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/*
* This 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;
* version 2.1 of the License.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xc_private.h"
#include "xenguest.h"
#define SUSPEND_LOCK_FILE "/var/lib/xen/suspend_evtchn"
static int lock_suspend_event(xc_interface *xch, int domid)
{
int fd, rc;
mode_t mask;
char buf[128];
char suspend_file[256];
snprintf(suspend_file, sizeof(suspend_file), "%s_%d_lock.d",
SUSPEND_LOCK_FILE, domid);
mask = umask(022);
fd = open(suspend_file, O_CREAT | O_EXCL | O_RDWR, 0666);
if (fd < 0)
{
ERROR("Can't create lock file for suspend event channel %s\n",
suspend_file);
return -EINVAL;
}
umask(mask);
snprintf(buf, sizeof(buf), "%10ld", (long)getpid());
rc = write_exact(fd, buf, strlen(buf));
close(fd);
return rc;
}
static int unlock_suspend_event(xc_interface *xch, int domid)
{
int fd, pid, n;
char buf[128];
char suspend_file[256];
snprintf(suspend_file, sizeof(suspend_file), "%s_%d_lock.d",
SUSPEND_LOCK_FILE, domid);
fd = open(suspend_file, O_RDWR);
if (fd < 0)
return -EINVAL;
n = read(fd, buf, 127);
close(fd);
if (n > 0)
{
sscanf(buf, "%d", &pid);
/* We are the owner, so we can simply delete the file */
if (pid == getpid())
{
unlink(suspend_file);
return 0;
}
}
return -EPERM;
}
int xc_await_suspend(xc_interface *xch, xc_evtchn *xce, int suspend_evtchn)
{
int rc;
do {
rc = xc_evtchn_pending(xce);
if (rc < 0) {
ERROR("error polling suspend notification channel: %d", rc);
return -1;
}
} while (rc != suspend_evtchn);
/* harmless for one-off suspend */
if (xc_evtchn_unmask(xce, suspend_evtchn) < 0)
ERROR("failed to unmask suspend notification channel: %d", rc);
return 0;
}
int xc_suspend_evtchn_release(xc_interface *xch, xc_evtchn *xce, int domid, int suspend_evtchn)
{
if (suspend_evtchn >= 0)
xc_evtchn_unbind(xce, suspend_evtchn);
return unlock_suspend_event(xch, domid);
}
int xc_suspend_evtchn_init(xc_interface *xch, xc_evtchn *xce, int domid, int port)
{
int rc, suspend_evtchn = -1;
if (lock_suspend_event(xch, domid))
return -EINVAL;
suspend_evtchn = xc_evtchn_bind_interdomain(xce, domid, port);
if (suspend_evtchn < 0) {
ERROR("failed to bind suspend event channel: %d", suspend_evtchn);
goto cleanup;
}
rc = xc_domain_subscribe_for_suspend(xch, domid, port);
if (rc < 0) {
ERROR("failed to subscribe to domain: %d", rc);
goto cleanup;
}
/* event channel is pending immediately after binding */
xc_await_suspend(xch, xce, suspend_evtchn);
return suspend_evtchn;
cleanup:
if (suspend_evtchn != -1)
xc_suspend_evtchn_release(xch, xce, domid, suspend_evtchn);
return -1;
}
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