@matheusbsbs / matheus-bagliano / commits / e100bea481

rebase -i: stop overwriting ORIG_HEAD buffer

After rebasing, ORIG_HEAD is supposed to point to the old HEAD of the rebased branch. The code used find_unique_abbrev() to obtain the object name of the old HEAD and wrote to both .git/rebase-merge/orig-head (used by `rebase --abort` to go back to the previous state) and to ORIG_HEAD. The buffer find_unique_abbrev() gives back is volatile, unfortunately, and was overwritten after the former file is written but before ORIG_FILE is written, leaving an incorrect object name in it. Avoid relying on the volatile buffer of find_unique_abbrev(), and instead supply our own buffer to keep the object name. I think that all of the users of head_hash should actually be using opts->orig_head instead as passing a string rather than a struct object_id around is a hang over from the scripted implementation. This patch just fixes the immediate bug and adds a regression test based on Caspar's reproduction example[1]. The users will be converted to use struct object_id and head_hash removed in the next few commits. [1] https://lore.kernel.org/git/CAFzd1+7PDg2PZgKw7U0kdepdYuoML9wSN4kofmB_-8NHrbbrHg@mail.gmail.com Reported-by: Caspar Duregger <herr.kaste@gmail.com> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Phillip Wood committed Nov 4, 2020 at 15:29 UTC e100bea48102dca7e21359993085e89c7f154f9d

2 files changed +16 -5

builtin/rebase.c

+5 -5

@@ -270,15 +270,15 @@ static int edit_todo_file(unsigned flags)

270 }

271

272 static int get_revision_ranges(struct commit *upstream, struct commit *onto,

273 - struct object_id *orig_head, const char **head_hash,

273 + struct object_id *orig_head, char *head_hash,

274 char **revisions, char **shortrevisions)

275 {

276 struct commit *base_rev = upstream ? upstream : onto;

277 const char *shorthead;

278

279 - *head_hash = find_unique_abbrev(orig_head, GIT_MAX_HEXSZ);

279 + find_unique_abbrev_r(head_hash, orig_head, GIT_MAX_HEXSZ);

280 *revisions = xstrfmt("%s...%s", oid_to_hex(&base_rev->object.oid),

281 - *head_hash);

281 + head_hash);

282

283 shorthead = find_unique_abbrev(orig_head, DEFAULT_ABBREV);

284

@@ -327,7 +327,7 @@ static void split_exec_commands(const char *cmd, struct string_list *commands)

327 static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)

328 {

329 int ret;

330 - const char *head_hash = NULL;

330 + char head_hash[GIT_MAX_HEXSZ];

331 char *revisions = NULL, *shortrevisions = NULL;

332 struct strvec make_script_args = STRVEC_INIT;

333 struct todo_list todo_list = TODO_LIST_INIT;

@@ -335,7 +335,7 @@ static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)

335 struct string_list commands = STRING_LIST_INIT_DUP;

336

337 if (get_revision_ranges(opts->upstream, opts->onto, &opts->orig_head,

338 - &head_hash, &revisions, &shortrevisions))

338 + head_hash, &revisions, &shortrevisions))

339 return -1;

340

341 if (init_basic_state(&replay,

t/t3404-rebase-interactive.sh

+11

@@ -1797,6 +1797,17 @@ test_expect_success 'todo has correct onto hash' '

1797 test_i18ngrep "^# Rebase ..* onto $onto" actual

1798 '

1799

1800 +test_expect_success 'ORIG_HEAD is updated correctly' '

1801 + test_when_finished "git checkout master && git branch -D test-orig-head" &&

1802 + git checkout -b test-orig-head A &&

1803 + git commit --allow-empty -m A1 &&

1804 + git commit --allow-empty -m A2 &&

1805 + git commit --allow-empty -m A3 &&

1806 + git commit --allow-empty -m A4 &&

1807 + git rebase master &&

1808 + test_cmp_rev ORIG_HEAD test-orig-head@{1}

1809 +'

1810 +

1811 # This must be the last test in this file

1812 test_expect_success '$EDITOR and friends are unchanged' '

1813 test_editor_unchanged