Bugfix/1827 invalid cross device link

fsspec/implementations/local.py

@@ -391,7 +391,10 @@ def _open(self):
                     self.f = compress(self.f, mode=self.mode)
             else:
                 # TODO: check if path is writable?
-                i, name = tempfile.mkstemp()
+                i, name = tempfile.mkstemp(
+                    dir=os.path.dirname(self.path),
+                    prefix=os.path.basename(self.path) + "-",
+                )
                 os.close(i)  # we want normal open and normal buffered file
                 self.temp = name
                 self.f = open(name, mode=self.mode)
@@ -434,7 +437,7 @@ def commit(self):
         try:
             mask = 0o666
             os.chmod(self.path, mask & ~get_umask(mask))
-        except RuntimeError:
+        except (RuntimeError, PermissionError):
             pass
 
     def discard(self):

fsspec/implementations/tests/test_local.py

@@ -1,4 +1,5 @@
 import bz2
+import errno
 import gzip
 import os
 import os.path
@@ -562,6 +563,33 @@ def test_multiple_filesystems_use_umask_cache(tmpdir):
     assert get_umask.cache_info().hits == 1
 
 
+def test_transaction_chmod_catch_permission_error(tmpdir):
+    fs = LocalFileSystem()
+    with patch("os.chmod", side_effect=PermissionError("Operation not permitted")):
+        with fs.transaction, fs.open(tmpdir + "/afile", "wb") as f:
+            f.write(b"data")
+
+
+def test_transaction_cross_device_but_mock_temp_dir_on_wrong_device(tmpdir):
+    # If the temporary file for a transaction is not on the correct device,
+    # os.rename in shutil.move will raise EXDEV and lookup('chmod') will raise
+    # a PermissionError.
+    fs = LocalFileSystem()
+    with (
+        patch(
+            "os.rename",
+            side_effect=OSError(errno.EXDEV, "Invalid cross-device link"),
+        ),
+        patch(
+            "os.chmod",
+            side_effect=PermissionError("Operation not permitted"),
+        ),
+        pytest.raises(PermissionError, match="Operation not permitted"),
+    ):
+        with fs.transaction, fs.open(tmpdir + "/afile", "wb") as f:
+            f.write(b"data")
+
+
 def test_make_path_posix():
     cwd = os.getcwd()
     if WIN: