boot-entry: plug through XAT_FDROOT

src/shared/boot-entry.c

@@ -22,7 +22,7 @@ static int entry_token_load_one(int rfd, const char *dir, BootEntryTokenType *ty
         _cleanup_fclose_ FILE *f = NULL;
         int r;
 
-        assert(rfd >= 0 || rfd == AT_FDCWD);
+        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
         assert(dir);
         assert(type);
         assert(*type == BOOT_ENTRY_TOKEN_AUTO);
@@ -58,7 +58,7 @@ static int entry_token_load_one(int rfd, const char *dir, BootEntryTokenType *ty
 static int entry_token_load(int rfd, const char *conf_root, BootEntryTokenType *type, char **token) {
         int r;
 
-        assert(rfd >= 0 || rfd == AT_FDCWD);
+        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
         assert(type);
         assert(*type == BOOT_ENTRY_TOKEN_AUTO);
         assert(token);
@@ -98,7 +98,7 @@ static int entry_token_from_os_release(int rfd, BootEntryTokenType *type, char *
         _cleanup_free_ char *id = NULL, *image_id = NULL;
         int r;
 
-        assert(rfd >= 0 || rfd == AT_FDCWD);
+        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
         assert(type);
         assert(IN_SET(*type, BOOT_ENTRY_TOKEN_AUTO, BOOT_ENTRY_TOKEN_OS_IMAGE_ID, BOOT_ENTRY_TOKEN_OS_ID));
         assert(token);
@@ -151,7 +151,7 @@ int boot_entry_token_ensure_at(
 
         int r;
 
-        assert(rfd >= 0 || rfd == AT_FDCWD);
+        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
         assert(type);
         assert(token);
 
@@ -229,11 +229,12 @@ int boot_entry_token_ensure(
         if (*token)
                 return 0; /* Already set. */
 
-        _cleanup_close_ int rfd = -EBADF;
-
-        rfd = open(empty_to_root(root), O_CLOEXEC | O_DIRECTORY | O_PATH);
-        if (rfd < 0)
-                return -errno;
+        _cleanup_close_ int rfd = XAT_FDROOT;
+        if (!empty_or_root(root)) {
+                rfd = open(root, O_CLOEXEC | O_DIRECTORY | O_PATH);
+                if (rfd < 0)
+                        return -errno;
+        }
 
         return boot_entry_token_ensure_at(rfd, conf_root, machine_id, machine_id_is_random, type, token);
 }