feat(protocol): client-message channel and rsync partial exit 23 (2.30.0)

tests/integration/test_features.py

@@ -203,9 +203,9 @@ class TestDeviceSpecial:
                                    flags=["--devices"], port=port)
         finally:
             out, err = _stop_captured_server(server)
-        assert result.returncode != 0, (
-            f"a failed device mknod must be a transfer error like rsync (got exit 0): "
-            f"{(out + err)[:300]}"
+        assert result.returncode == 23, (
+            f"a failed device mknod must exit 23 (rsync partial transfer), got "
+            f"{result.returncode}: {(out + err)[:300]}"
         )
         received = get_dest_received_dir(DEVICE_DEST, DEVICE_SOURCE)
         assert not os.path.lexists(os.path.join(received, "chardev")), (
@@ -215,6 +215,38 @@ class TestDeviceSpecial:
             f"receiver did not log the device creation error: out={out!r} err={err!r}"
         )
 
+    @pytest.mark.skipif(os.geteuid() != 0, reason="requires root to create device nodes")
+    def test_devices_nonroot_partial_removes_transferred_sources(self):
+        """rsync parity for a partial receiver run under --remove-source-files:
+        the successfully transferred regular source is still removed, the
+        un-creatable device source is kept, and the client exits 23 (verified
+        against rsync 3.4.1: it removes ok.txt/ok2.txt, keeps the device, and
+        exits 23)."""
+        if os.geteuid() != 0 or shutil.which("setpriv") is None:
+            pytest.skip("requires root + setpriv to run the receiver unprivileged")
+        self._setup()
+        os.mknod(os.path.join(DEVICE_SOURCE, "chardev"), stat.S_IFCHR | 0o666,
+                 os.makedev(1, 3))
+        os.makedirs(DEVICE_DEST, exist_ok=True)
+        os.chmod(DEVICE_DEST, 0o777)
+        server, port = _start_captured_server(
+            prefix=["setpriv", "--reuid=65534", "--regid=65534", "--clear-groups"])
+        try:
+            result, _ = run_client(DEVICE_SOURCE, DEVICE_DEST,
+                                   flags=["--devices", "--remove-source-files"], port=port)
+        finally:
+            out, err = _stop_captured_server(server)
+        assert result.returncode == 23, (
+            f"a partial receiver run must exit 23, got {result.returncode}: "
+            f"{(out + err)[:300]}"
+        )
+        assert not os.path.exists(os.path.join(DEVICE_SOURCE, "plain.txt")), (
+            "a successfully transferred source must be removed even on a partial run"
+        )
+        assert os.path.exists(os.path.join(DEVICE_SOURCE, "chardev")), (
+            "the source device that failed to materialize must be kept"
+        )
+
     @pytest.mark.skipif(os.geteuid() != 0, reason="requires root to create device nodes")
     def test_devices_recreates_real_char_device(self, shared_server):
         """Root-only: a source char device node is recreated on the destination
@@ -334,6 +366,57 @@ def setup_test_data():
     shutil.rmtree(DEST_DIR, ignore_errors=True)
 
 
+class TestClientStderrChannel:
+    """--stderr=client: the client's own diagnostics go to the peer's stderr."""
+
+    @pytest.mark.ci
+    def test_client_diagnostic_reaches_server_stderr(self):
+        """A client-side warning emitted during the transfer is forwarded over
+        the STATUS_CLIENT_MSG channel and printed on the server's stderr, not the
+        client's.  A dangling symlink under -L is the deterministic trigger."""
+        source = os.path.join(TEST_DATA_DIR, "client_msg_src")
+        dest = os.path.join(TEST_DATA_DIR, "client_msg_dst")
+        clean_dir(source)
+        clean_dir(dest)
+        with open(os.path.join(source, "plain.txt"), "wb") as f:
+            f.write(b"payload\n")
+        os.symlink("no-such-referent", os.path.join(source, "dangling"))
+        server, port = _start_captured_server()
+        try:
+            result, _ = run_client(source, dest, flags=["-L", "--stderr=client"],
+                                   port=port)
+        finally:
+            out, err = _stop_captured_server(server)
+        assert "symlink has no referent" in (out + err), (
+            f"client diagnostic did not reach the server stderr: out={out!r} err={err!r}"
+        )
+        assert "symlink has no referent" not in (result.stderr or ""), (
+            f"client diagnostic must not also be written locally: {result.stderr!r}"
+        )
+
+    @pytest.mark.ci
+    def test_no_msgs2stderr_alias_uses_client_channel(self):
+        """--no-msgs2stderr is rsync's spelling of --stderr=client and now
+        forwards the client's diagnostics to the server too."""
+        source = os.path.join(TEST_DATA_DIR, "client_msg_alias_src")
+        dest = os.path.join(TEST_DATA_DIR, "client_msg_alias_dst")
+        clean_dir(source)
+        clean_dir(dest)
+        with open(os.path.join(source, "plain.txt"), "wb") as f:
+            f.write(b"payload\n")
+        os.symlink("no-such-referent", os.path.join(source, "dangling"))
+        server, port = _start_captured_server()
+        try:
+            result, _ = run_client(source, dest, flags=["-L", "--no-msgs2stderr"],
+                                   port=port)
+        finally:
+            out, err = _stop_captured_server(server)
+        assert "symlink has no referent" in (out + err), (
+            f"--no-msgs2stderr did not route to the server: out={out!r} err={err!r}"
+        )
+        assert "symlink has no referent" not in (result.stderr or "")
+
+
 class TestDryRun:
     def test_trust_sender_transfer_completes(self, shared_server):
         """--trust-sender is a receiver-local policy (never sent to the peer).