[WIP/FIX] Lock write operations to XMPP

I *think* that fixes stream errors with two threads writing at once.
Even if it doesn't, I think it's always a nice-to-have.

src/XMPP/Component.c

@@ -76,6 +76,7 @@ XMPPInitialiseCompStream(char *host, int port)
     comp = Malloc(sizeof(*comp));
     comp->host = StrDuplicate(host);
     comp->stream = stream;
+    pthread_mutex_init(&comp->write_lock, NULL);
 
     return comp;
 }
@@ -112,6 +113,8 @@ XMPPAuthenticateCompStream(XMPPComponent *comp, char *shared)
         return false;
     }
 
+    pthread_mutex_lock(&comp->write_lock);
+
     stream = comp->stream;
     as = comp->host;
     StreamPrintf(stream, 
@@ -178,6 +181,7 @@ XMPPAuthenticateCompStream(XMPPComponent *comp, char *shared)
     Free(handshake);
 end:
     XMLFreeLexer(sax);
+    pthread_mutex_unlock(&comp->write_lock);
     return ret;
 }
 
@@ -188,6 +192,7 @@ XMPPEndCompStream(XMPPComponent *comp)
     {
         return;
     }
+    pthread_mutex_destroy(&comp->write_lock);
     StreamClose(comp->stream);
     Free(comp->host);
     Free(comp);

src/XMPP/MUC.c

@@ -17,6 +17,9 @@ XMPPQueryMUC(XMPPComponent *jabber, char *muc, MUCInfo *out)
     {
         return false;
     }
+
+    pthread_mutex_lock(&jabber->write_lock);
+
     iq_query = XMLCreateTag("iq");
     query = XMLCreateTag("query");
 
@@ -47,6 +50,7 @@ XMPPQueryMUC(XMPPComponent *jabber, char *muc, MUCInfo *out)
         {
             XMLFreeElement(iq_query);
             ParseeWakeupThread();
+            pthread_mutex_unlock(&jabber->write_lock);
             return false;
         }
         query = XMLookForUnique(iq_query, "query");
@@ -58,6 +62,7 @@ XMPPQueryMUC(XMPPComponent *jabber, char *muc, MUCInfo *out)
         {
             XMLFreeElement(iq_query);
             ParseeWakeupThread();
+            pthread_mutex_unlock(&jabber->write_lock);
             return false;
         }
 
@@ -74,6 +79,7 @@ XMPPQueryMUC(XMPPComponent *jabber, char *muc, MUCInfo *out)
         }
     }
     /* Wake it up once we're done */
+    pthread_mutex_unlock(&jabber->write_lock);
     ParseeWakeupThread();
     return true;
 }

src/XMPP/Stanza.c

@@ -15,6 +15,8 @@ XMPPSendPlain(XMPPComponent *comp, char *fr, char *to, char *msg, char *type)
     {
         return;
     }
+    
+    pthread_mutex_lock(&comp->write_lock);
 
     message = XMLCreateTag("message");
     XMLAddAttr(message, "from", (from = StrConcat(3, fr, "@", comp->host)));
@@ -56,6 +58,8 @@ XMPPSendPlain(XMPPComponent *comp, char *fr, char *to, char *msg, char *type)
     StreamFlush(comp->stream);
     XMLFreeElement(message);
     Free(from);
+
+    pthread_mutex_unlock(&comp->write_lock);
 }
 void
 XMPPSendMUC(XMPPComponent *comp, char *fr, char *as, char *to, char *msg, char *type)
@@ -67,6 +71,8 @@ XMPPSendMUC(XMPPComponent *comp, char *fr, char *as, char *to, char *msg, char *
         return;
     }
 
+    pthread_mutex_lock(&comp->write_lock);
+
     message = XMLCreateTag("message");
     XMLAddAttr(message, "from", 
         (from = StrConcat(5, fr, "@", comp->host, "/", as)));
@@ -86,6 +92,8 @@ XMPPSendMUC(XMPPComponent *comp, char *fr, char *as, char *to, char *msg, char *
     XMLFreeElement(message);
     Free(from);
     Free(id);
+
+    pthread_mutex_unlock(&comp->write_lock);
 }
 void
 XMPPJoinMUC(XMPPComponent *comp, char *fr, char *muc)
@@ -97,6 +105,8 @@ XMPPJoinMUC(XMPPComponent *comp, char *fr, char *muc)
         return;
     }
 
+    pthread_mutex_lock(&comp->write_lock);
+
     presence = XMLCreateTag("presence");
     x = XMLCreateTag("x");
     XMLAddAttr(presence, "from", (from = StrConcat(3, fr, "@", comp->host)));
@@ -112,6 +122,8 @@ XMPPJoinMUC(XMPPComponent *comp, char *fr, char *muc)
     XMLFreeElement(presence);
     Free(from);
     Free(id);
+
+    pthread_mutex_unlock(&comp->write_lock);
 }
 void
 XMPPKillThread(XMPPComponent *jabber, char *killer)
@@ -124,6 +136,8 @@ XMPPKillThread(XMPPComponent *jabber, char *killer)
         return;
     }
 
+    pthread_mutex_lock(&jabber->write_lock);
+
     from = StrConcat(3, killer, "@", jabber->host);
     message = XMLCreateTag("message");
     XMLAddAttr(message, "from", from);
@@ -136,6 +150,8 @@ XMPPKillThread(XMPPComponent *jabber, char *killer)
     StreamFlush(jabber->stream);
     XMLFreeElement(message);
     Free(from);
+
+    pthread_mutex_unlock(&jabber->write_lock);
 }
 bool
 XMPPIsKiller(XMLElement *stanza)

src/include/XMPP.h

@@ -3,9 +3,14 @@
 
 #include <Cytoplasm/Stream.h>
 
+#include <pthread.h>
+
 #include <XML.h>
 
 typedef struct XMPPComponent {
+    /* A lock for all write operations */
+    pthread_mutex_t write_lock;
+
     char *host;
     Stream *stream;
 } XMPPComponent;