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netsurf/content/handlers/javascript/fetcher.c

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/*
* Copyright 2012 Vincent Sanders <vince@kyllikki.org>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf 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; version 2 of the License.
*
* NetSurf 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/>.
*/
/** \file
* implementation for javascript scheme fetcher
*
* This fetcher implements http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#javascript-protocol
*/
#include <stdbool.h>
#include <stdlib.h>
#include <libwapcaplet/libwapcaplet.h>
#include "utils/nsurl.h"
#include "utils/corestrings.h"
#include "utils/ring.h"
#include "content/fetch.h"
#include "content/fetchers.h"
#include "javascript/fetcher.h"
/** Context for an resource fetch */
struct fetch_javascript_context {
struct fetch_javascript_context *r_next, *r_prev;
struct fetch *fetchh; /**< Handle for this fetch */
bool aborted; /**< Flag indicating fetch has been aborted */
bool locked; /**< Flag indicating entry is already entered */
nsurl *url; /**< The URL being fetched */
};
static struct fetch_javascript_context *ring = NULL;
/** issue fetch callbacks with locking */
static inline bool fetch_javascript_send_callback(const fetch_msg *msg,
struct fetch_javascript_context *ctx)
{
ctx->locked = true;
fetch_send_callback(msg, ctx->fetchh);
ctx->locked = false;
return ctx->aborted;
}
/**
* called from poll to progress fetch.
*
* \todo This is currently completely unimplemented and just returns 204
*/
static bool fetch_javascript_handler(struct fetch_javascript_context *ctx)
{
fetch_msg msg;
int code = 204;
/* content is going to return error code */
fetch_set_http_code(ctx->fetchh, code);
msg.type = FETCH_FINISHED;
fetch_javascript_send_callback(&msg, ctx);
return true;
}
/** callback to initialise the resource fetcher. */
static bool fetch_javascript_initialise(lwc_string *scheme)
{
return true;
}
/** callback to finalise the resource fetcher. */
static void fetch_javascript_finalise(lwc_string *scheme)
{
}
static bool fetch_javascript_can_fetch(const nsurl *url)
{
return true;
}
/** callback to set up a resource fetch context. */
static void *
fetch_javascript_setup(struct fetch *fetchh,
nsurl *url,
bool only_2xx,
bool downgrade_tls,
const char *post_urlenc,
const struct fetch_multipart_data *post_multipart,
const char **headers)
{
struct fetch_javascript_context *ctx;
ctx = calloc(1, sizeof(*ctx));
if (ctx == NULL)
return NULL;
ctx->url = nsurl_ref(url);
ctx->fetchh = fetchh;
RING_INSERT(ring, ctx);
return ctx;
}
/** callback to free a resource fetch */
static void fetch_javascript_free(void *ctx)
{
struct fetch_javascript_context *c = ctx;
if (c->url != NULL) {
nsurl_unref(c->url);
}
RING_REMOVE(ring, c);
free(ctx);
}
/** callback to start a resource fetch */
static bool fetch_javascript_start(void *ctx)
{
return true;
}
/** callback to abort a resource fetch */
static void fetch_javascript_abort(void *ctx)
{
struct fetch_javascript_context *c = ctx;
/* To avoid the poll loop having to deal with the fetch context
* disappearing from under it, we simply flag the abort here.
* The poll loop itself will perform the appropriate cleanup.
*/
c->aborted = true;
}
/** callback to poll for additional resource fetch contents */
static void fetch_javascript_poll(lwc_string *scheme)
{
struct fetch_javascript_context *c, *next;
if (ring == NULL) return;
/* Iterate over ring, processing each pending fetch */
c = ring;
do {
/* Ignore fetches that have been flagged as locked.
* This allows safe re-entrant calls to this function.
* Re-entrancy can occur if, as a result of a callback,
* the interested party causes fetch_poll() to be called
* again.
*/
if (c->locked == true) {
next = c->r_next;
continue;
}
/* Only process non-aborted fetches */
if (c->aborted == false) {
/* resource fetches can be processed in one go */
fetch_javascript_handler(c);
}
/* Compute next fetch item at the last possible moment
* as processing this item may have added to the ring
*/
next = c->r_next;
fetch_remove_from_queues(c->fetchh);
fetch_free(c->fetchh);
/* Advance to next ring entry, exiting if we've reached
* the start of the ring or the ring has become empty
*/
} while ( (c = next) != ring && ring != NULL);
}
/**
* Register javascript scheme fetcher with fetcher factory.
*
* \return NSERROR_OK on success or appropriate error code on faliure.
*/
nserror fetch_javascript_register(void)
{
lwc_string *scheme = lwc_string_ref(corestring_lwc_javascript);
const struct fetcher_operation_table fetcher_ops = {
.initialise = fetch_javascript_initialise,
.acceptable = fetch_javascript_can_fetch,
.setup = fetch_javascript_setup,
.start = fetch_javascript_start,
.abort = fetch_javascript_abort,
.free = fetch_javascript_free,
.poll = fetch_javascript_poll,
.finalise = fetch_javascript_finalise
};
return fetcher_add(scheme, &fetcher_ops);
}