/*
* loopback block device utilities
*
- * Copyright (C) 2011, Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2011-2012, Red Hat, Inc. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
+#include <limits.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <linux/loop.h>
#include "utils_loop.h"
-char *crypt_loop_get_device(void)
+#define LOOP_DEV_MAJOR 7
+
+#ifndef LO_FLAGS_AUTOCLEAR
+#define LO_FLAGS_AUTOCLEAR 4
+#endif
+
+#ifndef LOOP_CTL_GET_FREE
+#define LOOP_CTL_GET_FREE 0x4C82
+#endif
+
+static char *crypt_loop_get_device_old(void)
{
char dev[20];
int i, loop_fd;
struct stat st;
struct loop_info64 lo64 = {0};
- for(i = 0; i < 256; i++) {
+ for (i = 0; i < 256; i++) {
sprintf(dev, "/dev/loop%d", i);
if (stat(dev, &st) || !S_ISBLK(st.st_mode))
return NULL;
if (loop_fd < 0)
return NULL;
- if(ioctl(loop_fd, LOOP_GET_STATUS64, &lo64) && errno == ENXIO) {
+ if (ioctl(loop_fd, LOOP_GET_STATUS64, &lo64) &&
+ errno == ENXIO) {
close(loop_fd);
return strdup(dev);
}
return NULL;
}
-int crypt_loop_attach(const char *loop, const char *file,
- int offset, int *readonly)
+char *crypt_loop_get_device(void)
+{
+ char dev[64];
+ int i, loop_fd;
+ struct stat st;
+
+ loop_fd = open("/dev/loop-control", O_RDONLY);
+ if (loop_fd < 0)
+ return crypt_loop_get_device_old();
+
+ i = ioctl(loop_fd, LOOP_CTL_GET_FREE);
+ if (i < 0) {
+ close(loop_fd);
+ return NULL;
+ }
+ close(loop_fd);
+
+ if (sprintf(dev, "/dev/loop%d", i) < 0)
+ return NULL;
+
+ if (stat(dev, &st) || !S_ISBLK(st.st_mode))
+ return NULL;
+
+ return strdup(dev);
+}
+
+int crypt_loop_attach(const char *loop, const char *file, int offset,
+ int autoclear, int *readonly)
{
struct loop_info64 lo64 = {0};
int loop_fd = -1, file_fd = -1, r = 1;
strncpy((char*)lo64.lo_file_name, file, LO_NAME_SIZE);
lo64.lo_offset = offset;
- lo64.lo_flags |= LO_FLAGS_AUTOCLEAR;
+ if (autoclear)
+ lo64.lo_flags |= LO_FLAGS_AUTOCLEAR;
if (ioctl(loop_fd, LOOP_SET_FD, file_fd) < 0)
goto out;
(void)ioctl(loop_fd, LOOP_CLR_FD, 0);
goto out;
}
+
+ /* Verify that autoclear is really set */
+ if (autoclear) {
+ memset(&lo64, 0, sizeof(lo64));
+ if (ioctl(loop_fd, LOOP_GET_STATUS64, &lo64) < 0 ||
+ !(lo64.lo_flags & LO_FLAGS_AUTOCLEAR)) {
+ (void)ioctl(loop_fd, LOOP_CLR_FD, 0);
+ goto out;
+ }
+ }
+
r = 0;
out:
if (r && loop_fd >= 0)
return r ? -1 : loop_fd;
}
-char *crypt_loop_backing_file(const char *loop)
+int crypt_loop_detach(const char *loop)
+{
+ int loop_fd = -1, r = 1;
+
+ loop_fd = open(loop, O_RDONLY);
+ if (loop_fd < 0)
+ return 1;
+
+ if (!ioctl(loop_fd, LOOP_CLR_FD, 0))
+ r = 0;
+
+ close(loop_fd);
+ return r;
+}
+
+static char *_ioctl_backing_file(const char *loop)
{
struct loop_info64 lo64 = {0};
int loop_fd;
return strdup((char*)lo64.lo_file_name);
}
+static char *_sysfs_backing_file(const char *loop)
+{
+ struct stat st;
+ char buf[PATH_MAX];
+ size_t len;
+ int fd;
+
+ if (stat(loop, &st) || !S_ISBLK(st.st_mode))
+ return NULL;
+
+ snprintf(buf, sizeof(buf), "/sys/dev/block/%d:%d/loop/backing_file",
+ major(st.st_rdev), minor(st.st_rdev));
+
+ fd = open(buf, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ len = read(fd, buf, PATH_MAX);
+ close(fd);
+ if (len < 2)
+ return NULL;
+
+ buf[len - 1] = '\0';
+ return strdup(buf);
+}
+
+char *crypt_loop_backing_file(const char *loop)
+{
+ char *bf = _sysfs_backing_file(loop);
+ return bf ?: _ioctl_backing_file(loop);
+}
+
int crypt_loop_device(const char *loop)
{
struct stat st;
+ if (!loop)
+ return 0;
+
if (stat(loop, &st) || !S_ISBLK(st.st_mode) ||
major(st.st_rdev) != LOOP_DEV_MAJOR)
return 0;