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/*
* Copyright (c) 2015 Balabit
* Copyright (c) 2015 Balazs Scheidler <balazs.scheidler@balabit.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* As an additional exemption you are allowed to compile & link against the
* OpenSSL libraries as published by the OpenSSL project. See the file
* COPYING for details.
*
*/
#include "python-main.h"
#include "python-module.h"
#include "python-helpers.h"
#include "python-global-code-loader.h"
#include "cfg.h"
#include "messages.h"
/*
* Some information about how we embed the Python interpreter:
* - instead of using the __main__ module, we use a separate _syslogng
* module as we want to replace it every time syslog-ng is reloaded
* - hanlding of our separate main module is implemented by this module
* - this separate __main__ module requires some magic though (most of it
* is in _py_construct_main_module(), see below.
* - the PyObject reference to the current main module is stored in the
* GlobalConfig instance (using the ModuleConfig mechanism)
* - the current main module is switched during config initialization, e.g.
* during runtime, _syslogng module refers to the main module of the current
* config
* - since _syslogng is different for each initialized syslog-ng
* configuration, it is not possible to use variables between reloads,
* _except_ by storing them in other, imported modules.
* - it is currently not possible to hook into the init/deinit mechanism in
* the global context (from Python), but it is possible for a DestDriver.
* It is doable also in the global context, but has not yet been done.
*/
static PyObject *
_py_construct_main_module(void)
{
PyObject *module;
PyObject *module_dict;
PyObject *modules = PyImport_GetModuleDict();
/* make sure the module registry doesn't contain our module */
if (PyDict_DelItemString(modules, "_syslogng") < 0)
PyErr_Clear();
/* create a new module */
module = PyImport_AddModule("_syslogng");
if (!module)
{
gchar buf[256];
msg_error("Error creating syslog-ng main module",
evt_tag_str("exception", _py_format_exception_text(buf, sizeof(buf))));
_py_finish_exception_handling();
return NULL;
}
/* make sure __builtins__ is there, it is normally automatically done for
* __main__ and any imported modules */
module_dict = PyModule_GetDict(module);
if (PyDict_GetItemString(module_dict, "__builtins__") == NULL)
{
PyObject *builtins_module = PyImport_ImportModule(PYTHON_BUILTIN_MODULE_NAME);
if (builtins_module == NULL ||
PyDict_SetItemString(module_dict, "__builtins__", builtins_module) < 0)
g_assert_not_reached();
Py_XDECREF(builtins_module);
}
/* return a reference */
Py_INCREF(module);
return module;
}
/* switch the _syslogng main module to the one in a specific configuration */
void
_py_switch_main_module(PythonConfig *pc)
{
PyObject *modules = PyImport_GetModuleDict();
if (pc->main_module)
{
Py_INCREF(pc->main_module);
PyDict_SetItemString(modules, "_syslogng", pc->main_module);
}
else
{
PyDict_DelItemString(modules, "_syslogng");
}
}
/* get the current main module in a production context by using the Python
* module registry instead of the GlobalConfig machinery. This only works
* once _py_switch_to_main_module() has been called (e.g. past init()).
*
* returns borrowed reference. */
PyObject *
_py_get_current_main_module(void)
{
return PyImport_AddModule("_syslogng");
}
/* get the current main module as stored in the current GlobalConfig.
* returns borrowed reference */
PyObject *
_py_get_main_module(PythonConfig *pc)
{
if (!pc->main_module)
pc->main_module = _py_construct_main_module();
return pc->main_module;
}
gboolean
_py_evaluate_global_code(PythonConfig *pc, const gchar *filename, const gchar *code)
{
PyObject *module;
PyObject *dict;
PyObject *code_object;
gchar buf[256];
module = _py_get_main_module(pc);
if (!module)
return FALSE;
/* NOTE: this has become a tad more difficult than PyRun_SimpleString(),
* because we want proper backtraces originating from this module. Should
* we only use PyRun_SimpleString(), we would not get source lines in our
* backtraces.
*
* This implementation basically mimics what an import would do, compiles
* the code as it was coming from a "virtual" file and then executes the
* compiled code in the context of the _syslogng module.
*
* Since we attach a __loader__ to the module, that will be called when
* the source is needed to report backtraces. Its implementation is in
* the python-global-code-loader.c, that simply returns the source when
* its get_source() method is called.
*/
dict = PyModule_GetDict(module);
PyDict_SetItemString(dict, "__loader__", py_global_code_loader_new(code));
code_object = Py_CompileString((char *) code, filename, Py_file_input);
if (!code_object)
{
msg_error("Error compiling Python global code block",
evt_tag_str("exception", _py_format_exception_text(buf, sizeof(buf))));
_py_finish_exception_handling();
return FALSE;
}
module = PyImport_ExecCodeModuleEx("_syslogng", code_object, (char *) filename);
Py_DECREF(code_object);
if (!module)
{
msg_error("Error evaluating global Python block",
evt_tag_str("exception", _py_format_exception_text(buf, sizeof(buf))));
_py_finish_exception_handling();
return FALSE;
}
return TRUE;
}
gboolean
python_evaluate_global_code(GlobalConfig *cfg, const gchar *code, YYLTYPE *yylloc)
{
PyGILState_STATE gstate;
gchar buf[256];
PythonConfig *pc = python_config_get(cfg);
gboolean result;
gstate = PyGILState_Ensure();
g_snprintf(buf, sizeof(buf), "%s{python-global-code:%d}", cfg->filename, yylloc->first_line);
result = _py_evaluate_global_code(pc, buf, code);
PyGILState_Release(gstate);
return result;
}
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