Keep Python Printer Agent Exceptions Out of the Host (#15819)

# Description  A Python printer agent plugin could take the host down, and one of its operations could never report its result. This PR fixes both in `PrinterAgentPluginCapabilityTrampoline.hpp`. ## Changes ### A faulty printer agent no longer throws into the GUI `IPrinterAgent` reports failure through return values, and none of its callers catch. A Python `raise`, a missing override or a wrongly typed return from a printer agent plugin therefore escaped the trampoline as a C++ exception. Every trampoline operation now catches, logs `Printer agent plugin '<key>': <operation> failed: <error>`, and answers with what `NetworkAgent` returns when no printer agent is set. `BBLPrinterAgent` returns the same values when the Bambu plug-in is unavailable: - `-1` for every `int` status code - `false` for `start_discovery` and `fetch_filament_info` - `""` for `get_user_selected_machine` - an empty `AgentInfo` for `get_agent_info` (registration already rejects an empty agent ID) - `FilamentSyncMode::none` for `get_filament_sync_mode` `ORCA_PY_AGENT_OVERRIDE(ret, name, ...)` derives the fallback from the return type through `printer_agent_failure<ret>()`, so the call sites carry no fallback values of their own. An exception is the safety net for plugin bugs, not an error channel. A plugin reports an expected failure by returning a code, as the Bambu plug-in does. A raise is logged as a failure and collapses to the generic `-1`, so the GUI shows the generic message instead of the specific one (`-18` cancelled, `-4020` FTP upload failed, …). ### `bind_detect` results now reach the host `detect` is an out-parameter (`detectResult&`). pybind11 casts a reference argument to an override with a copy, so a plugin that filled in `detect` wrote to a throwaway object and the host always saw an empty `detectResult`. It is now passed so that Python edits the caller's struct. Plugins see the same `DetectResult` argument as before. ## TODO - Expose the `BAMBU_NETWORK_*` return codes to Python (the `orca.printer_agent` binding and the generated stub from `scripts/generate_orca_python_stubs.py`). Plugins can already return them, but only as hard-coded numbers. # Screenshots/Recordings/Graphs  ## Tests  - New `tests/slic3rutils/test_plugin_printer_agent.cpp`: an agent whose operations raise, one that omits them, and one that returns the wrong type all answer like a missing agent, and the interpreter stays usable. A working agent's answers reach the host unchanged, including `request_bind_ticket`'s out-param and the fields a plugin writes into `bind_detect`'s `detect`. - The `bind_detect` check failed before the fix (`"" == "192.168.0.2"`) and passes after. - `slic3rutils` passes under `ctest` (144/144); full Release build clean on Linux. - End to end on Linux with a test plugin whose chosen operations raise (`start_discovery`, `get_filament_sync_mode`, `disconnect_printer`): selecting the plugin's agent in the printer preset and switching back logged each raise as a `Printer agent plugin '…': <operation> failed` line, and the app kept running and closed cleanly (exit 0). Without the guard, the first raise (`start_discovery`, on selecting the agent) ended the app with `Uncaught exception` and SIGABRT (exit 134); that run used a build whose printer-agent files are identical to `main`.  [How to Download Pull Requests Artifacts for Testing](https://www.orcaslicer.com/wiki/how_to_download_pr_artifacts)
2026-09-27 02:41:17 +00:00 · 2026-09-22 16:57:55 +08:00
parent 811b587eb0 57b3a040e2
commit 323cd3afe1
3 changed files with 244 additions and 98 deletions
@@ -13,6 +13,7 @@ add_executable(${_TEST_NAME}_tests
    test_plugin_capabilities_in_use.cpp
    test_plugin_install.cpp
    test_plugin_lifecycle.cpp
+    test_plugin_printer_agent.cpp
    test_slicing_pipeline_bindings.cpp
    test_slicing_pipeline_config.cpp
    test_plugin_sort.cpp
@@ -0,0 +1,161 @@
+#include <catch2/catch_all.hpp>
+
+#include <slic3r/plugin/PluginManager.hpp>
+#include <slic3r/plugin/PythonInterpreter.hpp>
+#include <slic3r/plugin/PythonPluginBridge.hpp>
+#include <slic3r/plugin/PythonPluginInterface.hpp>
+#include <slic3r/Utils/IPrinterAgent.hpp>
+
+#include <pybind11/embed.h>
+#include <pybind11/pybind11.h>
+
+#include <memory>
+#include <string>
+
+namespace py = pybind11;
+using namespace Slic3r;
+
+namespace {
+
+// Same idiom as ScopedPluginManager in test_plugin_lifecycle.cpp: the trampolines refuse to call
+// into Python unless PythonInterpreter::instance() reports initialized.
+struct ScopedPluginManager
+{
+    bool initialized = PluginManager::instance().initialize();
+
+    ~ScopedPluginManager()
+    {
+        PluginManager::instance().shutdown();
+        PythonInterpreter::instance().shutdown();
+    }
+};
+
+// The host reaches a printer agent plugin through IPrinterAgent, so the tests do too. The Python
+// instance carries the overrides, so it has to outlive every call, as PluginInstanceHandle ensures
+// in production.
+struct Agent
+{
+    py::object                     instance;
+    std::shared_ptr<IPrinterAgent> agent;
+
+    IPrinterAgent* operator->() const { return agent.get(); }
+    IPrinterAgent& operator*() const { return *agent; }
+};
+
+Agent make_agent(const std::string& body)
+{
+    (void) PythonPluginBridge::instance(); // force the embedded module registration into the binary
+    py::dict globals;
+    globals["orca"] = py::module_::import("orca");
+
+    py::exec("class Agent(orca.printer_agent.PrinterAgentBase):\n"
+             "    def get_name(self): return 'agent'\n" + body, globals);
+    py::object instance   = globals["Agent"]();
+    auto       capability = instance.cast<std::shared_ptr<PluginCapabilityInterface>>();
+    capability->set_audit_plugin_key("agent_plugin");
+    return {instance, std::dynamic_pointer_cast<IPrinterAgent>(capability)};
+}
+
+// One operation per return type and dispatch shape; the rest share their macro.
+const std::string OPERATIONS[] = {"get_agent_info", "disconnect_printer", "start_discovery", "get_user_selected_machine",
+                                  "get_filament_sync_mode", "install_device_cert", "start_local_print", "request_bind_ticket"};
+
+// What NetworkAgent answers when no printer agent is set.
+void check_answers_like_no_agent(IPrinterAgent& agent)
+{
+    std::string ticket = "untouched";
+
+    CHECK(agent.get_agent_info().id.empty());
+    CHECK(agent.disconnect_printer() == -1);
+    CHECK_FALSE(agent.start_discovery(true, false));
+    CHECK(agent.get_user_selected_machine().empty());
+    CHECK(agent.get_filament_sync_mode() == FilamentSyncMode::none);
+    CHECK_NOTHROW(agent.install_device_cert("dev", true));
+    CHECK(agent.start_local_print(PrintParams{}, nullptr, nullptr) == -1);
+    CHECK(agent.request_bind_ticket(&ticket) == -1);
+    CHECK(ticket == "untouched");
+}
+
+std::string define_all(const std::string& signature_tail, const std::string& statement)
+{
+    std::string body;
+    for (const std::string& operation : OPERATIONS)
+        body += "    def " + operation + "(self" + signature_tail + "): " + statement + "\n";
+    return body;
+}
+
+} // namespace
+
+TEST_CASE("A printer agent operation that raises answers like a missing agent", "[PluginPrinterAgent][Python]")
+{
+    ScopedPluginManager plugin_system; // declared first: destroyed last
+    if (!plugin_system.initialized)
+        SKIP("Bundled Python interpreter unavailable: " + PythonInterpreter::instance().last_error());
+    py::gil_scoped_acquire gil; // released before plugin_system's destructor shuts Python down
+
+    auto agent = make_agent(define_all(", *args", "raise RuntimeError('boom')"));
+    REQUIRE(agent.agent);
+
+    check_answers_like_no_agent(*agent);
+
+    // The interpreter stays usable.
+    CHECK(py::eval("1 + 1").cast<int>() == 2);
+}
+
+TEST_CASE("A printer agent that omits its operations answers like a missing agent", "[PluginPrinterAgent][Python]")
+{
+    ScopedPluginManager plugin_system;
+    if (!plugin_system.initialized)
+        SKIP("Bundled Python interpreter unavailable: " + PythonInterpreter::instance().last_error());
+    py::gil_scoped_acquire gil;
+
+    auto agent = make_agent("");
+    REQUIRE(agent.agent);
+
+    check_answers_like_no_agent(*agent);
+}
+
+TEST_CASE("A printer agent operation returning the wrong type answers like a missing agent", "[PluginPrinterAgent][Python]")
+{
+    ScopedPluginManager plugin_system;
+    if (!plugin_system.initialized)
+        SKIP("Bundled Python interpreter unavailable: " + PythonInterpreter::instance().last_error());
+    py::gil_scoped_acquire gil;
+
+    auto agent = make_agent(define_all(", *args", "return object()"));
+    REQUIRE(agent.agent);
+
+    check_answers_like_no_agent(*agent);
+}
+
+TEST_CASE("A working printer agent's answers reach the host unchanged", "[PluginPrinterAgent][Python]")
+{
+    ScopedPluginManager plugin_system;
+    if (!plugin_system.initialized)
+        SKIP("Bundled Python interpreter unavailable: " + PythonInterpreter::instance().last_error());
+    py::gil_scoped_acquire gil;
+
+    auto agent = make_agent("    def get_agent_info(self): return orca.printer_agent.AgentInfo('id', 'name', '1', 'description')\n"
+                            "    def disconnect_printer(self): return 7\n"
+                            "    def start_discovery(self, start, sending): return start and not sending\n"
+                            "    def get_user_selected_machine(self): return 'machine'\n"
+                            "    def get_filament_sync_mode(self): return orca.printer_agent.FilamentSyncMode.Pull\n"
+                            "    def request_bind_ticket(self): return (3, 'ticket')\n"
+                            "    def bind_detect(self, dev_ip, sec_link, detect):\n"
+                            "        detect.dev_id = dev_ip\n"
+                            "        return 0\n");
+    REQUIRE(agent.agent);
+
+    std::string  ticket;
+    detectResult detect;
+
+    CHECK(agent->get_agent_info().id == "id");
+    CHECK(agent->disconnect_printer() == 7);
+    CHECK(agent->start_discovery(true, false));
+    CHECK(agent->get_user_selected_machine() == "machine");
+    CHECK(agent->get_filament_sync_mode() == FilamentSyncMode::pull);
+    CHECK(agent->request_bind_ticket(&ticket) == 3);
+    CHECK(ticket == "ticket");
+    CHECK(agent->bind_detect("192.168.0.2", "secure", detect) == 0);
+    CHECK(detect.dev_id == "192.168.0.2");
+}