decoder.c

Go to the documentation of this file.

/*
 * This file is part of the libsigrokdecode project.
 *
 * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2012 Bert Vermeulen <bert@biot.com>
 *
 * This program 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 "config.h"
#include "libsigrokdecode.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
#include "libsigrokdecode-internal.h"
#include <glib.h>

/**
 * @file
 *
 * Listing, loading, unloading, and handling protocol decoders.
 */

/**
 * @defgroup grp_decoder Protocol decoders
 *
 * Handling protocol decoders.
 *
 * @{
 */

/** @cond PRIVATE */

/* The list of protocol decoders. */
static GSList *pd_list = NULL;

/* srd.c */
extern SRD_PRIV GSList *searchpaths;

/* session.c */
extern SRD_PRIV GSList *sessions;
extern SRD_PRIV int max_session_id;

/* module_sigrokdecode.c */
extern SRD_PRIV PyObject *mod_sigrokdecode;

/** @endcond */

static gboolean srd_check_init(void)
{
        if (max_session_id < 0) {
                srd_err("Library is not initialized.");
                return FALSE;
        } else
                return TRUE;
}

/**
 * Returns the list of supported/loaded protocol decoders.
 *
 * This is a GSList containing the names of the decoders as strings.
 *
 * @return List of decoders, NULL if none are supported or loaded.
 *
 * @since 0.2.0
 */
SRD_API const GSList *srd_decoder_list(void)
{
        return pd_list;
}

/**
 * Get the decoder with the specified ID.
 *
 * @param id The ID string of the decoder to return.
 *
 * @return The decoder with the specified ID, or NULL if not found.
 *
 * @since 0.1.0
 */
SRD_API struct srd_decoder *srd_decoder_get_by_id(const char *id)
{
        GSList *l;
        struct srd_decoder *dec;

        for (l = pd_list; l; l = l->next) {
                dec = l->data;
                if (!strcmp(dec->id, id))
                        return dec;
        }

        return NULL;
}

static int get_channels(const struct srd_decoder *d, const char *attr,
                GSList **pdchl)
{
        PyObject *py_channellist, *py_entry;
        struct srd_channel *pdch;
        int ret, num_channels, i;

        if (!PyObject_HasAttrString(d->py_dec, attr))
                /* No channels of this type specified. */
                return SRD_OK;

        py_channellist = PyObject_GetAttrString(d->py_dec, attr);
        if (!PyTuple_Check(py_channellist)) {
                srd_err("Protocol decoder %s %s attribute is not a tuple.",
                                d->name, attr);
                return SRD_ERR_PYTHON;
        }

        if ((num_channels = PyTuple_Size(py_channellist)) == 0)
                /* Empty channellist. */
                return SRD_OK;

        ret = SRD_OK;
        for (i = 0; i < num_channels; i++) {
                py_entry = PyTuple_GetItem(py_channellist, i);
                if (!PyDict_Check(py_entry)) {
                        srd_err("Protocol decoder %s %s attribute is not "
                                "a list with dict elements.", d->name, attr);
                        ret = SRD_ERR_PYTHON;
                        break;
                }

                if (!(pdch = g_try_malloc(sizeof(struct srd_channel)))) {
                        srd_err("Failed to g_malloc() struct srd_channel.");
                        ret = SRD_ERR_MALLOC;
                        break;
                }

                if ((py_dictitem_as_str(py_entry, "id", &pdch->id)) != SRD_OK) {
                        ret = SRD_ERR_PYTHON;
                        break;
                }
                if ((py_dictitem_as_str(py_entry, "name", &pdch->name)) != SRD_OK) {
                        ret = SRD_ERR_PYTHON;
                        break;
                }
                if ((py_dictitem_as_str(py_entry, "desc", &pdch->desc)) != SRD_OK) {
                        ret = SRD_ERR_PYTHON;
                        break;
                }
                pdch->order = i;

                *pdchl = g_slist_append(*pdchl, pdch);
        }

        Py_DecRef(py_channellist);

        return ret;
}

static int get_options(struct srd_decoder *d)
{
        PyObject *py_opts, *py_opt, *py_val, *py_default, *py_item;
        Py_ssize_t opt, i;
        struct srd_decoder_option *o;
        GVariant *gvar;
        gint64 lval;
        double dval;
        int overflow;
        char *sval;

        if (!PyObject_HasAttrString(d->py_dec, "options"))
                /* No options, that's fine. */
                return SRD_OK;

        /* If present, options must be a tuple. */
        py_opts = PyObject_GetAttrString(d->py_dec, "options");
        if (!PyTuple_Check(py_opts)) {
                srd_err("Protocol decoder %s: options attribute is not "
                                "a tuple.", d->id);
                return SRD_ERR_PYTHON;
        }

        for (opt = 0; opt < PyTuple_Size(py_opts); opt++) {
                py_opt = PyTuple_GetItem(py_opts, opt);
                if (!PyDict_Check(py_opt)) {
                        srd_err("Protocol decoder %s options: each option "
                                        "must consist of a dictionary.", d->name);
                        return SRD_ERR_PYTHON;
                }
                if (!(py_val = PyDict_GetItemString(py_opt, "id"))) {
                        srd_err("Protocol decoder %s option %d has no "
                                        "id.", d->name);
                        return SRD_ERR_PYTHON;
                }
                o = g_malloc0(sizeof(struct srd_decoder_option));
                py_str_as_str(py_val, &o->id);

                if ((py_val = PyDict_GetItemString(py_opt, "desc")))
                        py_str_as_str(py_val, &o->desc);

                if ((py_default = PyDict_GetItemString(py_opt, "default"))) {
                        if (PyUnicode_Check(py_default)) {
                                /* UTF-8 string */
                                py_str_as_str(py_default, &sval);
                                o->def = g_variant_new_string(sval);
                                g_free(sval);
                        } else if (PyLong_Check(py_default)) {
                                /* Long */
                                lval = PyLong_AsLongAndOverflow(py_default, &overflow);
                                if (overflow) {
                                        /* Value is < LONG_MIN or > LONG_MAX */
                                        PyErr_Clear();
                                        srd_err("Protocol decoder %s option 'default' has "
                                                        "invalid default value.", d->name);
                                        return SRD_ERR_PYTHON;
                                }
                                o->def = g_variant_new_int64(lval);
                        } else if (PyFloat_Check(py_default)) {
                                /* Float */
                                if ((dval = PyFloat_AsDouble(py_default)) == -1.0) {
                                        PyErr_Clear();
                                        srd_err("Protocol decoder %s option 'default' has "
                                                        "invalid default value.", d->name);
                                        return SRD_ERR_PYTHON;
                                }
                                o->def = g_variant_new_double(dval);
                        } else {
                                srd_err("Protocol decoder %s option 'default' has "
                                                "value of unsupported type '%s'.", d->name,
                                                Py_TYPE(py_default)->tp_name);
                                return SRD_ERR_PYTHON;
                        }
                        g_variant_ref_sink(o->def);
                }

                if ((py_val = PyDict_GetItemString(py_opt, "values"))) {
                        /* A default is required if a list of values is
                         * given, since it's used to verify their type. */
                        if (!o->def) {
                                srd_err("No default for option '%s'", o->id);
                                return SRD_ERR_PYTHON;
                        }
                        if (!PyTuple_Check(py_val)) {
                                srd_err("Option '%s' values should be a tuple.", o->id);
                                return SRD_ERR_PYTHON;
                        }
                        for (i = 0; i < PyTuple_Size(py_val); i++) {
                                py_item = PyTuple_GetItem(py_val, i);
                                if (Py_TYPE(py_default) != Py_TYPE(py_item)) {
                                        srd_err("All values for option '%s' must be "
                                                        "of the same type as the default.",
                                                        o->id);
                                        return SRD_ERR_PYTHON;
                                }
                                if (PyUnicode_Check(py_item)) {
                                        /* UTF-8 string */
                                        py_str_as_str(py_item, &sval);
                                        gvar = g_variant_new_string(sval);
                                        g_variant_ref_sink(gvar);
                                        g_free(sval);
                                        o->values = g_slist_append(o->values, gvar);
                                } else if (PyLong_Check(py_item)) {
                                        /* Long */
                                        lval = PyLong_AsLongAndOverflow(py_item, &overflow);
                                        if (overflow) {
                                                /* Value is < LONG_MIN or > LONG_MAX */
                                                PyErr_Clear();
                                                srd_err("Protocol decoder %s option 'values' "
                                                                "has invalid value.", d->name);
                                                return SRD_ERR_PYTHON;
                                        }
                                        gvar = g_variant_new_int64(lval);
                                        g_variant_ref_sink(gvar);
                                        o->values = g_slist_append(o->values, gvar);
                                } else if (PyFloat_Check(py_item)) {
                                        /* Float */
                                        if ((dval = PyFloat_AsDouble(py_item)) == -1.0) {
                                                PyErr_Clear();
                                                srd_err("Protocol decoder %s option 'default' has "
                                                                "invalid default value.", d->name);
                                                return SRD_ERR_PYTHON;
                                        }
                                        gvar = g_variant_new_double(dval);
                                        g_variant_ref_sink(gvar);
                                        o->values = g_slist_append(o->values, gvar);
                                }
                        }
                }
                d->options = g_slist_append(d->options, o);
        }

        return SRD_OK;
}

/**
 * Load a protocol decoder module into the embedded Python interpreter.
 *
 * @param module_name The module name to be loaded.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_load(const char *module_name)
{
        PyObject *py_basedec, *py_method, *py_attr, *py_annlist, *py_ann;
        PyObject *py_bin_classes, *py_bin_class, *py_ann_rows, *py_ann_row;
        PyObject *py_ann_classes, *py_long;
        struct srd_decoder *d;
        int ret, i, j;
        char **ann, **bin, *ann_row_id, *ann_row_desc;
        struct srd_channel *pdch;
        GSList *l, *ann_classes;
        struct srd_decoder_annotation_row *ann_row;

        if (!srd_check_init())
                return SRD_ERR;

        if (!module_name)
                return SRD_ERR_ARG;

        if (PyDict_GetItemString(PyImport_GetModuleDict(), module_name)) {
                /* Module was already imported. */
                return SRD_OK;
        }

        srd_dbg("Loading protocol decoder '%s'.", module_name);

        py_basedec = py_method = py_attr = NULL;

        if (!(d = g_try_malloc0(sizeof(struct srd_decoder)))) {
                srd_dbg("Failed to g_malloc() struct srd_decoder.");
                ret = SRD_ERR_MALLOC;
                goto err_out;
        }

        ret = SRD_ERR_PYTHON;

        /* Import the Python module. */
        if (!(d->py_mod = PyImport_ImportModule(module_name))) {
                srd_exception_catch("Import of '%s' failed.", module_name);
                goto err_out;
        }

        /* Get the 'Decoder' class as Python object. */
        if (!(d->py_dec = PyObject_GetAttrString(d->py_mod, "Decoder"))) {
                /* This generated an AttributeError exception. */
                PyErr_Clear();
                srd_err("Decoder class not found in protocol decoder %s.",
                        module_name);
                goto err_out;
        }

        if (!(py_basedec = PyObject_GetAttrString(mod_sigrokdecode, "Decoder"))) {
                srd_dbg("sigrokdecode module not loaded.");
                goto err_out;
        }

        if (!PyObject_IsSubclass(d->py_dec, py_basedec)) {
                srd_err("Decoder class in protocol decoder module %s is not "
                        "a subclass of sigrokdecode.Decoder.", module_name);
                goto err_out;
        }
        Py_CLEAR(py_basedec);

        /*
         * Check that thіs decoder has the correct PD API version.
         * PDs of different API versions are incompatible and cannot work.
         */
        py_long = PyObject_GetAttrString(d->py_dec, "api_version");
        if (PyLong_AsLong(py_long) != 2) {
                srd_err("Only PDs of API version 2 are supported.");
                goto err_out;
        }
        Py_CLEAR(py_long);

        /* Check for a proper start() method. */
        if (!PyObject_HasAttrString(d->py_dec, "start")) {
                srd_err("Protocol decoder %s has no start() method Decoder "
                        "class.", module_name);
                goto err_out;
        }
        py_method = PyObject_GetAttrString(d->py_dec, "start");
        if (!PyFunction_Check(py_method)) {
                srd_err("Protocol decoder %s Decoder class attribute 'start' "
                        "is not a method.", module_name);
                goto err_out;
        }
        Py_CLEAR(py_method);

        /* Check for a proper decode() method. */
        if (!PyObject_HasAttrString(d->py_dec, "decode")) {
                srd_err("Protocol decoder %s has no decode() method Decoder "
                        "class.", module_name);
                goto err_out;
        }
        py_method = PyObject_GetAttrString(d->py_dec, "decode");
        if (!PyFunction_Check(py_method)) {
                srd_err("Protocol decoder %s Decoder class attribute 'decode' "
                        "is not a method.", module_name);
                goto err_out;
        }
        Py_CLEAR(py_method);

        /* Store required fields in newly allocated strings. */
        if (py_attr_as_str(d->py_dec, "id", &(d->id)) != SRD_OK)
                goto err_out;

        if (py_attr_as_str(d->py_dec, "name", &(d->name)) != SRD_OK)
                goto err_out;

        if (py_attr_as_str(d->py_dec, "longname", &(d->longname)) != SRD_OK)
                goto err_out;

        if (py_attr_as_str(d->py_dec, "desc", &(d->desc)) != SRD_OK)
                goto err_out;

        if (py_attr_as_str(d->py_dec, "license", &(d->license)) != SRD_OK)
                goto err_out;

        /* All options and their default values. */
        if (get_options(d) != SRD_OK)
                goto err_out;

        /* Check and import required channels. */
        if (get_channels(d, "channels", &d->channels) != SRD_OK)
                goto err_out;

        /* Check and import optional channels. */
        if (get_channels(d, "optional_channels", &d->opt_channels) != SRD_OK)
                goto err_out;

        /*
         * Fix order numbers for the optional channels.
         *
         * Example:
         * Required channels: r1, r2, r3. Optional: o1, o2, o3, o4.
         * 'order' fields in the d->channels list = 0, 1, 2.
         * 'order' fields in the d->opt_channels list = 3, 4, 5, 6.
         */
        for (l = d->opt_channels; l; l = l->next) {
                pdch = l->data;
                pdch->order += g_slist_length(d->channels);
        }

        /* Convert annotation class attribute to GSList of char **. */
        d->annotations = NULL;
        if (PyObject_HasAttrString(d->py_dec, "annotations")) {
                py_annlist = PyObject_GetAttrString(d->py_dec, "annotations");
                if (!PyTuple_Check(py_annlist)) {
                        srd_err("Protocol decoder %s annotations should "
                                        "be a tuple.", module_name);
                        goto err_out;
                }
                for (i = 0; i < PyTuple_Size(py_annlist); i++) {
                        py_ann = PyTuple_GetItem(py_annlist, i);
                        if (!PyTuple_Check(py_ann) || PyTuple_Size(py_ann) != 2) {
                                srd_err("Protocol decoder %s annotation %d should "
                                                "be a tuple with two elements.", module_name, i + 1);
                                goto err_out;
                        }

                        if (py_strseq_to_char(py_ann, &ann) != SRD_OK) {
                                goto err_out;
                        }
                        d->annotations = g_slist_append(d->annotations, ann);
                }
        }

        /* Convert annotation_rows to GSList of 'struct srd_decoder_annotation_row'. */
        d->annotation_rows = NULL;
        if (PyObject_HasAttrString(d->py_dec, "annotation_rows")) {
                py_ann_rows = PyObject_GetAttrString(d->py_dec, "annotation_rows");
                if (!PyTuple_Check(py_ann_rows)) {
                        srd_err("Protocol decoder %s annotation row list "
                                "must be a tuple.", module_name);
                        goto err_out;
                }
                for (i = 0; i < PyTuple_Size(py_ann_rows); i++) {
                        py_ann_row = PyTuple_GetItem(py_ann_rows, i);
                        if (!PyTuple_Check(py_ann_row)) {
                                srd_err("Protocol decoder %s annotation rows "
                                        "must be tuples.", module_name);
                                goto err_out;
                        }
                        if (PyTuple_Size(py_ann_row) != 3
                                        || !PyUnicode_Check(PyTuple_GetItem(py_ann_row, 0))
                                        || !PyUnicode_Check(PyTuple_GetItem(py_ann_row, 1))
                                        || !PyTuple_Check(PyTuple_GetItem(py_ann_row, 2))) {
                                srd_err("Protocol decoder %s annotation rows "
                                        "must contain tuples containing two "
                                        "strings and a tuple.", module_name);
                                goto err_out;
                        }

                        if (py_str_as_str(PyTuple_GetItem(py_ann_row, 0), &ann_row_id) != SRD_OK)
                                goto err_out;

                        if (py_str_as_str(PyTuple_GetItem(py_ann_row, 1), &ann_row_desc) != SRD_OK)
                                goto err_out;

                        py_ann_classes = PyTuple_GetItem(py_ann_row, 2);
                        ann_classes = NULL;
                        for (j = 0; j < PyTuple_Size(py_ann_classes); j++) {
                                py_long = PyTuple_GetItem(py_ann_classes, j);
                                if (!PyLong_Check(py_long)) {
                                        srd_err("Protocol decoder %s annotation row class "
                                                "list must only contain numbers.", module_name);
                                        goto err_out;
                                }
                                ann_classes = g_slist_append(ann_classes,
                                        GINT_TO_POINTER(PyLong_AsLong(py_long)));
                        }

                        ann_row = g_malloc0(sizeof(struct srd_decoder_annotation_row));
                        ann_row->id = ann_row_id;
                        ann_row->desc = ann_row_desc;
                        ann_row->ann_classes = ann_classes;
                        d->annotation_rows = g_slist_append(d->annotation_rows, ann_row);
                }
        }

        /* Convert binary class to GSList of char *. */
        d->binary = NULL;
        if (PyObject_HasAttrString(d->py_dec, "binary")) {
                py_bin_classes = PyObject_GetAttrString(d->py_dec, "binary");
                if (!PyTuple_Check(py_bin_classes)) {
                        srd_err("Protocol decoder %s binary classes should "
                                        "be a tuple.", module_name);
                        goto err_out;
                }
                for (i = 0; i < PyTuple_Size(py_bin_classes); i++) {
                        py_bin_class = PyTuple_GetItem(py_bin_classes, i);
                        if (!PyTuple_Check(py_bin_class)) {
                                srd_err("Protocol decoder %s binary classes "
                                                "should consist of tuples.", module_name);
                                goto err_out;
                        }
                        if (PyTuple_Size(py_bin_class) != 2
                                        || !PyUnicode_Check(PyTuple_GetItem(py_bin_class, 0))
                                        || !PyUnicode_Check(PyTuple_GetItem(py_bin_class, 1))) {
                                srd_err("Protocol decoder %s binary classes should "
                                                "contain tuples with two strings.", module_name);
                                goto err_out;
                        }

                        if (py_strseq_to_char(py_bin_class, &bin) != SRD_OK) {
                                goto err_out;
                        }
                        d->binary = g_slist_append(d->binary, bin);
                }
        }

        /* Append it to the list of supported/loaded decoders. */
        pd_list = g_slist_append(pd_list, d);

        ret = SRD_OK;

err_out:
        if (ret != SRD_OK) {
                Py_XDECREF(py_method);
                Py_XDECREF(py_basedec);
                Py_XDECREF(d->py_dec);
                Py_XDECREF(d->py_mod);
                g_free(d);
        }

        return ret;
}

/**
 * Return a protocol decoder's docstring.
 *
 * @param dec The loaded protocol decoder.
 *
 * @return A newly allocated buffer containing the protocol decoder's
 *         documentation. The caller is responsible for free'ing the buffer.
 *
 * @since 0.1.0
 */
SRD_API char *srd_decoder_doc_get(const struct srd_decoder *dec)
{
        PyObject *py_str;
        char *doc;

        if (!srd_check_init())
                return NULL;

        if (!dec)
                return NULL;

        if (!PyObject_HasAttrString(dec->py_mod, "__doc__"))
                return NULL;

        if (!(py_str = PyObject_GetAttrString(dec->py_mod, "__doc__"))) {
                srd_exception_catch("");
                return NULL;
        }

        doc = NULL;
        if (py_str != Py_None)
                py_str_as_str(py_str, &doc);
        Py_DecRef(py_str);

        return doc;
}

static void free_channels(GSList *channellist)
{
        GSList *l;
        struct srd_channel *pdch;

        if (channellist == NULL)
                return;

        for (l = channellist; l; l = l->next) {
                pdch = l->data;
                g_free(pdch->id);
                g_free(pdch->name);
                g_free(pdch->desc);
                g_free(pdch);
        }
        g_slist_free(channellist);
}

/**
 * Unload the specified protocol decoder.
 *
 * @param dec The struct srd_decoder to be unloaded.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_unload(struct srd_decoder *dec)
{
        struct srd_decoder_option *o;
        struct srd_session *sess;
        GSList *l;

        if (!srd_check_init())
                return SRD_ERR;

        if (!dec)
                return SRD_ERR_ARG;

        srd_dbg("Unloading protocol decoder '%s'.", dec->name);

        /*
         * Since any instances of this decoder need to be released as well,
         * but they could be anywhere in the stack, just free the entire
         * stack. A frontend reloading a decoder thus has to restart all
         * instances, and rebuild the stack.
         */
        for (l = sessions; l; l = l->next) {
                sess = l->data;
                srd_inst_free_all(sess, NULL);
        }

        for (l = dec->options; l; l = l->next) {
                o = l->data;
                g_free(o->id);
                g_free(o->desc);
                g_variant_unref(o->def);
                g_free(o);
        }
        g_slist_free(dec->options);

        free_channels(dec->channels);
        free_channels(dec->opt_channels);
        g_free(dec->id);
        g_free(dec->name);
        g_free(dec->longname);
        g_free(dec->desc);
        g_free(dec->license);

        /* The module's Decoder class. */
        Py_XDECREF(dec->py_dec);
        /* The module itself. */
        Py_XDECREF(dec->py_mod);

        g_free(dec);

        return SRD_OK;
}

static void srd_decoder_load_all_path(char *path)
{
        GDir *dir;
        const gchar *direntry;

        if (!(dir = g_dir_open(path, 0, NULL)))
                /* Not really fatal */
                return;

        /* This ignores errors returned by srd_decoder_load(). That
         * function will have logged the cause, but in any case we
         * want to continue anyway. */
        while ((direntry = g_dir_read_name(dir)) != NULL) {
                /* The directory name is the module name (e.g. "i2c"). */
                srd_decoder_load(direntry);
        }
        g_dir_close(dir);

}

/**
 * Load all installed protocol decoders.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_load_all(void)
{
        GSList *l;

        if (!srd_check_init())
                return SRD_ERR;

        for (l = searchpaths; l; l = l->next)
                srd_decoder_load_all_path(l->data);

        return SRD_OK;
}

/**
 * Unload all loaded protocol decoders.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_unload_all(void)
{
        GSList *l;
        struct srd_decoder *dec;

        for (l = pd_list; l; l = l->next) {
                dec = l->data;
                srd_decoder_unload(dec);
        }
        g_slist_free(pd_list);
        pd_list = NULL;

        return SRD_OK;
}

/** @} */