
  10. 05/11 ref_transaction_delete(): remove "have_old" parameterMichael Haggerty, Feb 8, 2015
  11. Stefan BellerFeb 9, 2015
  12. 06/11 commit: add tests of commit racesMichael Haggerty, Feb 8, 2015
  13. Stefan BellerFeb 9, 2015
  14. Junio C HamanoFeb 10, 2015
  15. Michael HaggertyFeb 11, 2015
  16. Junio C HamanoFeb 11, 2015
  17. Stefan BellerFeb 11, 2015
  18. Junio C HamanoFeb 11, 2015
  19. 07/11 commit: avoid race when creating orphan commitsMichael Haggerty, Feb 8, 2015
  20. Stefan BellerFeb 9, 2015
  21. Michael HaggertyFeb 11, 2015
  22. 08/11 ref_transaction_create(): check that new_sha1 is validMichael Haggerty, Feb 8, 2015
  23. Stefan BellerFeb 9, 2015
  24. 09/11 ref_transaction_delete(): check that old_sha1 is not null_sha1Michael Haggerty, Feb 8, 2015
  25. Stefan BellerFeb 9, 2015
  26. 10/11 ref_transaction_verify(): new function to check a reference's valueMichael Haggerty, Feb 8, 2015
  27. Stefan BellerFeb 9, 2015
  28. Michael HaggertyFeb 11, 2015
  29. 11/11 update_ref(): improve documentationMichael Haggerty, Feb 8, 2015
  30. Stefan BellerFeb 9, 2015
  31. Junio C HamanoFeb 9, 2015
  32. Stefan BellerFeb 9, 2015
  33. Michael HaggertyFeb 9, 2015
  34. Stefan BellerFeb 9, 2015
  35. Junio C HamanoFeb 9, 2015

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