cosmopolitan/libc/sock/winsockblock.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/errno.h"
#include "libc/nt/winsock.h"
#include "libc/sock/internal.h"
#include "libc/sock/sock.h"
#include "libc/str/str.h"

textwindows int64_t __winsockblock(int64_t fh, unsigned eventbit, int64_t rc) {
  int64_t eh;
  struct NtWsaNetworkEvents ev;
  if (rc != -1) return rc;
  if (WSAGetLastError() != EWOULDBLOCK) return __winsockerr();
  eh = WSACreateEvent();
  bzero(&ev, sizeof(ev));
  /* The proper way to reset the state of an event object used with the
     WSAEventSelect function is to pass the handle of the event object
     to the WSAEnumNetworkEvents function in the hEventObject parameter.
     This will reset the event object and adjust the status of active FD
     events on the socket in an atomic fashion. -- MSDN */
  if (WSAEventSelect(fh, eh, 1u << eventbit) != -1 &&
      WSAEnumNetworkEvents(fh, eh, &ev) != -1) {
    if (!ev.iErrorCode[eventbit]) {
      rc = 0;
    } else {
      errno = ev.iErrorCode[eventbit];
    }
  } else {
    __winsockerr();
  }
  WSACloseEvent(eh);
  return rc;
}