python: Add py3compat.h

This adds a shared header file with macros that enable compatibility
between Python 2 and 3.
The macros are the ones used in ldb/tdb, with some additions
that make sense when the header is shared among several modules.
See the module for a summary of contents.

Signed-off-by: Petr Viktorin <pviktori@redhat.com>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>

python/py3compat.h

@@ -0,0 +1,167 @@
+/*
+   Unix SMB/CIFS implementation.
+   Python 3 compatibility macros
+   Copyright (C) Petr Viktorin <pviktori@redhat.com> 2015
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _SAMBA_PY3COMPAT_H_
+#define _SAMBA_PY3COMPAT_H_
+#include <Python.h>
+
+/* Quick docs:
+ *
+ * The IS_PY3 preprocessor constant is 1 on Python 3, and 0 on Python 2.
+ *
+ * "PyStr_*" works like PyUnicode_* on Python 3, but uses bytestrings (str)
+ * under Python 2.
+ *
+ * "PyBytes_*" work like in Python 3; on Python 2 they are aliased to their
+ * PyString_* names.
+ *
+ * "PyInt_*" works like PyLong_*
+ *
+ * Syntax for module initialization is as in Python 3, except the entrypoint
+ * function definition and declaration:
+ *     PyMODINIT_FUNC PyInit_modulename(void);
+ *     PyMODINIT_FUNC PyInit_modulename(void)
+ *     {
+ *         ...
+ *     }
+ * is replaced by:
+ *     MODULE_INIT_FUNC(modulename)
+ *     {
+ *         ...
+ *     }
+ *
+ * In the entrypoint, create a module using PyModule_Create and PyModuleDef,
+ * and return it. See Python 3 documentation for details.
+ * For Python 2 compatibility, always set PyModuleDef.m_size to -1.
+ *
+ */
+
+#if PY_MAJOR_VERSION >= 3
+
+/***** Python 3 *****/
+
+#define IS_PY3 1
+
+/* Strings */
+
+#define PyStr_Type PyUnicode_Type
+#define PyStr_Check PyUnicode_Check
+#define PyStr_CheckExact PyUnicode_CheckExact
+#define PyStr_FromString PyUnicode_FromString
+#define PyStr_FromStringAndSize PyUnicode_FromStringAndSize
+#define PyStr_FromFormat PyUnicode_FromFormat
+#define PyStr_FromFormatV PyUnicode_FromFormatV
+#define PyStr_AsString PyUnicode_AsUTF8
+#define PyStr_Concat PyUnicode_Concat
+#define PyStr_Format PyUnicode_Format
+#define PyStr_InternInPlace PyUnicode_InternInPlace
+#define PyStr_InternFromString PyUnicode_InternFromString
+#define PyStr_Decode PyUnicode_Decode
+
+#define PyStr_AsUTF8String PyUnicode_AsUTF8String // returns PyBytes
+#define PyStr_AsUTF8 PyUnicode_AsUTF8
+#define PyStr_AsUTF8AndSize PyUnicode_AsUTF8AndSize
+
+/* Ints */
+
+#define PyInt_Type PyLong_Type
+#define PyInt_Check PyLong_Check
+#define PyInt_CheckExact PyLong_CheckExact
+#define PyInt_FromString PyLong_FromString
+#define PyInt_FromLong PyLong_FromLong
+#define PyInt_FromSsize_t PyLong_FromSsize_t
+#define PyInt_FromSize_t PyLong_FromSize_t
+#define PyInt_AsLong PyLong_AsLong
+#define PyInt_AS_LONG PyLong_AS_LONG
+#define PyInt_AsUnsignedLongLongMask PyLong_AsUnsignedLongLongMask
+#define PyInt_AsSsize_t PyLong_AsSsize_t
+
+/* Module init */
+
+#define MODULE_INIT_FUNC(name) \
+    PyMODINIT_FUNC PyInit_ ## name(void); \
+    PyMODINIT_FUNC PyInit_ ## name(void)
+
+#else
+
+/***** Python 2 *****/
+
+#define IS_PY3 0
+
+/* Strings */
+
+#define PyStr_Type PyString_Type
+#define PyStr_Check PyString_Check
+#define PyStr_CheckExact PyString_CheckExact
+#define PyStr_FromString PyString_FromString
+#define PyStr_FromStringAndSize PyString_FromStringAndSize
+#define PyStr_FromFormat PyString_FromFormat
+#define PyStr_FromFormatV PyString_FromFormatV
+#define PyStr_AsString PyString_AsString
+#define PyStr_Format PyString_Format
+#define PyStr_InternInPlace PyString_InternInPlace
+#define PyStr_InternFromString PyString_InternFromString
+#define PyStr_Decode PyString_Decode
+
+#define PyStr_AsUTF8String(str) (Py_INCREF(str), (str))
+#define PyStr_AsUTF8 PyString_AsString
+#define PyStr_AsUTF8AndSize(pystr, sizeptr) \
+    ((*sizeptr=PyString_Size(pystr)), PyString_AsString(pystr))
+
+#define PyBytes_Type PyString_Type
+#define PyBytes_Check PyString_Check
+#define PyBytes_CheckExact PyString_CheckExact
+#define PyBytes_FromString PyString_FromString
+#define PyBytes_FromStringAndSize PyString_FromStringAndSize
+#define PyBytes_FromFormat PyString_FromFormat
+#define PyBytes_FromFormatV PyString_FromFormatV
+#define PyBytes_Size PyString_Size
+#define PyBytes_GET_SIZE PyString_GET_SIZE
+#define PyBytes_AsString PyString_AsString
+#define PyBytes_AS_STRING PyString_AS_STRING
+#define PyBytes_AsStringAndSize PyString_AsStringAndSize
+#define PyBytes_Concat PyString_Concat
+#define PyBytes_ConcatAndDel PyString_ConcatAndDel
+#define _PyBytes_Resize _PyString_Resize
+
+/* Module init */
+
+#define PyModuleDef_HEAD_INIT 0
+
+typedef struct PyModuleDef {
+    int m_base;
+    const char* m_name;
+    const char* m_doc;
+    Py_ssize_t m_size;
+    PyMethodDef *m_methods;
+} PyModuleDef;
+
+#define PyModule_Create(def) \
+    Py_InitModule3((def)->m_name, (def)->m_methods, (def)->m_doc)
+
+#define MODULE_INIT_FUNC(name) \
+    static PyObject *PyInit_ ## name(void); \
+    void init ## name(void); \
+    void init ## name(void) { PyInit_ ## name(); } \
+    static PyObject *PyInit_ ## name(void)
+
+
+#endif
+
+#endif