Surface SMB tree setup errors as OSError

src/smbclient/_io.py

@@ -381,7 +381,11 @@ class SMBRawIO(io.RawIOBase):
     def __init__(
         self, path, mode="r", share_access=None, desired_access=None, file_attributes=None, create_options=0, **kwargs
     ):
-        tree, fd_path = get_smb_tree(path, **kwargs)
+        # get_smb_tree runs outside the SMBFileTransaction layer that normally translates these.
+        try:
+            tree, fd_path = get_smb_tree(path, **kwargs)
+        except SMBResponseException as exc:
+            raise SMBOSError(exc.status, path) from exc
 
         self.share_access = share_access
         self.fd = Open(tree, fd_path)

tests/test_smbclient_os.py

@@ -2186,3 +2186,14 @@ def test_dfs_nonexisting_path(smb_dfs_share):
 
     with pytest.raises(SMBOSError):
         smbclient.lstat(fake_file)
+
+
+def test_open_file_missing_share_raises_os_error(smb_real):
+    # A missing share fails tree connect with STATUS_BAD_NETWORK_NAME, a non-OSError
+    # that must surface as SMBOSError so except OSError / ignore_errors callers catch it.
+    bad_path = rf"\\{smb_real[2]}\does_not_exist\file.txt"
+
+    with pytest.raises(SMBOSError) as exc_info:
+        smbclient.open_file(bad_path, username=smb_real[0], password=smb_real[1], port=smb_real[3])
+
+    assert exc_info.value.filename == bad_path

tests/test_smbclient_pool.py

@@ -8,7 +8,13 @@
 import smbclient._io as io
 import smbclient._pool as pool
 from smbprotocol.dfs import DFSReferralResponse
-from smbprotocol.exceptions import BadNetworkName, InvalidParameter, ObjectPathNotFound
+from smbprotocol.exceptions import (
+    BadNetworkName,
+    InvalidParameter,
+    ObjectPathNotFound,
+    SMBOSError,
+)
+from smbprotocol.header import NtStatus
 
 from .conftest import DC_REFERRAL, DOMAIN_NAME, DOMAIN_REFERRAL
 
@@ -150,3 +156,16 @@ def test_resolve_dfs_referral_no_links(reset_config, monkeypatch, mocker):
 
     with pytest.raises(ObjectPathNotFound):
         list(io._resolve_dfs(raw_io))
+
+
+def test_raw_io_translates_smb_response_to_os_error(mocker):
+    # Anything escaping get_smb_tree here must surface as OSError so the
+    # rmtree, remove, rmdir, and scandir error paths route it correctly.
+    mocker.patch.object(io, "get_smb_tree", side_effect=BadNetworkName())
+
+    path = r"\\server\share\missing"
+    with pytest.raises(SMBOSError) as exc_info:
+        io.SMBRawIO(path)
+
+    assert exc_info.value.ntstatus == NtStatus.STATUS_BAD_NETWORK_NAME
+    assert exc_info.value.filename == path