Merge branch 'pk/rebase-in-c-4-opts'

Rewrite "git rebase" in C.

* pk/rebase-in-c-4-opts:
  builtin rebase: support --root
  builtin rebase: add support for custom merge strategies
  builtin rebase: support `fork-point` option
  merge-base --fork-point: extract libified function
  builtin rebase: support --rebase-merges[=[no-]rebase-cousins]
  builtin rebase: support `--allow-empty-message` option
  builtin rebase: support `--exec`
  builtin rebase: support `--autostash` option
  builtin rebase: support `-C` and `--whitespace=<type>`
  builtin rebase: support `--gpg-sign` option
  builtin rebase: support `--autosquash`
  builtin rebase: support `keep-empty` option
  builtin rebase: support `ignore-date` option
  builtin rebase: support `ignore-whitespace` option
  builtin rebase: support --committer-date-is-author-date
  builtin rebase: support --rerere-autoupdate
  builtin rebase: support --signoff
  builtin rebase: allow selecting the rebase "backend"

1 files changed, 82 insertions, 0 deletions

diff --git a/commit.c b/commit.c
index dc8a39d52a..d566d7e45c 100644
--- a/commit.c
+++ b/commit.c
@@ -17,6 +17,8 @@
 #include "sha1-lookup.h"
 #include "wt-status.h"
 #include "advice.h"
+#include "refs.h"
+#include "commit-reach.h"
 
 static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
 
@@ -843,6 +845,86 @@ void sort_in_topological_order(struct commit_list **list, enum rev_sort_order so
 		clear_author_date_slab(&author_date);
 }
 
+struct rev_collect {
+	struct commit **commit;
+	int nr;
+	int alloc;
+	unsigned int initial : 1;
+};
+
+static void add_one_commit(struct object_id *oid, struct rev_collect *revs)
+{
+	struct commit *commit;
+
+	if (is_null_oid(oid))
+		return;
+
+	commit = lookup_commit(the_repository, oid);
+	if (!commit ||
+	    (commit->object.flags & TMP_MARK) ||
+	    parse_commit(commit))
+		return;
+
+	ALLOC_GROW(revs->commit, revs->nr + 1, revs->alloc);
+	revs->commit[revs->nr++] = commit;
+	commit->object.flags |= TMP_MARK;
+}
+
+static int collect_one_reflog_ent(struct object_id *ooid, struct object_id *noid,
+				  const char *ident, timestamp_t timestamp,
+				  int tz, const char *message, void *cbdata)
+{
+	struct rev_collect *revs = cbdata;
+
+	if (revs->initial) {
+		revs->initial = 0;
+		add_one_commit(ooid, revs);
+	}
+	add_one_commit(noid, revs);
+	return 0;
+}
+
+struct commit *get_fork_point(const char *refname, struct commit *commit)
+{
+	struct object_id oid;
+	struct rev_collect revs;
+	struct commit_list *bases;
+	int i;
+	struct commit *ret = NULL;
+
+	memset(&revs, 0, sizeof(revs));
+	revs.initial = 1;
+	for_each_reflog_ent(refname, collect_one_reflog_ent, &revs);
+
+	if (!revs.nr && !get_oid(refname, &oid))
+		add_one_commit(&oid, &revs);
+
+	for (i = 0; i < revs.nr; i++)
+		revs.commit[i]->object.flags &= ~TMP_MARK;
+
+	bases = get_merge_bases_many(commit, revs.nr, revs.commit);
+
+	/*
+	 * There should be one and only one merge base, when we found
+	 * a common ancestor among reflog entries.
+	 */
+	if (!bases || bases->next)
+		goto cleanup_return;
+
+	/* And the found one must be one of the reflog entries */
+	for (i = 0; i < revs.nr; i++)
+		if (&bases->item->object == &revs.commit[i]->object)
+			break; /* found */
+	if (revs.nr <= i)
+		goto cleanup_return;
+
+	ret = bases->item;
+
+cleanup_return:
+	free_commit_list(bases);
+	return ret;
+}
+
 static const char gpg_sig_header[] = "gpgsig";
 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;