[ADD/WIP] Push all the Janet changes

This is still unstable(and I still need to design/document the exposed
API)! Do(n't) go and use it!

src/Extensions/PushStanza.c

@@ -0,0 +1,98 @@
+#ifdef JANET
+
+#include "Extensions/Internal.h"
+
+typedef struct ExtensionStanzaReply {
+    pthread_mutex_t lock;
+    pthread_cond_t cond;
+
+    XMLElement *stanza;
+
+    Extension *ext;
+    bool reply, ack;
+    char *type;
+} ExtensionStanzaReply;
+
+static void
+OnStanzaResponse(JanetEVGenericMessage msg)
+{
+    ExtensionStanzaReply *reply = msg.argp;
+    Extension *ext = reply->ext;
+    Janet args[2] = {
+        ExtensionsFromXML(NULL, reply->stanza),
+        janet_cstringv(reply->type)
+    };
+    Janet ret;
+
+    if (TryCall(ext, "on-stanza", 2, args, &ret))
+    {
+        pthread_mutex_lock(&reply->lock);
+        reply->ack = true;
+        reply->reply = janet_truthy(ret);
+        pthread_cond_signal(&reply->cond);
+        pthread_mutex_unlock(&reply->lock);
+        return;
+    }
+    pthread_mutex_lock(&reply->lock);
+    reply->ack = true;
+    reply->reply = false;
+    pthread_cond_signal(&reply->cond);
+    pthread_mutex_unlock(&reply->lock);
+}
+bool
+ExtensionPushStanza(Extensions *ctx, XMLElement *stanza, StanzaType t)
+{
+    bool veto = false;
+    size_t i;
+
+    char *table[STANZA_TYPE_COUNT] = {
+        "raw",
+        "message",
+        "iq",
+        "presence"
+    };
+    char *key;
+    Extension *val;
+    if (!ctx || !stanza)
+    {
+        return false;
+    }
+
+    pthread_mutex_lock(&ctx->mtx);
+    for (i = 0; IterateReentrant(ctx->extensions, key, val, i); )
+    {
+        ExtensionStanzaReply *reply = Malloc(sizeof(*reply));
+        JanetEVGenericMessage msg = {
+            /* We except a veto boolean. */
+            .tag = JANET_STANZA_PUSH,
+        };
+
+        pthread_mutex_init(&reply->lock, NULL);
+        pthread_cond_init(&reply->cond, NULL);
+        reply->ext = val;
+        reply->reply = false;
+        reply->ack = false;
+        reply->type = table[t];
+        reply->stanza = stanza;
+        msg.argp = reply;
+
+        janet_ev_post_event(val->vm, OnStanzaResponse, msg);
+        pthread_mutex_lock(&reply->lock);
+        while (!reply->ack)
+        {
+            pthread_cond_wait(&reply->cond, &reply->lock);
+        }
+        pthread_mutex_unlock(&reply->lock);
+        pthread_mutex_destroy(&reply->lock);
+        pthread_cond_destroy(&reply->cond);
+        if (reply->reply)
+        {
+            veto = true;
+        }
+        Free(reply);
+    }
+    pthread_mutex_unlock(&ctx->mtx);
+
+    return veto;
+}
+#endif