rebase: pass correct arguments to post-checkout hook

If a rebase started with "rebase [--apply|--merge] <upstream> <branch>"
detects that <upstream> is an ancestor of <branch> then it fast-forwards
and checks out <branch>. Unfortunately in that case it passed the null
oid as the first argument to the post-checkout hook rather than the oid
of HEAD.

A side effect of this change is that the call to update_ref() which
updates HEAD now always receives the old value of HEAD. This provides
protection against another process updating HEAD during the checkout.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/reset.c b/reset.c
index f214df3d96ca218a25c780b2dc79ca4ca76999de..315fef91d33aaa4b74c3b90ab026ff39bc81d9b5 100644 (file)
--- a/reset.c
+++ b/reset.c
@@ -18,7 +18,7 @@ int reset_head(struct repository *r, struct object_id *oid, const char *action,
        unsigned run_hook = flags & RESET_HEAD_RUN_POST_CHECKOUT_HOOK;
        unsigned refs_only = flags & RESET_HEAD_REFS_ONLY;
        unsigned update_orig_head = flags & RESET_ORIG_HEAD;
-       struct object_id head_oid;
+       struct object_id *head = NULL, head_oid;
        struct tree_desc desc[2] = { { NULL }, { NULL } };
        struct lock_file lock = LOCK_INIT;
        struct unpack_trees_options unpack_tree_opts = { 0 };
@@ -26,8 +26,7 @@ int reset_head(struct repository *r, struct object_id *oid, const char *action,
        const char *reflog_action;
        struct strbuf msg = STRBUF_INIT;
        size_t prefix_len;
-       struct object_id *orig = NULL, oid_orig,
-               *old_orig = NULL, oid_old_orig;
+       struct object_id *old_orig = NULL, oid_old_orig;
        int ret = 0, nr = 0;
 
        if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
@@ -38,7 +37,9 @@ int reset_head(struct repository *r, struct object_id *oid, const char *action,
                goto leave_reset_head;
        }
 
-       if ((!oid || !reset_hard) && get_oid("HEAD", &head_oid)) {
+       if (!get_oid("HEAD", &head_oid)) {
+               head = &head_oid;
+       } else if (!oid || !reset_hard) {
                ret = error(_("could not determine HEAD revision"));
                goto leave_reset_head;
        }
@@ -98,13 +99,12 @@ reset_head_refs:
        if (update_orig_head) {
                if (!get_oid("ORIG_HEAD", &oid_old_orig))
                        old_orig = &oid_old_orig;
-               if (!get_oid("HEAD", &oid_orig)) {
-                       orig = &oid_orig;
+               if (head) {
                        if (!reflog_orig_head) {
                                strbuf_addstr(&msg, "updating ORIG_HEAD");
                                reflog_orig_head = msg.buf;
                        }
-                       update_ref(reflog_orig_head, "ORIG_HEAD", orig,
+                       update_ref(reflog_orig_head, "ORIG_HEAD", head,
                                   old_orig, 0, UPDATE_REFS_MSG_ON_ERR);
                } else if (old_orig)
                        delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
@@ -116,7 +116,7 @@ reset_head_refs:
                reflog_head = msg.buf;
        }
        if (!switch_to_branch)
-               ret = update_ref(reflog_head, "HEAD", oid, orig,
+               ret = update_ref(reflog_head, "HEAD", oid, head,
                                 detach_head ? REF_NO_DEREF : 0,
                                 UPDATE_REFS_MSG_ON_ERR);
        else {
@@ -128,7 +128,7 @@ reset_head_refs:
        }
        if (run_hook)
                run_hook_le(NULL, "post-checkout",
-                           oid_to_hex(orig ? orig : null_oid()),
+                           oid_to_hex(head ? head : null_oid()),
                            oid_to_hex(oid), "1", NULL);
 
 leave_reset_head:

diff --git a/t/t5403-post-checkout-hook.sh b/t/t5403-post-checkout-hook.sh
index 272b02687ba95403f487f6b6dde668a6be4361b1..17ab518f26894d9367a32560662f54eb21c503d1 100755 (executable)
--- a/t/t5403-post-checkout-hook.sh
+++ b/t/t5403-post-checkout-hook.sh
@@ -72,6 +72,19 @@ test_rebase () {
                test_cmp_rev rebase-on-me $new &&
                test $flag = 1
        '
+
+       test_expect_success "rebase $args fast-forward branch checkout runs post-checkout hook" '
+               test_when_finished "test_might_fail git rebase --abort" &&
+               test_when_finished "rm -f .git/post-checkout.args" &&
+               git update-ref refs/heads/rebase-fast-forward three &&
+               git checkout two  &&
+               rm -f .git/post-checkout.args &&
+               git rebase $args HEAD rebase-fast-forward  &&
+               read old new flag <.git/post-checkout.args &&
+               test_cmp_rev two $old &&
+               test_cmp_rev three $new &&
+               test $flag = 1
+       '
 }
 
 test_rebase --apply &&