path: root/alsa-binding/Alsa-RegEvt.c

/*
 * AlsaLibMapping -- provide low level interface with ALSA lib (extracted from alsa-json-gateway code)
 * Copyright (C) 2015,2016,2017, Fulup Ar Foll fulup@iot.bzh
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.

 */

#define _GNU_SOURCE  // needed for vasprintf

#include <sys/inotify.h>

#include <afb-timer.h>

#include "Alsa-ApiHat.h"

// Defines for inotify events
#define INOTIFY_EVENT_SIZE      (sizeof(struct inotify_event))
#define INOTIFY_EVENT_BUF_LEN   (1024 * (INOTIFY_EVENT_SIZE + 16))

#define DIR_TO_WATCH	"/dev/snd/by-path"

#ifndef MAX_SND_HAL
#define MAX_SND_HAL 10
#endif

typedef enum {
    SUBSCRIPTION_CARD_ADDED_EVENTS = 0,
    SUBSCRIPTION_CARD_REMOVED_EVENTS = 1
} SubscriptionCardEventTypeT;

typedef struct {
    int fd;
    int wd;
    sd_event_source *src;
    afb_event_t afbevt;
} sndCardEvtHandleT;

// generic sndctrl event handle hook to event callback when pooling
typedef struct {
    struct pollfd pfds;
    sd_event_source *src;
    snd_ctl_t *ctlDev;
    int mode;
    afb_event_t afbevt;
} ctrlEvtHandleT;

typedef struct {
    int available;
    ctrlEvtHandleT *evtHandle;
} sndHandleT;

typedef struct {
    sndHandleT sndHandles[MAX_SND_CARD];
    sndCardEvtHandleT *cardAdded;
    sndCardEvtHandleT *cardRemoved;
    afb_api_t apiHandle;
} sndCardsT;

typedef struct {
    char *createdFileName;
    sndCardsT *sndCards;
} sndCardCardFileEventHandleT;

typedef struct {
    int  cardid;
    char *devid;
    char *apiprefix;
    char *drivername;
    char *shortname;
    char *longname;
} cardRegistryT;

cardRegistryT *cardRegistry[MAX_SND_HAL + 1];

STATIC int getHalIdxFromCardid (int cardid) {
    
    for (int idx = 0; idx < MAX_SND_HAL; idx++) {
        if (!cardRegistry[idx]) return -1;
        if (cardRegistry[idx]->cardid == cardid) return idx;
    }
    
    return -1;
}

PUBLIC json_object *alsaCheckQuery(afb_req_t request, queryValuesT *queryValues) {

    json_object *tmpJ;
    int done;

    // get query from request
    json_object *queryInJ = afb_req_json(request);

    done = json_object_object_get_ex(queryInJ, "devid", &tmpJ);
    if (!done) {
        afb_req_fail_f(request, "devid-missing", "Invalid query='%s'", json_object_get_string(queryInJ));
        goto OnErrorExit;
    }
    queryValues->devid = json_object_get_string(tmpJ);

    done = json_object_object_get_ex(queryInJ, "mode", &tmpJ);
    if (!done) queryValues->mode = QUERY_QUIET; // default quiet
    else queryValues->mode = json_object_get_int(tmpJ);

    return queryInJ;

OnErrorExit:
    return NULL;
}

STATIC void updateSelectedAlsaCardsAvailabilityAndFireEvents(sndCardsT *sndCards, int first, int last) {
    int idx, available;
    char *cardId;

    if (first < 0 || first >= MAX_SND_CARD)
        return;

    if (last < 0 || last >= MAX_SND_CARD)
        return;

    if (last < first)
        return;

    for (idx = first; idx < (last + 1); idx++) {
        available = snd_card_load(idx);
        if (available && ! sndCards->sndHandles[idx].available) {
            sndCards->sndHandles[idx].available = 1;

            if (sndCards->cardAdded)
                afb_event_push(sndCards->cardAdded->afbevt, getCardInfo(idx));
        }
        else if (! available && sndCards->sndHandles[idx].available) {
            sndCards->sndHandles[idx].available = 0;

            if (sndCards->cardRemoved && (asprintf(&cardId, "hw:%i", idx) > 0))
                afb_event_push(sndCards->cardRemoved->afbevt, json_object_new_string(cardId));

            if (sndCards->sndHandles[idx].evtHandle) {
                sd_event_source_unref(sndCards->sndHandles[idx].evtHandle->src);
                afb_event_unref(sndCards->sndHandles[idx].evtHandle->afbevt);
                snd_ctl_close(sndCards->sndHandles[idx].evtHandle->ctlDev);
                free(sndCards->sndHandles[idx].evtHandle);
                sndCards->sndHandles[idx].evtHandle = NULL;
            }
        }
    }
}

STATIC void updateAllAlsaCardsAvailabilityAndFireEvents(sndCardsT *sndCards) {
    updateSelectedAlsaCardsAvailabilityAndFireEvents(sndCards, 0, (MAX_SND_CARD - 1));
}

// This routine is called every few microseconds to verify when the newly created sound card file will be openable (using timer event firing)
STATIC int sndCardTimerForCreatedFileCB(TimerHandleT *context) {
    int createdFileCardNb;

    sndCardCardFileEventHandleT *createdFileHandle = (sndCardCardFileEventHandleT *) context->context;

    createdFileCardNb = getCardNbFromCardPath(createdFileHandle->createdFileName);
    if(createdFileCardNb < 0) {
        AFB_ERROR("Error %i happened when tried to get created card name file '%s' card nb",
                  createdFileCardNb,
                  createdFileHandle->createdFileName);
        return -1;
    }

    updateSelectedAlsaCardsAvailabilityAndFireEvents(createdFileHandle->sndCards, createdFileCardNb, createdFileCardNb);

    free(createdFileHandle->createdFileName);
    free(createdFileHandle);

    context->count = 1;

    return 1;
}

// This routine is called when sound cards are added/removed (when inotify '/dev/snd/by-path' events are fired)
STATIC int sndCardEventCB(sd_event_source* src, int fd, uint32_t revents, void* userData) {
    ssize_t length, i = 0;
    char buffer[INOTIFY_EVENT_BUF_LEN];
    char *createdFile;

    struct inotify_event *event;

    sndCardCardFileEventHandleT *createdFileHandle;
    TimerHandleT *createdFileTimerHandle;

    sndCardsT *sndCards = (sndCardsT *) userData;

    if (revents & EPOLLERR) {
        AFB_ERROR("An error has been send by event loop polling, prevent new errors to be fired by deleting event src");

        sd_event_source_unref(src);

        afb_event_unref(sndCards->cardAdded->afbevt);
        afb_event_unref(sndCards->cardRemoved->afbevt);

        inotify_rm_watch(sndCards->cardAdded->fd, sndCards->cardAdded->wd);
        close(sndCards->cardAdded->fd);

        free(sndCards->cardAdded);
        free(sndCards->cardRemoved);

        sndCards->cardAdded = NULL;
        sndCards->cardRemoved = NULL;

        goto OnErrorExit;
    }

    if (revents & EPOLLIN) {
        length = read(fd, buffer, INOTIFY_EVENT_BUF_LEN);
        if (length < 0) {
            AFB_ERROR("Nothing read using inotify");
            goto OnErrorExit;
        }

        while (i < length) {
            event = (struct inotify_event *) &buffer[i];

            if(event->len &&
               (event->mask & IN_CREATE) &&
               ! (event->mask & IN_ISDIR) &&
               (asprintf(&createdFile, "%s/%s", DIR_TO_WATCH, event->name) > 0)) {
                createdFileHandle = calloc(1, sizeof(sndCardCardFileEventHandleT));
                createdFileHandle->createdFileName = strdup(createdFile);
                createdFileHandle->sndCards = sndCards;

                createdFileTimerHandle = calloc(1, sizeof(TimerHandleT));

                createdFileTimerHandle->uid = "sound card file creation delay";
                createdFileTimerHandle->count = 10;
                createdFileTimerHandle->delay = 2;

                TimerEvtStart(sndCards->apiHandle, createdFileTimerHandle, sndCardTimerForCreatedFileCB, (void *) createdFileHandle);
            }

            if(event->len && (event->mask & IN_DELETE) && ! (event->mask & IN_ISDIR))
                updateAllAlsaCardsAvailabilityAndFireEvents(sndCards);

            i += INOTIFY_EVENT_SIZE + event->len;
        }
    }

    return 0;

OnErrorExit:
    return -1;
}

// This routine is called when ALSA control events are fired
STATIC int sndCtlEventCB(sd_event_source* src, int fd, uint32_t revents, void* userData) {
    int err, ctlNumid;
    sndHandleT *sndHandle = (sndHandleT *) userData;
    ctrlEvtHandleT *evtHandle = (ctrlEvtHandleT*) sndHandle->evtHandle;
    snd_ctl_event_t *eventId;
    json_object *ctlEventJ;
    unsigned int mask;
    int iface;
    int device;
    int subdev;
    const char*ctlName;
    ctlRequestT ctlRequest;
    snd_ctl_elem_id_t *elemId;

    if ((revents & EPOLLERR) != 0) {
        AFB_ERROR("An error has been send by event loop polling, prevent new errors to be fired by deleting event src");
        sd_event_source_unref(src);
        afb_event_unref(sndHandle->evtHandle->afbevt);
        snd_ctl_close(sndHandle->evtHandle->ctlDev);
        free(sndHandle->evtHandle);
        sndHandle->evtHandle = NULL;
        goto OnErrorExit;
    }

    if ((revents & EPOLLHUP) != 0) {
        AFB_NOTICE("SndCtl hanghup [car disconnected]");
        goto ExitOnSucess;
    }

    if ((revents & EPOLLIN) != 0) {
        // initialise event structure on stack
        snd_ctl_event_alloca(&eventId);
        snd_ctl_elem_id_alloca(&elemId);

        err = snd_ctl_read(evtHandle->ctlDev, eventId);
        if (err < 0) goto OnErrorExit;

        // we only process sndctrl element
        if (snd_ctl_event_get_type(eventId) != SND_CTL_EVENT_ELEM) goto ExitOnSucess;

        // we only process value changed events
        mask = snd_ctl_event_elem_get_mask(eventId);
        if (!(mask & SND_CTL_EVENT_MASK_VALUE)) goto ExitOnSucess;

        snd_ctl_event_elem_get_id(eventId, elemId);

        err = alsaGetSingleCtl(evtHandle->ctlDev, elemId, &ctlRequest, evtHandle->mode);
        if (err) goto OnErrorExit;

        // If CTL as a value use it as container for response
        if (ctlRequest.valuesJ) ctlEventJ = ctlRequest.valuesJ;
        else {
            ctlEventJ = json_object_new_object();
            ctlNumid = snd_ctl_event_elem_get_numid(eventId);
            json_object_object_add(ctlEventJ, "id", json_object_new_int(ctlNumid));
        }

        if (evtHandle->mode >= QUERY_COMPACT) {
            ctlName = snd_ctl_event_elem_get_name(eventId);
            json_object_object_add(ctlEventJ, "name", json_object_new_string(ctlName));
        }

        if (evtHandle->mode >= QUERY_VERBOSE) {
            iface = snd_ctl_event_elem_get_interface(eventId);
            device = snd_ctl_event_elem_get_device(eventId);
            subdev = snd_ctl_event_elem_get_subdevice(eventId);
            json_object_object_add(ctlEventJ, "ifc", json_object_new_int(iface));
            json_object_object_add(ctlEventJ, "dev", json_object_new_int(device));
            json_object_object_add(ctlEventJ, "sub", json_object_new_int(subdev));
        }

        AFB_DEBUG("sndCtlEventCB=%s", json_object_get_string(ctlEventJ));
        afb_event_push(evtHandle->afbevt, ctlEventJ);
    }

ExitOnSucess:
    return 0;

OnErrorExit:
    AFB_WARNING("sndCtlEventCB: Error detected");
    return -1;
}

// Subscribe to each time a sound card is added/removed (using inotify '/dev/snd/by-path' events)
STATIC afb_event_t alsaEvtSubscribeSoundCardEvent(afb_req_t request, sndCardsT *sndCards, SubscriptionCardEventTypeT subscriptionType) {
    int fd = -1, wd = -1, err;

    // Update card list
    updateAllAlsaCardsAvailabilityAndFireEvents(sndCards);

    if (! sndCards->cardAdded && ! sndCards->cardRemoved) {
        fd = inotify_init();
        if (fd < 0) {
            afb_req_fail_f(request, "inotify-init", "Error %s happened while getting file descriptor for inotify", strerror(errno));
            goto OnErrorExit;
        }

        wd = inotify_add_watch(fd, DIR_TO_WATCH, IN_CREATE | IN_DELETE);
        if (wd < 0) {
            afb_req_fail_f(request,
                           "inotify-watch",
                           "Error %s happened while setting watchdog on '%s' directory using inotify",
                           strerror(errno),
                           DIR_TO_WATCH);
            goto OnErrorExit;
        }

        sndCards->cardAdded = malloc(sizeof (sndCardEvtHandleT));
        if (! sndCards->cardAdded) {
            afb_req_fail(request, "card-added-event", "Error while allocating card added event handle");
            goto OnErrorExit;
        }

        sndCards->cardRemoved = malloc(sizeof (sndCardEvtHandleT));
        if (! sndCards->cardRemoved) {
            afb_req_fail(request, "card-removed-event", "Error while allocating card removed event handle");
            goto OnErrorExit;
        }

        sndCards->cardAdded->fd = fd;
        sndCards->cardRemoved->fd = fd;

        sndCards->cardAdded->wd = wd;
        sndCards->cardRemoved->wd = wd;

        sndCards->cardAdded->afbevt = afb_daemon_make_event("soundcard-added");
        if (!afb_event_is_valid(sndCards->cardAdded->afbevt)) {
            afb_req_fail_f(request, "register-event", "Cannot register new binder event name=%s", "soundcard-added");
            goto OnErrorExit;
        }

        sndCards->cardRemoved->afbevt = afb_daemon_make_event("soundcard-removed");
        if (!afb_event_is_valid(sndCards->cardRemoved->afbevt)) {
            afb_req_fail_f(request, "register-event", "Cannot register new binder event name=%s", "soundcard-added");
            goto OnErrorExit;
        }

        // register sound event to binder main loop
        err = sd_event_add_io(afb_daemon_get_event_loop(),
                              &sndCards->cardAdded->src,
                              fd,
                              EPOLLIN,
                              sndCardEventCB,
                              sndCards);
        if (err < 0) {
            afb_req_fail_f(request, "register-mainloop", "Cannot hook sound card events to mainloop err=%d", err);
            goto OnErrorExit;
        }

        sndCards->cardRemoved->src = sndCards->cardAdded->src;
    }

    if(subscriptionType == SUBSCRIPTION_CARD_ADDED_EVENTS)
        return sndCards->cardAdded->afbevt;

    if(subscriptionType == SUBSCRIPTION_CARD_REMOVED_EVENTS)
        return sndCards->cardRemoved->afbevt;

    return NULL;

OnErrorExit:
    if(afb_event_is_valid(sndCards->cardRemoved->afbevt))
        afb_event_unref(sndCards->cardRemoved->afbevt);

    if(afb_event_is_valid(sndCards->cardAdded->afbevt))
        afb_event_unref(sndCards->cardAdded->afbevt);

    free(sndCards->cardRemoved);
    free(sndCards->cardAdded);

    if (wd != -1)
        inotify_rm_watch(fd, wd);

    if (fd != -1)
        close(fd);

    return NULL;
}

// Subscribe to every Alsa CtlEvent send by a given board
STATIC afb_event_t alsaEvtSubscribeAlsaControlEvent(afb_req_t request, sndCardsT *sndCards, queryValuesT *queryValues) {
    sndHandleT *currentSndHandle = NULL;
    snd_ctl_t *ctlDev = NULL;
    int err, cardId;
    snd_ctl_card_info_t *cardinfo;

    // open control interface for devid
    err = snd_ctl_open(&ctlDev, queryValues->devid, SND_CTL_READONLY);
    if (err < 0) {
        afb_req_fail_f(request, "devid-unknown", "SndCard devid=%s Not Found err=%s", queryValues->devid, snd_strerror(err));
        goto OnErrorExit;
    }

    snd_ctl_card_info_alloca(&cardinfo);
    err = snd_ctl_card_info(ctlDev, cardinfo);
    if (err < 0) {
        afb_req_fail_f(request, "devid-invalid", "SndCard devid=%s Not Found err=%s", queryValues->devid, snd_strerror(err));
        goto OnErrorExit;
    }

    cardId = snd_ctl_card_info_get_card(cardinfo);

    if(cardId < 0 || cardId >= MAX_SND_CARD) {
        afb_req_fail_f(request, "devid-invalid", "SndCard cardId=%i invalid", cardId);
        goto OnErrorExit;
    }

    currentSndHandle = &sndCards->sndHandles[cardId];

    // if not subscription exist for the event let's create one
    if (! currentSndHandle->evtHandle) {
        currentSndHandle->evtHandle = malloc(sizeof (ctrlEvtHandleT));
        currentSndHandle->evtHandle->ctlDev = ctlDev;
        currentSndHandle->evtHandle->mode = queryValues->mode;

        // subscribe for sndctl events attached to devid
        err = snd_ctl_subscribe_events(currentSndHandle->evtHandle->ctlDev, 1);
        if (err < 0) {
            afb_req_fail_f(request, "subscribe-fail", "Cannot subscribe events from devid=%s err=%d", queryValues->devid, err);
            goto OnErrorExit;
        }

        // get pollfd attach to this sound board
        snd_ctl_poll_descriptors(currentSndHandle->evtHandle->ctlDev, &currentSndHandle->evtHandle->pfds, 1);

        // register sound event to binder main loop
        err = sd_event_add_io(afb_daemon_get_event_loop(),
                              &currentSndHandle->evtHandle->src,
                              currentSndHandle->evtHandle->pfds.fd,
                              EPOLLIN,
                              sndCtlEventCB,
                              currentSndHandle);
        if (err < 0) {
            afb_req_fail_f(request, "register-mainloop", "Cannot hook events to mainloop devid=%s err=%d", queryValues->devid, err);
            goto OnErrorExit;
        }

        // create binder event attached to devid name
        currentSndHandle->evtHandle->afbevt = afb_daemon_make_event(queryValues->devid);
        if (!afb_event_is_valid(currentSndHandle->evtHandle->afbevt)) {
            afb_req_fail_f(request, "register-event", "Cannot register new binder event name=%s", queryValues->devid);
            goto OnErrorExit;
        }
    }
    else if (ctlDev) {
        snd_ctl_close(ctlDev);
    }

    return currentSndHandle->evtHandle->afbevt;

OnErrorExit:
    if (ctlDev)
        snd_ctl_close(ctlDev);

    return NULL;
}

// Subscribe to alsacore event
PUBLIC void alsaEvtSubcribe(afb_req_t request) {
    static sndCardsT *sndCards = NULL;
    afb_event_t eventToSubscribe;
    int err;
    queryValuesT queryValues;

    json_object *queryJ;

    if(! sndCards) {
        sndCards = calloc(1, sizeof(sndCardsT));
        sndCards->apiHandle = afb_req_get_api(request);
    }

    queryJ = alsaCheckQuery(request, &queryValues);
    if (!queryJ) return;

    if(! strcasecmp(queryValues.devid, "added"))
        eventToSubscribe = alsaEvtSubscribeSoundCardEvent(request, sndCards, SUBSCRIPTION_CARD_ADDED_EVENTS);
    else if(! strcasecmp(queryValues.devid, "removed"))
        eventToSubscribe = alsaEvtSubscribeSoundCardEvent(request, sndCards, SUBSCRIPTION_CARD_REMOVED_EVENTS);
    else
        eventToSubscribe = alsaEvtSubscribeAlsaControlEvent(request, sndCards, &queryValues);

    if(! eventToSubscribe)
        return;

    // subscribe to binder event
    err = afb_req_subscribe(request, eventToSubscribe);
    if (err) {
        afb_req_fail_f(request, "register-eventname", "Cannot subscribe binder event");
        return;
    }

    afb_req_success(request, NULL, NULL);
}

// Subscribe to every Alsa CtlEvent send by a given board

STATIC json_object *alsaProbeCardId(afb_req_t request) {
    char devid [32];
    const char *ctlName, *shortname, *longname, *mixername, *drivername;
    int done, mode, card, err, index, idx;
    json_object *responseJ, *tmpJ;
    snd_ctl_t *ctlDev;
    snd_ctl_card_info_t *cardinfo;

    json_object* queryJ = afb_req_json(request);
        
    done = json_object_object_get_ex(queryJ, "sndname", &tmpJ);
    if (!done || json_object_get_type(tmpJ) != json_type_string) {
        afb_req_fail_f(request, "argument-missing", "sndname=SndCardName missing");
        goto OnErrorExit;
    }
    const char *sndname = json_object_get_string(tmpJ);
    
    done = json_object_object_get_ex(queryJ, "mode", &tmpJ);
    if (!done) {
        mode = 0;
    } else {
        mode = json_object_get_int(tmpJ);        
    }
    

    // loop on potential card number
    snd_ctl_card_info_alloca(&cardinfo);
    char *driverId = NULL; // when not name match use drivername as backup plan
    for (card = 0; card < MAX_SND_CARD; card++) {

        // build card devid and probe it
        snprintf(devid, sizeof (devid), "hw:%i", card);

        // open control interface for devid
        err = snd_ctl_open(&ctlDev, devid, SND_CTL_READONLY);
        if (err < 0) continue;

        // extract sound card information
        snd_ctl_card_info(ctlDev, cardinfo);
        index = snd_ctl_card_info_get_card(cardinfo);
        ctlName = snd_ctl_card_info_get_id(cardinfo);
        shortname = snd_ctl_card_info_get_name(cardinfo);
        longname = snd_ctl_card_info_get_longname(cardinfo);
        mixername  = snd_ctl_card_info_get_mixername(cardinfo);
        drivername = snd_ctl_card_info_get_driver(cardinfo);

        snd_ctl_close(ctlDev);
        
        // check if short|long name match
        if (!strcasecmp(sndname, ctlName)) break;
        if (!strcasecmp(sndname, shortname)) break;
        
        // if name does not match search for a free HAL with driver name matching
        if (driverId==NULL && getHalIdxFromCardid(card)<0 && !strcasecmp(sndname, drivername)) driverId=strdup(devid);
    }

    if (card == MAX_SND_CARD) {
        if (!driverId) {
            afb_req_fail_f(request, "ctlDev-notfound", "Fail to find card with name=%s", sndname);
            goto OnErrorExit;
        } 
                
        // refresh devid and clean up driverId
        strncpy (devid, driverId, sizeof(devid));       
        free(driverId);
        
        err = snd_ctl_open(&ctlDev, devid, SND_CTL_READONLY);
        if (err < 0) {
            afb_req_fail_f(request, "ctlDev-notfound", "Fail to find card with name=%s devid=%s", sndname, devid);
            goto OnErrorExit;
        }

        // Sound not found by name, backup to driver name
        snd_ctl_card_info(ctlDev, cardinfo);
        index = snd_ctl_card_info_get_card(cardinfo);
        ctlName = snd_ctl_card_info_get_id(cardinfo);
        shortname = snd_ctl_card_info_get_name(cardinfo);
        longname = snd_ctl_card_info_get_longname(cardinfo);
        mixername  = snd_ctl_card_info_get_mixername(cardinfo);
        drivername = snd_ctl_card_info_get_driver(cardinfo);
        AFB_WARNING("alsaProbeCardId Fallback to HAL=%s ==> devid=%s name=%s long=%s\n ", drivername, devid, shortname, longname);
        snd_ctl_close(ctlDev);
    }

    // proxy ctlevent as a binder event
    responseJ = json_object_new_object();
    json_object_object_add(responseJ, "index", json_object_new_int(index));
    json_object_object_add(responseJ, "cardid", json_object_new_int(card));
    json_object_object_add(responseJ, "devid", json_object_new_string(devid));
    json_object_object_add(responseJ, "shortname", json_object_new_string(shortname));
    
    if (mode > 0) {
        json_object_object_add(responseJ, "longname", json_object_new_string(longname));
        json_object_object_add(responseJ, "mixername", json_object_new_string(mixername));
        json_object_object_add(responseJ, "drivername", json_object_new_string(drivername));
        
    }

    // search for a HAL binder card mapping name to api prefix
    for (idx = 0; (idx < MAX_SND_HAL && cardRegistry[idx]); idx++) {
        if (!strcmp(cardRegistry[idx]->shortname, shortname)) {
            json_object_object_add(responseJ, "halapi", json_object_new_string(cardRegistry[idx]->apiprefix));
            break;
        }
    }

    return responseJ;

OnErrorExit:
    return NULL;
}

// Make alsaProbeCardId compatible with AFB request

PUBLIC void alsaGetCardId(afb_req_t request) {

    json_object *responseJ = alsaProbeCardId(request);
    if (responseJ) afb_req_success(request, responseJ, NULL);
}


// Return HAL information about a given sound card ID

STATIC int getHalApiFromCardid(int cardid, json_object *responseJ) {

    
    int idx = getHalIdxFromCardid (cardid);
    if (idx < 0) goto OnErrorExit;
    
    json_object_object_add(responseJ, "api", json_object_new_string(cardRegistry[idx]->apiprefix));
    if (cardRegistry[idx]->shortname)json_object_object_add(responseJ, "shortname", json_object_new_string(cardRegistry[idx]->shortname));
    if (cardRegistry[idx]->longname) json_object_object_add(responseJ, "longname", json_object_new_string(cardRegistry[idx]->longname));

    return 0;

OnErrorExit:
    return -1;
}


// Return list of active resgistrated HAL with corresponding sndcard

PUBLIC void alsaActiveHal(afb_req_t request) {
    json_object *responseJ = json_object_new_array();

    for (int idx = 0; idx < MAX_SND_HAL; idx++) {
        if (!cardRegistry[idx]) break;

        json_object *haldevJ = json_object_new_object();
        json_object_object_add(haldevJ, "api", json_object_new_string(cardRegistry[idx]->apiprefix));
        if (cardRegistry[idx]->devid) json_object_object_add(haldevJ, "devid", json_object_new_string(cardRegistry[idx]->devid));
        if (cardRegistry[idx]->shortname)json_object_object_add(haldevJ, "shortname", json_object_new_string(cardRegistry[idx]->shortname));
        if (cardRegistry[idx]->drivername)json_object_object_add(haldevJ, "drivername", json_object_new_string(cardRegistry[idx]->drivername));
        if (cardRegistry[idx]->longname) json_object_object_add(haldevJ, "longname", json_object_new_string(cardRegistry[idx]->longname));
        json_object_array_add(responseJ, haldevJ);
    }

    afb_req_success(request, responseJ, NULL);
}


// Register loaded HAL with board Name and API prefix

PUBLIC void alsaRegisterHal(afb_req_t request) {
    static int index = 0;
    json_object *responseJ;
    const char *shortname, *apiPrefix;

    apiPrefix = afb_req_value(request, "prefix");
    if (apiPrefix == NULL) {
        afb_req_fail_f(request, "argument-missing", "prefix=BindingApiPrefix missing");
        goto OnErrorExit;
    }

    shortname = afb_req_value(request, "sndname");
    if (shortname == NULL) {
        afb_req_fail_f(request, "argument-missing", "sndname=SndCardName missing");
        goto OnErrorExit;
    }

    if (index == MAX_SND_HAL) {
        afb_req_fail_f(request, "alsahal-toomany", "Fail to register sndname=[%s]", shortname);
        goto OnErrorExit;
    }

    // alsaGetCardId should be check to register only valid card
    responseJ = alsaProbeCardId(request);
    if (responseJ) {
        json_object *tmpJ;
        int done;

        cardRegistry[index] = malloc(sizeof (cardRegistry));
        cardRegistry[index]->apiprefix = strdup(apiPrefix);
        cardRegistry[index]->shortname = strdup(shortname);
        
        json_object_object_get_ex(responseJ, "cardid", &tmpJ);
        cardRegistry[index]->cardid = json_object_get_int(tmpJ);

        done = json_object_object_get_ex(responseJ, "devid", &tmpJ);
        if (done) cardRegistry[index]->devid = strdup(json_object_get_string(tmpJ));
        else cardRegistry[index]->devid = NULL;

        done = json_object_object_get_ex(responseJ, "drivername", &tmpJ);
        if (done) cardRegistry[index]->drivername = strdup(json_object_get_string(tmpJ));
        else cardRegistry[index]->drivername = NULL;

        done = json_object_object_get_ex(responseJ, "longname", &tmpJ);
        if (done) cardRegistry[index]->longname = strdup(json_object_get_string(tmpJ));
        else cardRegistry[index]->longname = NULL;

        // make sure register close with a null value
        index++;
        cardRegistry[index] = NULL;

        afb_req_success(request, responseJ, NULL);
    }

    // If OK return sound card Alsa ID+Info
    return;

OnErrorExit:
    return;
}

PUBLIC void alsaPcmInfo (afb_req_t request) {
    int done, mode, err;
    json_object *tmpJ, *responseJ = NULL;
    snd_pcm_t *pcmHandle = NULL;
    snd_pcm_info_t * pcmInfo = NULL;
    
    json_object* queryJ = afb_req_json(request);
    
    done = json_object_object_get_ex(queryJ, "name", &tmpJ);
    if (!done || json_object_get_type(tmpJ) != json_type_string) {
        afb_req_fail_f(request, "name:invalid", "PCM 'name:xxx' missing or not a string query='%s'", json_object_get_string(queryJ));
        goto OnErrorExit;
    }
    const char *pcmName = json_object_get_string(tmpJ);
    
    done = json_object_object_get_ex(queryJ, "stream", &tmpJ);
    if (done && json_object_get_type(tmpJ) != json_type_int) {
        afb_req_fail_f(request, "stream:invalid", "PCM 'stream:SND_PCM_STREAM_PLAYBACK/SND_PCM_STREAM_CAPTURE' should be integer query='%s'", json_object_get_string(queryJ));
        goto OnErrorExit;
    }
    snd_pcm_stream_t pcmStream = json_object_get_int(tmpJ);
    
    done = json_object_object_get_ex(queryJ, "mode", &tmpJ);
    if (!done) {
        mode = 0;
    } else {
        mode = json_object_get_int(tmpJ);        
    }
    
    // open PCM from its name
    err= snd_pcm_open(&pcmHandle, pcmName, pcmStream, 0);
    if (err < 0) {
        afb_req_fail_f(request, "pcm:invalid", "PCM 'name:%s' does cannot open error=%s", pcmName, snd_strerror(err));
        goto OnErrorExit;
    }
    
    // get pcm info
    snd_pcm_info_alloca(&pcmInfo);      
    err = snd_pcm_info(pcmHandle,pcmInfo);
    if (err < 0)  {
        afb_req_fail_f(request, "pcm:error", "PCM 'name:%s' fail to retrieve info error=%s", pcmName, snd_strerror(err));
        goto OnErrorExit;
    }

    // get sub-device number
    int cardId = snd_pcm_info_get_card(pcmInfo);
    if (cardId < 0 )   {
        afb_req_fail_f(request, "pcm:error", "PCM 'name:%s' fail to retrieve sndcard device error=%s", pcmName, snd_strerror(cardId));
        goto OnErrorExit;
    }
    
    // prepare an object for response
    responseJ = json_object_new_object();
    
    err = getHalApiFromCardid (cardId, responseJ);
    if (err < 0 )   {
        afb_req_fail_f(request, "pcm:error", "PCM 'name:%s' snddev=hw:%d fail to retrieve hal API", pcmName, cardId);
        goto OnErrorExit;
    }

    json_object_object_add(responseJ, "type", json_object_new_int(snd_pcm_type(pcmHandle)));

    // in mode mode we return full info about PCM
    if (mode > 0) {
        json_object_object_add(responseJ, "stream", json_object_new_int(snd_pcm_info_get_stream (pcmInfo)));
        json_object_object_add(responseJ, "cardid", json_object_new_int(snd_pcm_info_get_card(pcmInfo)));      
        json_object_object_add(responseJ, "devid" , json_object_new_int(snd_pcm_info_get_device (pcmInfo)));     
        json_object_object_add(responseJ, "subid" , json_object_new_int(snd_pcm_info_get_subdevice (pcmInfo)));     
    }
    
    // in super mode we also return information about snd card
    if (mode > 1) {
        
        json_object_object_add(responseJ, "id"     , json_object_new_string(snd_pcm_info_get_id (pcmInfo)));
        json_object_object_add(responseJ, "name"   , json_object_new_string(snd_pcm_info_get_name (pcmInfo)));
        json_object_object_add(responseJ, "subdev" , json_object_new_string(snd_pcm_info_get_subdevice_name (pcmInfo)));       
    }
    
    afb_req_success(request, responseJ, NULL);
    snd_pcm_close (pcmHandle);
    return;
    
OnErrorExit:
    if (responseJ) json_object_put (responseJ);
    if (pcmHandle) snd_pcm_close (pcmHandle);
    return;
}