fix: XRootDHelper.exists supports non posix filesystem (object store) (…

…#1348)

snakemake/remote/XRootD.py

@@ -7,6 +7,7 @@
 from os.path import abspath, join, normpath
 import re
 
+from stat import S_ISREG
 from snakemake.remote import AbstractRemoteObject, AbstractRemoteProvider
 from snakemake.exceptions import WorkflowError, XRootDFileException
 
@@ -142,23 +143,30 @@ def _parse_url(self, url):
         return domain, dirname, filename
 
     def exists(self, url):
+
         domain, dirname, filename = self._parse_url(url)
-        status, dirlist = self.get_client(domain).dirlist(dirname)
+
+        status, statInfo = self.get_client(domain).stat(os.path.join(dirname, filename))
+
         if not status.ok:
             if status.errno == 3011:
                 return False
-            else:
-                raise XRootDFileException(
-                    "Error listing directory "
-                    + dirname
-                    + " on domain "
-                    + domain
-                    + "\n"
-                    + repr(status)
-                    + "\n"
-                    + repr(dirlist)
-                )
-        return filename in [f.name for f in dirlist.dirlist]
+            raise XRootDFileException(
+                "Error stating URL "
+                + os.path.join(dirname, filename)
+                + " on domain "
+                + domain
+                + "\n"
+                + repr(status)
+                + "\n"
+                + repr(statInfo)
+            )
+
+        return True
+        # return not (
+        #     (statInfo.flags & StatInfoFlags.IS_DIR)
+        #     or (statInfo.flags & StatInfoFlags.OTHER)
+        # )
 
     def _get_statinfo(self, url):
         domain, dirname, filename = self._parse_url(url)