/* Copyright (C) 1994,1996,1997,1998,1999,2001,2002 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include <alloca.h> #include <sys/poll.h> #include <sys/types.h> #include <errno.h> #include <string.h> #include <sys/time.h> #include <sys/param.h> #include <unistd.h> /* Poll the file descriptors described by the NFDS structures starting at FDS. If TIMEOUT is nonzero and not -1, allow TIMEOUT milliseconds for an event to occur; if TIMEOUT is -1, block until an event occurs. Returns the number of file descriptors with events, zero if timed out, or -1 for errors. */ int poll(struct pollfd *fds, nfds_t nfds, int timeout) { static int max_fd_size; struct timeval tv; fd_set *rset, *wset, *xset; struct pollfd *f; int ready; int maxfd = 0; int bytes; if (!max_fd_size) max_fd_size = getdtablesize (); bytes = howmany (max_fd_size, __NFDBITS); rset = alloca (bytes); wset = alloca (bytes); xset = alloca (bytes); /* We can't call FD_ZERO, since FD_ZERO only works with sets of exactly __FD_SETSIZE size. */ bzero (rset, bytes); bzero (wset, bytes); bzero (xset, bytes); for (f = fds; f < &fds[nfds]; ++f) { f->revents = 0; if (f->fd >= 0) { if (f->fd >= max_fd_size) { /* The user provides a file descriptor number which is higher than the maximum we got from the `getdtablesize' call. Maybe this is ok so enlarge the arrays. */ fd_set *nrset, *nwset, *nxset; int nbytes; max_fd_size = roundup (f->fd, __NFDBITS); nbytes = howmany (max_fd_size, __NFDBITS); nrset = alloca (nbytes); nwset = alloca (nbytes); nxset = alloca (nbytes); bzero ((char *) nrset + bytes, nbytes - bytes); bzero ((char *) nwset + bytes, nbytes - bytes); bzero ((char *) nxset + bytes, nbytes - bytes); rset = memcpy (nrset, rset, bytes); wset = memcpy (nwset, wset, bytes); xset = memcpy (nxset, xset, bytes); bytes = nbytes; } if (f->events & POLLIN) FD_SET (f->fd, rset); if (f->events & POLLOUT) FD_SET (f->fd, wset); if (f->events & POLLPRI) FD_SET (f->fd, xset); if (f->fd > maxfd && (f->events & (POLLIN|POLLOUT|POLLPRI))) maxfd = f->fd; } } tv.tv_sec = timeout / 1000; tv.tv_usec = (timeout % 1000) * 1000; while (1) { ready = select (maxfd + 1, rset, wset, xset, timeout == -1 ? NULL : &tv); /* It might be that one or more of the file descriptors is invalid. We now try to find and mark them and then try again. */ if (ready == -1 && errno == EBADF) { fd_set *sngl_rset = alloca (bytes); fd_set *sngl_wset = alloca (bytes); fd_set *sngl_xset = alloca (bytes); struct timeval sngl_tv; /* Clear the original set. */ bzero (rset, bytes); bzero (wset, bytes); bzero (xset, bytes); /* This means we don't wait for input. */ sngl_tv.tv_sec = 0; sngl_tv.tv_usec = 0; maxfd = -1; /* Reset the return value. */ ready = 0; for (f = fds; f < &fds[nfds]; ++f) if (f->fd != -1 && (f->events & (POLLIN|POLLOUT|POLLPRI)) && (f->revents & POLLNVAL) == 0) { int n; bzero (sngl_rset, bytes); bzero (sngl_wset, bytes); bzero (sngl_xset, bytes); if (f->events & POLLIN) FD_SET (f->fd, sngl_rset); if (f->events & POLLOUT) FD_SET (f->fd, sngl_wset); if (f->events & POLLPRI) FD_SET (f->fd, sngl_xset); n = select (f->fd + 1, sngl_rset, sngl_wset, sngl_xset, &sngl_tv); if (n != -1) { /* This descriptor is ok. */ if (f->events & POLLIN) FD_SET (f->fd, rset); if (f->events & POLLOUT) FD_SET (f->fd, wset); if (f->events & POLLPRI) FD_SET (f->fd, xset); if (f->fd > maxfd) maxfd = f->fd; if (n > 0) /* Count it as being available. */ ++ready; } else if (errno == EBADF) f->revents |= POLLNVAL; } /* Try again. */ continue; } break; } if (ready > 0) for (f = fds; f < &fds[nfds]; ++f) { if (f->fd >= 0) { if (FD_ISSET (f->fd, rset)) f->revents |= POLLIN; if (FD_ISSET (f->fd, wset)) f->revents |= POLLOUT; if (FD_ISSET (f->fd, xset)) f->revents |= POLLPRI; } } return ready; }