reset: allow the caller to specify the current HEAD object

When calling `reset_head()` we automatically derive the commit that the
callers wants to move from by reading the HEAD commit. Some callers may
already have resolved it, or they may want to move from a different
commit that doesn't match HEAD.

Introduce a new `oid_from` option that lets the caller specify the
commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/reset.c b/reset.c
index ed9df6ca5c089dff72738715ffd07657d5ff227c..7ff72de5d24475106139dd12040d36a172924dcc 100644 (file)
--- a/reset.c
+++ b/reset.c
@@ -121,7 +121,10 @@ int reset_head(struct repository *r, const struct reset_head_opts *opts)
                goto leave_reset_head;
        }
 
-       if (!repo_get_oid(r, "HEAD", &head_oid)) {
+       if (opts->oid_from) {
+               oidcpy(&head_oid, opts->oid_from);
+               head = &head_oid;
+       } else if (!repo_get_oid(r, "HEAD", &head_oid)) {
                head = &head_oid;
        } else if (!oid || !reset_hard) {
                ret = error(_("could not determine HEAD revision"));

diff --git a/reset.h b/reset.h
index cb0700ffa732b70606a92c691b9443bbefcf1677..51ce1145431f5b1244b5631ed5cfbd90269c76e6 100644 (file)
--- a/reset.h
+++ b/reset.h
@@ -37,6 +37,11 @@ struct reset_head_opts {
         * The commit to checkout/reset to. Defaults to HEAD.
         */
        const struct object_id *oid;
+       /*
+        * The commit to checkout/reset from when doing a two-way merge. This
+        * is used as one of the sides to merge.
+        */
+       const struct object_id *oid_from;
        /*
         * Optional value to set ORIG_HEAD. Defaults to HEAD.
         */