Move to support Audio-4a High Level API

3 files changed, 889 insertions, 0 deletions

diff --git a/alsa-hook/CMakeLists.txt b/alsa-hook/CMakeLists.txt
new file mode 100644
index 0000000..5f3cc6d
--- /dev/null
+++ b/alsa-hook/CMakeLists.txt
@@ -0,0 +1,38 @@
+###########################################################################
+# Copyright 2015, 2016, 2017 IoT.bzh
+#
+# author: 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.
+###########################################################################
+
+# Activate ALSA  dynamic build build mode get resolve "snd_dlsym_start"
+add_compile_options(-DPIC)
+
+PROJECT_TARGET_ADD(policy_alsa_hook)
+
+    # Define targets
+    ADD_LIBRARY(${TARGET_NAME} MODULE PolicyAlsaHook.c)
+
+    # Alsa Plugin properties
+    SET_TARGET_PROPERTIES(${TARGET_NAME} PROPERTIES
+	PREFIX ""
+        OUTPUT_NAME ${TARGET_NAME}
+    )
+
+    # Library dependencies (include updates automatically)
+    TARGET_LINK_LIBRARIES(${TARGET_NAME}
+        ${link_libraries}
+    )
+    install(TARGETS ${TARGET_NAME} LIBRARY DESTINATION lib)
+
diff --git a/alsa-hook/PolicyAlsaHook.c b/alsa-hook/PolicyAlsaHook.c
new file mode 100644
index 0000000..5e63825
--- /dev/null
+++ b/alsa-hook/PolicyAlsaHook.c
@@ -0,0 +1,640 @@
+/*
+ * Copyright (C) 2016 "IoT.bzh"
+ * Author 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.
+ *
+ * AfbCallBack (snd_ctl_hal_t *handle, int numid, void **response);
+ *  AlsaHookInit is mandatory and called with numid=0
+ *
+ * Syntax in .asoundrc file
+ *   CrlLabel    { cb MyFunctionName name "My_Second_Control" }
+ *
+ * Testing:
+ *   aplay -DAlsaHook /usr/share/sounds/alsa/test.wav
+ *
+ * References:
+ *  https://www.spinics.net/lists/alsa-devel/msg54235.html
+ *  https://github.com/shivdasgujare/utilities/blob/master/nexuss/alsa-scenario-hook/src/alsa-wrapper.c
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <alloca.h>
+
+#include <alsa/asoundlib.h>
+#include <alsa/conf.h>
+#include <alsa/pcm.h>
+
+#include <systemd/sd-event.h>
+#include <json-c/json.h>
+
+#include "afb/afb-wsj1.h"
+#include "afb/afb-ws-client.h"
+#include "afb/afb-proto-ws.h"
+
+#include <pthread.h>
+#include <semaphore.h>
+
+#define PLUGIN_ENTRY_POINT AlsaInstallHook
+    // Fulup Note: What ever you may find on Internet you should use
+    // SND_CONFIG_DLSYM_VERSION_HOOK and not SND_CONFIG_DLSYM_VERSION_HOOK
+    SND_DLSYM_BUILD_VERSION(PLUGIN_ENTRY_POINT, SND_PCM_DLSYM_VERSION)
+
+// this should be more than enough
+#define MAX_API_CALL 10
+#define MAX_EVT_CALL 10
+
+// timeout in ms
+#define REQUEST_DEFAULT_TIMEOUT 500
+#ifndef MAINLOOP_WATCHDOG
+#define MAINLOOP_WATCHDOG 100000
+#endif
+
+// closing message is added to query when PCM is closed
+#define CLOSING_MSG ",\"source\":-1}"
+
+// Currently not implemented
+#define UNUSED_ARG(x) UNUSED_ ## x __attribute__((__unused__))
+   
+typedef struct {
+    const char *apiverb;
+    json_object *queryJ;
+    sd_event_source *evtSource;
+    char *callIdTag;
+    void *afbClient;
+} afbRequestT;
+
+typedef struct {
+    const char *search;
+    const char *value;
+    int signal;
+} afbEventT;
+
+typedef struct {
+    char *name;
+    const char *api;
+    char *uid;
+    snd_pcm_t *pcm;
+    const char *uri;
+    struct afb_proto_ws *pws;
+    sd_event *sdLoop;
+    int verbose;
+    int synchronous;
+    sem_t semaphore;
+    long timeout;
+    int count;
+    int error;
+    afbRequestT **request;
+    afbRequestT **release;
+    afbEventT **event;
+} afbClientT;
+
+
+static void *LoopInThread(void *handle) {
+    afbClientT *afbClient = (afbClientT*) handle;
+    int count=0;
+    int watchdog= MAINLOOP_WATCHDOG *1000;
+
+    /* loop until end */
+    for (;;) {
+
+        if (afbClient->verbose) printf("ON-MAINLOOP ping=%d\n", count++);
+        sd_event_run(afbClient->sdLoop, watchdog);
+    }
+
+    return NULL;
+}
+
+// lost connect with the AudioDaemon
+static void OnHangupCB(void *handle) {
+
+    afbClientT *afbClient = (afbClientT*) handle;
+    SNDERR("(Hoops) Lost Connection to %s", afbClient->uri);
+
+    // try to close PCM when impossible terminate client
+    int err = snd_pcm_close (afbClient->pcm);
+    if (err) exit(1);
+}
+
+typedef enum {
+    HOOK_INSTALL,
+    HOOK_CLOSE,
+} hookActionT;
+
+void OnEventCB(void *handle, const char *event, int evtid, struct json_object *dataJ) {
+    afbClientT *afbClient = (afbClientT*) handle;
+    afbEventT **afbEvent = afbClient->event;
+    json_object *tmpJ;
+    int done;
+    
+    // if no event handler just ignore events
+    if (!afbEvent) goto OnErrorExit;
+
+    if (afbClient->verbose) printf("ON-EVENT processing signal event=%s search=%s\n", event, json_object_get_string(dataJ));
+
+    // loop on event/signal mapping table
+    for (int index=0; afbEvent[index]!= NULL; index++) {
+        done = json_object_object_get_ex(dataJ,afbEvent[index]->search, &tmpJ);
+        if (done) {
+            const char *value=json_object_get_string(tmpJ);
+            if (!strcmp(afbEvent[index]->value, value)) {
+                if (afbEvent[index]->signal) 
+                    if (afbClient->verbose) printf("ON-EVENT search=%s value=%s signal=%d\n", afbEvent[index]->search, value, afbEvent[index]->signal);
+                    if (afbEvent[index]->signal) kill (getpid(), afbEvent[index]->signal);
+            }
+        }
+    }
+    
+    return;
+
+OnErrorExit:
+    if (afbClient->verbose) SNDERR("ON-EVENT Fail/Ignored %s(%s)\n", event, json_object_get_string(dataJ));
+    return;
+}
+
+static void OnSuccessCB(void* UNUSED_ARG(ctx) , void* handle, json_object* responseJ, const char* info) {
+    
+    afbRequestT *afbRequest= (afbRequestT*)handle;
+    afbClientT *afbClient=(afbClientT*)afbRequest->afbClient;
+
+    if (afbClient->verbose) printf("OnSuccessCB callid='%s' response='%s' info='%s'\n", afbRequest->callIdTag, json_object_get_string(responseJ), info);
+
+    // Cancel timeout for this request
+    sd_event_source_unref(afbRequest->evtSource);
+    free(afbRequest->callIdTag);
+    
+    // When not more waiting call release semaphore
+    afbClient->count--;
+    if (afbClient->synchronous) {
+        if (afbClient->verbose) printf("OnSuccessCB One Request Done\n");
+        sem_post (&afbClient->semaphore);
+        afbClient->error=0;
+    } else if (afbClient->count == 0) {
+        if (afbClient->verbose) printf("OnSuccessCB No More Waiting Request\n");
+        sem_post (&afbClient->semaphore);
+    }
+}
+
+static void OnFailureCB(void* UNUSED_ARG(ctx), void* handle, const char *status, const char *info) {
+    
+    afbRequestT *afbRequest= (afbRequestT*)handle;
+    afbClientT *afbClient=(afbClientT*)afbRequest->afbClient;
+
+    if (afbClient->verbose) printf("OnFailureCB callid='%s' status='%s' info='%s'\n", afbRequest->callIdTag, status, info);
+
+    // Cancel timeout for this request
+    sd_event_source_unref(afbRequest->evtSource);
+    free(afbRequest->callIdTag);
+
+    afbClient->error=1;
+    sem_post (&afbClient->semaphore);
+}
+
+
+/* the callback interface for pws */
+static struct afb_proto_ws_client_itf itf = {
+    .on_reply_success = OnSuccessCB,
+    .on_reply_fail = OnFailureCB,
+    .on_event_create = NULL,
+    .on_event_remove = NULL,
+    .on_event_subscribe = NULL,
+    .on_event_unsubscribe = NULL,
+    .on_event_push = OnEventCB,
+    .on_event_broadcast = NULL,
+    .on_subcall = NULL,
+};
+
+int OnTimeoutCB (sd_event_source* source, uint64_t timer, void* handle) {
+    afbClientT *afbClient= (afbClientT*)handle;
+
+    SNDERR("\nON-TIMEOUT Call Request Fail URI=%s\n", afbClient->uri);
+
+    // Close PCM and release waiting client
+    afbClient->error=1;
+    sem_post (&afbClient->semaphore);
+
+    return 0;
+}
+
+// Call AGL binder asynchronously by with a timeout
+static int CallWithTimeout(afbClientT *afbClient, afbRequestT *afbRequest, int count) {
+    uint64_t usec;
+    int err;
+
+    // create a unique tag for request
+    (void) asprintf(&afbRequest->callIdTag, "%d:%s", count, afbRequest->apiverb);
+
+    // create a timer with ~250us accuracy
+    sd_event_now(afbClient->sdLoop, CLOCK_MONOTONIC, &usec);
+    sd_event_add_time(afbClient->sdLoop, &afbRequest->evtSource, CLOCK_MONOTONIC, usec+afbClient->timeout*1000, 250, OnTimeoutCB, afbClient);
+
+    // release action is optional
+    if (afbRequest->apiverb) {
+        if (afbClient->verbose) printf("CALL-REQUEST verb=%s tag=%s\n", afbRequest->apiverb, afbRequest->callIdTag);
+        err = afb_proto_ws_client_call(afbClient->pws, afbRequest->apiverb, afbRequest->queryJ, afbClient->uid, afbRequest);
+        if (err < 0 ) goto OnErrorExit;        
+    }
+    
+    // save client handle in request
+    afbRequest->afbClient = afbClient;    
+    afbClient->count ++;
+    
+    // in synchronous mode we wait for CB to return
+    if (afbClient->synchronous) sem_wait(&afbClient->semaphore);
+
+    return 0;
+
+OnErrorExit:
+    fprintf(stderr, "LaunchCallRequest: Fail call %s//%s&%s", afbClient->uri, afbRequest->apiverb, json_object_get_string(afbRequest->queryJ));
+    return 1;
+}
+
+static int LaunchCallRequest(afbClientT *afbClient, hookActionT action) {
+
+    pthread_t tid;
+    int err, idx;
+
+    switch (action) {
+        case HOOK_INSTALL: {
+
+            // init waiting counting semaphore
+            if (sem_init(&afbClient->semaphore, 1, 0) == -1) {
+               fprintf(stderr, "LaunchCallRequest: Fail Semaphore Init: %s\n", afbClient->uri);
+            }
+
+            // Create a main loop
+            err = sd_event_default(&afbClient->sdLoop);
+            if (err < 0) {
+                fprintf(stderr, "LaunchCallRequest: Connection to default event loop failed: %s\n", strerror(-err));
+                goto OnErrorExit;
+            }
+
+            // start a thread with a mainloop to monitor Audio-Agent
+            err = pthread_create(&tid, NULL, &LoopInThread, afbClient);
+            if (err) goto OnErrorExit;
+
+            afbClient->pws = afb_ws_client_connect_api(afbClient->sdLoop, afbClient->uri, &itf, afbClient);
+            if (afbClient->pws == NULL) {
+                fprintf(stderr, "LaunchCallRequest: Connection to %s failed\n", afbClient->uri);
+                goto OnErrorExit;
+            }
+
+            // register hanghup callback
+            afb_proto_ws_on_hangup(afbClient->pws, OnHangupCB);
+
+
+            // If no request exit now
+            if (!afbClient->release) {
+                fprintf(stderr, "LaunchCallRequest: HOOK_INSTALL:fatal mandatory request call missing in asoundrc\n");
+                goto OnErrorExit;;
+            }
+            
+            // send call request to audio-agent asynchronously (respond with thread mainloop context)
+            for (idx = 0; afbClient->request[idx] != NULL; idx++) {
+                err = CallWithTimeout(afbClient, afbClient->request[idx], idx);
+                if (err) goto OnErrorExit;
+            }
+            // launch counter to keep track of waiting request call
+            afbClient->count=idx;        
+            break;
+        }
+        
+        case HOOK_CLOSE: {
+            
+            // If no request exit now
+            if (!afbClient->release) {
+                if (afbClient->verbose) printf("LaunchCallRequest:optional HOOK_CLOSE no release control call\n");
+                break;
+            }
+
+            // send call request to audio-agent asynchronously (respond with thread mainloop context)
+            for (idx = 0; afbClient->release[idx] != NULL; idx++) {
+                err = CallWithTimeout(afbClient, afbClient->release[idx], idx);
+                if (err) goto OnErrorExit;
+            }
+            // launch counter to keep track of waiting request call
+            afbClient->count=idx;        
+            break;
+        }
+        
+    default:
+       fprintf(stderr, "LaunchCallRequest (hoops): Unknown action"); 
+       goto OnErrorExit;
+    }
+    
+    return 0;
+
+OnErrorExit:
+    return -1;
+}
+
+static int AlsaCloseHook(snd_pcm_hook_t *hook) {
+
+    afbClientT *afbClient = (afbClientT*) snd_pcm_hook_get_private (hook);
+
+    // launch call request and create a waiting mainloop thread
+    int err = LaunchCallRequest(afbClient, HOOK_CLOSE);
+    if (err < 0) {
+        fprintf (stderr, "PCM Fail to Enter Mainloop\n");
+        goto OnErrorExit;
+    }
+
+    // wait for all call request to return
+    if (!afbClient->synchronous) sem_wait(&afbClient->semaphore);
+    if (afbClient->error) {
+        fprintf (stderr, "AlsaCloseHook: Notice exit before audio-4a response\n");
+        goto OnErrorExit;
+    }
+
+    if (afbClient->verbose) fprintf(stdout, "\nAlsaHook Close Success PCM=%s URI=%s\n", snd_pcm_name(afbClient->pcm), afbClient->uri);
+    return 0;
+
+OnErrorExit:
+    fprintf(stderr, "\nAlsaPcmHook Plugin Close Fail PCM=%s\n", snd_pcm_name(afbClient->pcm));
+    return 0;
+}
+
+// Get an asoundrc compound and return it as a JSON object
+static json_object* AlsaGetJson (snd_config_t *ctlconfig, const char *id, const char*label) {
+    
+    json_object *queryJ;
+    snd_config_type_t ctype;
+    char* query;
+    
+    // each control is a sting that contain a json object
+    ctype = snd_config_get_type(ctlconfig);
+    snd_config_get_string(ctlconfig,  (const char**) &query);
+    if (ctype != SND_CONFIG_TYPE_STRING) {
+        SNDERR("Invalid signal number for %s value=%s", label, query);
+        goto OnErrorExit;
+    }
+
+    // cleanup string for json_tokener
+    for (int idx = 0; query[idx] != '\0'; idx++) {
+        if (query[idx] == '\'') query[idx] = '"';
+    }
+    queryJ = json_tokener_parse(query);
+    if (!queryJ) {
+        SNDERR("Not a valid Json object control='%s' query='%s'", id, query);
+        goto OnErrorExit;
+    }
+    
+    return queryJ;
+    
+OnErrorExit:
+    return NULL;
+}
+
+static int AlsaGetActions (snd_config_t *node, afbRequestT **afbRequest, const char*id) {
+    const char *callConf, *apiverb;
+    snd_config_type_t ctype;
+    snd_config_iterator_t currentCall, follow;
+    int callCount=0;
+
+    ctype = snd_config_get_type(node);
+    if (ctype != SND_CONFIG_TYPE_COMPOUND) {
+        snd_config_get_string(node, &callConf);
+        SNDERR("Invalid compound type for %s", callConf);
+        goto OnErrorExit;
+    }
+
+
+    // loop on each call
+    snd_config_for_each(currentCall, follow, node) {
+        snd_config_t *ctlconfig = snd_config_iterator_entry(currentCall);
+
+        // ignore empty line
+        if (snd_config_get_id(ctlconfig, &apiverb) < 0) continue;
+
+        // allocate an empty call request
+        afbRequest[callCount] = calloc(1, sizeof (afbRequestT));
+        afbRequest[callCount]->apiverb=strdup(apiverb);
+        afbRequest[callCount]->queryJ= AlsaGetJson(ctlconfig, id, apiverb);
+        if (!afbRequest[callCount]->queryJ) goto OnErrorExit;
+
+        // move to next call if any
+        callCount ++;
+        if (callCount == MAX_EVT_CALL) {
+            SNDERR("Too Many call MAX_EVT_CALL=%d", MAX_EVT_CALL);
+            goto OnErrorExit;
+        }
+        afbRequest[callCount]=NULL; // afbEvent array is NULL terminated
+    }
+    
+    return 0;
+
+OnErrorExit:
+    return 1;
+}
+
+static int AlsaGetEvents (snd_config_t *node, afbEventT **afbEvent, const char*id) {
+
+    const char *confEvents, *evtpattern;
+    snd_config_type_t ctype;
+    snd_config_iterator_t currentEvt, follow;
+    snd_config_t *itemConf;
+    int callCount=0;
+    int err;
+
+    ctype = snd_config_get_type(node);
+    if (ctype != SND_CONFIG_TYPE_COMPOUND) {
+        snd_config_get_string(node, &confEvents);
+        SNDERR("Invalid compound type for %s", confEvents);
+        goto OnErrorExit;
+    }
+
+    // loop on each call
+    snd_config_for_each(currentEvt, follow, node) {
+        snd_config_t *ctlconfig = snd_config_iterator_entry(currentEvt);
+
+        // ignore empty line
+        if (snd_config_get_id(ctlconfig, &evtpattern) < 0) continue;
+
+        // allocate an empty call request
+        afbEvent[callCount] = calloc(1, sizeof (afbEventT));
+
+        // extract signal num from config label
+        for (int idx=0; evtpattern[idx] != '\0'; idx++) {
+            if (evtpattern[idx]=='-' && evtpattern[idx+1] != '\0') {
+                int done= sscanf (&evtpattern[idx+1], "%d",&afbEvent[callCount]->signal);
+                if (done != 1) {
+                    SNDERR("Invalid Signal '%s' definition should be something like Sig-xx", evtpattern);
+                    goto OnErrorExit;
+                }
+                break;
+            }
+        }
+
+        // extract signal key value search pattern
+        ctype = snd_config_get_type(ctlconfig);
+        if (ctype != SND_CONFIG_TYPE_COMPOUND) {
+            snd_config_get_string(ctlconfig, &confEvents);
+            SNDERR("Invalid event search pattern for %s value=%s", evtpattern, confEvents);
+            goto OnErrorExit;
+        }
+
+        // pattern should have a search
+        err = snd_config_search(ctlconfig, "search", &itemConf);
+        if (!err) {
+            const char *search;
+            if (snd_config_get_string(itemConf, &search) < 0) {
+                SNDERR("Invalid event/signal 'search' should be a string %s", confEvents);
+                goto OnErrorExit;
+            }
+            afbEvent[callCount]->search=strdup(search);
+        } else {
+            SNDERR("Missing 'search' from event/signal 'search' from signal definition %s", confEvents);
+            goto OnErrorExit;                    
+        }
+
+        // pattern should have a value
+        err = snd_config_search(ctlconfig, "value", &itemConf);
+        if (!err) {
+            const char *value;
+            if (snd_config_get_string(itemConf, &value) < 0) {
+                SNDERR("Invalid event/signal 'value' should be a string %s", confEvents);
+                goto OnErrorExit;
+            }
+            afbEvent[callCount]->value=strdup(value);
+        } else {
+            SNDERR("Missing 'value' from event/signal 'value' from signal definition %s", confEvents);
+            goto OnErrorExit;                    
+        }
+
+
+        // move to next call if any
+        callCount ++;
+        if (callCount == MAX_EVT_CALL) {
+            SNDERR("Too Many call MAX_EVT_CALL=%d", MAX_EVT_CALL);
+            goto OnErrorExit;
+        }
+        afbEvent[callCount]=NULL; // afbEvent array is NULL terminated
+    }
+    return 0;
+
+OnErrorExit:
+    return 1;
+}
+
+// Function call when Plugin PCM is OPEN
+int PLUGIN_ENTRY_POINT (snd_pcm_t *pcm, snd_config_t *conf) {
+    snd_pcm_hook_t *h_close = NULL;
+    snd_config_iterator_t it, next;
+    afbClientT *afbClient = malloc(sizeof (afbClientT));
+    int err;
+
+    // start populating client handle
+    afbClient->pcm = pcm;
+    afbClient->name= strdup(snd_pcm_name(pcm));
+    afbClient->verbose = 0;
+    (void) asprintf(&afbClient->uid, "alsa-hook-pid:%d", getpid());
+
+    
+    // Get PCM arguments from asoundrc
+    snd_config_for_each(it, next, conf) {
+        snd_config_t *node = snd_config_iterator_entry(it);
+        const char *id;
+
+        // ignore comment en empty lines
+        if (snd_config_get_id(node, &id) < 0) continue;
+        if (strcmp(id, "comment") == 0 || strcmp(id, "hint") == 0) continue;
+
+        if (strcmp(id, "uri") == 0) {
+            const char *uri;
+            if (snd_config_get_string(node, &uri) < 0) {
+                SNDERR("Invalid String for %s", id);
+                goto OnErrorExit;
+            }
+            afbClient->uri=strdup(uri);
+            continue;
+        }
+
+        if (strcmp(id, "verbose") == 0) {
+            afbClient->verbose= snd_config_get_bool(node);
+            if (afbClient->verbose < 0) {
+                SNDERR("Invalid Boolean for %s", id);
+                goto OnErrorExit;
+            }
+            continue;
+        }
+        
+        if (strcmp(id, "synchronous") == 0) {
+            afbClient->synchronous= snd_config_get_bool(node);
+            if (afbClient->synchronous < 0) {
+                SNDERR("Invalid Boolean for %s", id);
+                goto OnErrorExit;
+            }
+            continue;
+        }
+        
+        if (strcmp(id, "timeout") == 0) {
+            if (snd_config_get_integer(node, &afbClient->timeout) < 0) {
+                SNDERR("Invalid timeout Integer %s", id);
+                goto OnErrorExit;
+            }
+            continue;
+        }
+        
+        if (strcmp(id, "request") == 0) {
+            afbClient->request =  malloc(MAX_API_CALL * sizeof(afbRequestT*));;
+            int err= AlsaGetActions(node, afbClient->request , id);
+            if (err) goto OnErrorExit;
+            continue;
+        }
+                
+        if (strcmp(id, "release") == 0) {
+            afbClient->release =  malloc(MAX_API_CALL * sizeof(afbRequestT*));;
+            int err= AlsaGetActions(node, afbClient->release, id);
+            if (err) goto OnErrorExit;
+            continue;
+        }
+        
+        if (strcmp(id, "events") == 0) {
+            afbClient->event=  malloc(MAX_API_CALL * sizeof(afbRequestT*));;
+            int err= AlsaGetEvents(node, afbClient->event, id);
+            if (err) goto OnErrorExit;
+            continue;
+        }
+    }
+
+    if (afbClient->verbose) fprintf(stdout, "\nAlsaHook Install Start PCM=%s URI=%s\n", snd_pcm_name(afbClient->pcm), afbClient->uri);
+
+    err = snd_pcm_hook_add(&h_close, afbClient->pcm, SND_PCM_HOOK_TYPE_CLOSE, AlsaCloseHook, afbClient);
+    if (err < 0) goto OnErrorExit;
+
+    // launch call request and create a waiting mainloop thread
+    err = LaunchCallRequest(afbClient, HOOK_INSTALL);
+    if (err < 0) {
+        fprintf (stderr, "PCM Fail to Enter Mainloop\n");
+        goto OnErrorExit;
+    }
+
+    // wait for all call request to return
+    if (!afbClient->synchronous) sem_wait(&afbClient->semaphore);
+    if (afbClient->error) {
+        fprintf (stderr, "PCM Authorisation Deny from AAAA Controller (AGL Advanced Audio Agent)\n");
+        goto OnErrorExit;
+    }
+
+    if (afbClient->verbose) fprintf(stdout, "\nAlsaHook Install Success PCM=%s URI=%s\n", afbClient->name, afbClient->uri);
+    return 0;
+
+OnErrorExit:
+    fprintf(stderr, "\nAlsaPcmHook Plugin Policy Control Fail PCM=%s\n", afbClient->name);
+    if (h_close)
+        snd_pcm_hook_remove(h_close);
+
+    return -EINVAL;
+}
+
diff --git a/alsa-hook/README.md b/alsa-hook/README.md
new file mode 100644
index 0000000..a51ec19
--- /dev/null
+++ b/alsa-hook/README.md
@@ -0,0 +1,211 @@
+Alsa-Hook-Plugin
+
+Object: Provide a Hook on Alsa PCM to check permission again AGL Advance Audio Agent
+Status: Release Candidate
+Author: Fulup Ar Foll fulup@iot.bzh
+Date  : August-2017
+ References: https://www.spinics.net/lists/alsa-devel/msg54235.html
+
+
+## Functionalities:
+ - Execute a set of unix/ws RPC request again AGL binders to allow/deny access
+ - Keep websocket open in an idependant thread in order to monitor event received from AGL audio agent
+
+## Installation
+ - Alsaplugins are typically search in /usr/share/alsa-lib. Nevertheless a full path might be given
+ - This plugin implement a hook on a slave PCM. Typically this slave PCM is a dedicated virtual channel (eg: navigation, emergency,...)
+ - Config should be place in ~/.asoundrc (see config sample in PROJECT_ROOT/conf.d/alsa)
+
+## Test
+ - Install a full .asoundrc from conf.d/project/alsa.d
+ - Check SoundCard ==> speaker-test -Dhw:v1340   -c2 -twav
+ - Check MixerPCM  ==> speaker-test -DSpeakers   -c2 -twav 
+ - Check SoftVol   ==> speaker-test -DMusicPCM   -c2 -twav 
+ - Check Plugin    ==> speaker-test -DMultimedia -c2 -twav
+ - Check MultiMedia aplay -DDMyNavPCM /usr/share/sounds/alsa/test.wav
+
+
+## Pulse audio integration
+
+By default Pulse only auto detect hardware sound card and virtual channel should be specified
+
+    1) update ~/.asoundrc file and check basic ALSA virtual channel works as expected
+    2) kill/restart pulseaudio server to force alsa hookplugin loading
+    3) declare alsa virtual channel as pulse sink
+       - pacmd load-module module-alsa-sink device=MusicPCM
+       - pacmd load-module module-alsa-sink device=NavPCM control=NavAlsaCtl
+       - pacmd list-sinks | grep -i music
+    4) check your virtual pulse sink work
+       - paplay -d alsa_output.MusicPCM /usr/share/sounds/alsa/test.wav
+       - paplay -d alsa_output.NavPCM /usr/share/sounds/alsa/Front_Center.wav
+
+optional integration with ALSA legacy apps
+
+    5) start audio-pol4a controller
+       - repeat previous step(3) this time with device=Multimedia device=Navigation, ....
+    6) check virtual channel with policy controller protection
+       - paplay -d alsa_output.Multimedia /usr/share/sounds/alsa/test.wav
+       - paplay -d alsa_output.Navigation /usr/share/sounds/alsa/Front_Center.wav
+
+
+Bug/Feature: 
+    1) when softvol control is initialised from plugin and not
+       from AGL binding. At 1st run ctl has invalid TLV and cannot be used
+       Bypass Solution: 
+         * start audio-binder before playing sound (binding create control before softvol plugin)
+         * run a dummy aplay -DMyNavPCM "" to get a clean control
+    2) When using Audio-Pol4a to protect virtual channel, the audio policy controller should
+       run before adding virtual channel into pulse.
+    3) In order to leverage SMACK to protect virtual audio role, a Pulse rooting plugin should be used.
+
+
+## Alsa Config Sample
+
+```
+# ------------------------------------------------------
+# Mixer PCM allow to play multiple stream simultaneously
+# ------------------------------------------------------
+pcm.Speakers { 
+    type dmix            
+    slave {pcm "hw:v1340"}  #Jabra Solmate 1
+    ipc_key 1001          # ipc_key should be unique to each dmix
+} 
+
+# -----------------------------------------------------
+#  Register ControllerHookPlugin (ToiBeFix fullpath)
+# -----------------------------------------------------
+pcm_hook_type.CtlHookPlugin {
+    install "AlsaInstallHook" 
+    lib "/home/fulup/Workspace/Audio-4a/alsa-4a/build/alsa-hook/policy_alsa_hook.so"
+}
+
+
+# -------------------------------------------------------
+# Define one Audio Virtual Channel per Audio Roles
+# -------------------------------------------------------
+pcm.MusicPCM {
+    type softvol
+
+    # Point Slave on HOOK for policies control
+    slave.pcm "Speakers"
+
+    # name should match with HAL definition
+    control.name  "Playback Multimedia"
+}
+
+pcm.NaviPCM {
+    type softvol
+
+    # Point Slave on HOOK for policies control
+    slave.pcm "Speakers"
+
+    # name should match with HAL definition
+    control.name  "Playback Navigation"
+}
+
+pcm.UrgentPCM {
+    type softvol
+
+    # Point Slave on HOOK for policies control
+    slave.pcm "Speakers"
+
+    # name should match with HAL definition
+    control.name  "Playback Emergency"
+}
+
+# ----------------------------------------------------
+# Define one hooked PCM channel per Audio Roles
+# ----------------------------------------------------
+pcm.Multimedia {
+    type hooks
+    slave {pcm "MusicPCM"}
+    hooks.0 {
+        comment "Defined used hook sharelib and provide arguments/config to install func"
+        type "CtlHookPlugin"
+        hook_args {
+
+            # print few log messages (default false)
+            verbose true 
+
+            # uri to audio-4a policy engine
+            uri="unix:/var/tmp/pol4a"
+
+            # timeout in ms (default 500)
+            timeout 5000
+
+            # force API synchronous mode
+            synchronous true
+
+            # api subcall to request a role
+            request {
+                multimedia-role "{'uid':'alsa-hook-client'}"
+                signal-timeout  "{'timeout':180, 'music':'quit'}"
+            } 
+
+            # api subcall to request a role
+            release {
+                release-role "{'uid':'alsa-hook-client'}"
+            } 
+   
+            # map AGL event on Unix signal. Search in event for json key=value
+            events {   
+                sig-02 {search music, value quit}
+                sig-31 {search event, value start}
+                sig-32 {search event, value start}
+            }
+        }
+    }
+}
+
+pcm.Navigation {
+    type hooks
+    slave {pcm "NaviPCM"}
+    hooks.0 {
+        comment "Defined used hook sharelib and provide arguments/config to install func"
+        type "CtlHookPlugin"
+        hook_args {
+
+            # print few log messages (default false)
+            verbose true 
+
+            # uri to audio-4a policy engine
+            uri="unix:/var/tmp/pol4a"
+
+            # timeout in ms (default 500)
+            timeout 5000
+
+            # force API synchronous mode
+            synchronous true
+
+            # api subcall to request a role
+            request {
+                navigation-role "{'uid':'alsa-hook-client'}"
+                signal-timeout  "{'timeout':5, 'navi':'quit'}"
+            } 
+
+            # api subcall to request a role
+            release {
+                release-role "{'uid':'alsa-hook-client'}"
+            } 
+   
+            # map AGL event on Unix signal. Search in event for json key=value
+            events {   
+                sig-02 {search navi, value quit}
+                sig-31 {search event, value start}
+                sig-32 {search event, value start}
+            }
+        }
+    }
+}
+
+
+```
+
+NOTE:
+
+* Hook plugin is loaded by Alsa libasound within client context. It inherits client process attributes, as UID/GID and
+SMACK label when running on AGL. The smack label is control by AGL security framework.
+As a result a control request succeeds only when client application permission match requested audio role inside Cynara security database.
+
+* Hook plugin keep a connection with the Audio-Agent until PCM is closed by the application. This connection allow the
+Audio-Agent to send events. eg: pause, quit, mute, ...
\ No newline at end of file