Changes after code review

Returning -1 instead of 0 from start_server function

firmware/src/sgx/src/untrusted/io.c

@@ -57,27 +57,27 @@ static int start_server(int port, const char *host) {
 
     if (hostinfo == NULL) {
         LOG("Host not found.\n");
-        return 0;
+        return -1;
     }
 
     // socket create and verification
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd == -1) {
         LOG("Socket creation failed...\n");
-        return 0;
+        return -1;
     }
 
     explicit_bzero(&servaddr, sizeof(servaddr));
 
     if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &(int){1}, sizeof(int)) <
         0) {
         LOG("Socket option setting failed failed\n");
-        return 0;
+        return -1;
     }
 
     if (setsockopt(sockfd, SOL_TCP, TCP_NODELAY, &(int){1}, sizeof(int)) < 0) {
         LOG("Socket option setting failed failed\n");
-        return 0;
+        return -1;
     }
 
     // Set address and port
@@ -88,13 +88,13 @@ static int start_server(int port, const char *host) {
     // Binding newly created socket to given IP and verification
     if ((bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr))) != 0) {
         LOG("Socket bind failed...\n");
-        return 0;
+        return -1;
     }
 
     // Now server is ready to listen and verification
     if ((listen(sockfd, 5)) != 0) {
         LOG("Listen failed...\n");
-        return 0;
+        return -1;
     }
 
     LOG("Server listening...\n");
@@ -116,7 +116,7 @@ static bool accept_connection() {
 bool io_init(int port, const char *host) {
     connfd = -1;
     serverfd = start_server(port, host);
-    return serverfd;
+    return (serverfd != -1);
 }
 
 void io_finalise() {