Remove some immediatly overwritten writes

Fix local variable being modified just before it goes out of scope

When memcpy-ing in a buffer, only memset the part of the buffer not modified by the memcpy, not the whole buffer

Also reorder the memset after the memcpy, to potentially avoid cache misses (NOT profiled)

Author: tux3

toxcore/Messenger.c

@@ -580,10 +580,12 @@ int m_copy_statusmessage(Messenger *m, int32_t friendnumber, uint8_t *buf, uint3
 {
     if (friend_not_valid(m, friendnumber))
         return -1;
-
-    memset(buf, 0, maxlen);
-    memcpy(buf, m->friendlist[friendnumber].statusmessage, MIN(maxlen, m->friendlist[friendnumber].statusmessage_length));
-    return MIN(maxlen, m->friendlist[friendnumber].statusmessage_length);
+    
+    int msglen = MIN(maxlen, m->friendlist[friendnumber].statusmessage_length);
+    
+    memcpy(buf, m->friendlist[friendnumber].statusmessage, msglen);
+    memset(buf+msglen, 0, maxlen-msglen);
+    return msglen;
 }
 
 /* return the size of friendnumber's user status.
@@ -596,9 +598,10 @@ int m_get_self_statusmessage_size(Messenger *m)
 
 int m_copy_self_statusmessage(Messenger *m, uint8_t *buf, uint32_t maxlen)
 {
-    memset(buf, 0, maxlen);
-    memcpy(buf, m->statusmessage, MIN(maxlen, m->statusmessage_length));
-    return MIN(maxlen, m->statusmessage_length);
+    int msglen = MIN(maxlen, m->statusmessage_length);
+    memcpy(buf, m->statusmessage, msglen);
+    memset(buf+msglen, 0, maxlen-msglen);
+    return msglen;
 }
 
 uint8_t m_get_userstatus(Messenger *m, int32_t friendnumber)
@@ -2693,7 +2696,6 @@ void messenger_save(Messenger *m, uint8_t *data)
     memset(relays, 0, len);
     copy_connected_tcp_relays(m->net_crypto, relays, NUM_SAVED_TCP_RELAYS);
     memcpy(data, relays, len);
-    data += len;
 }
 
 static int messenger_load_state_callback(void *outer, const uint8_t *data, uint32_t length, uint16_t type)