Provide python bindings for the HBAC evaluator library

Fixes for python HBAC bindings

These changes were proposed during a review:
 * Change the signature of str_concat_sequence() to const char *
 * use a getsetter for HbacRule.enabled to allow string true/false and
   integer 1/0 in addition to bool
 * fix a minor memory leak (HbacRequest.rule_name)
 * remove overzealous discard consts

Fix python HBAC bindings for python <= 2.4

Several parts of the HBAC python bindings did not work with old Python
versions, such as the one shipped in RHEL5.

The changes include:
* a compatibility wrapper around python set object
* PyModule_AddIntMacro compat macro
* Py_ssize_t compat definition
* Do not use PyUnicode_FromFormat
* several function prototypes and structures used to have "char
  arguments where they have "const char *" in recent versions.
  This caused compilation warnings this patch mitigates by using
  the discard_const hack on python 2.4

Remove dead code from python HBAC bindings

https://fedorahosted.org/sssd/ticket/935

Handle allocation error in python HBAC bindings

https://fedorahosted.org/sssd/ticket/934

HBAC rule validation Python bindings

https://fedorahosted.org/sssd/ticket/943

1 files changed, 63 insertions, 0 deletions

diff --git a/src/util/sss_python.h b/src/util/sss_python.h
new file mode 100644
index 000000000..135c28771
--- /dev/null
+++ b/src/util/sss_python.h
@@ -0,0 +1,63 @@
+#ifndef __SSS_PYTHON_H__
+#define __SSS_PYTHON_H__
+
+#include <Python.h>
+#include <stdbool.h>
+#include "util/util.h"
+
+#if PY_VERSION_HEX < 0x02050000
+#define sss_py_const_p(type, value) discard_const_p(type, (value))
+#else
+#define sss_py_const_p(type, value) (value)
+#endif
+
+/* Py_ssize_t compatibility for python < 2.5 as per
+ * http://www.python.org/dev/peps/pep-0353/ */
+#ifndef HAVE_PY_SSIZE_T
+typedef int Py_ssize_t;
+#endif
+
+#ifndef PY_SSIZE_T_MAX
+#define PY_SSIZE_T_MAX INT_MAX
+#endif
+
+#ifndef PY_SSIZE_T_MIN
+#define PY_SSIZE_T_MIN INT_MIN
+#endif
+
+/* Wrappers providing the subset of C API for python's set objects we use */
+PyObject *sss_python_set_new(void);
+int sss_python_set_add(PyObject *set, PyObject *key);
+bool sss_python_set_check(PyObject *set);
+
+/* Unicode compatibility */
+PyObject *sss_python_unicode_from_string(const char *u);
+
+/* Exceptions compatibility */
+PyObject *
+sss_exception_with_doc(char *name, char *doc, PyObject *base, PyObject *dict);
+
+/* PyModule_AddIntMacro() compatibility */
+#if !HAVE_DECL_PYMODULE_ADDINTMACRO
+#define PyModule_AddIntMacro(m, c) PyModule_AddIntConstant(m, sss_py_const_p(char, #c), c)
+#endif
+
+/* Convenience macros */
+#define TYPE_READY(module, type, name) do {         \
+    if (PyType_Ready(&type) < 0)                    \
+        return;                                     \
+    Py_INCREF(&type);                               \
+    PyModule_AddObject(module,                      \
+                       discard_const_p(char, name), \
+                       (PyObject *) &type);         \
+} while(0);                                         \
+
+#define SAFE_SET(old, new) do {         \
+    PyObject *__simple_set_tmp = NULL;  \
+    __simple_set_tmp = old;             \
+    Py_INCREF(new);                     \
+    old = new;                          \
+    Py_XDECREF(__simple_set_tmp);       \
+} while(0);
+
+#endif /* __SSS_PYTHON_H__ */