asheplyakov/propagator
2
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

tools.c: added do_losetup_fd helper function

Browse Source 
Useful to setup a loopback device backed by an anonymous file
(created by memfd_create, open(O_TMPFILE), and similar).
This commit is contained in:
Alexey Sheplyakov 2021-08-18 20:56:01 +04:00
parent f6a430fd36
commit 08ec5c3a78
2 changed files with 43 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
tools.c
View File

@ -656,10 +656,12 @@ int string_array_length(char ** a)
return i;
}
int do_losetup(char * device, char * target)
/* setup loop device from file descriptor targfd */
int do_losetup_fd(char *device, int targfd, const char *name)
{
int i, loopfd, targfd;
int i, loopfd;
struct loop_info loopInfo;
memset(&loopInfo, 0, sizeof(loopInfo));
my_insmod("loop", NULL);
/* wait for udev's dust settles down */
@ -670,19 +672,10 @@ int do_losetup(char * device, char * target)
return -1;
}
targfd = open( target, O_RDONLY );
if ( targfd < 0 )
{
log_message( "losetup: error opening %s: %s", target, strerror(errno) );
close( loopfd );
return -1;
}
if ( ioctl(loopfd, LOOP_SET_FD, targfd) < 0 )
{
log_message( "losetup: error setting up loopback device: %s", strerror(errno) );
close( loopfd );
close( targfd );
return -1;
}
/* Note: LOOP_SET_FD triggers change event. While processing it
@ -693,18 +686,19 @@ int do_losetup(char * device, char * target)
*/
udev_settle();
memset(&loopInfo, 0, sizeof(loopInfo));
strcpy(loopInfo.lo_name, target);
if (name) {
strcpy(loopInfo.lo_name, name);
if ( ioctl(loopfd, LOOP_SET_STATUS, &loopInfo) < 0 )
log_message( "losetup: error setting up loopback device: %s", strerror(errno) );
if ( ioctl(loopfd, LOOP_SET_STATUS, &loopInfo) < 0 )
log_message( "losetup: error setting up loopback device: %s", strerror(errno) );
/* Same here: LOOP_SET_STATUS triggers change event, give udev
* a chance to process it without concurrent access to the loop
* device. In other words, prevent the caller of this function
* from mounting the device while udev still running blkid on it
*/
udev_settle();
/* Same here: LOOP_SET_STATUS triggers change event, give udev
* a chance to process it without concurrent access to the loop
* device. In other words, prevent the caller of this function
* from mounting the device while udev still running blkid on it
*/
udev_settle();
}
close( loopfd );
/* udev might be monitoring loopback device (with fanotify) and
@ -713,6 +707,20 @@ int do_losetup(char * device, char * target)
* (which is going to mount the newly configured loopback device)
*/
udev_settle();
close( targfd );
return 0;
}
int do_losetup(char * device, char * target)
{
int ret = 0, targfd;
targfd = open( target, O_RDONLY );
if ( targfd < 0 )
{
log_message( "losetup: error opening %s: %s", target, strerror(errno) );
return -1;
}
ret = do_losetup_fd(device, targfd, target);
close(targfd);
return ret;
}

13
tools.h
View File

@ -44,6 +44,19 @@ int pass_env(int);
char ** list_directory(char * direct);
int string_array_length(char ** a);
int do_losetup(char * device, char * target);
/**
* Setup a loopback device backed by fd.
*
* @param device path to loopback device
* @param fd backing file descriptor
* @param name for pretty output from losetup, typically name of the backing file.
* @return 0 on success, otherwise -1
*
* @note: should be used instead of do_losetup for anonymous files,
* i.e. ones created by memfd_create, open(O_TMPFILE), etc
*/
int do_losetup_fd(char *device, int fd, const char *name);
char * get_ramdisk_path(const char *);
char * get_uid_file_path(const char *, const char *);
enum return_type verify_ramdisk_digest(const char *filename, const char *sha256_hash);