fd-util: add wildcard_fd_is_valid() helper and use it tree-wide

Many *at()-style helpers accept a directory fd that may be either a
regular, valid fd (>= 0) or one of the special AT_FDCWD/XAT_FDROOT
wildcard values, and open-code that check in their assertions. Add a
wildcard_fd_is_valid() helper for it and use it tree-wide.

src/shared/boot-entry.c

@@ -21,7 +21,7 @@ static int entry_token_load_one(int rfd, const char *dir, BootEntryTokenType *ty
         _cleanup_fclose_ FILE *f = NULL;
         int r;
 
-        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
         assert(dir);
         assert(type);
         assert(*type == BOOT_ENTRY_TOKEN_AUTO);
@@ -57,7 +57,7 @@ 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 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
         assert(type);
         assert(*type == BOOT_ENTRY_TOKEN_AUTO);
         assert(token);
@@ -97,7 +97,7 @@ 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 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
         assert(type);
         assert(IN_SET(*type, BOOT_ENTRY_TOKEN_AUTO, BOOT_ENTRY_TOKEN_OS_IMAGE_ID, BOOT_ENTRY_TOKEN_OS_ID));
         assert(token);
@@ -150,7 +150,7 @@ int boot_entry_token_ensure_at(
 
         int r;
 
-        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
         assert(type);
         assert(token);
 

src/shared/btrfs-util.c

@@ -109,7 +109,7 @@ int btrfs_get_block_device_at_full(int dir_fd, const char *path, uint64_t *ret_d
          * ret - the returned block device
          */
 
-        assert(dir_fd >= 0 || IN_SET(dir_fd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(dir_fd));
 
         fd = xopenat(dir_fd, path, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
         if (fd < 0)

src/shared/conf-parser.c

@@ -603,7 +603,7 @@ static int normalize_root_fd(const char *root, int *root_fd, int *ret_opened_fd)
         /* Normalizes a root dir specification: if root_fd is already valid, keep it. Otherwise, we open the
          * specified dir */
 
-        if (*root_fd >= 0 || IN_SET(*root_fd, AT_FDCWD, XAT_FDROOT)) {
+        if (wildcard_fd_is_valid(*root_fd)) {
                 *ret_opened_fd = -EBADF;
                 return 0;
         }

src/shared/find-esp.c

@@ -323,7 +323,7 @@ static int verify_esp(
                 unprivileged_mode = FLAGS_SET(flags, VERIFY_ESP_UNPRIVILEGED_MODE);
         int r;
 
-        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
         assert(path);
 
         /* This logs about all errors, except:
@@ -420,7 +420,7 @@ int find_esp_and_warn_at_full(
         VerifyESPFlags flags;
         int r;
 
-        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
 
         /* This logs about all errors except:
          *
@@ -733,7 +733,7 @@ static int verify_xbootldr(
                 unprivileged_mode = FLAGS_SET(flags, VERIFY_ESP_UNPRIVILEGED_MODE);
         int r;
 
-        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
         assert(path);
 
         _cleanup_free_ char *p = NULL;
@@ -796,7 +796,7 @@ int find_xbootldr_and_warn_at_full(
 
         /* Similar to find_esp_and_warn(), but finds the XBOOTLDR partition. Returns the same errors. */
 
-        assert(rfd >= 0 || IN_SET(rfd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(rfd));
 
         flags = verify_esp_flags_init(unprivileged_mode, "SYSTEMD_RELAX_XBOOTLDR_CHECKS");
 

src/shared/kernel-config.c

@@ -28,7 +28,7 @@ int load_kernel_install_conf_at(
         };
         int r;
 
-        assert(root_fd >= 0 || IN_SET(root_fd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(root_fd));
 
         if (conf_root) {
                 _cleanup_free_ char *conf = path_join(conf_root, "install.conf");

src/shared/kernel-image.c

@@ -130,7 +130,7 @@ int inspect_kernel_full(
         _cleanup_close_ int fd = -EBADF;
         int r;
 
-        assert(dir_fd >= 0 || IN_SET(dir_fd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(dir_fd));
 
         fd = xopenat(dir_fd, filename, O_RDONLY|O_CLOEXEC);
         if (fd < 0)

src/shared/vpick.c

@@ -190,7 +190,7 @@ static int pin_choice(
         _cleanup_free_ char *resolved_path = NULL;
         int r;
 
-        assert(toplevel_fd >= 0 || IN_SET(toplevel_fd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(toplevel_fd));
         assert(inode_path);
         assert(filter);
         assert(ret);
@@ -322,7 +322,7 @@ static int make_choice(
         _cleanup_close_ int inode_fd = TAKE_FD(_inode_fd);
         int r;
 
-        assert(toplevel_fd >= 0 || IN_SET(toplevel_fd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(toplevel_fd));
         assert(inode_path);
         assert(filter);
         assert(ret);
@@ -513,7 +513,7 @@ static int path_pick_one(
         uint32_t filter_type_mask;
         int r;
 
-        assert(toplevel_fd >= 0 || IN_SET(toplevel_fd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(toplevel_fd));
         assert(path);
         assert(filter);
         assert(ret);
@@ -662,7 +662,7 @@ int path_pick(const char *toplevel_path,
         _cleanup_(pick_result_done) PickResult best = PICK_RESULT_NULL;
         int r;
 
-        assert(toplevel_fd >= 0 || IN_SET(toplevel_fd, AT_FDCWD, XAT_FDROOT));
+        assert(wildcard_fd_is_valid(toplevel_fd));
         assert(path);
         assert(filters || n_filters == 0);
         assert(ret);