On Mon, Jul 26, 2010 at 5:44 PM, Balbir Singh <[email protected]> wrote: > On Tue, Jul 6, 2010 at 9:50 AM, Eric Brower <[email protected]> wrote: >> Split cgroup_find_parent cgroup/parent on-disk validation from cgroup parent >> name generation. This solves a chicken-and-egg problem for callers that need >> to obtain a parent name from a cgroup that has not yet been created, such as >> cgroup_create_cgroup_from_parent(). The new function enforces the documented >> behavior (return NULL) when a "root" cgroup is specified. >> >> Modify cgroup_create_cgroup_from_parent() to use this new function, and >> clean up >> a few possibly-erroneous return values. >> >> Signed-off-by: Eric Brower <[email protected]> >> Acked-by: Balbir Singh <[email protected]> >> > > Hi, Eric > > I could not apply any of the other patches, the patch utilities > complain about the patch being corrupt. Could you please retest on > your side? > > Balbir >
My apologies-- let's try this again... Split cgroup_find_parent cgroup/parent on-disk validation from cgroup parent name generation. This solves a chicken-and-egg problem for callers that need to obtain a parent name from a cgroup that has not yet been created, such as cgroup_create_cgroup_from_parent(). The new function enforces the documented behavior (return NULL) when a "root" cgroup is specified. Modify cgroup_create_cgroup_from_parent() to use this new function, and clean up a few possibly-erroneous return values. Signed-off-by: Eric Brower <[email protected]> Acked-by: Balbir Singh <[email protected]> diff -ruPp a/src/api.c b/src/api.c --- a/src/api.c 2010-07-05 10:54:45.955407274 -0700 +++ b/src/api.c 2010-07-05 11:01:52.680407275 -0700 @@ -1435,8 +1435,56 @@ err: } /** + * Obtain the calculated parent name of specified cgroup; no validation + * of the existence of the child or parent group is performed. + * + * Given the path-like hierarchy of cgroup names, this function returns + * the dirname() of the cgroup name as the likely parent name; the caller + * is responsible for validating parent as appropriate. + * + * @param cgroup The cgroup to query for parent's name + * @param parent Output, name of parent's group, or NULL if the + * provided cgroup is the root group. + * Caller is responsible to free the returned string. + * @return 0 on success, > 0 on error + */ +static int cgroup_get_parent_name(struct cgroup *cgroup, char **parent) +{ + int ret = 0; + char *dir = NULL; + char *pdir = NULL; + + dir = strdup(cgroup->name); + if (!dir) { + return ECGFAIL; + } + cgroup_dbg("group name is %s\n", dir); + + pdir = dirname(dir); + cgroup_dbg("parent's group name is %s\n", pdir); + + /* check for root group */ + if (strlen(cgroup->name) == 0 || !strcmp(cgroup->name, pdir)) { + cgroup_dbg("specified cgroup \"%s\" is root group\n", + cgroup->name); + *parent = NULL; + } + else { + *parent = strdup(pdir); + } + free(dir); + + if (*parent == NULL) + ret = ECGFAIL; + + return ret; +} + +/** * Find the parent of the specified directory. It returns the parent (the - * parent is usually name/.. unless name is a mount point. + * parent is usually name/.. unless name is a mount point. It is assumed + * both the cgroup (and, therefore, parent) already exist, and will fail + * otherwise. * * @param cgroup The cgroup * @param parent Output, name of parent's group (if the group has parent) or @@ -1450,7 +1498,6 @@ static int cgroup_find_parent(struct cgr char *parent_path = NULL; struct stat stat_child, stat_parent; char *controller = NULL; - char *dir = NULL, *parent_dir = NULL; int ret = 0; *parent = NULL; @@ -1490,20 +1537,7 @@ static int cgroup_find_parent(struct cgr ret = 0; cgroup_dbg("Parent is on different device\n"); } else { - dir = strdup(cgroup->name); - cgroup_dbg("group name is %s\n", dir); - if (!dir) { - ret = ECGFAIL; - goto free_parent; - } - - parent_dir = dirname(dir); - cgroup_dbg("parent's group name is %s\n", parent_dir); - *parent = strdup(parent_dir); - free(dir); - - if (*parent == NULL) - ret = ECGFAIL; + ret = cgroup_get_parent_name(cgroup, parent); } free_parent: @@ -1529,7 +1563,7 @@ int cgroup_create_cgroup_from_parent(str if (!cgroup_initialized) return ECGROUPNOTINITIALIZED; - ret = cgroup_find_parent(cgroup, &parent); + ret = cgroup_get_parent_name(cgroup, &parent); if (ret) return ret; @@ -1543,16 +1577,21 @@ int cgroup_create_cgroup_from_parent(str cgroup_dbg("parent is %s\n", parent); parent_cgroup = cgroup_new_cgroup(parent); - if (!parent_cgroup) + if (!parent_cgroup) { + ret = ECGFAIL; goto err_nomem; + } - if (cgroup_get_cgroup(parent_cgroup)) + if (cgroup_get_cgroup(parent_cgroup)) { + ret = ECGFAIL; goto err_parent; + } cgroup_dbg("got parent group for %s\n", parent_cgroup->name); ret = cgroup_copy_cgroup(cgroup, parent_cgroup); - if (ret) + if (ret) { goto err_parent; + } cgroup_dbg("copied parent group %s to %s\n", parent_cgroup->name, cgroup->name); -- E ------------------------------------------------------------------------------ The Palm PDK Hot Apps Program offers developers who use the Plug-In Development Kit to bring their C/C++ apps to Palm for a share of $1 Million in cash or HP Products. Visit us here for more details: http://ad.doubleclick.net/clk;226879339;13503038;l? http://clk.atdmt.com/CRS/go/247765532/direct/01/ _______________________________________________ Libcg-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libcg-devel
