/src/scripting/python/core.c

  1/* Python scripting engine */
  2
  3#ifdef HAVE_CONFIG_H
  4#include "config.h"
  5#endif
  6
  7#include <Python.h>
  8#include <osdefs.h>
  9
 10#include <stdlib.h>
 11
 12#include "elinks.h"
 13
 14#include "config/home.h"
 15#include "main/module.h"
 16#include "scripting/python/core.h"
 17#include "scripting/python/dialogs.h"
 18#include "scripting/python/document.h"
 19#include "scripting/python/keybinding.h"
 20#include "scripting/python/load.h"
 21#include "scripting/python/menu.h"
 22#include "scripting/python/open.h"
 23#include "scripting/python/python.h"
 24#include "scripting/scripting.h"
 25#include "session/session.h"
 26#include "util/env.h"
 27#include "util/string.h"
 28
 29struct session *python_ses = NULL;
 30
 31PyObject *python_elinks_err = NULL;
 32PyObject *python_hooks = NULL;
 33
 34/* Error reporting. */
 35
 36void
 37alert_python_error(void)
 38{
 39	unsigned char *msg = "(no traceback available)";
 40	PyObject *err_type = NULL, *err_value = NULL, *err_traceback = NULL;
 41	PyObject *tb_module = NULL;
 42	PyObject *msg_list = NULL;
 43	PyObject *empty_string = NULL;
 44	PyObject *msg_string = NULL;
 45	unsigned char *temp;
 46
 47	/*
 48	 * Retrieve the current error indicator and use the format_exception()
 49	 * function in Python's traceback module to produce an informative
 50	 * error message. It returns a list of Python string objects.
 51	 */
 52	PyErr_Fetch(&err_type, &err_value, &err_traceback);
 53	PyErr_NormalizeException(&err_type, &err_value, &err_traceback);
 54	if (!err_type) goto end;
 55
 56	tb_module = PyImport_ImportModule("traceback");
 57	if (!tb_module) goto end;
 58
 59	msg_list = PyObject_CallMethod(tb_module, "format_exception", "OOO",
 60				       err_type,
 61				       err_value ? err_value : Py_None,
 62				       err_traceback ? err_traceback : Py_None);
 63	if (!msg_list) goto end;
 64
 65	/*
 66	 * Use the join() method of an empty Python string to join the list
 67	 * of strings into one Python string containing the entire error
 68	 * message. Then get the contents of the Python string.
 69	 */
 70	empty_string = PyString_FromString("");
 71	if (!empty_string) goto end;
 72
 73	msg_string = PyObject_CallMethod(empty_string, "join", "O", msg_list);
 74	if (!msg_string) goto end;
 75
 76	temp = (unsigned char *) PyString_AsString(msg_string);
 77	if (temp) msg = temp;
 78
 79end:
 80	report_scripting_error(&python_scripting_module, python_ses, msg);
 81
 82	Py_XDECREF(err_type);
 83	Py_XDECREF(err_value);
 84	Py_XDECREF(err_traceback);
 85	Py_XDECREF(tb_module);
 86	Py_XDECREF(msg_list);
 87	Py_XDECREF(empty_string);
 88	Py_XDECREF(msg_string);
 89
 90	/* In case another error occurred while reporting the original error: */
 91	PyErr_Clear();
 92}
 93
 94/* Prepend ELinks directories to Python's search path. */
 95
 96static int
 97set_python_search_path(void)
 98{
 99	struct string new_python_path;
100	unsigned char *old_python_path;
101	int result = -1;
102
103	if (!init_string(&new_python_path)) return result;
104
105	if (elinks_home && !add_format_to_string(&new_python_path, "%s%c",
106						 elinks_home, DELIM))
107		goto end;
108
109	if (!add_to_string(&new_python_path, CONFDIR))
110		goto end;
111
112	old_python_path = (unsigned char *) getenv("PYTHONPATH");
113	if (old_python_path && !add_format_to_string(&new_python_path, "%c%s",
114						     DELIM, old_python_path))
115		goto end;
116
117	result = env_set("PYTHONPATH", new_python_path.source, -1);
118
119end:
120	done_string(&new_python_path);
121	return result;
122}
123
124/* Determine whether or not a user-supplied hooks module exists. */
125
126static int
127hooks_module_exists(void)
128{
129	PyObject *imp_module = NULL, *result = NULL;
130	int found_hooks = 0;
131
132	/*
133	 * Use the find_module() function in Python's imp module to look for
134	 * the hooks module in Python's search path. An ImportError exception
135	 * indicates that no such module was found; any other exception will
136	 * be reported as an error.
137	 */
138	imp_module = PyImport_ImportModule("imp");
139	if (!imp_module) goto python_error;
140
141	result = PyObject_CallMethod(imp_module, "find_module", "s", "hooks");
142	if (result) {
143		found_hooks = 1;
144		goto end;
145	} else if (PyErr_ExceptionMatches(PyExc_ImportError)) {
146		PyErr_Clear();
147		goto end;
148	}
149
150python_error:
151	alert_python_error();
152
153end:
154	Py_XDECREF(imp_module);
155	Py_XDECREF(result);
156	return found_hooks;
157}
158
159/* Module-level documentation for the Python interpreter's elinks module. */
160
161static char module_doc[] =
162PYTHON_DOCSTRING("Interface to the ELinks web browser.\n\
163\n\
164Functions:\n\
165\n\
166bind_key() -- Bind a keystroke to a callable object.\n\
167current_document() -- Return the body of the document being viewed.\n\
168current_header() -- Return the header of the document being viewed.\n\
169current_link_url() -- Return the URL of the currently selected link.\n\
170current_title() -- Return the title of the document being viewed.\n\
171current_url() -- Return the URL of the document being viewed.\n\
172info_box() -- Display information to the user.\n\
173input_box() -- Prompt for user input.\n\
174load() -- Load a document into the ELinks cache.\n\
175menu() -- Display a menu.\n\
176open() -- View a document.\n\
177\n\
178Exception classes:\n\
179\n\
180error -- Errors internal to ELinks.\n\
181\n\
182Other public objects:\n\
183\n\
184home -- A string containing the pathname of the ~/.elinks directory, or\n\
185        None if ELinks has no configuration directory.\n");
186
187void
188init_python(struct module *module)
189{
190	PyObject *elinks_module, *module_dict, *module_name;
191
192	if (set_python_search_path() != 0) return;
193
194	/* Treat warnings as errors so they can be caught and handled;
195	 * otherwise they would be printed to stderr.
196	 *
197	 * NOTE: PySys_ResetWarnOptions() and PySys_AddWarnOption() have been
198	 * available and stable for many years but they're not officially
199	 * documented as part of Python's public API, so in theory these two
200	 * functions might no longer be available in some hypothetical future
201	 * version of Python. */
202	PySys_ResetWarnOptions();
203	PySys_AddWarnOption("error");
204
205	Py_Initialize();
206
207	if (!hooks_module_exists()) return;
208
209	elinks_module = Py_InitModule3("elinks", NULL, module_doc);
210	if (!elinks_module) goto python_error;
211
212	/* If @elinks_home is NULL, Py_BuildValue() returns a None reference. */
213	if (PyModule_AddObject(elinks_module, "home",
214			       Py_BuildValue("s", elinks_home)) != 0)
215		goto python_error;
216
217	python_elinks_err = PyErr_NewException("elinks.error", NULL, NULL);
218	if (!python_elinks_err) goto python_error;
219
220	if (PyModule_AddObject(elinks_module, "error", python_elinks_err) != 0)
221		goto python_error;
222
223	module_dict = PyModule_GetDict(elinks_module);
224	if (!module_dict) goto python_error;
225	module_name = PyString_FromString("elinks");
226	if (!module_name) goto python_error;
227
228	if (python_init_dialogs_interface(module_dict, module_name) != 0
229	    || python_init_document_interface(module_dict, module_name) != 0
230	    || python_init_keybinding_interface(module_dict, module_name) != 0
231	    || python_init_load_interface(module_dict, module_name) != 0
232	    || python_init_menu_interface(module_dict, module_name) != 0
233	    || python_init_open_interface(module_dict, module_name) != 0)
234		goto python_error;
235
236	python_hooks = PyImport_ImportModule("hooks");
237	if (!python_hooks) goto python_error;
238
239	return;
240
241python_error:
242	alert_python_error();
243}
244
245void
246cleanup_python(struct module *module)
247{
248	if (Py_IsInitialized()) {
249		PyObject *temp;
250
251		python_done_keybinding_interface();
252
253		/* This is equivalent to Py_CLEAR(), but it works with older
254		 * versions of Python predating that macro: */
255		temp = python_hooks;
256		python_hooks = NULL;
257		Py_XDECREF(temp);
258
259		Py_Finalize();
260	}
261}
262
263/* Add methods to a Python extension module. */
264
265int
266add_python_methods(PyObject *dict, PyObject *name, PyMethodDef *methods)
267{
268	PyMethodDef *method;
269
270	for (method = methods; method && method->ml_name; method++) {
271		PyObject *function = PyCFunction_NewEx(method, NULL, name);
272		int result;
273
274		if (!function) return -1;
275		result = PyDict_SetItemString(dict, method->ml_name, function);
276		Py_DECREF(function);
277		if (result != 0) return -1;
278	}
279	return 0;
280}