iopause.c

   1 #include "taia.h"
   2 #include "select.h"
   3 #include "iopause.h"
   4
   5 void iopause(iopause_fd *x,unsigned int len,struct taia *deadline,struct taia *stamp)
   6 {
   7   struct taia t;
   8   int millisecs;
   9   double d;
  10   int i;
  11
  12   if (taia_less(deadline,stamp))
  13     millisecs = 0;
  14   else {
  15     t = *stamp;
  16     taia_sub(&t,deadline,&t);
  17     d = taia_approx(&t);
  18     if (d > 1000.0) d = 1000.0;
  19     millisecs = d * 1000.0 + 20.0;
  20   }
  21
  22   for (i = 0;i < len;++i)
  23     x[i].revents = 0;
  24
  25 #ifdef IOPAUSE_POLL
  26
  27   poll(x,len,millisecs);
  28   /* XXX: some kernels apparently need x[0] even if len is 0 */
  29   /* XXX: how to handle EAGAIN? are kernels really this dumb? */
  30   /* XXX: how to handle EINVAL? when exactly can this happen? */
  31
  32 #else
  33 {
  34
  35   struct timeval tv;
  36   fd_set rfds;
  37   fd_set wfds;
  38   int nfds;
  39   int fd;
  40
  41   FD_ZERO(&rfds);
  42   FD_ZERO(&wfds);
  43
  44   nfds = 1;
  45   for (i = 0;i < len;++i) {
  46     fd = x[i].fd;
  47     if (fd < 0) continue;
  48     if (fd >= 8 * sizeof(fd_set)) continue; /*XXX*/
  49
  50     if (fd >= nfds) nfds = fd + 1;
  51     if (x[i].events & IOPAUSE_READ) FD_SET(fd,&rfds);
  52     if (x[i].events & IOPAUSE_WRITE) FD_SET(fd,&wfds);
  53   }
  54
  55   tv.tv_sec = millisecs / 1000;
  56   tv.tv_usec = 1000 * (millisecs % 1000);
  57
  58   if (select(nfds,&rfds,&wfds,(fd_set *) 0,&tv) <= 0)
  59     return;
  60     /* XXX: for EBADF, could seek out and destroy the bad descriptor */
  61
  62   for (i = 0;i < len;++i) {
  63     fd = x[i].fd;
  64     if (fd < 0) continue;
  65     if (fd >= 8 * sizeof(fd_set)) continue; /*XXX*/
  66
  67     if (x[i].events & IOPAUSE_READ)
  68       if (FD_ISSET(fd,&rfds)) x[i].revents |= IOPAUSE_READ;
  69     if (x[i].events & IOPAUSE_WRITE)
  70       if (FD_ISSET(fd,&wfds)) x[i].revents |= IOPAUSE_WRITE;
  71   }
  72
  73 }
  74 #endif
  75
  76 }