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/* libguestfs - the guestfsd daemon
* Copyright (C) 2009-2020 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <config.h>
#ifdef HAVE_WINDOWS_H
#include <windows.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <sys/types.h>
#include "daemon.h"
#include "actions.h"
#ifdef WIN32
static int sync_win32 (void);
#endif
#ifdef HAVE_FSYNC
static void fsync_devices (void);
#endif
int
do_sync (void)
{
if (sync_disks () == -1) {
reply_with_perror ("sync");
return -1;
}
return 0;
}
/* This is a replacement for sync(2) which is called from
* this file and from other places in the daemon. It works
* on Windows too.
*/
int
sync_disks (void)
{
#if defined(HAVE_SYNC)
sync ();
/* On Linux, sync(2) doesn't perform a barrier, so qemu (which may
* have a writeback cache, even with cache=none) will still have
* some unwritten data. Force the data out of any qemu caches, by
* calling fsync on all block devices. Note we still need the
* call to sync above in order to schedule the writes.
* Thanks to: Avi Kivity, Kevin Wolf.
*/
#ifdef HAVE_FSYNC
fsync_devices ();
#endif
return 0;
#elif defined(WIN32)
return sync_win32 ();
#else
#error "no known sync() API"
#endif
}
#ifdef HAVE_FSYNC
static void
fsync_devices (void)
{
DIR *dir;
struct dirent *d;
int fd;
dir = opendir ("/sys/block");
if (!dir) {
perror ("opendir: /sys/block");
return;
}
for (;;) {
errno = 0;
d = readdir (dir);
if (!d) break;
if (STREQLEN (d->d_name, "sd", 2) ||
STREQLEN (d->d_name, "hd", 2) ||
STREQLEN (d->d_name, "ubd", 3) ||
STREQLEN (d->d_name, "vd", 2) ||
STREQLEN (d->d_name, "sr", 2)) {
CLEANUP_FREE char *dev_path = NULL;
if (asprintf (&dev_path, "/dev/%s", d->d_name) == -1) {
perror ("asprintf");
continue;
}
/* Ignore the root device. */
if (is_root_device (dev_path))
continue;
fd = open (dev_path, O_RDONLY|O_CLOEXEC);
if (fd == -1) {
perror (dev_path);
continue;
}
/* fsync the device. */
if (verbose)
fprintf (stderr, "fsync %s\n", dev_path);
if (fsync (fd) == -1)
perror ("fsync");
if (close (fd) == -1)
perror ("close");
}
}
/* Check readdir didn't fail */
if (errno != 0)
perror ("readdir: /sys/block");
/* Close the directory handle */
if (closedir (dir) == -1)
perror ("closedir: /sys/block");
}
#endif /* HAVE_FSYNC */
#ifdef WIN32
static int
sync_win32 (void)
{
DWORD n1, n2;
n1 = GetLogicalDriveStrings (0, NULL);
if (n1 == 0)
return -1;
TCHAR buffer[n1+2]; /* sic */
n2 = GetLogicalDriveStrings (n1, buffer);
if (n2 == 0)
return -1;
TCHAR *p = buffer;
/* The MSDN example code itself assumes that there is always one
* drive in the system. However we will be better than that and not
* make the assumption ...
*/
while (*p) {
HANDLE drive;
DWORD drive_type;
/* Ignore removable drives. */
drive_type = GetDriveType (p);
if (drive_type == DRIVE_FIXED) {
/* To open the volume you have to specify the volume name, not
* the mount point. MSDN documents use of the constant 50
* below.
*/
TCHAR volname[50];
if (!GetVolumeNameForVolumeMountPoint (p, volname, 50))
return -1;
drive = CreateFile (volname, GENERIC_READ|GENERIC_WRITE,
FILE_SHARE_READ|FILE_SHARE_WRITE,
NULL, OPEN_EXISTING, 0, 0);
if (drive == INVALID_HANDLE_VALUE)
return -1;
BOOL r;
/* This always fails in Wine:
* http://bugs.winehq.org/show_bug.cgi?id=14915
*/
r = FlushFileBuffers (drive);
CloseHandle (drive);
if (!r)
return -1;
}
/* Skip to next \0 character. */
while (*p++);
}
return 0;
}
#endif /* WIN32 */
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