From 105103332422ca78b26af062c6aaff9d640d6eee Mon Sep 17 00:00:00 2001
From: Adriaan de Groot <groot@kde.org>
Date: Tue, 7 Nov 2023 21:33:18 +0100
Subject: [PATCH] libcalamares: create Python module libcalamares by hand

From inside Calamares, register libcalamares to the
interpreter by hand; from external Python processes
the regular extension library hooks are called.

Tested by running ./build/localmodule dummypython
(which means that the shared library is not present
in the current directory, so then `import libcalamares`
fails if the module is not already registered --
a test scenario that previous attempt at module
import missed).
---
 src/libcalamares/python/PythonJob.cpp | 36 ++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/libcalamares/python/PythonJob.cpp b/src/libcalamares/python/PythonJob.cpp
index 4f00ca7fe..6c3a79c4a 100644
--- a/src/libcalamares/python/PythonJob.cpp
+++ b/src/libcalamares/python/PythonJob.cpp
@@ -22,6 +22,9 @@
 
 namespace py = pybind11;
 
+// Forward-declare function generated by PYBIND11_MODULE
+static void pybind11_init_libcalamares( ::pybind11::module_& variable );
+
 namespace
 {
 
@@ -242,7 +245,38 @@ Job::exec()
     // Import, but do not keep the handle lying around
     try
     {
-        auto calamaresModule = py::module_::import( "libcalamares" );
+        // import() only works if the library can be found through
+        // normal Python import mechanisms -- and after installation,
+        // libcalamares can not be found. An alternative, like using
+        // PYBIND11_EMBEDDED_MODULE, falls foul of not being able
+        // to `import libcalamares` from external Python scripts,
+        // which are used in tests.
+        //
+        //      auto calamaresModule = py::module_::import( "libcalamares" );
+        //
+        // Using the constructor directly generates compiler warnings
+        // because this is deprecated.
+        //
+        //      auto calamaresModule = py::module_("libcalamares");
+        //
+        // So create it by hand, using code cribbed from pybind11/embed.h
+        // to register an extension module. This does not make it
+        // available to the current interpreter.
+        //
+        static ::pybind11::module_::module_def libcalamares_def;
+        auto calamaresModule = py::module_::create_extension_module( "libcalamares", nullptr, &libcalamares_def );
+        pybind11_init_libcalamares( calamaresModule );
+
+        // Add libcalamares to the main namespace (as if it has already
+        // been imported) and also to sys.modules under its own name.
+        // Now `import libcalamares` in modules will find the already-
+        // loaded module.
+        auto scope = py::module_::import( "__main__" ).attr( "__dict__" );
+        scope["libcalamares"] = calamaresModule;
+
+        auto sys = scope["sys"].attr("modules");
+        sys["libcalamares"] = calamaresModule;
+
         calamaresModule.attr( "job" ) = Calamares::Python::JobProxy( this );
         calamaresModule.attr( "globalstorage" )
             = Calamares::Python::GlobalStorageProxy( JobQueue::instance()->globalStorage() );