Add events when ALSA card are added/removed

Add 'soundcard-added'/'soundcard-removed' application framework
events to be notified when ALSA card are added/removed.

Use subscribe verb and json '{ "devid" : "added" }' to subscribe
to added card events.
Use subscribe verb and json '{ "devid" : "removed" }' to subscribe
to removed card events.

Bug-AGL: SPEC-2749

Change-Id: Ia021d7f6984b2263a5011121a69f17bb4ee2bf9e
Signed-off-by: Jonathan Aillet <jonathan.aillet@iot.bzh>

1 files changed, 271 insertions, 2 deletions

diff --git a/alsa-binding/Alsa-RegEvt.c b/alsa-binding/Alsa-RegEvt.c
index c9ac5f1..28b66b1 100644
--- a/alsa-binding/Alsa-RegEvt.c
+++ b/alsa-binding/Alsa-RegEvt.c
@@ -18,14 +18,35 @@
 
 #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
 
-// generic sndctrl event handle hook to event callback when pooling
+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;
@@ -35,14 +56,23 @@ typedef struct {
 } 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;
@@ -88,6 +118,144 @@ 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) {
@@ -173,6 +341,101 @@ OnErrorExit:
     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) {
@@ -263,12 +526,18 @@ PUBLIC void alsaEvtSubcribe(afb_req_t request) {
 
     if(! sndCards) {
         sndCards = calloc(1, sizeof(sndCardsT));
+        sndCards->apiHandle = afb_req_get_api(request);
     }
 
     queryJ = alsaCheckQuery(request, &queryValues);
     if (!queryJ) return;
 
-    eventToSubscribe = alsaEvtSubscribeAlsaControlEvent(request, sndCards, &queryValues);
+    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;