Fixes to the Python scripting by M. Levinson

AUTHORS

@@ -331,6 +331,9 @@ Len Lattanzi <Len_Lattanzi@StanfordAlumni.org>
 M. K. Srikant <srix@vsnl.com>
 	Small fix in forms
 
+M. Levinson <levinsm@users.sourceforge.net>
+	Python scripting fixes
+
 Marco Bodrato <bodrato@linuz.sns.it>
 	Twinterm support
 

contrib/python/README.Python

@@ -1,13 +1,8 @@
-If you want to use Python scripting with ELinks add
---with-python to the configure invocation copy hooks.py to ~/.elinks
-When your Python installation is your own build, you could give prefix
-to the configure, eg.
---with-python=/usr/local when Python binary is placed in /usr/local/bin, etc.
+If you want to use Python scripting with ELinks, add --with-python to the
+configure invocation and copy hooks.py to your ~/.elinks directory.
 
-When 'configure' cannot find -lpython make symbolic link to the appropriate
-library, eg.
-# cd /usr/local/lib
-# ln -s libpython2.4.so.1.0 libpython.so
+If configure cannot find Python you can supply a path, e.g.
+--with-python=/usr/local/bin if your Python binary is in /usr/local/bin, etc.
 
 For the present hooks.py is not very usable. You are welcome to make it better.
 Good Luck!

src/scripting/python/core.c

@@ -4,7 +4,6 @@
 #include "config.h"
 #endif
 
-#include "scripting/python/core.h"
 #include <Python.h>
 
 #include <stdio.h>
@@ -14,24 +13,91 @@
 
 #include "config/home.h"
 #include "main/module.h"
+#include "scripting/scripting.h"
+#include "scripting/python/core.h"
+#include "scripting/python/python.h"
 #include "util/env.h"
 #include "util/file.h"
 #include "util/string.h"
 
 
-PyObject *pDict, *pModule;
+PyObject *pDict = NULL, *pModule = NULL;
+
+/* Error reporting. */
+
+void
+alert_python_error(struct session *ses)
+{
+	unsigned char *msg = "(no traceback available)";
+	PyObject *err_type = NULL, *err_value = NULL, *err_traceback = NULL;
+	PyObject *tb_module = NULL;
+	PyObject *tb_dict;
+	PyObject *format_function;
+	PyObject *msg_list = NULL;
+	PyObject *empty_string = NULL;
+	PyObject *join_method = NULL;
+	PyObject *msg_string = NULL;
+	unsigned char *temp;
+
+	/*
+	 * Retrieve the current error indicator and use the format_exception()
+	 * function in Python's traceback module to produce an informative
+	 * error message. It returns a list of Python string objects.
+	 */
+	PyErr_Fetch(&err_type, &err_value, &err_traceback);
+	PyErr_NormalizeException(&err_type, &err_value, &err_traceback);
+	if (!err_traceback) goto end;
+
+	tb_module = PyImport_ImportModule("traceback");
+	if (!tb_module) goto end;
+
+	tb_dict = PyModule_GetDict(tb_module);
+	format_function = PyDict_GetItemString(tb_dict, "format_exception");
+	if (!format_function || !PyCallable_Check(format_function)) goto end;
+
+	msg_list = PyObject_CallFunction(format_function, "OOO",
+					 err_type, err_value, err_traceback);
+	if (!msg_list) goto end;
+
+	/*
+	 * Use the join() method of an empty Python string to join the list
+	 * of strings into one Python string containing the entire error
+	 * message. Then get the contents of the Python string.
+	 */
+	empty_string = PyString_FromString("");
+	if (!empty_string) goto end;
+
+	join_method = PyObject_GetAttrString(empty_string, "join");
+	if (!join_method || !PyCallable_Check(join_method)) goto end;
+
+	msg_string = PyObject_CallFunction(join_method, "O", msg_list);
+	if (!msg_string) goto end;
+
+	temp = (unsigned char *)PyString_AsString(msg_string);
+	if (temp) msg = temp;
+
+end:
+	report_scripting_error(&python_scripting_module, ses, msg);
+
+	Py_XDECREF(err_type);
+	Py_XDECREF(err_value);
+	Py_XDECREF(err_traceback);
+	Py_XDECREF(tb_module);
+	Py_XDECREF(msg_list);
+	Py_XDECREF(empty_string);
+	Py_XDECREF(join_method);
+	Py_XDECREF(msg_string);
+
+	/* In case another error occurred while reporting the original error: */
+	PyErr_Clear();
+}
 
 void
 cleanup_python(struct module *module)
 {
 	if (Py_IsInitialized()) {
-		if (pModule) {
-			Py_DECREF(pModule);
-		}
-		if (PyErr_Occurred()) {
-			PyErr_Print();
-			PyErr_Clear();
-		}
+		Py_XDECREF(pDict);
+		Py_XDECREF(pModule);
 		Py_Finalize();
 	}
 }
@@ -44,15 +110,25 @@ init_python(struct module *module)
 	if (!python_path) return;
 	env_set("PYTHONPATH", python_path, -1);
 	mem_free(python_path);
+
+	/* Treat warnings as errors so they can be caught and handled;
+	 * otherwise they would be printed to stderr.
+	 *
+	 * NOTE: PySys_ResetWarnOptions() and PySys_AddWarnOption() have been
+	 * available and stable for many years but they're not officially
+	 * documented as part of Python's public API, so in theory these two
+	 * functions might no longer be available in some hypothetical future
+	 * version of Python. */
+	PySys_ResetWarnOptions();
+	PySys_AddWarnOption("error");
+
 	Py_Initialize();
 	pModule = PyImport_ImportModule("hooks");
 
 	if (pModule) {
 		pDict = PyModule_GetDict(pModule);
+		Py_INCREF(pDict);
 	} else {
-		if (PyErr_Occurred()) {
-			PyErr_Print();
-			PyErr_Clear();
-		}
+		alert_python_error(NULL);
 	}
 }

src/scripting/python/core.h

@@ -3,7 +3,9 @@
 #define EL__SCRIPTING_PYTHON_CORE_H
 
 struct module;
+struct session;
 
+void alert_python_error(struct session *ses);
 void init_python(struct module *module);
 void cleanup_python(struct module *module);
 

src/scripting/python/hooks.c

@@ -32,29 +32,29 @@ do_script_hook_goto_url(struct session *ses, unsigned char **url)
 
 	if (pFunc && PyCallable_Check(pFunc)) {
 		PyObject *pValue;
-		unsigned char *str;
+		unsigned char *current_url;
 
 		if (!ses || !have_location(ses)) {
-			str = NULL;
+			current_url = NULL;
 		} else {
-			str = struri(cur_loc(ses)->vs.uri);
+			current_url = struri(cur_loc(ses)->vs.uri);
 		}
 
-		pValue = PyObject_CallFunction(pFunc, "ss", *url, str);
-		if (pValue && (pValue != Py_None)) {
-			const unsigned char *res = PyString_AsString(pValue);
-
-			if (res) {
-				unsigned char *new_url = stracpy((unsigned char *)res);
+		pValue = PyObject_CallFunction(pFunc, "ss", *url, current_url);
+		if (pValue) {
+			if (pValue != Py_None) {
+				const unsigned char *str;
+				unsigned char *new_url;
 
+				str = PyString_AsString(pValue);
+				if (str) {
+					new_url = stracpy((unsigned char *)str);
 					if (new_url) mem_free_set(url, new_url);
 				}
+			}
 			Py_DECREF(pValue);
 		} else {
-			if (PyErr_Occurred()) {
-				PyErr_Print();
-				PyErr_Clear();
-			}
+			alert_python_error(ses);
 		}
 	}
 }
@@ -72,26 +72,26 @@ script_hook_goto_url(va_list ap, void *data)
 }
 
 static void
-do_script_hook_follow_url(unsigned char **url)
+do_script_hook_follow_url(struct session *ses, unsigned char **url)
 {
 	PyObject *pFunc = PyDict_GetItemString(pDict, "follow_url_hook");
 
 	if (pFunc && PyCallable_Check(pFunc)) {
 		PyObject *pValue = PyObject_CallFunction(pFunc, "s", *url);
-		if (pValue && (pValue != Py_None)) {
-			const unsigned char *str = PyString_AsString(pValue);
+		if (pValue) {
+			if (pValue != Py_None) {
+				const unsigned char *str;
 				unsigned char *new_url;
 
+				str = PyString_AsString(pValue);
 				if (str) {
 					new_url = stracpy((unsigned char *)str);
 					if (new_url) mem_free_set(url, new_url);
 				}
+			}
 			Py_DECREF(pValue);
 		} else {
-			if (PyErr_Occurred()) {
-				PyErr_Print();
-				PyErr_Clear();
-			}
+			alert_python_error(ses);
 		}
 	}
 }
@@ -100,15 +100,17 @@ static enum evhook_status
 script_hook_follow_url(va_list ap, void *data)
 {
 	unsigned char **url = va_arg(ap, unsigned char **);
+	struct session *ses = va_arg(ap, struct session *);
 
 	if (pDict && *url)
-		do_script_hook_follow_url(url);
+		do_script_hook_follow_url(ses, url);
 
 	return EVENT_HOOK_STATUS_NEXT;
 }
 
 static void
-do_script_hook_pre_format_html(unsigned char *url, struct cache_entry *cached,
+do_script_hook_pre_format_html(struct session *ses, unsigned char *url,
+			       struct cache_entry *cached,
 			       struct fragment *fragment)
 {
 	PyObject *pFunc = PyDict_GetItemString(pDict, "pre_format_html_hook");
@@ -118,21 +120,21 @@ do_script_hook_pre_format_html(unsigned char *url, struct cache_entry *cached,
 		                                         fragment->data,
 		                                         fragment->length);
 
-		if (pValue && (pValue != Py_None)) {
-			const unsigned char *str = PyString_AsString(pValue);
+		if (pValue) {
+			if (pValue != Py_None) {
+				const unsigned char *str;
+				int len;
 
+				str = PyString_AsString(pValue);
 				if (str) {
-				int len = PyString_Size(pValue); /* strlen(str); */
-
+					len = PyString_Size(pValue);
 					add_fragment(cached, 0, str, len);
 					normalize_cache_entry(cached, len);
 				}
+			}
 			Py_DECREF(pValue);
 		} else {
-			if (PyErr_Occurred()) {
-				PyErr_Print();
-				PyErr_Clear();
-			}
+			alert_python_error(ses);
 		}
 	}
 }
@@ -146,7 +148,7 @@ script_hook_pre_format_html(va_list ap, void *data)
 	unsigned char *url = struri(cached->uri);
 
 	if (pDict && ses && url && cached->length && *fragment->data)
-		do_script_hook_pre_format_html(url, cached, fragment);
+		do_script_hook_pre_format_html(ses, url, cached, fragment);
 
 	return EVENT_HOOK_STATUS_NEXT;
 }
@@ -159,20 +161,21 @@ do_script_hook_get_proxy(unsigned char **new_proxy_url, unsigned char *url)
 	if (pFunc && PyCallable_Check(pFunc)) {
 		PyObject *pValue = PyObject_CallFunction(pFunc, "s", url);
 
-		if (pValue && (pValue != Py_None)) {
-			const unsigned char *str = PyString_AsString(pValue);
+		if (pValue) {
+			if (pValue != Py_None) {
+				const unsigned char *str;
+				unsigned char *new_url;
 
+				str = PyString_AsString(pValue);
 				if (str) {
-				unsigned char *new_url = stracpy((unsigned char *)str);
-
-				if (new_url) mem_free_set(new_proxy_url, new_url);
+					new_url = stracpy((unsigned char *)str);
+					if (new_url) mem_free_set(new_proxy_url,
+								  new_url);
+				}
 			}
 			Py_DECREF(pValue);
 		} else {
-			if (PyErr_Occurred()) {
-				PyErr_Print();
-				PyErr_Clear();
-			}
+			alert_python_error(NULL);
 		}
 	}
 }
@@ -198,14 +201,9 @@ do_script_hook_quit(void)
 		PyObject *pValue = PyObject_CallFunction(pFunc, NULL);
 
 		if (pValue) {
-			if (pValue != Py_None) {
 			Py_DECREF(pValue);
-			}
 		} else {
-			if (PyErr_Occurred()) {
-				PyErr_Print();
-				PyErr_Clear();
-			}
+			alert_python_error(NULL);
 		}
 	}
 }

src/scripting/scripting.c

@@ -24,10 +24,14 @@
 #include "scripting/ruby/ruby.h"
 #include "scripting/smjs/smjs.h"
 
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 
 /* Error reporting. */
 
-#if defined(CONFIG_SCRIPTING_RUBY) || defined(CONFIG_SCRIPTING_SPIDERMONKEY)
+#if defined(CONFIG_SCRIPTING_RUBY) || defined(CONFIG_SCRIPTING_SPIDERMONKEY) || defined(CONFIG_SCRIPTING_PYTHON)
 void
 report_scripting_error(struct module *module, struct session *ses,
 		       unsigned char *msg)
@@ -38,6 +42,7 @@ report_scripting_error(struct module *module, struct session *ses,
 	if (!ses) {
 		if (list_empty(terminals)) {
 			usrerror("[%s error] %s", module->name, msg);
+			sleep(3);
 			return;
 		}