1 files changed, 139 insertions, 0 deletions
diff --git a/libmount/src/hook_mkdir.c b/libmount/src/hook_mkdir.c
new file mode 100644
index 0000000..da9c407
--- /dev/null
+++ b/libmount/src/hook_mkdir.c
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * This file is part of libmount from util-linux project.
+ *
+ * Copyright (C) 2022 Karel Zak <kzak@redhat.com>
+ *
+ * libmount is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ *
+ * Please, see the comment in libmount/src/hooks.c to understand how hooks work.
+ */
+#include "mountP.h"
+#include "fileutils.h"
+
+static int hookset_deinit(struct libmnt_context *cxt, const struct libmnt_hookset *hs)
+{
+	void *data = NULL;
+
+	DBG(HOOK, ul_debugobj(hs, "deinit '%s'", hs->name));
+
+	/* remove all our hooks and free hook data */
+	while (mnt_context_remove_hook(cxt, hs, 0, &data) == 0) {
+		if (data)
+			free(data);
+		data = NULL;
+	}
+
+	return 0;
+}
+
+static int is_mkdir_required(struct libmnt_context *cxt, const char *tgt, mode_t *mode, int *rc)
+{
+	struct libmnt_optlist *ol;
+	struct libmnt_opt *opt;
+	const char *mstr = NULL;
+
+	assert(cxt);
+	assert(cxt->map_userspace);
+	assert(tgt);
+	assert(mode);
+	assert(rc);
+
+	*mode = 0;
+	*rc = 0;
+
+	ol = mnt_context_get_optlist(cxt);
+	if (!ol)
+		return -ENOMEM;
+
+	opt = mnt_optlist_get_named(ol, "X-mount.mkdir", cxt->map_userspace);
+	if (!opt)
+		opt = mnt_optlist_get_named(ol, "x-mount.mkdir", cxt->map_userspace);
+	if (!opt)
+		return 0;
+
+	if (mnt_is_path(tgt))
+		return 0;
+
+	mstr = mnt_opt_get_value(opt);
+
+	if (mstr && *mstr) {
+		char *end = NULL;
+
+		if (*mstr == '"')
+			mstr++;
+
+		errno = 0;
+		*mode = strtol(mstr, &end, 8);
+
+		if (errno || !end || !(*end == '"' || *end == '\0')) {
+			DBG(HOOK, ul_debug("failed to parse mkdir mode '%s'", mstr));
+			*rc = -MNT_ERR_MOUNTOPT;
+			return 0;
+		}
+	}
+
+	if (!*mode)
+		*mode = S_IRWXU |			/* 0755 */
+		       S_IRGRP | S_IXGRP |
+		       S_IROTH | S_IXOTH;
+
+	DBG(HOOK, ul_debug("mkdir %s (%o) wanted", tgt, *mode));
+
+	return 1;
+}
+
+static int hook_prepare_target(
+			struct libmnt_context *cxt,
+			const struct libmnt_hookset *hs,
+			void *data __attribute__((__unused__)))
+{
+	int rc = 0;
+	mode_t mode = 0;
+	const char *tgt;
+
+	assert(cxt);
+
+	tgt = mnt_fs_get_target(cxt->fs);
+	if (!tgt)
+		return 0;
+
+	if (cxt->action == MNT_ACT_MOUNT
+	    && is_mkdir_required(cxt, tgt, &mode, &rc)) {
+
+		struct libmnt_cache *cache;
+
+		/* supported only for root or non-suid mount(8) */
+		if (!mnt_context_is_restricted(cxt)) {
+			rc = ul_mkdir_p(tgt, mode);
+			if (rc)
+				DBG(HOOK, ul_debugobj(hs, "mkdir %s failed: %m", tgt));
+		} else
+			rc = -EPERM;
+
+		if (rc == 0) {
+			cache = mnt_context_get_cache(cxt);
+			if (cache) {
+				char *path = mnt_resolve_path(tgt, cache);
+				if (path && strcmp(path, tgt) != 0)
+					rc = mnt_fs_set_target(cxt->fs, path);
+			}
+		}
+	}
+
+	return rc;
+}
+
+const struct libmnt_hookset hookset_mkdir =
+{
+	.name = "__mkdir",
+
+	.firststage = MNT_STAGE_PREP_TARGET,
+	.firstcall = hook_prepare_target,
+
+	.deinit = hookset_deinit
+};