Start adding a more useful python module around libpacemaker

python/pacemaker/Makefile.am

@@ -1,5 +1,5 @@
 #
-# Copyright 2023-2024 the Pacemaker project contributors
+# Copyright 2023-2025 the Pacemaker project contributors
 #
 # The version control history for this file may have further details.
 #
@@ -9,6 +9,13 @@
 
 include $(top_srcdir)/mk/common.mk
 
+pyexec_LTLIBRARIES = _pcmksupport.la
+
+_pcmksupport_la_SOURCES = pcmksupport.c
+_pcmksupport_la_CPPFLAGS = $(PYTHON_CFLAGS)
+_pcmksupport_la_LDFLAGS = $(AM_LDFLAGS) -module -avoid-version -export-symbols-regex PyInit__pcmksupport
+_pcmksupport_la_LIBADD = $(top_builddir)/lib/pacemaker/libpacemaker.la
+
 pkgpython_PYTHON = __init__.py 		\
 		   _library.py 		\
 		   exitstatus.py

python/pacemaker/pcmksupport.c

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2025 the Pacemaker project contributors
+ *
+ * The version control history for this file may have further details.
+ *
+ * This source code is licensed under the GNU Lesser General Public License
+ * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
+ */
+
+#include <Python.h>
+#include <libxml/tree.h>
+
+#include <pacemaker.h>
+
+/* This file defines a c-based low level module that wraps libpacemaker
+ * functions and returns python objects.  This is necessary because most
+ * libpacemaker functions return an xmlNode **, which needs to be coerced
+ * through the PyCapsule type into something that libxml2's python
+ * bindings can work with.
+ */
+
+/* Base exception class for any errors in the _pcmksupport module */
+static PyObject *PacemakerError;
+
+PyMODINIT_FUNC PyInit__pcmksupport(void);
+
+static PyObject *
+py_list_standards(PyObject *self, PyObject *args)
+{
+    int rc;
+    xmlNodePtr xml = NULL;
+
+    if (!PyArg_ParseTuple(args, "")) {
+        return NULL;
+    }
+
+    rc = pcmk_list_standards(&xml);
+    if (rc != pcmk_rc_ok) {
+        PyErr_SetString(PacemakerError, pcmk_rc_str(rc));
+        return NULL;
+    }
+
+    return PyCapsule_New(xml, "xmlNodePtr", NULL);
+}
+
+static PyMethodDef pcmksupportMethods[] = {
+    { "list_standards", py_list_standards, METH_VARARGS, NULL },
+    { NULL, NULL, 0, NULL }
+};
+
+static struct PyModuleDef moduledef = {
+    PyModuleDef_HEAD_INIT,
+    "_pcmksupport",
+    NULL,
+    -1,
+    pcmksupportMethods,
+    NULL,
+    NULL,
+    NULL,
+    NULL
+};
+
+PyMODINIT_FUNC
+PyInit__pcmksupport(void)
+{
+    PyObject *module = PyModule_Create(&moduledef);
+
+    if (module == NULL) {
+        return NULL;
+    }
+
+    /* Add the base exception to the module */
+    PacemakerError = PyErr_NewException("_pcmksupport.PacemakerError", NULL, NULL);
+
+    /* FIXME: When we can support Python >= 3.10, we can use PyModule_AddObjectRef */
+    if (PyModule_AddObject(module, "PacemakerError", PacemakerError) < 0) {
+        Py_XDECREF(PacemakerError);
+        return NULL;
+    }
+
+    return module;
+}