Move the invalid fd check to after checking if fd == AT_FDCWD in the fchownat() function

src/build/libroot/fs_darwin.cpp

@@ -206,18 +206,18 @@ fchownat(int fd, const char* path, uid_t owner, gid_t group, int flag)
 		return -1;
 	}
 
-	if (fd < 0) {
-		// Invalid file descriptor
-		errno = EBADF;
-		return -1;
-	}
-
 	if (fd == AT_FDCWD || path != NULL && path[0] == '/') {
 		// call chown() ignoring fd
 		return (flag & AT_SYMLINK_NOFOLLOW) != 0 ? lchown(path, owner, group)
 			: chown(path, owner, group);
 	}
 
+	if (fd < 0) {
+		// Invalid file descriptor
+		errno = EBADF;
+		return -1;
+	}
+
 	char *fullPath = (char *)malloc(MAXPATHLEN);
 	if (fullPath == NULL) {
 		// ran out of memory allocating dirpath