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c187253fc2
This removes code which actually never happens, and is already taken care of in the function. This is in the second part of select, when the __mach_msg() function over the portset has returned something else than MACH_MSG_SUCCESS. I guess in the past the value returned by __mach_msg() was stored in err, so this code was necessary to set back err to 0, but now it is stored in msgerr, so err is already still 0 by default. It can thus never contain MACH_RCV_TIMED_OUT, i.e. the code is dead. The first case mentioned in the comment is already handled: on time out with no message, err is already still the default 0. On time out due to poll, err would still be 0, unless some of the io_select RPCs has returned EINTR, in which case it contains EINTR. If any other io_select RPCs had returned a proper answer, got!=0, and thus err is set to 0 just below. The code is thus indeed not useful any more.
492 lines
12 KiB
C
492 lines
12 KiB
C
/* Guts of both `select' and `poll' for Hurd.
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Copyright (C) 1991-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sys/types.h>
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#include <sys/poll.h>
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#include <hurd.h>
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#include <hurd/fd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <stdint.h>
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/* All user select types. */
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#define SELECT_ALL (SELECT_READ | SELECT_WRITE | SELECT_URG)
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/* Used to record that a particular select rpc returned. Must be distinct
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from SELECT_ALL (which better not have the high bit set). */
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#define SELECT_RETURNED ((SELECT_ALL << 1) & ~SELECT_ALL)
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/* Check the first NFDS descriptors either in POLLFDS (if nonnnull) or in
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each of READFDS, WRITEFDS, EXCEPTFDS that is nonnull. If TIMEOUT is not
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NULL, time out after waiting the interval specified therein. Returns
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the number of ready descriptors, or -1 for errors. */
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int
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_hurd_select (int nfds,
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struct pollfd *pollfds,
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fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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const struct timespec *timeout, const sigset_t *sigmask)
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{
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int i;
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mach_port_t portset;
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int got;
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error_t err;
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fd_set rfds, wfds, xfds;
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int firstfd, lastfd;
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mach_msg_timeout_t to = 0;
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struct
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{
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struct hurd_userlink ulink;
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struct hurd_fd *cell;
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mach_port_t io_port;
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int type;
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mach_port_t reply_port;
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} d[nfds];
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sigset_t oset;
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union typeword /* Use this to avoid unkosher casts. */
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{
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mach_msg_type_t type;
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uint32_t word;
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};
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assert (sizeof (union typeword) == sizeof (mach_msg_type_t));
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assert (sizeof (uint32_t) == sizeof (mach_msg_type_t));
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if (nfds < 0 || (pollfds == NULL && nfds > FD_SETSIZE))
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{
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errno = EINVAL;
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return -1;
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}
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if (timeout != NULL)
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{
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if (timeout->tv_sec < 0 || timeout->tv_nsec < 0)
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{
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errno = EINVAL;
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return -1;
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}
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to = (timeout->tv_sec * 1000 +
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(timeout->tv_nsec + 999999) / 1000000);
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}
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if (sigmask && __sigprocmask (SIG_SETMASK, sigmask, &oset))
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return -1;
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if (pollfds)
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{
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/* Collect interesting descriptors from the user's `pollfd' array.
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We do a first pass that reads the user's array before taking
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any locks. The second pass then only touches our own stack,
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and gets the port references. */
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for (i = 0; i < nfds; ++i)
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if (pollfds[i].fd >= 0)
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{
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int type = 0;
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if (pollfds[i].events & POLLIN)
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type |= SELECT_READ;
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if (pollfds[i].events & POLLOUT)
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type |= SELECT_WRITE;
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if (pollfds[i].events & POLLPRI)
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type |= SELECT_URG;
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d[i].io_port = pollfds[i].fd;
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d[i].type = type;
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}
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else
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d[i].type = 0;
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HURD_CRITICAL_BEGIN;
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__mutex_lock (&_hurd_dtable_lock);
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for (i = 0; i < nfds; ++i)
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if (d[i].type != 0)
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{
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const int fd = (int) d[i].io_port;
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if (fd < _hurd_dtablesize)
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{
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d[i].cell = _hurd_dtable[fd];
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d[i].io_port = _hurd_port_get (&d[i].cell->port, &d[i].ulink);
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if (d[i].io_port != MACH_PORT_NULL)
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continue;
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}
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/* If one descriptor is bogus, we fail completely. */
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while (i-- > 0)
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if (d[i].type != 0)
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_hurd_port_free (&d[i].cell->port,
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&d[i].ulink, d[i].io_port);
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break;
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}
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__mutex_unlock (&_hurd_dtable_lock);
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HURD_CRITICAL_END;
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if (i < nfds)
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{
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if (sigmask)
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__sigprocmask (SIG_SETMASK, &oset, NULL);
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errno = EBADF;
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return -1;
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}
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lastfd = i - 1;
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firstfd = i == 0 ? lastfd : 0;
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}
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else
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{
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/* Collect interested descriptors from the user's fd_set arguments.
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Use local copies so we can't crash from user bogosity. */
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if (readfds == NULL)
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FD_ZERO (&rfds);
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else
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rfds = *readfds;
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if (writefds == NULL)
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FD_ZERO (&wfds);
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else
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wfds = *writefds;
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if (exceptfds == NULL)
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FD_ZERO (&xfds);
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else
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xfds = *exceptfds;
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HURD_CRITICAL_BEGIN;
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__mutex_lock (&_hurd_dtable_lock);
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if (nfds > _hurd_dtablesize)
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nfds = _hurd_dtablesize;
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/* Collect the ports for interesting FDs. */
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firstfd = lastfd = -1;
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for (i = 0; i < nfds; ++i)
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{
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int type = 0;
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if (readfds != NULL && FD_ISSET (i, &rfds))
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type |= SELECT_READ;
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if (writefds != NULL && FD_ISSET (i, &wfds))
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type |= SELECT_WRITE;
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if (exceptfds != NULL && FD_ISSET (i, &xfds))
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type |= SELECT_URG;
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d[i].type = type;
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if (type)
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{
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d[i].cell = _hurd_dtable[i];
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d[i].io_port = _hurd_port_get (&d[i].cell->port, &d[i].ulink);
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if (d[i].io_port == MACH_PORT_NULL)
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{
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/* If one descriptor is bogus, we fail completely. */
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while (i-- > 0)
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if (d[i].type != 0)
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_hurd_port_free (&d[i].cell->port, &d[i].ulink,
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d[i].io_port);
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break;
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}
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lastfd = i;
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if (firstfd == -1)
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firstfd = i;
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}
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}
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__mutex_unlock (&_hurd_dtable_lock);
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HURD_CRITICAL_END;
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if (i < nfds)
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{
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if (sigmask)
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__sigprocmask (SIG_SETMASK, &oset, NULL);
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errno = EBADF;
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return -1;
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}
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}
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err = 0;
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got = 0;
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/* Send them all io_select request messages. */
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if (firstfd == -1)
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/* But not if there were no ports to deal with at all.
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We are just a pure timeout. */
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portset = __mach_reply_port ();
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else
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{
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portset = MACH_PORT_NULL;
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for (i = firstfd; i <= lastfd; ++i)
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if (d[i].type)
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{
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int type = d[i].type;
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d[i].reply_port = __mach_reply_port ();
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err = __io_select (d[i].io_port, d[i].reply_port,
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/* Poll only if there's a single descriptor. */
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(firstfd == lastfd) ? to : 0,
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&type);
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switch (err)
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{
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case MACH_RCV_TIMED_OUT:
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/* No immediate response. This is normal. */
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err = 0;
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if (firstfd == lastfd)
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/* When there's a single descriptor, we don't need a
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portset, so just pretend we have one, but really
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use the single reply port. */
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portset = d[i].reply_port;
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else if (got == 0)
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/* We've got multiple reply ports, so we need a port set to
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multiplex them. */
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{
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/* We will wait again for a reply later. */
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if (portset == MACH_PORT_NULL)
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/* Create the portset to receive all the replies on. */
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err = __mach_port_allocate (__mach_task_self (),
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MACH_PORT_RIGHT_PORT_SET,
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&portset);
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if (! err)
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/* Put this reply port in the port set. */
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__mach_port_move_member (__mach_task_self (),
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d[i].reply_port, portset);
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}
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break;
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default:
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/* No other error should happen. Callers of select
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don't expect to see errors, so we simulate
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readiness of the erring object and the next call
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hopefully will get the error again. */
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type = SELECT_ALL;
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/* FALLTHROUGH */
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case 0:
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/* We got an answer. */
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if ((type & SELECT_ALL) == 0)
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/* Bogus answer; treat like an error, as a fake positive. */
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type = SELECT_ALL;
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/* This port is already ready already. */
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d[i].type &= type;
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d[i].type |= SELECT_RETURNED;
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++got;
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break;
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}
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_hurd_port_free (&d[i].cell->port, &d[i].ulink, d[i].io_port);
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}
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}
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/* Now wait for reply messages. */
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if (!err && got == 0)
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{
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/* Now wait for io_select_reply messages on PORT,
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timing out as appropriate. */
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union
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{
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mach_msg_header_t head;
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#ifdef MACH_MSG_TRAILER_MINIMUM_SIZE
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struct
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{
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mach_msg_header_t head;
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NDR_record_t ndr;
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error_t err;
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} error;
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struct
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{
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mach_msg_header_t head;
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NDR_record_t ndr;
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error_t err;
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int result;
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mach_msg_trailer_t trailer;
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} success;
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#else
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struct
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{
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mach_msg_header_t head;
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union typeword err_type;
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error_t err;
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} error;
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struct
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{
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mach_msg_header_t head;
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union typeword err_type;
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error_t err;
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union typeword result_type;
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int result;
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} success;
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#endif
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} msg;
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mach_msg_option_t options = (timeout == NULL ? 0 : MACH_RCV_TIMEOUT);
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error_t msgerr;
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while ((msgerr = __mach_msg (&msg.head,
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MACH_RCV_MSG | MACH_RCV_INTERRUPT | options,
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0, sizeof msg, portset, to,
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MACH_PORT_NULL)) == MACH_MSG_SUCCESS)
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{
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/* We got a message. Decode it. */
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#define IO_SELECT_REPLY_MSGID (21012 + 100) /* XXX */
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#ifdef MACH_MSG_TYPE_BIT
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const union typeword inttype =
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{ type:
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{ MACH_MSG_TYPE_INTEGER_T, sizeof (integer_t) * 8, 1, 1, 0, 0 }
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};
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#endif
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if (msg.head.msgh_id == IO_SELECT_REPLY_MSGID &&
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msg.head.msgh_size >= sizeof msg.error &&
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!(msg.head.msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
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#ifdef MACH_MSG_TYPE_BIT
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msg.error.err_type.word == inttype.word
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#endif
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)
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{
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/* This is a properly formatted message so far.
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See if it is a success or a failure. */
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if (msg.error.err == EINTR &&
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msg.head.msgh_size == sizeof msg.error)
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{
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/* EINTR response; poll for further responses
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and then return quickly. */
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err = EINTR;
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goto poll;
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}
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if (msg.error.err ||
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msg.head.msgh_size != sizeof msg.success ||
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#ifdef MACH_MSG_TYPE_BIT
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msg.success.result_type.word != inttype.word ||
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#endif
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(msg.success.result & SELECT_ALL) == 0)
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{
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/* Error or bogus reply. Simulate readiness. */
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__mach_msg_destroy (&msg.head);
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msg.success.result = SELECT_ALL;
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}
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/* Look up the respondent's reply port and record its
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readiness. */
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{
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int had = got;
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if (firstfd != -1)
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for (i = firstfd; i <= lastfd; ++i)
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if (d[i].type
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&& d[i].reply_port == msg.head.msgh_local_port)
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{
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d[i].type &= msg.success.result;
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d[i].type |= SELECT_RETURNED;
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++got;
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}
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assert (got > had);
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}
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}
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if (msg.head.msgh_remote_port != MACH_PORT_NULL)
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__mach_port_deallocate (__mach_task_self (),
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msg.head.msgh_remote_port);
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if (got)
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poll:
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{
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/* Poll for another message. */
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to = 0;
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options |= MACH_RCV_TIMEOUT;
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}
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}
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if (msgerr == MACH_RCV_INTERRUPTED)
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/* Interruption on our side (e.g. signal reception). */
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err = EINTR;
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if (got)
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/* At least one descriptor is known to be ready now, so we will
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return success. */
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err = 0;
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}
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if (firstfd != -1)
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for (i = firstfd; i <= lastfd; ++i)
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if (d[i].type)
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__mach_port_destroy (__mach_task_self (), d[i].reply_port);
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if (firstfd == -1 || (firstfd != lastfd && portset != MACH_PORT_NULL))
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/* Destroy PORTSET, but only if it's not actually the reply port for a
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single descriptor (in which case it's destroyed in the previous loop;
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not doing it here is just a bit more efficient). */
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__mach_port_destroy (__mach_task_self (), portset);
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if (err)
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{
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if (sigmask)
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__sigprocmask (SIG_SETMASK, &oset, NULL);
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return __hurd_fail (err);
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}
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if (pollfds)
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/* Fill in the `revents' members of the user's array. */
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for (i = 0; i < nfds; ++i)
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{
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int type = d[i].type;
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int_fast16_t revents = 0;
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if (type & SELECT_RETURNED)
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{
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if (type & SELECT_READ)
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revents |= POLLIN;
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if (type & SELECT_WRITE)
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revents |= POLLOUT;
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if (type & SELECT_URG)
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revents |= POLLPRI;
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}
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pollfds[i].revents = revents;
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}
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else
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{
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/* Below we recalculate GOT to include an increment for each operation
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allowed on each fd. */
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got = 0;
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/* Set the user bitarrays. We only ever have to clear bits, as all
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desired ones are initially set. */
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if (firstfd != -1)
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for (i = firstfd; i <= lastfd; ++i)
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{
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int type = d[i].type;
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if ((type & SELECT_RETURNED) == 0)
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type = 0;
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if (type & SELECT_READ)
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got++;
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else if (readfds)
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FD_CLR (i, readfds);
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if (type & SELECT_WRITE)
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got++;
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else if (writefds)
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FD_CLR (i, writefds);
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if (type & SELECT_URG)
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got++;
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else if (exceptfds)
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FD_CLR (i, exceptfds);
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}
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}
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if (sigmask && __sigprocmask (SIG_SETMASK, &oset, NULL))
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return -1;
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return got;
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}
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