按源保护 PythonPlugin inittab 初始化边界

core/wasm_shims/pythonplugin/python_plugin.cc

@@ -113,10 +113,27 @@ int check_python_path_entries(const char *iniFilename,
 
 } // namespace
 
-PythonPlugin *PythonPlugin::instantiate(struct _inittab *) {
+PythonPlugin *PythonPlugin::instantiate(struct _inittab *inittab) {
     static PythonPlugin plugin;
-    python_plugin = &plugin;
-    python_plugin->status = PLUGIN_OK;
+    if (!python_plugin) {
+        python_plugin = &plugin;
+        python_plugin->status = PLUGIN_OK;
+        if (inittab) {
+            for (int i = 0; inittab[i].name != nullptr; ++i) {
+                // LinuxCNC source basis: python_plugin.cc reports
+                // PLUGIN_INITTAB_FAILED when a built-in module from the
+                // _inittab cannot be initialized.
+                if (!inittab[i].initfunc || inittab[i].initfunc() == nullptr) {
+                    python_plugin->error_msg = "failed to initialize built-in module";
+                    python_plugin->status = PLUGIN_INITTAB_FAILED;
+                    break;
+                }
+            }
+        }
+    }
+    if (!python_plugin->usable()) {
+        return nullptr;
+    }
     return python_plugin;
 }
 

core/wasm_shims/pythonplugin/python_plugin_inittab_probe_main.cc

@@ -0,0 +1,39 @@
+#include "pythonplugin/python_plugin.hh"
+
+namespace {
+
+PyObject *init_bad_module() {
+    return nullptr;
+}
+
+} // namespace
+
+// LinuxCNC source basis: src/emc/pythonplugin/python_plugin.cc
+// PythonPlugin::PythonPlugin(struct _inittab*) reports PLUGIN_INITTAB_FAILED
+// when a built-in Python module from the first caller's inittab cannot be
+// initialized; instantiate() then returns nullptr for the unusable plugin.
+int main() {
+    _inittab bad_modules[] = {
+        {"cnc_sim_bad_module", init_bad_module},
+        {nullptr, nullptr},
+    };
+
+    PythonPlugin *plugin = PythonPlugin::instantiate(bad_modules);
+    if (plugin != nullptr) {
+        return 1;
+    }
+    if (python_plugin == nullptr) {
+        return 2;
+    }
+    if (python_plugin->plugin_status() != PLUGIN_INITTAB_FAILED) {
+        return 3;
+    }
+    if (python_plugin->usable()) {
+        return 4;
+    }
+    if (python_plugin->last_errmsg() != "failed to initialize built-in module") {
+        return 5;
+    }
+
+    return 0;
+}