/*
* Returns: 0 = success, < 0 error, 1 not found
*/
int loopcxt_find_by_backing_file(struct loopdev_cxt *lc, const char *filename,
uint64_t offset, int flags)
{
int rc, hasst;
struct stat st;
if (!filename)
return -EINVAL;
hasst = !stat(filename, &st);
rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED);
if (rc)
return rc;
while ((rc = loopcxt_next(lc)) == 0) {
if (loopcxt_is_used(lc, hasst ? &st : NULL,
filename, offset, flags))
break;
}
loopcxt_deinit_iterator(lc);
return rc;
}
/*
* Note that LOOP_CTL_GET_FREE ioctl is supported since kernel 3.1. In older
* kernels we have to check all loop devices to found unused one.
*
* See kernel commit 770fe30a46a12b6fb6b63fbe1737654d28e8484.
*/
int loopcxt_find_unused(struct loopdev_cxt *lc)
{
int rc = -1;
DBG(lc, loopdev_debug("find_unused requested"));
if (lc->flags & LOOPDEV_FL_CONTROL) {
int ctl = open(_PATH_DEV_LOOPCTL, O_RDWR);
if (ctl >= 0)
rc = ioctl(ctl, LOOP_CTL_GET_FREE);
if (rc >= 0) {
char name[16];
snprintf(name, sizeof(name), "loop%d", rc);
rc = loopiter_set_device(lc, name);
}
if (ctl >= 0)
close(ctl);
DBG(lc, loopdev_debug("find_unused by loop-control [rc=%d]", rc));
}
if (rc < 0) {
rc = loopcxt_init_iterator(lc, LOOPITER_FL_FREE);
if (rc)
return rc;
rc = loopcxt_next(lc);
loopcxt_deinit_iterator(lc);
DBG(lc, loopdev_debug("find_unused by scan [rc=%d]", rc));
}
return rc;
}
/*
* @lc: context
*
* Deinitialize loop context
*/
void loopcxt_deinit(struct loopdev_cxt *lc)
{
if (!lc)
return;
DBG(lc, loopdev_debug("de-initialize"));
free(lc->filename);
lc->filename = NULL;
loopcxt_set_device(lc, NULL);
loopcxt_deinit_iterator(lc);
}
static int delete_all_loops(struct loopdev_cxt *lc)
{
int res = 0;
if (loopcxt_init_iterator(lc, LOOPITER_FL_USED))
return -1;
while (loopcxt_next(lc) == 0)
res += delete_loop(lc);
loopcxt_deinit_iterator(lc);
return res;
}
static int show_all_loops(struct loopdev_cxt *lc, const char *file,
uint64_t offset, int flags)
{
struct stat sbuf, *st = &sbuf;
if (loopcxt_init_iterator(lc, LOOPITER_FL_USED))
return -1;
if (!file || stat(file, st))
st = NULL;
while (loopcxt_next(lc) == 0) {
if (file && !loopcxt_is_used(lc, st, file, offset, flags))
continue;
printf_loopdev(lc);
}
loopcxt_deinit_iterator(lc);
return 0;
}
/*
* @lc: context, has to initialized by loopcxt_init_iterator()
*
* Returns: 0 on success, -1 on error, 1 at the end of scanning. The details
* about the current loop device are available by
* loopcxt_get_{fd,backing_file,device,offset, ...} functions.
*/
int loopcxt_next(struct loopdev_cxt *lc)
{
struct loopdev_iter *iter;
if (!lc)
return -EINVAL;
DBG(lc, loopdev_debug("iter: next"));
iter = &lc->iter;
if (iter->done)
return 1;
/* A) Look for used loop devices in /proc/partitions ("losetup -a" only)
*/
if (iter->flags & LOOPITER_FL_USED) {
char buf[BUFSIZ];
if (!iter->proc)
iter->proc = fopen(_PATH_PROC_PARTITIONS, "r");
while (iter->proc && fgets(buf, sizeof(buf), iter->proc)) {
unsigned int m;
char name[128];
if (sscanf(buf, " %u %*s %*s %128[^\n ]",
&m, name) != 2 || m != LOOPDEV_MAJOR)
continue;
if (loopiter_set_device(lc, name) == 0)
return 0;
}
goto done;
}
/* B) Classic way, try first eight loop devices (default number
* of loop devices). This is enough for 99% of all cases.
*/
if (iter->default_check) {
for (++iter->ncur; iter->ncur < LOOPDEV_DEFAULT_NNODES;
iter->ncur++) {
char name[16];
snprintf(name, sizeof(name), "loop%d", iter->ncur);
if (loopiter_set_device(lc, name) == 0)
return 0;
}
iter->default_check = 0;
}
/* C) the worst possibility, scan whole /dev or /dev/loop/<N>
*/
if (!iter->minors) {
iter->nminors = (lc->flags & LOOPDEV_FL_DEVSUBDIR) ?
loop_scandir(_PATH_DEV_LOOP, &iter->minors, 0) :
loop_scandir(_PATH_DEV, &iter->minors, 1);
iter->ncur = -1;
}
for (++iter->ncur; iter->ncur < iter->nminors; iter->ncur++) {
char name[16];
snprintf(name, sizeof(name), "loop%d", iter->minors[iter->ncur]);
if (loopiter_set_device(lc, name) == 0)
return 0;
}
done:
loopcxt_deinit_iterator(lc);
return 1;
}
