The buffer containing the oid for ORIG_HEAD is overwritten before ORIG_HEAD is created. This series fixes that bug and then converts the code to use struct object_id rather than passing around strings. Thanks to Caspar for reporting the bug and providing a reproducible example Changes since v1: * Updated the commit message to patch 1 as suggested by Junio * Moved the conversion from find_unique_abbrev() to oid_to_hex() from patch 1 to patch 4 * Fixed a compilation error in patch 3 (the required change was in patch 4 by a mistake) Cc: Johannes Schindelin Johannes.Schindelin@xxxxxx [Johannes.Schindelin@xxxxxx], Caspar Duregger herr.kaste@xxxxxxxxx [herr.kaste@xxxxxxxxx] Phillip Wood (4): rebase -i: stop overwriting ORIG_HEAD buffer rebase -i: use struct object_id rather than looking up commit rebase -i: use struct object_id when writing state rebase -i: simplify get_revision_ranges() builtin/rebase.c | 20 ++++++++++---------- sequencer.c | 15 ++++++--------- sequencer.h | 7 ++++--- t/t3404-rebase-interactive.sh | 11 +++++++++++ 4 files changed, 31 insertions(+), 22 deletions(-) base-commit: 2e673356aefa8ed19be3c878f966ad6189ecb510 Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-773%2Fphillipwood%2Fwip%2Frebase-fix-orig_head-handling-v2 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-773/phillipwood/wip/rebase-fix-orig_head-handling-v2 Pull-Request: https://github.com/gitgitgadget/git/pull/773 Range-diff vs v1: 1: 24f2c4a623 ! 1: da05958c58 rebase -i: stop overwriting ORIG_HEAD buffer @@ Metadata ## Commit message ## rebase -i: stop overwriting ORIG_HEAD buffer - After rebasing ORIG_HEAD is supposed to point to the old HEAD of the - rebased branch. Unfortunately the buffer storing the oid was - overwritten with a new oid before ORIG_HEAD was created. The buffer is - also used when writing .git/rebase-merge/orig-head which is used by - `rebase --abort` to restore the previous head. Luckily that file is - written before the buffer is overwritten. As we want the full oid - find_unique_abbrev() is replaced with oid_to_hex_r() rather than - find_unique_abbrev_r(). + 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. The users will be converted to use + 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@xxxxxxxxxxxxxx + Reported-by: Caspar Duregger <herr.kaste@xxxxxxxxx> Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> @@ builtin/rebase.c: static int edit_todo_file(unsigned flags) const char *shorthead; - *head_hash = find_unique_abbrev(orig_head, GIT_MAX_HEXSZ); -+ oid_to_hex_r(head_hash, orig_head); ++ find_unique_abbrev_r(head_hash, orig_head, GIT_MAX_HEXSZ); *revisions = xstrfmt("%s...%s", oid_to_hex(&base_rev->object.oid), - *head_hash); + head_hash); 2: 589aed08f1 = 2: da499f1e4c rebase -i: use struct object_id rather than looking up commit 3: 11494a7b79 ! 3: 076d212915 rebase -i: use struct object_id when writing state @@ builtin/rebase.c: static int get_revision_ranges(struct commit *upstream, struct { FILE *interactive; +@@ builtin/rebase.c: static int do_interactive_rebase(struct rebase_options *opts, unsigned flags) + + if (init_basic_state(&replay, + opts->head_name ? opts->head_name : "detached HEAD", +- opts->onto, head_hash)) { ++ opts->onto, &opts->orig_head)) { + free(revisions); + free(shortrevisions); + ## sequencer.c ## @@ sequencer.c: static void write_strategy_opts(struct replay_opts *opts) 4: ed78f8628a ! 4: faae3ccff5 rebase -i: simplify get_revision_ranges() @@ Commit message use a opts->orig_head instead we can stop returning head_hash from get_revision_ranges(). + Because we want to pass the full object names back to the caller in + `revisions` the find_unique_abbrev_r() call that was used to initialize + `head_hash` is replaced with oid_to_hex(). + Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> ## builtin/rebase.c ## @@ builtin/rebase.c: static int edit_todo_file(unsigned flags) struct commit *base_rev = upstream ? upstream : onto; const char *shorthead; -- oid_to_hex_r(head_hash, orig_head); +- find_unique_abbrev_r(head_hash, orig_head, GIT_MAX_HEXSZ); *revisions = xstrfmt("%s...%s", oid_to_hex(&base_rev->object.oid), - head_hash); + oid_to_hex(orig_head)); @@ builtin/rebase.c: static int do_interactive_rebase(struct rebase_options *opts, return -1; if (init_basic_state(&replay, - opts->head_name ? opts->head_name : "detached HEAD", -- opts->onto, head_hash)) { -+ opts->onto, &opts->orig_head)) { - free(revisions); - free(shortrevisions); - -- gitgitgadget
