css.c

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/*
 * Copyright 2009 John-Mark Bell <jmb@netsurf-browser.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/>.
 */

#include <assert.h>
#include <libwapcaplet/libwapcaplet.h>
#include <dom/dom.h>

#include "content/content_protected.h"
#include "content/fetch.h"
#include "content/hlcache.h"
#include "desktop/system_colour.h"
#include "utils/corestrings.h"
#include "utils/utils.h"
#include "utils/http.h"
#include "utils/log.h"
#include "utils/messages.h"

#include "css/css.h"
#include "css/hints.h"
#include "css/internal.h"

/* Define to trace import fetches */
#undef NSCSS_IMPORT_TRACE

struct content_css_data;

/**
 * Type of callback called when a CSS object has finished
 *
 * \param css  CSS object that has completed
 * \param pw   Client-specific data
 */
typedef void (*nscss_done_callback)(struct content_css_data *css, void *pw);

/**
 * CSS content data
 */
struct content_css_data
{
        css_stylesheet *sheet;          /**< Stylesheet object */
        char *charset;                  /**< Character set of stylesheet */
        struct nscss_import *imports;   /**< Array of imported sheets */
        uint32_t import_count;          /**< Number of sheets imported */
        uint32_t next_to_register;      /**< Index of next import to register */
        nscss_done_callback done;       /**< Completion callback */
        void *pw;                       /**< Client data */
};

/**
 * CSS content data
 */
typedef struct nscss_content
{
        struct content base;            /**< Underlying content object */

        struct content_css_data data;   /**< CSS data */
} nscss_content;

/**
 * Context for import fetches
 */
typedef struct {
        struct content_css_data *css;           /**< Object containing import */
        uint32_t index;                         /**< Index into parent sheet's
                                                 *   imports array */
} nscss_import_ctx;

static bool nscss_convert(struct content *c);
static void nscss_destroy(struct content *c);
static nserror nscss_clone(const struct content *old, struct content **newc);
static bool nscss_matches_quirks(const struct content *c, bool quirks);
static content_type nscss_content_type(void);

static nserror nscss_create_css_data(struct content_css_data *c,
                const char *url, const char *charset, bool quirks,
                nscss_done_callback done, void *pw);
static css_error nscss_process_css_data(struct content_css_data *c, const char *data,
                unsigned int size);
static css_error nscss_convert_css_data(struct content_css_data *c);
static void nscss_destroy_css_data(struct content_css_data *c);

static void nscss_content_done(struct content_css_data *css, void *pw);
static css_error nscss_handle_import(void *pw, css_stylesheet *parent,
                lwc_string *url);
static nserror nscss_import(hlcache_handle *handle,
                const hlcache_event *event, void *pw);
static css_error nscss_import_complete(nscss_import_ctx *ctx);

static css_error nscss_register_imports(struct content_css_data *c);
static css_error nscss_register_import(struct content_css_data *c,
                const hlcache_handle *import);


static css_stylesheet *blank_import;


/**
 * Initialise a CSS content
 *
 * \param handler content handler
 * \param imime_type mime-type
 * \param params Content-Type parameters
 * \param llcache handle to content
 * \param fallback_charset The character set to fallback to.
 * \param quirks allow quirks
 * \param c Content to initialise
 * \return NSERROR_OK or error cod eon faliure
 */
static nserror
nscss_create(const content_handler *handler,
             lwc_string *imime_type,
             const http_parameter *params,
             llcache_handle *llcache,
             const char *fallback_charset,
             bool quirks,
             struct content **c)
{
        nscss_content *result;
        const char *charset = NULL;
        const char *xnsbase = NULL;
        lwc_string *charset_value = NULL;
        nserror error;

        result = calloc(1, sizeof(nscss_content));
        if (result == NULL)
                return NSERROR_NOMEM;

        error = content__init(&result->base, handler, imime_type,
                        params, llcache, fallback_charset, quirks);
        if (error != NSERROR_OK) {
                free(result);
                return error;
        }

        /* Find charset specified on HTTP layer, if any */
        error = http_parameter_list_find_item(params, corestring_lwc_charset,
                        &charset_value);
        if (error != NSERROR_OK || lwc_string_length(charset_value) == 0) {
                /* No charset specified, use fallback, if any */
                /** \todo libcss will take this as gospel, which is wrong */
                charset = fallback_charset;
        } else {
                charset = lwc_string_data(charset_value);
        }

        /* Compute base URL for stylesheet */
        xnsbase = llcache_handle_get_header(llcache, "X-NS-Base");
        if (xnsbase == NULL) {
                xnsbase = nsurl_access(content_get_url(&result->base));
        }

        error = nscss_create_css_data(&result->data,
                        xnsbase, charset, result->base.quirks,
                        nscss_content_done, result);
        if (error != NSERROR_OK) {
                content_broadcast_error(&result->base, NSERROR_NOMEM, NULL);
                if (charset_value != NULL)
                        lwc_string_unref(charset_value);
                free(result);
                return error;
        }

        if (charset_value != NULL)
                lwc_string_unref(charset_value);

        *c = (struct content *) result;

        return NSERROR_OK;
}

/**
 * Create a struct content_css_data, creating a stylesheet object
 *
 * \param c        Struct to populate
 * \param url      URL of stylesheet
 * \param charset  Stylesheet charset
 * \param quirks   Stylesheet quirks mode
 * \param done     Callback to call when content has completed
 * \param pw       Client data for \a done
 * \return NSERROR_OK on success, NSERROR_NOMEM on memory exhaustion
 */
static nserror nscss_create_css_data(struct content_css_data *c,
                const char *url, const char *charset, bool quirks,
                nscss_done_callback done, void *pw)
{
        css_error error;
        css_stylesheet_params params;

        c->pw = pw;
        c->done = done;
        c->next_to_register = (uint32_t) -1;
        c->import_count = 0;
        c->imports = NULL;
        if (charset != NULL)
                c->charset = strdup(charset);
        else
                c->charset = NULL;

        params.params_version = CSS_STYLESHEET_PARAMS_VERSION_1;
        params.level = CSS_LEVEL_DEFAULT;
        params.charset = charset;
        params.url = url;
        params.title = NULL;
        params.allow_quirks = quirks;
        params.inline_style = false;
        params.resolve = nscss_resolve_url;
        params.resolve_pw = NULL;
        params.import = nscss_handle_import;
        params.import_pw = c;
        params.color = ns_system_colour;
        params.color_pw = NULL;
        params.font = NULL;
        params.font_pw = NULL;

        error = css_stylesheet_create(&params, &c->sheet);
        if (error != CSS_OK) {
                return NSERROR_NOMEM;
        }

        return NSERROR_OK;
}

/**
 * Process CSS source data
 *
 * \param c     Content structure
 * \param data  Data to process
 * \param size  Number of bytes to process
 * \return true on success, false on failure
 */
static bool
nscss_process_data(struct content *c, const char *data, unsigned int size)
{
        nscss_content *css = (nscss_content *) c;
        css_error error;

        error = nscss_process_css_data(&css->data, data, size);
        if (error != CSS_OK && error != CSS_NEEDDATA) {
                content_broadcast_error(c, NSERROR_CSS, NULL);
        }

        return (error == CSS_OK || error == CSS_NEEDDATA);
}

/**
 * Process CSS data
 *
 * \param c     CSS content object
 * \param data  Data to process
 * \param size  Number of bytes to process
 * \return CSS_OK on success, appropriate error otherwise
 */
static css_error nscss_process_css_data(struct content_css_data *c,
                const char *data, unsigned int size)
{
        return css_stylesheet_append_data(c->sheet,
                        (const uint8_t *) data, size);
}

/**
 * Convert a CSS content ready for use
 *
 * \param c  Content to convert
 * \return true on success, false on failure
 */
bool nscss_convert(struct content *c)
{
        nscss_content *css = (nscss_content *) c;
        css_error error;

        error = nscss_convert_css_data(&css->data);
        if (error != CSS_OK) {
                content_broadcast_error(c, NSERROR_CSS, NULL);
                return false;
        }

        return true;
}

/**
 * Convert CSS data ready for use
 *
 * \param c  CSS data to convert
 * \return CSS error
 */
static css_error nscss_convert_css_data(struct content_css_data *c)
{
        css_error error;

        error = css_stylesheet_data_done(c->sheet);

        /* Process pending imports */
        if (error == CSS_IMPORTS_PENDING) {
                /* We must not have registered any imports yet */
                assert(c->next_to_register == (uint32_t) -1);

                /* Start registering, until we find one that
                 * hasn't finished fetching */
                c->next_to_register = 0;
                error = nscss_register_imports(c);
        } else if (error == CSS_OK) {
                /* No imports, and no errors, so complete conversion */
                c->done(c, c->pw);
        } else {
                const char *url;

                if (css_stylesheet_get_url(c->sheet, &url) == CSS_OK) {
                        NSLOG(netsurf, INFO, "Failed converting %p %s (%d)",
                              c, url, error);
                } else {
                        NSLOG(netsurf, INFO, "Failed converting %p (%d)", c,
                              error);
                }
        }

        return error;
}

/**
 * Clean up a CSS content
 *
 * \param c  Content to clean up
 */
void nscss_destroy(struct content *c)
{
        nscss_content *css = (nscss_content *) c;

        nscss_destroy_css_data(&css->data);
}

/**
 * Clean up CSS data
 *
 * \param c  CSS data to clean up
 */
static void nscss_destroy_css_data(struct content_css_data *c)
{
        uint32_t i;

        for (i = 0; i < c->import_count; i++) {
                if (c->imports[i].c != NULL) {
                        hlcache_handle_release(c->imports[i].c);
                }
                c->imports[i].c = NULL;
        }

        free(c->imports);

        if (c->sheet != NULL) {
                css_stylesheet_destroy(c->sheet);
                c->sheet = NULL;
        }

        free(c->charset);
}

nserror nscss_clone(const struct content *old, struct content **newc)
{
        const nscss_content *old_css = (const nscss_content *) old;
        nscss_content *new_css;
        const uint8_t *data;
        size_t size;
        nserror error;

        new_css = calloc(1, sizeof(nscss_content));
        if (new_css == NULL)
                return NSERROR_NOMEM;

        /* Clone content */
        error = content__clone(old, &new_css->base);
        if (error != NSERROR_OK) {
                content_destroy(&new_css->base);
                return error;
        }

        /* Simply replay create/process/convert */
        error = nscss_create_css_data(&new_css->data,
                        nsurl_access(content_get_url(&new_css->base)),
                        old_css->data.charset,
                        new_css->base.quirks,
                        nscss_content_done, new_css);
        if (error != NSERROR_OK) {
                content_destroy(&new_css->base);
                return error;
        }

        data = content__get_source_data(&new_css->base, &size);
        if (size > 0) {
                if (nscss_process_data(&new_css->base,
                                       (char *)data,
                                       (unsigned int)size) == false) {
                        content_destroy(&new_css->base);
                        return NSERROR_CLONE_FAILED;
                }
        }

        if (old->status == CONTENT_STATUS_READY ||
                        old->status == CONTENT_STATUS_DONE) {
                if (nscss_convert(&new_css->base) == false) {
                        content_destroy(&new_css->base);
                        return NSERROR_CLONE_FAILED;
                }
        }

        *newc = (struct content *) new_css;

        return NSERROR_OK;
}

bool nscss_matches_quirks(const struct content *c, bool quirks)
{
        return c->quirks == quirks;
}

/* exported interface documented in netsurf/css.h */
css_stylesheet *nscss_get_stylesheet(struct hlcache_handle *h)
{
        nscss_content *c = (nscss_content *) hlcache_handle_get_content(h);

        assert(c != NULL);

        return c->data.sheet;
}

/* exported interface documented in netsurf/css.h */
struct nscss_import *nscss_get_imports(hlcache_handle *h, uint32_t *n)
{
        nscss_content *c = (nscss_content *) hlcache_handle_get_content(h);

        assert(c != NULL);
        assert(n != NULL);

        *n = c->data.import_count;

        return c->data.imports;
}

/**
 * Compute the type of a content
 *
 * \return CONTENT_CSS
 */
content_type nscss_content_type(void)
{
        return CONTENT_CSS;
}

/*****************************************************************************
 * Object completion                                                         *
 *****************************************************************************/

/**
 * Handle notification that a CSS object is done
 *
 * \param css  CSS object
 * \param pw   Private data
 */
void nscss_content_done(struct content_css_data *css, void *pw)
{
        struct content *c = pw;
        uint32_t i;
        size_t size;
        css_error error;

        /* Retrieve the size of this sheet */
        error = css_stylesheet_size(css->sheet, &size);
        if (error != CSS_OK) {
                content_broadcast_error(c, NSERROR_CSS, NULL);
                content_set_error(c);
                return;
        }
        c->size += size;

        /* Add on the size of the imported sheets */
        for (i = 0; i < css->import_count; i++) {
                if (css->imports[i].c != NULL) {
                        struct content *import = hlcache_handle_get_content(
                                        css->imports[i].c);

                        if (import != NULL) {
                                c->size += import->size;
                        }
                }
        }

        /* Finally, catch the content's users up with reality */
        content_set_ready(c);
        content_set_done(c);
}

/*****************************************************************************
 * Import handling                                                           *
 *****************************************************************************/

/**
 * Handle notification of the need for an imported stylesheet
 *
 * \param pw      CSS object requesting the import
 * \param parent  Stylesheet requesting the import
 * \param url     URL of the imported sheet
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error nscss_handle_import(void *pw, css_stylesheet *parent,
                lwc_string *url)
{
        content_type accept = CONTENT_CSS;
        struct content_css_data *c = pw;
        nscss_import_ctx *ctx;
        hlcache_child_context child;
        struct nscss_import *imports;
        const char *referer;
        css_error error;
        nserror nerror;

        nsurl *ns_url;
        nsurl *ns_ref;

        assert(parent == c->sheet);

        error = css_stylesheet_get_url(c->sheet, &referer);
        if (error != CSS_OK) {
                return error;
        }

        ctx = malloc(sizeof(*ctx));
        if (ctx == NULL)
                return CSS_NOMEM;

        ctx->css = c;
        ctx->index = c->import_count;

        /* Increase space in table */
        imports = realloc(c->imports, (c->import_count + 1) *
                        sizeof(struct nscss_import));
        if (imports == NULL) {
                free(ctx);
                return CSS_NOMEM;
        }
        c->imports = imports;

        /** \todo fallback charset */
        child.charset = NULL;
        error = css_stylesheet_quirks_allowed(c->sheet, &child.quirks);
        if (error != CSS_OK) {
                free(ctx);
                return error;
        }

        /* Create content */

        /** \todo Why aren't we getting a relative url part, to join? */
        nerror = nsurl_create(lwc_string_data(url), &ns_url);
        if (nerror != NSERROR_OK) {
                free(ctx);
                return CSS_NOMEM;
        }

        /** \todo Constructing nsurl for referer here is silly, avoid */
        nerror = nsurl_create(referer, &ns_ref);
        if (nerror != NSERROR_OK) {
                nsurl_unref(ns_url);
                free(ctx);
                return CSS_NOMEM;
        }

        /* Avoid importing ourself */
        if (nsurl_compare(ns_url, ns_ref, NSURL_COMPLETE)) {
                c->imports[c->import_count].c = NULL;
                /* No longer require context as we're not fetching anything */
                free(ctx);
                ctx = NULL;
        } else {
                nerror = hlcache_handle_retrieve(ns_url,
                                0, ns_ref, NULL, nscss_import, ctx,
                                &child, accept,
                                &c->imports[c->import_count].c);
                if (nerror != NSERROR_OK) {
                        free(ctx);
                        return CSS_NOMEM;
                }
        }

        nsurl_unref(ns_url);
        nsurl_unref(ns_ref);

#ifdef NSCSS_IMPORT_TRACE
        NSLOG(netsurf, INFO, "Import %d '%s' -> (handle: %p ctx: %p)",
              c->import_count, lwc_string_data(url),
              c->imports[c->import_count].c, ctx);
#endif

        c->import_count++;

        return CSS_OK;
}

/**
 * Handler for imported stylesheet events
 *
 * \param handle  Handle for stylesheet
 * \param event   Event object
 * \param pw      Callback context
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror nscss_import(hlcache_handle *handle,
                const hlcache_event *event, void *pw)
{
        nscss_import_ctx *ctx = pw;
        css_error error = CSS_OK;

#ifdef NSCSS_IMPORT_TRACE
        NSLOG(netsurf, INFO, "Event %d for %p (%p)", event->type, handle, ctx);
#endif

        assert(ctx->css->imports[ctx->index].c == handle);

        switch (event->type) {
        case CONTENT_MSG_DONE:
                error = nscss_import_complete(ctx);
                break;

        case CONTENT_MSG_ERROR:
                hlcache_handle_release(handle);
                ctx->css->imports[ctx->index].c = NULL;

                error = nscss_import_complete(ctx);
                /* Already released handle */
                break;
        default:
                break;
        }

        /* Preserve out-of-memory. Anything else is OK */
        return error == CSS_NOMEM ? NSERROR_NOMEM : NSERROR_OK;
}

/**
 * Handle an imported stylesheet completing
 *
 * \param ctx  Import context
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error nscss_import_complete(nscss_import_ctx *ctx)
{
        css_error error = CSS_OK;

        /* If this import is the next to be registered, do so */
        if (ctx->css->next_to_register == ctx->index)
                error = nscss_register_imports(ctx->css);

#ifdef NSCSS_IMPORT_TRACE
        NSLOG(netsurf, INFO, "Destroying import context %p for %d", ctx,
              ctx->index);
#endif

        /* No longer need import context */
        free(ctx);

        return error;
}

/*****************************************************************************
 * Import registration                                                       *
 *****************************************************************************/

/**
 * Register imports with a stylesheet
 *
 * \param c  CSS object containing the imports
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error nscss_register_imports(struct content_css_data *c)
{
        uint32_t index;
        css_error error;

        assert(c->next_to_register != (uint32_t) -1);
        assert(c->next_to_register < c->import_count);

        /* Register imported sheets */
        for (index = c->next_to_register; index < c->import_count; index++) {
                /* Stop registering if we encounter one whose fetch hasn't
                 * completed yet. We'll resume at this point when it has
                 * completed.
                 */
                if (c->imports[index].c != NULL &&
                        content_get_status(c->imports[index].c) !=
                                CONTENT_STATUS_DONE) {
                        break;
                }

                error = nscss_register_import(c, c->imports[index].c);
                if (error != CSS_OK)
                        return error;
        }

        /* Record identity of the next import to register */
        c->next_to_register = (uint32_t) index;

        if (c->next_to_register == c->import_count) {
                /* No more imports: notify parent that we're DONE */
                c->done(c, c->pw);
        }

        return CSS_OK;
}


/**
 * Register an import with a stylesheet
 *
 * \param c       CSS object that requested the import
 * \param import  Cache handle of import, or NULL for blank
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error nscss_register_import(struct content_css_data *c,
                const hlcache_handle *import)
{
        css_stylesheet *sheet;
        css_error error;

        if (import != NULL) {
                nscss_content *s =
                        (nscss_content *) hlcache_handle_get_content(import);
                sheet = s->data.sheet;
        } else {
                /* Create a blank sheet if needed. */
                if (blank_import == NULL) {
                        css_stylesheet_params params;

                        params.params_version = CSS_STYLESHEET_PARAMS_VERSION_1;
                        params.level = CSS_LEVEL_DEFAULT;
                        params.charset = NULL;
                        params.url = "";
                        params.title = NULL;
                        params.allow_quirks = false;
                        params.inline_style = false;
                        params.resolve = nscss_resolve_url;
                        params.resolve_pw = NULL;
                        params.import = NULL;
                        params.import_pw = NULL;
                        params.color = ns_system_colour;
                        params.color_pw = NULL;
                        params.font = NULL;
                        params.font_pw = NULL;

                        error = css_stylesheet_create(&params, &blank_import);
                        if (error != CSS_OK) {
                                return error;
                        }

                        error = css_stylesheet_data_done(blank_import);
                        if (error != CSS_OK) {
                                css_stylesheet_destroy(blank_import);
                                return error;
                        }
                }

                sheet = blank_import;
        }

        error = css_stylesheet_register_import(c->sheet, sheet);
        if (error != CSS_OK) {
                return error;
        }

        return error;
}

/**
 * Clean up after the CSS content handler
 */
static void nscss_fini(void)
{
        if (blank_import != NULL) {
                css_stylesheet_destroy(blank_import);
                blank_import = NULL;
        }
        css_hint_fini();
}

static const content_handler css_content_handler = {
        .fini = nscss_fini,
        .create = nscss_create,
        .process_data = nscss_process_data,
        .data_complete = nscss_convert,
        .destroy = nscss_destroy,
        .clone = nscss_clone,
        .matches_quirks = nscss_matches_quirks,
        .type = nscss_content_type,
        .no_share = false,
};

/* exported interface documented in netsurf/css.h */
nserror nscss_init(void)
{
        nserror error;

        error = content_factory_register_handler("text/css",
                        &css_content_handler);
        if (error != NSERROR_OK)
                goto error;

        error = css_hint_init();
        if (error != NSERROR_OK)
                goto error;

        return NSERROR_OK;

error:
        nscss_fini();

        return error;
}