From 857b27579968dfb947d0cedb19480e5472336a84 Mon Sep 17 00:00:00 2001
From: ANIS <119749586+assinscreedFC@users.noreply.github.com>
Date: Sat, 6 Jun 2026 01:12:11 +0200
Subject: [PATCH] Forward kwargs from cat_ranges to cat_file

AbstractFileSystem.cat_ranges accepts **kwargs but dropped them when
calling cat_file, so parameters such as a cache's block_size were
silently ignored and every range read bypassed the cache. The async
AsyncFileSystem._cat_ranges already forwards them.

Pass **kwargs through to cat_file, matching the async implementation.

Fixes #2016
---
 fsspec/spec.py            |  2 +-
 fsspec/tests/test_spec.py | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/fsspec/spec.py b/fsspec/spec.py
index 3a71b2227..a390bf060 100644
--- a/fsspec/spec.py
+++ b/fsspec/spec.py
@@ -874,7 +874,7 @@ def cat_ranges(
         out = []
         for p, s, e in zip(paths, starts, ends):
             try:
-                out.append(self.cat_file(p, s, e))
+                out.append(self.cat_file(p, s, e, **kwargs))
             except Exception as e:
                 if on_error == "return":
                     out.append(e)
diff --git a/fsspec/tests/test_spec.py b/fsspec/tests/test_spec.py
index 8880c255c..7fc828243 100644
--- a/fsspec/tests/test_spec.py
+++ b/fsspec/tests/test_spec.py
@@ -1456,3 +1456,21 @@ def test_expand_path_with_magic_input():
         "bucket/file?.txt",
     ]
     assert sorted(paths) == sorted(expected)
+
+
+def test_cat_ranges_forwards_kwargs():
+    # See GH#2016: cat_ranges must forward **kwargs to cat_file, otherwise
+    # parameters such as a cache's block_size are silently dropped.
+    received = []
+
+    class RecordingFS(AbstractFileSystem):
+        cachable = False
+
+        def cat_file(self, path, start=None, end=None, **kwargs):
+            received.append(kwargs)
+            return b""
+
+    fs = RecordingFS()
+    fs.cat_ranges(["a", "b"], [0, 0], [1, 1], block_size=42)
+
+    assert received == [{"block_size": 42}, {"block_size": 42}]