socket_tcp_listen.c

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/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */


case OP_SOCK_TCP_LISTEN: {
 /* Pops backlog, port; pushes listen fd (>0) or 0 */
 Value backlogv = pop_value(vm);
 Value portv = pop_value(vm);
 int fd = 0;
#ifdef __unix__
 if (portv.type != VAL_INT || backlogv.type != VAL_INT) {
 fprintf(stderr, "Runtime type error: tcp_listen expects (int port, int backlog)\n");
 free_value(backlogv);
 free_value(portv);
 push_value(vm, make_int(0));
 break;
 }
 int port = (int)portv.i;
 int backlog = (int)backlogv.i;
 int s = socket(AF_INET, SOCK_STREAM, 0);
 if (s >= 0) {
 int yes = 1;
 setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
 struct sockaddr_in addr;
 memset(&addr, 0, sizeof(addr));
 addr.sin_family = AF_INET;
 addr.sin_addr.s_addr = htonl(INADDR_ANY);
 addr.sin_port = htons((uint16_t)port);
 if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) == 0) {
 if (listen(s, backlog > 0 ? backlog : 1) == 0) {
 fd = s;
 } else {
 close(s);
 }
 } else {
 close(s);
 }
 }
#else
 (void)fd;
#endif
 free_value(backlogv);
 free_value(portv);
 push_value(vm, make_int(fd > 0 ? fd : 0));
 break;
}