elinks/src/scripting/python/hooks.c

/* Python scripting hooks */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <Python.h>

#include <stdarg.h>
#include <string.h>

#include "elinks.h"

#include "cache/cache.h"
#include "main/event.h"
#include "protocol/uri.h"
#include "scripting/python/core.h"
#include "session/session.h"
#include "util/memory.h"
#include "util/string.h"

extern PyObject *python_hooks;

/*
 * A utility function for script_hook_url() and script_hook_get_proxy():
 * Free a char * and replace it with the contents of a Python string.
 * (Py_None is ignored.)
 */

static PyObject *
replace_with_python_string(unsigned char **dest, PyObject *object)
{
	unsigned char *str;

	if (object == Py_None) return object;

	str = (unsigned char *) PyString_AsString(object);
	if (!str) return NULL;

	str = stracpy(str);
	if (!str) return PyErr_NoMemory();

	mem_free_set(dest, str);
	return object;
}

/* Call a Python hook for a goto-url or follow-url event. */

static enum evhook_status
script_hook_url(va_list ap, void *data)
{
	unsigned char **url = va_arg(ap, unsigned char **);
	struct session *ses = va_arg(ap, struct session *);
	char *method = data;
	struct session *saved_python_ses = python_ses;
	PyObject *result;

	evhook_use_params(url && ses);

	if (!python_hooks || !url || !*url
	    || !PyObject_HasAttrString(python_hooks, method))
		return EVENT_HOOK_STATUS_NEXT;

	python_ses = ses;

	result = PyObject_CallMethod(python_hooks, method, "s", *url);

	if (!result || !replace_with_python_string(url, result))
		alert_python_error();

	Py_XDECREF(result);

	python_ses = saved_python_ses;

	return EVENT_HOOK_STATUS_NEXT;
}

/* Call a Python hook for a pre-format-html event. */

static enum evhook_status
script_hook_pre_format_html(va_list ap, void *data)
{
	struct session *ses = va_arg(ap, struct session *);
	struct cache_entry *cached = va_arg(ap, struct cache_entry *);
	struct fragment *fragment = get_cache_fragment(cached);
	unsigned char *url = struri(cached->uri);
	char *method = "pre_format_html_hook";
	struct session *saved_python_ses = python_ses;
	PyObject *result;
	int success = 0;

	evhook_use_params(ses && cached);

	if (!python_hooks || !cached->length || !*fragment->data
	    || !PyObject_HasAttrString(python_hooks, method))
		return EVENT_HOOK_STATUS_NEXT;

	python_ses = ses;

	result = PyObject_CallMethod(python_hooks, method, "ss#", url,
				     fragment->data, fragment->length);
	if (!result) goto error;

	if (result != Py_None) {
		unsigned char *str;
		Py_ssize_t len;

		if (PyString_AsStringAndSize(result, (char **) &str, &len) != 0)
			goto error;

		/* This assumes the Py_ssize_t len is not too large to
		 * fit in the off_t parameter of normalize_cache_entry().
		 * add_fragment() itself seems to assume the same thing,
		 * and there is no standard OFF_MAX macro against which
		 * ELinks could check the value.  */
		(void) add_fragment(cached, 0, str, len);
		normalize_cache_entry(cached, len);
	}

	success = 1;

error:
	if (!success) alert_python_error();

	Py_XDECREF(result);

	python_ses = saved_python_ses;

	return EVENT_HOOK_STATUS_NEXT;
}

/* Call a Python hook for a get-proxy event. */

static enum evhook_status
script_hook_get_proxy(va_list ap, void *data)
{
	unsigned char **proxy = va_arg(ap, unsigned char **);
	unsigned char *url = va_arg(ap, unsigned char *);
	char *method = "proxy_for_hook";
	PyObject *result;

	evhook_use_params(proxy && url);

	if (!python_hooks || !proxy || !url
	    || !PyObject_HasAttrString(python_hooks, method))
		return EVENT_HOOK_STATUS_NEXT;

	result = PyObject_CallMethod(python_hooks, method, "s", url);

	if (!result || !replace_with_python_string(proxy, result))
		alert_python_error();

	Py_XDECREF(result);

	return EVENT_HOOK_STATUS_NEXT;
}

/* Call a Python hook for a quit event. */

static enum evhook_status
script_hook_quit(va_list ap, void *data)
{
	char *method = "quit_hook";
	PyObject *result;

	if (!python_hooks || !PyObject_HasAttrString(python_hooks, method))
		return EVENT_HOOK_STATUS_NEXT;

	result = PyObject_CallMethod(python_hooks, method, NULL);
	if (!result) alert_python_error();

	Py_XDECREF(result);

	return EVENT_HOOK_STATUS_NEXT;
}

struct event_hook_info python_scripting_hooks[] = {
	{ "goto-url", 0, script_hook_url, "goto_url_hook" },
	{ "follow-url", 0, script_hook_url, "follow_url_hook" },
	{ "pre-format-html", 0, script_hook_pre_format_html, NULL },
	{ "get-proxy", 0, script_hook_get_proxy, NULL },
	{ "quit", 0, script_hook_quit, NULL },
	NULL_EVENT_HOOK_INFO,
};