1 files changed, 65 insertions, 0 deletions
diff --git a/lib/fstree/hardlink.c b/lib/fstree/hardlink.c
new file mode 100644
index 0000000..8a79d46
--- /dev/null
+++ b/lib/fstree/hardlink.c
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * hardlink.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+
+#include "fstree.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+tree_node_t *fstree_add_hard_link(fstree_t *fs, const char *path,
+				  const char *target)
+{
+	struct stat sb;
+	tree_node_t *n;
+
+	memset(&sb, 0, sizeof(sb));
+	sb.st_mode = S_IFLNK | 0777;
+
+	n = fstree_add_generic(fs, path, &sb, target);
+	if (n != NULL) {
+		if (canonicalize_name(n->data.target)) {
+			free(n);
+			errno = EINVAL;
+			return NULL;
+		}
+
+		n->mode = FSTREE_MODE_HARD_LINK;
+	}
+
+	return n;
+}
+
+int fstree_resolve_hard_link(fstree_t *fs, tree_node_t *node)
+{
+	tree_node_t *start = node;
+
+	while (node->mode == FSTREE_MODE_HARD_LINK ||
+	       node->mode == FSTREE_MODE_HARD_LINK_RESOLVED) {
+		if (node->mode == FSTREE_MODE_HARD_LINK_RESOLVED) {
+			node = node->data.target_node;
+		} else {
+			node = fstree_get_node_by_path(fs, fs->root,
+						       node->data.target,
+						       false, false);
+			if (node == NULL)
+				return -1;
+		}
+
+		if (node == start) {
+			errno = EMLINK;
+			return -1;
+		}
+	}
+
+	start->mode = FSTREE_MODE_HARD_LINK_RESOLVED;
+	start->data.target_node = node;
+
+	node->link_count += 1;
+	return 0;
+}