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Ian Jackson
9976f3874d
Closing the fd before unhooking it from the list runs the risk that a
concurrent thread calls xentoolcore_restrict_all will operate on the
old fd value, which might refer to a new fd by then. So we need to do
it in the other order.
Sadly this weakens the guarantee provided by xentoolcore_restrict_all
slightly, but not (I think) in a problematic way. It would be
possible to implement the previous guarantee, but it would involve
replacing all of the close() calls in all of the individual osdep
parts of all of the individual libraries with calls to a new function
which does
dup2("/dev/null", thing->fd);
pthread_mutex_lock(&handles_lock);
thing->fd = -1;
pthread_mutex_unlock(&handles_lock);
close(fd);
which would be terribly tedious.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Release-acked-by: Julien Grall <julien.grall@linaro.org>
93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
/*
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* This 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;
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* version 2.1 of the License.
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*
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* This 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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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <unistd.h>
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#include <stdlib.h>
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#include "private.h"
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static int all_restrict_cb(Xentoolcore__Active_Handle *ah, domid_t domid) {
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xenevtchn_handle *xce = CONTAINER_OF(ah, *xce, tc_ah);
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if (xce->fd < 0)
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/* just in case */
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return 0;
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return xenevtchn_restrict(xce, domid);
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}
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xenevtchn_handle *xenevtchn_open(xentoollog_logger *logger, unsigned open_flags)
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{
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xenevtchn_handle *xce = malloc(sizeof(*xce));
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int rc;
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if (!xce) return NULL;
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xce->fd = -1;
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xce->logger = logger;
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xce->logger_tofree = NULL;
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xce->tc_ah.restrict_callback = all_restrict_cb;
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xentoolcore__register_active_handle(&xce->tc_ah);
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if (!xce->logger) {
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xce->logger = xce->logger_tofree =
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(xentoollog_logger*)
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xtl_createlogger_stdiostream(stderr, XTL_PROGRESS, 0);
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if (!xce->logger) goto err;
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}
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rc = osdep_evtchn_open(xce);
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if ( rc < 0 ) goto err;
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return xce;
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err:
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xentoolcore__deregister_active_handle(&xce->tc_ah);
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osdep_evtchn_close(xce);
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xtl_logger_destroy(xce->logger_tofree);
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free(xce);
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return NULL;
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}
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int xenevtchn_close(xenevtchn_handle *xce)
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{
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int rc;
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if ( !xce )
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return 0;
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xentoolcore__deregister_active_handle(&xce->tc_ah);
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rc = osdep_evtchn_close(xce);
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xtl_logger_destroy(xce->logger_tofree);
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free(xce);
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return rc;
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}
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int xenevtchn_restrict(xenevtchn_handle *xce, domid_t domid)
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{
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return osdep_evtchn_restrict(xce, domid);
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}
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/*
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* Local variables:
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* mode: C
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* c-file-style: "BSD"
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* c-basic-offset: 4
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* tab-width: 4
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* indent-tabs-mode: nil
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* End:
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*/
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