fd_poll_write.c

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/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2026 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */


case OP_FD_POLL_WRITE: {
 /* Pops timeout_ms:int, fd:int; pushes 1 if writable, 0 on timeout, -1 on error */
 Value to = pop_value(vm);
 Value fdv = pop_value(vm);
 int rc = -1;
#ifdef __unix__
 if (fdv.type != VAL_INT || to.type != VAL_INT) {
 fprintf(stderr, "Runtime type error: fd_poll_write expects (int fd, int timeout_ms)\n");
 rc = -1;
 } else {
 int fd = (int)fdv.i;
 int timeout_ms = (int)to.i;
 struct pollfd pfd;
 pfd.fd = fd;
 pfd.events = POLLOUT;
 pfd.revents = 0;
 int pr = poll(&pfd, 1, timeout_ms);
 if (pr > 0) {
 if (pfd.revents & (POLLERR | POLLHUP | POLLNVAL)) {
 rc = 0; /* treat as not writable */
 } else if (pfd.revents & POLLOUT) {
 rc = 1;
 } else {
 rc = 0;
 }
 } else if (pr == 0) {
 rc = 0; /* timeout */
 } else {
 rc = -1; /* error */
 }
 }
#else
 (void)to; (void)fdv;
#endif
 free_value(to);
 free_value(fdv);
 push_value(vm, make_int(rc));
 break;
}