/*
* cgroup_path_get: Calculate the full path for a particular subsystem, plus
* a passed-in (to be appended) relative cgpath for a container.
* @path: a char** into which a pointer to the answer is copied
* @subsystem: subsystem of interest (i.e. freezer).
* @cgpath: a container's (relative) cgroup path, i.e. "/lxc/c1".
*
* Returns 0 on success, -1 on error.
*
* The answer is written in a static char[MAXPATHLEN] in this function and
* should not be freed.
*/
extern int cgroup_path_get(char **path, const char *subsystem, const char *cgpath)
{
static char buf[MAXPATHLEN];
static char retbuf[MAXPATHLEN];
int rc;
/* lxc_cgroup_set passes a state object for the subsystem,
* so trim it to just the subsystem part */
if (subsystem) {
rc = snprintf(retbuf, MAXPATHLEN, "%s", subsystem);
if (rc < 0 || rc >= MAXPATHLEN) {
ERROR("subsystem name too long");
return -1;
}
char *s = index(retbuf, '.');
if (s)
*s = '\0';
DEBUG("%s: called for subsys %s name %s\n", __func__, retbuf, cgpath);
}
if (get_cgroup_mount(subsystem ? retbuf : NULL, buf)) {
ERROR("cgroup is not mounted");
return -1;
}
rc = snprintf(retbuf, MAXPATHLEN, "%s/%s", buf, cgpath);
if (rc < 0 || rc >= MAXPATHLEN) {
ERROR("name too long");
return -1;
}
DEBUG("%s: returning %s for subsystem %s", __func__, retbuf, subsystem);
*path = retbuf;
return 0;
}
/*
* lxc_cgroup_path_get: put into *path the pathname for
* %subsystem and cgroup %name. If %subsystem is NULL, then
* the first mounted cgroup will be used (for nr_tasks)
*/
int lxc_cgroup_path_get(char **path, const char *subsystem, const char *name)
{
static char buf[MAXPATHLEN];
static char retbuf[MAXPATHLEN];
/* what lxc_cgroup_set calls subsystem is actually the filename, i.e.
'devices.allow'. So for our purposee we trim it */
if (subsystem) {
snprintf(retbuf, MAXPATHLEN, "%s", subsystem);
char *s = index(retbuf, '.');
if (s)
*s = '\0';
DEBUG("%s: called for subsys %s name %s\n", __func__, retbuf, name);
}
if (get_cgroup_mount(subsystem ? retbuf : NULL, buf)) {
ERROR("cgroup is not mounted");
return -1;
}
snprintf(retbuf, MAXPATHLEN, "%s/%s", buf, name);
DEBUG("%s: returning %s for subsystem %s", __func__, retbuf, subsystem);
*path = retbuf;
return 0;
}
int lxc_cgroup_path_get(char **path, const char *name)
{
char cgroup[MAXPATHLEN];
*path = &nsgroup_path[0];
/*
* report nsgroup_path string if already set
*/
if (**path != 0)
return 0;
if (get_cgroup_mount(MTAB, cgroup)) {
ERROR("cgroup is not mounted");
return -1;
}
snprintf(nsgroup_path, MAXPATHLEN, "%s/%s", cgroup, name);
return 0;
}
int lxc_cgroup_destroy(const char *name)
{
char cgmnt[MAXPATHLEN];
char cgname[MAXPATHLEN];
if (get_cgroup_mount(MTAB, cgmnt)) {
ERROR("cgroup is not mounted");
return -1;
}
snprintf(cgname, MAXPATHLEN, "%s/%s", cgmnt, name);
if (rmdir(cgname)) {
SYSERROR("failed to remove cgroup '%s'", cgname);
return -1;
}
DEBUG("'%s' unlinked", cgname);
return 0;
}
int lxc_cgroup_create(const char *name, pid_t pid)
{
char cgmnt[MAXPATHLEN];
char cgname[MAXPATHLEN];
char clonechild[MAXPATHLEN];
int flags;
if (get_cgroup_mount(MTAB, cgmnt)) {
ERROR("cgroup is not mounted");
return -1;
}
snprintf(cgname, MAXPATHLEN, "%s/%s", cgmnt, name);
/*
* There is a previous cgroup, assume it is empty,
* otherwise that fails
*/
if (!access(cgname, F_OK) && rmdir(cgname)) {
SYSERROR("failed to remove previous cgroup '%s'", cgname);
return -1;
}
if (get_cgroup_flags(MTAB, &flags)) {
SYSERROR("failed to get cgroup flags");
return -1;
}
/* We have the deprecated ns_cgroup subsystem */
if (flags & CGROUP_NS_CGROUP) {
WARN("using deprecated ns_cgroup");
return cgroup_rename_nsgroup(cgmnt, cgname, pid);
}
snprintf(clonechild, MAXPATHLEN, "%s/cgroup.clone_children", cgmnt);
/* we check if the kernel has clone_children, at this point if there
* no clone_children neither ns_cgroup, that means the cgroup is mounted
* without the ns_cgroup and it has not the compatibility flag
*/
if (access(clonechild, F_OK)) {
ERROR("no ns_cgroup option specified");
return -1;
}
/* we enable the clone_children flag of the cgroup */
if (cgroup_enable_clone_children(clonechild)) {
SYSERROR("failed to enable 'clone_children flag");
return -1;
}
/* Let's create the cgroup */
if (mkdir(cgname, 0700)) {
SYSERROR("failed to create '%s' directory", cgname);
return -1;
}
/* Let's add the pid to the 'tasks' file */
if (cgroup_attach(cgname, pid)) {
SYSERROR("failed to attach pid '%d' to '%s'", pid, cgname);
rmdir(cgname);
return -1;
}
return 0;
}
int lxc_ns_is_mounted(void)
{
static char buf[MAXPATHLEN];
return (get_cgroup_mount("ns", buf) == 0);
}
