ipc: socket recv()

src/ipc/sockio.c

@@ -44,12 +44,14 @@ ssize_t send(Thread *t, int sd, const void *buffer, size_t len, int flags) {
 
     if(family == AF_UNIX || family == AF_LOCAL) {
         // simply append to the peer's inbound list
-        void **newlist = realloc(peer->inbound, (peer->inboundCount + 1) * sizeof(void *));
+        void **newlist = realloc(peer->inbound, (peer->inboundCount+1) * sizeof(void *));
         if(!newlist) {
             socketRelease();
             return -ENOBUFS;
         }
 
+        size_t *newlen = realloc(peer->inboundLen, (peer->inboundCount+1) * sizeof(size_t));
+
         void *message = malloc(len);
         if(!message) {
             free(newlist);
@@ -60,8 +62,10 @@ ssize_t send(Thread *t, int sd, const void *buffer, size_t len, int flags) {
         // and send
         memcpy(message, buffer, len);
         newlist[peer->inboundCount] = message;
+        newlen[peer->inboundCount] = len;
         peer->inboundCount++;
         peer->inbound = newlist;
+        peer->inboundLen = newlen;
 
         socketRelease();
         return len;
@@ -71,3 +75,65 @@ ssize_t send(Thread *t, int sd, const void *buffer, size_t len, int flags) {
         return -ENOTCONN;
     }
 }
+
+/* recv(): receives a message from a socket connection
+ * params: t - calling thread
+ * params: sd - socket descriptor
+ * params: buffer - buffer to store message
+ * params: len - maximum size of the buffer
+ * params: flags - optional flags for the request
+ * returns: positive number of bytes received, negative error code on fail
+ */
+
+ssize_t recv(Thread *t, int sd, void *buffer, size_t len, int flags) {
+    Process *p;
+    if(t) p = getProcess(t->pid);
+    else p = getProcess(getPid());
+    if(!p) return -ESRCH;
+
+    if(!p->io[sd].valid || !p->io[sd].data || (p->io[sd].type != IO_SOCKET))
+        return -ENOTSOCK;
+
+    SocketDescriptor *self = (SocketDescriptor*) p->io[sd].data;
+    if(!self->peer) return -EDESTADDRREQ;   // not in connection mode
+
+    sa_family_t family = self->address.sa_family;
+    if(!self->inboundCount || !self->inbound || !self->inboundLen)
+        return -EWOULDBLOCK;    // no messages available
+
+    socketLock();
+
+    if(family == AF_UNIX || family == AF_LOCAL) {
+        // copy from the inbound list
+        void *message = self->inbound[0];   // FIFO
+        size_t truelen = self->inboundLen[0];
+
+        if(!message) {
+            socketRelease();
+            return -EWOULDBLOCK;
+        }
+
+        if(truelen > len) truelen = len;    // truncate longer messages
+        memcpy(buffer, message, truelen);
+
+        // and remove the received message from the queue
+        free(message);
+
+        self->inboundCount--;
+        if(!self->inboundCount) {
+            free(self->inbound);
+            free(self->inboundLen);
+        } else {
+            memmove(&self->inbound[0], &self->inbound[1], self->inboundCount * sizeof(void *));
+            memmove(&self->inboundLen[0], &self->inboundLen[1], self->inboundCount * sizeof(size_t));
+            self->inbound = realloc(self->inbound, self->inboundCount * sizeof(void *));
+            self->inboundLen = realloc(self->inboundLen, self->inboundCount * sizeof(void *));
+        }
+
+        return truelen;
+    } else {
+        /* TODO: handle other protocols in user space */
+        socketRelease();
+        return -ENOTCONN;
+    }
+}