cgroup_change_cgroup_flags: if wanted group is template group then this patch
enables cgroup_change_cgroup_flags procedure to create the control group on the
fly. It uses
cgroup_create_cgroup procedure - will be changed in the next patch.
Template cgroups are control groups which contains % variable like %U.
e.g.
@students devices people/students/%U
will create a cgroup /people/students/john if user john from group students run
a command and the people does not exist yet.
Changelog:
* not use cgroup_get_cgroup function (too robust for checking whether relevant
cgroup exist or not)
Signed-off-by: Ivana Hutarova Varekova <varek...@redhat.com>
---
src/api.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 130 insertions(+), 0 deletions(-)
diff --git a/src/api.c b/src/api.c
index ea75cca..1d8219b 100644
--- a/src/api.c
+++ b/src/api.c
@@ -2635,6 +2635,129 @@ static struct cgroup_rule
*cgroup_find_matching_rule(uid_t uid,
return ret;
}
+/* create control group based given template
+ * if the group already don't exist
+ * dest is template name with substitute variables
+ * tmp is used cgrules rule
+ */
+int cgroup_create_template_group(char *dest, struct cgroup_rule *tmp)
+{
+ char *prefix; /* investigate cgroup */
+ char *suffix; /* the rest of directory path not investigate yet */
+ struct cgroup *template_cgroup = NULL;
+ int ret = 0;
+ int i, j;
+ int exist;
+ int first;
+ struct cgroup_controller *controller;
+ char path[FILENAME_MAX];
+ DIR *dir;
+
+ prefix = (char *)malloc(sizeof(char *) * strlen(dest));
+ if (!prefix) {
+ last_errno = errno;
+ ret = ECGOTHER;
+ return ret;
+ }
+
+ /* nothing investigated yet */
+ suffix = dest;
+
+ while (suffix != NULL) {
+ /* prefix contains "not created/tested" directory cgroup which
+ * is closest to the root in given destination path
+ */
+
+ /* move suffix to deeper directory and prefix to path to it */
+ suffix = strchr(suffix, '/');
+ if (suffix != NULL) {
+ suffix[0] = '\0';
+ strcpy(prefix, dest);
+ suffix[0] = '/';
+ suffix++;
+ } else {
+ strcpy(prefix, dest);
+ }
+
+ first = 0;
+ i = 0;
+ /* test for which controllers wanted group does not exist*/
+ while (tmp->controllers[i] != NULL) {
+
+ /* test controller tmp->controllers[i] */
+ pthread_rwlock_rdlock(&cg_mount_table_lock);
+ exist = 1;
+ for (j = 0; j < CG_CONTROLLER_MAX &&
+ cg_mount_table[j].name[0] != '\0'; j++) {
+
+ if (strcmp(cg_mount_table[j].name,
+ tmp->controllers[i])) {
+ /* it is not wanted controller */
+ continue;
+ }
+
+ if (!cg_build_path_locked(prefix, path,
+ cg_mount_table[j].name))
+ continue;
+
+ dir = opendir(path);
+ if (dir != NULL) {
+ /* cgroup in given subsystem
+ * does not exist
+ */
+ closedir(dir);
+ continue;
+ }
+
+ /* control group for wanted controller exists */
+ exist = 0;
+ }
+ pthread_rwlock_unlock(&cg_mount_table_lock);
+
+ /* controller have not relevant group */
+ if (!exist) {
+ /* it is the first controller without relevant
+ group the group have to be created*/
+ if (first == 0) {
+ first = 1;
+ /* we investigate prefix group now.*/
+ template_cgroup =
+ cgroup_new_cgroup(prefix);
+ if (template_cgroup == NULL) {
+ ret = ECGFAIL;
+ goto finished;
+ }
+ }
+
+ /* and the controller have to be add */
+ controller = cgroup_add_controller(
+ template_cgroup, tmp->controllers[i]);
+ if (!controller) {
+ ret = ECGFAIL;
+ goto finished;
+ }
+ }
+ i++;
+ }
+
+ if (first == 1) {
+ /* new group have to be created */
+ ret = cgroup_create_cgroup(template_cgroup, 0);
+ if (ret != 0) {
+ cgroup_free(&template_cgroup);
+ goto finished;
+ }
+ cgroup_dbg("Group %s created\n", prefix);
+
+ cgroup_free(&template_cgroup);
+ }
+ }
+
+finished:
+ free(prefix);
+ return ret;
+}
+
int cgroup_change_cgroup_flags(uid_t uid, gid_t gid,
const char *procname, pid_t pid, int flags)
{
@@ -2783,7 +2906,14 @@ int cgroup_change_cgroup_flags(uid_t uid, gid_t gid,
newdest[j] = tmp->destination[i];
}
}
+
newdest[j] = 0;
+ if (strcmp(newdest, tmp->destination) != 0) {
+ /* destination tag contains templates */
+
+ cgroup_dbg("control group %s is template\n", newdest);
+ ret = cgroup_create_template_group(newdest, tmp);
+ }
/* Apply the rule */
ret = cgroup_change_cgroup_path(newdest,
------------------------------------------------------------------------------
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