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Prefer sysfs when reading backing file.

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git-svn-id: https://cryptsetup.googlecode.com/svn/trunk@457 36d66b0a-2a48-0410-832c-cd162a569da5
This commit is contained in:
Milan Broz
2011-03-13 23:51:33 +00:00
parent 762e9afd78
commit e905a36561
1 changed files with 34 additions and 1 deletions
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35
lib/utils_loop.c
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@@ -22,6 +22,7 @@
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <limits.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <linux/loop.h>
@@ -120,7 +121,7 @@ int crypt_loop_detach(const char *loop)
return r;
}
char *crypt_loop_backing_file(const char *loop)
static char *_ioctl_backing_file(const char *loop)
{
struct loop_info64 lo64 = {0};
int loop_fd;
@@ -142,6 +143,38 @@ char *crypt_loop_backing_file(const char *loop)
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;