1 files changed, 99 insertions, 0 deletions
diff --git a/merge.c b/merge.c
new file mode 100644
index 0000000..23866c9
--- /dev/null
+++ b/merge.c
@@ -0,0 +1,99 @@
+#include "cache.h"
+#include "lockfile.h"
+#include "commit.h"
+#include "run-command.h"
+#include "resolve-undo.h"
+#include "tree-walk.h"
+#include "unpack-trees.h"
+#include "dir.h"
+
+static const char *merge_argument(struct commit *commit)
+{
+	if (commit)
+		return oid_to_hex(&commit->object.oid);
+	else
+		return EMPTY_TREE_SHA1_HEX;
+}
+
+int try_merge_command(const char *strategy, size_t xopts_nr,
+		      const char **xopts, struct commit_list *common,
+		      const char *head_arg, struct commit_list *remotes)
+{
+	struct argv_array args = ARGV_ARRAY_INIT;
+	int i, ret;
+	struct commit_list *j;
+
+	argv_array_pushf(&args, "merge-%s", strategy);
+	for (i = 0; i < xopts_nr; i++)
+		argv_array_pushf(&args, "--%s", xopts[i]);
+	for (j = common; j; j = j->next)
+		argv_array_push(&args, merge_argument(j->item));
+	argv_array_push(&args, "--");
+	argv_array_push(&args, head_arg);
+	for (j = remotes; j; j = j->next)
+		argv_array_push(&args, merge_argument(j->item));
+
+	ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
+	argv_array_clear(&args);
+
+	discard_cache();
+	if (read_cache() < 0)
+		die(_("failed to read the cache"));
+	resolve_undo_clear();
+
+	return ret;
+}
+
+int checkout_fast_forward(const unsigned char *head,
+			  const unsigned char *remote,
+			  int overwrite_ignore)
+{
+	struct tree *trees[MAX_UNPACK_TREES];
+	struct unpack_trees_options opts;
+	struct tree_desc t[MAX_UNPACK_TREES];
+	int i, nr_trees = 0;
+	struct dir_struct dir;
+	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+
+	refresh_cache(REFRESH_QUIET);
+
+	if (hold_locked_index(lock_file, 0) < 0)
+		return -1;
+
+	memset(&trees, 0, sizeof(trees));
+	memset(&opts, 0, sizeof(opts));
+	memset(&t, 0, sizeof(t));
+	if (overwrite_ignore) {
+		memset(&dir, 0, sizeof(dir));
+		dir.flags |= DIR_SHOW_IGNORED;
+		setup_standard_excludes(&dir);
+		opts.dir = &dir;
+	}
+
+	opts.head_idx = 1;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+	opts.update = 1;
+	opts.verbose_update = 1;
+	opts.merge = 1;
+	opts.fn = twoway_merge;
+	setup_unpack_trees_porcelain(&opts, "merge");
+
+	trees[nr_trees] = parse_tree_indirect(head);
+	if (!trees[nr_trees++])
+		return -1;
+	trees[nr_trees] = parse_tree_indirect(remote);
+	if (!trees[nr_trees++])
+		return -1;
+	for (i = 0; i < nr_trees; i++) {
+		parse_tree(trees[i]);
+		init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
+	}
+	if (unpack_trees(nr_trees, t, &opts))
+		return -1;
+	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK)) {
+		rollback_lock_file(lock_file);
+		return error(_("unable to write new index file"));
+	}
+	return 0;
+}