repo: basic graft API

This represents (old-style) grafted commits, a.k.a an array of
overridden parents for a commit's OID.

src/graft.c

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "graft.h"
+
+int git__graft_register(git_graftmap *grafts, const git_oid *oid, git_array_oid_t parents)
+{
+	git_commit_graft *graft;
+	git_oid *parent_oid;
+	int error;
+	size_t i;
+
+	assert(grafts && oid);
+
+	graft = git__calloc(1, sizeof(*graft));
+	GIT_ERROR_CHECK_ALLOC(graft);
+
+	git_array_init_to_size(graft->parents, git_array_size(parents));
+	git_array_foreach(parents, i, parent_oid) {
+		git_oid *id = git_array_alloc(graft->parents);
+		GIT_ERROR_CHECK_ALLOC(id);
+
+		git_oid_cpy(id, parent_oid);
+	}
+	git_oid_cpy(&graft->oid, oid);
+
+	if ((error = git_oidmap_set(grafts, &graft->oid, graft)) < 0)
+		goto cleanup;
+
+	return 0;
+
+cleanup:
+	git_array_clear(graft->parents);
+	git__free(graft);
+	return error;
+}
+
+int git__graft_unregister(git_graftmap *grafts, const git_oid *oid)
+{
+	git_commit_graft *graft;
+	int error;
+
+	assert(grafts && oid);
+
+	if ((graft = git_oidmap_get(grafts, oid)) == NULL)
+		return GIT_ENOTFOUND;
+
+	if ((error = git_oidmap_delete(grafts, oid)) < 0)
+		return error;
+
+	git__free(graft);
+
+	return 0;
+}
+
+void git__graft_clear(git_graftmap *grafts)
+{
+	git_commit_graft *graft;
+
+	assert(grafts);
+
+	git_oidmap_foreach_value(grafts, graft, {
+		git__free(graft->parents.ptr);
+		git__free(graft);
+	});
+
+	git_oidmap_clear(grafts);
+}
+
+int git__graft_for_oid(git_commit_graft **out, git_graftmap *grafts, const git_oid *oid)
+{
+	assert(out && grafts && oid);
+	if ((*out = git_oidmap_get(grafts, oid)) == NULL)
+		return GIT_ENOTFOUND;
+	return 0;
+}

src/graft.h

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_graft_h__
+#define INCLUDE_graft_h__
+
+#include "common.h"
+#include "oidarray.h"
+#include "oidmap.h"
+
+/** graft commit */
+typedef struct {
+	git_oid oid;
+	git_array_oid_t parents;
+} git_commit_graft;
+
+/* A special type of git_oidmap with git_commit_grafts as values */
+typedef git_oidmap git_graftmap;
+
+int git__graft_register(git_graftmap *grafts, const git_oid *oid, git_array_oid_t parents);
+int git__graft_unregister(git_graftmap *grafts, const git_oid *oid);
+void git__graft_clear(git_graftmap *grafts);
+
+int git__graft_for_oid(git_commit_graft **out, git_graftmap *grafts, const git_oid *oid);
+
+#endif