runtime/platform/recv.nonblock.c

   1 /* Simulates MSG_DONTWAIT using fcntl() and O_NONBLOCK. */
   2
   3 static void fd_modify(int fd, int flags, int add, int shouldRemove)
   4 {
   5         int status;
   6
   7         if (flags & MSG_DONTWAIT) {
   8                 status = errno;
   9                 int f = fcntl(fd, F_GETFL);
  10                 fcntl(fd, F_SETFL, (f | add) & ~shouldRemove);
  11                 errno = status;
  12         }
  13 }
  14
  15 static void set_nonblock(int fd, int flags)
  16 {
  17         fd_modify(fd, flags, O_NONBLOCK, 0);
  18 }
  19
  20 static void clear_nonblock(int fd, int flags)
  21 {
  22         fd_modify(fd, flags, 0, O_NONBLOCK);
  23 }
  24
  25 int MLton_recv(int s, void *buf, int len, int flags)
  26 {
  27         int ret;
  28         set_nonblock(s, flags);
  29         ret = recv(s, buf, len, flags & ~MSG_DONTWAIT);
  30         clear_nonblock(s, flags);
  31         return ret;
  32 }
  33
  34 int MLton_recvfrom(int s, void *buf, int len, int flags, void *from,
  35                    socklen_t *fromlen)
  36 {
  37         int ret;
  38         set_nonblock(s, flags);
  39         ret = recvfrom(s, buf, len, flags & ~MSG_DONTWAIT, from, fromlen);
  40         clear_nonblock(s, flags);
  41         return ret;
  42 }