merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/merge.c

@@ -0,0 +1,109 @@
+#include "cache.h"
+#include "diff.h"
+#include "diffcore.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)
+{
+	return oid_to_hex(commit ? &commit->object.oid : the_hash_algo->empty_tree);
+}
+
+int try_merge_command(struct repository *r,
+		      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_index(r->index);
+	if (repo_read_index(r) < 0)
+		die(_("failed to read the cache"));
+	resolve_undo_clear_index(r->index);
+
+	return ret;
+}
+
+int checkout_fast_forward(struct repository *r,
+			  const struct object_id *head,
+			  const struct object_id *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 = LOCK_INIT;
+
+	refresh_index(r->index, REFRESH_QUIET, NULL, NULL, NULL);
+
+	if (repo_hold_locked_index(r, &lock_file, LOCK_REPORT_ON_ERROR) < 0)
+		return -1;
+
+	memset(&trees, 0, sizeof(trees));
+	memset(&t, 0, sizeof(t));
+
+	trees[nr_trees] = parse_tree_indirect(head);
+	if (!trees[nr_trees++]) {
+		rollback_lock_file(&lock_file);
+		return -1;
+	}
+	trees[nr_trees] = parse_tree_indirect(remote);
+	if (!trees[nr_trees++]) {
+		rollback_lock_file(&lock_file);
+		return -1;
+	}
+	for (i = 0; i < nr_trees; i++) {
+		parse_tree(trees[i]);
+		init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
+	}
+
+	memset(&opts, 0, sizeof(opts));
+	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 = r->index;
+	opts.dst_index = r->index;
+	opts.update = 1;
+	opts.verbose_update = 1;
+	opts.merge = 1;
+	opts.fn = twoway_merge;
+	setup_unpack_trees_porcelain(&opts, "merge");
+
+	if (unpack_trees(nr_trees, t, &opts)) {
+		rollback_lock_file(&lock_file);
+		clear_unpack_trees_porcelain(&opts);
+		return -1;
+	}
+	clear_unpack_trees_porcelain(&opts);
+
+	if (write_locked_index(r->index, &lock_file, COMMIT_LOCK))
+		return error(_("unable to write new index file"));
+	return 0;
+}