diff options
Diffstat (limited to 'libc/sysdeps/linux/common/poll.c')
| -rw-r--r-- | libc/sysdeps/linux/common/poll.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/common/poll.c b/libc/sysdeps/linux/common/poll.c new file mode 100644 index 000000000..cf3db35eb --- /dev/null +++ b/libc/sysdeps/linux/common/poll.c @@ -0,0 +1,192 @@ +/* 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; +} + |