allocate peer_fds on stack

luad.c

@@ -50,13 +50,12 @@ int open_socket(char * pathname) {
     return fd;
 }
 
-int * fds_from_msg(struct msghdr *msg) {
+int * fds_from_msg(struct msghdr *msg, int * peer_fds) {
     // * there may be multiple SCM_RIGHTS messages
     // * we expect three fds
     // * if we get some number other than three, we should
     //   close them and return NULL
 
-    int *peer_fds = (int *) calloc(3, sizeof(int));
     for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(msg);
          cmsg != NULL;
          cmsg = CMSG_NXTHDR(msg, cmsg)) {
@@ -218,16 +217,18 @@ int main(int argc, char **argv)
         if(pollfds[0].revents) {
             if(find_peer(0)) {
                 int len = recvmsg(socket, &msg , 0);
-                int *peer_fds = fds_from_msg(&msg);
-                char *argline = malloc(len);
-                if(! argline) {
-                    die("malloc failed");
-                }
-                memmove(argline, buf, len);
+                int peer_fds[3];
+                if(fds_from_msg(&msg, peer_fds)) {
+                    char *argline = malloc(len);
+                    if(! argline) {
+                        die("malloc failed");
+                    }
+                    memmove(argline, buf, len);
 
-                pid_t child_pid = fork_lua(L, argline, len, peer_fds);
-                if(child_pid >= 0) {
-                    register_peer(child_pid, &peer_addr, msg.msg_namelen);
+                    pid_t child_pid = fork_lua(L, argline, len, peer_fds);
+                    if(child_pid >= 0) {
+                        register_peer(child_pid, &peer_addr, msg.msg_namelen);
+                    }
                 }
             }
         }