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c3b287be74
During critical sections, signal handling is deferred and thus RPCs return EINTR, even if SA_RESTART is set. We thus have to restart the whole critical section in that case. This also adds HURD_CRITICAL_UNLOCK in the cases where one wants to break the section in the middle.
316 lines
8.6 KiB
C
316 lines
8.6 KiB
C
/* Copyright (C) 1991-2021 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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<https://www.gnu.org/licenses/>. */
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#include <hurd.h>
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#include <hurd/term.h>
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#include <hurd/fd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <lock-intern.h> /* For `struct mutex'. */
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#include "set-hooks.h"
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#include "hurdmalloc.h" /* XXX */
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struct mutex _hurd_dtable_lock = MUTEX_INITIALIZER; /* XXX ld bug; must init */
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struct hurd_fd **_hurd_dtable;
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int _hurd_dtablesize;
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DEFINE_HOOK (_hurd_fd_subinit, (void));
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/* Initialize the file descriptor table at startup. */
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static void
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init_dtable (void)
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{
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int i;
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__mutex_init (&_hurd_dtable_lock);
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/* The initial size of the descriptor table is that of the passed-in
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table. It will be expanded as necessary up to _hurd_dtable_rlimit. */
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_hurd_dtablesize = _hurd_init_dtablesize;
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/* Allocate the vector of pointers. */
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_hurd_dtable = malloc (_hurd_dtablesize * sizeof (*_hurd_dtable));
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if (_hurd_dtablesize != 0 && _hurd_dtable == NULL)
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__libc_fatal ("hurd: Can't allocate file descriptor table\n");
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/* Initialize the descriptor table. */
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for (i = 0; (unsigned int) i < _hurd_init_dtablesize; ++i)
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{
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if (_hurd_init_dtable[i] == MACH_PORT_NULL)
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/* An unused descriptor is marked by a null pointer. */
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_hurd_dtable[i] = NULL;
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else
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{
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/* Allocate a new file descriptor structure. */
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struct hurd_fd *new = malloc (sizeof (struct hurd_fd));
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if (new == NULL)
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__libc_fatal ("hurd: Can't allocate initial file descriptors\n");
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/* Initialize the port cells. */
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_hurd_port_init (&new->port, MACH_PORT_NULL);
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_hurd_port_init (&new->ctty, MACH_PORT_NULL);
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/* Install the port in the descriptor.
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This sets up all the ctty magic. */
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_hurd_port2fd (new, _hurd_init_dtable[i], 0);
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_hurd_dtable[i] = new;
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}
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}
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/* Clear out the initial descriptor table.
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Everything must use _hurd_dtable now. */
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__vm_deallocate (__mach_task_self (),
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(vm_address_t) _hurd_init_dtable,
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_hurd_init_dtablesize * sizeof (_hurd_init_dtable[0]));
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_hurd_init_dtable = NULL;
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_hurd_init_dtablesize = 0;
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/* Initialize the remaining empty slots in the table. */
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for (; i < _hurd_dtablesize; ++i)
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_hurd_dtable[i] = NULL;
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/* Run things that want to run after the file descriptor table
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is initialized. */
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RUN_HOOK (_hurd_fd_subinit, ());
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(void) &init_dtable; /* Avoid "defined but not used" warning. */
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}
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text_set_element (_hurd_subinit, init_dtable);
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/* XXX when the linker supports it, the following functions should all be
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elsewhere and just have text_set_elements here. */
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/* Called by `getdport' to do its work. */
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static file_t
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get_dtable_port (int fd)
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{
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struct hurd_fd *d = _hurd_fd_get (fd);
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file_t dport;
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if (!d)
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return __hurd_fail (EBADF), MACH_PORT_NULL;
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HURD_CRITICAL_BEGIN;
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dport = HURD_PORT_USE (&d->port,
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({
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error_t err;
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mach_port_t outport;
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err = __mach_port_mod_refs (__mach_task_self (),
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port,
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MACH_PORT_RIGHT_SEND,
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1);
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if (err)
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{
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errno = err;
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outport = MACH_PORT_NULL;
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}
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else
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outport = port;
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outport;
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}));
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HURD_CRITICAL_END;
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return dport;
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}
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file_t (*_hurd_getdport_fn) (int fd) = get_dtable_port;
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#include <hurd/signal.h>
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/* We are in the child fork; the dtable lock is still held.
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The parent has inserted send rights for all the normal io ports,
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but we must recover ctty-special ports for ourselves. */
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static error_t
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fork_child_dtable (void)
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{
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error_t err;
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int i;
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err = 0;
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for (i = 0; !err && i < _hurd_dtablesize; ++i)
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{
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struct hurd_fd *d = _hurd_dtable[i];
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if (d == NULL)
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continue;
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/* No other thread is using the send rights in the child task. */
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d->port.users = d->ctty.users = NULL;
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if (d->ctty.port != MACH_PORT_NULL)
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{
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/* There was a ctty-special port in the parent.
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We need to get one for ourselves too. */
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__mach_port_deallocate (__mach_task_self (), d->ctty.port);
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err = __term_open_ctty (d->port.port, _hurd_pid, _hurd_pgrp,
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&d->ctty.port);
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if (err)
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d->ctty.port = MACH_PORT_NULL;
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}
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/* XXX for each fd with a cntlmap, reauth and re-map_cntl. */
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}
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return err;
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(void) &fork_child_dtable; /* Avoid "defined but not used" warning. */
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}
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data_set_element (_hurd_fork_locks, _hurd_dtable_lock); /* XXX ld bug: bss */
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text_set_element (_hurd_fork_child_hook, fork_child_dtable);
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/* Called when our process group has changed. */
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static void
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ctty_new_pgrp (void)
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{
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int i;
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retry:
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HURD_CRITICAL_BEGIN;
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__mutex_lock (&_hurd_dtable_lock);
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if (__USEPORT (CTTYID, port == MACH_PORT_NULL))
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{
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/* We have no controlling terminal. If we haven't had one recently,
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but our pgrp is being pointlessly diddled anyway, then we will
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have nothing to do in the loop below because no fd will have a
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ctty port at all.
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More likely, a setsid call is responsible both for the change
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in pgrp and for clearing the cttyid port. In that case, setsid
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held the dtable lock while updating the dtable to clear all the
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ctty ports, and ergo must have finished doing so before we run here.
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So we can be sure, again, that the loop below has no work to do. */
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}
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else
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for (i = 0; i < _hurd_dtablesize; ++i)
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{
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struct hurd_fd *const d = _hurd_dtable[i];
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struct hurd_userlink ulink, ctty_ulink;
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io_t port, ctty;
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if (d == NULL)
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/* Nothing to do for an unused descriptor cell. */
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continue;
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port = _hurd_port_get (&d->port, &ulink);
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ctty = _hurd_port_get (&d->ctty, &ctty_ulink);
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if (ctty != MACH_PORT_NULL)
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{
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/* This fd has a ctty-special port. We need a new one, to tell
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the io server of our different process group. */
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io_t new;
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error_t err;
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if ((err = __term_open_ctty (port, _hurd_pid, _hurd_pgrp, &new)))
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{
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if (err == EINTR)
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{
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/* Got a signal while inside an RPC of the critical section, retry again */
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__mutex_unlock (&_hurd_dtable_lock);
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HURD_CRITICAL_UNLOCK;
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goto retry;
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}
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new = MACH_PORT_NULL;
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}
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_hurd_port_set (&d->ctty, new);
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}
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_hurd_port_free (&d->port, &ulink, port);
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_hurd_port_free (&d->ctty, &ctty_ulink, ctty);
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}
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__mutex_unlock (&_hurd_dtable_lock);
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HURD_CRITICAL_END;
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(void) &ctty_new_pgrp; /* Avoid "defined but not used" warning. */
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}
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text_set_element (_hurd_pgrp_changed_hook, ctty_new_pgrp);
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/* Called to reauthenticate the dtable when the auth port changes. */
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static void
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reauth_dtable (void)
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{
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int i;
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HURD_CRITICAL_BEGIN;
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__mutex_lock (&_hurd_dtable_lock);
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for (i = 0; i < _hurd_dtablesize; ++i)
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{
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struct hurd_fd *const d = _hurd_dtable[i];
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mach_port_t new, newctty, ref;
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if (d == NULL)
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/* Nothing to do for an unused descriptor cell. */
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continue;
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ref = __mach_reply_port ();
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/* Take the descriptor cell's lock. */
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__spin_lock (&d->port.lock);
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/* Reauthenticate the descriptor's port. */
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if (d->port.port != MACH_PORT_NULL
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&& ! __io_reauthenticate (d->port.port,
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ref, MACH_MSG_TYPE_MAKE_SEND)
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&& ! __USEPORT (AUTH, __auth_user_authenticate
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(port,
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ref, MACH_MSG_TYPE_MAKE_SEND,
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&new)))
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{
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/* Replace the port in the descriptor cell
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with the newly reauthenticated port. */
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if (d->ctty.port != MACH_PORT_NULL
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&& ! __io_reauthenticate (d->ctty.port,
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ref, MACH_MSG_TYPE_MAKE_SEND)
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&& ! __USEPORT (AUTH, __auth_user_authenticate
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(port,
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ref, MACH_MSG_TYPE_MAKE_SEND,
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&newctty)))
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_hurd_port_set (&d->ctty, newctty);
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_hurd_port_locked_set (&d->port, new);
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}
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else
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/* Lost. Leave this descriptor cell alone. */
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__spin_unlock (&d->port.lock);
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__mach_port_destroy (__mach_task_self (), ref);
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}
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__mutex_unlock (&_hurd_dtable_lock);
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HURD_CRITICAL_END;
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(void) &reauth_dtable; /* Avoid "defined but not used" warning. */
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}
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text_set_element (_hurd_reauth_hook, reauth_dtable);
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