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Commit b653309a by Serge Hallyn
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split up lxc_cgroup_load_meta2

This one's easier to review by looking at the before and after files. It splits up lxc_cgroup_load_meta2() by adding 3 helpers. The result seems easier to reason about. A question I had, is, should the kernel_subsystems ** be freed in the success case? I assumed it was being used elsewhere but I can't find where. Currently it is only being freed in the error case. I suspect we want to free it in the success case as well. Cc: Christian Seiler <christian@iwakd.de> Cc: Dwight Engen <dwight.engen@oracle.com> Signed-off-by: 's avatarSerge Hallyn <serge.hallyn@ubuntu.com>
parent 7cb14f34
Showing with 110 additions and 74 deletions
src/lxc/cgroup.c
......@@ -107,53 +107,22 @@ struct cgroup_meta_data *lxc_cgroup_load_meta()
return md;
}
struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
/* Step 1: determine all kernel subsystems */
static bool find_cgroup_subsystems(char ***kernel_subsystems)
{
FILE *proc_cgroups = NULL;
FILE *proc_self_cgroup = NULL;
FILE *proc_self_mountinfo = NULL;
bool all_kernel_subsystems = true;
bool all_named_subsystems = false;
struct cgroup_meta_data *meta_data = NULL;
char **kernel_subsystems = NULL;
size_t kernel_subsystems_count = 0;
size_t kernel_subsystems_capacity = 0;
size_t hierarchy_capacity = 0;
size_t mount_point_capacity = 0;
size_t mount_point_count = 0;
char **tokens = NULL;
size_t token_capacity = 0;
FILE *proc_cgroups;
bool bret = false;
char *line = NULL;
size_t sz = 0;
int r, saved_errno = 0;
/* if the subsystem whitelist is not specified, include all
* hierarchies that contain kernel subsystems by default but
* no hierarchies that only contain named subsystems
*
* if it is specified, the specifier @all will select all
* hierarchies, @kernel will select all hierarchies with
* kernel subsystems and @named will select all named
* hierarchies
*/
all_kernel_subsystems = subsystem_whitelist ?
(lxc_string_in_array("@kernel", subsystem_whitelist) || lxc_string_in_array("@all", subsystem_whitelist)) :
true;
all_named_subsystems = subsystem_whitelist ?
(lxc_string_in_array("@named", subsystem_whitelist) || lxc_string_in_array("@all", subsystem_whitelist)) :
false;
meta_data = calloc(1, sizeof(struct cgroup_meta_data));
if (!meta_data)
return NULL;
meta_data->ref = 1;
size_t kernel_subsystems_count = 0;
size_t kernel_subsystems_capacity = 0;
int r;
/* Step 1: determine all kernel subsystems */
process_lock();
proc_cgroups = fopen_cloexec("/proc/cgroups", "r");
process_unlock();
if (!proc_cgroups)
goto out_error;
return false;
while (getline(&line, &sz, proc_cgroups) != -1) {
char *tab1;
......@@ -180,24 +149,38 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
continue;
(void)hierarchy_number;
r = lxc_grow_array((void ***)&kernel_subsystems, &kernel_subsystems_capacity, kernel_subsystems_count + 1, 12);
r = lxc_grow_array((void ***)kernel_subsystems, &kernel_subsystems_capacity, kernel_subsystems_count + 1, 12);
if (r < 0)
goto out_error;
kernel_subsystems[kernel_subsystems_count] = strdup(line);
if (!kernel_subsystems[kernel_subsystems_count])
goto out_error;
goto out;
(*kernel_subsystems)[kernel_subsystems_count] = strdup(line);
if (!(*kernel_subsystems)[kernel_subsystems_count])
goto out;
kernel_subsystems_count++;
}
bret = true;
out:
process_lock();
fclose(proc_cgroups);
process_unlock();
proc_cgroups = NULL;
return bret;
}
/* Step 2: determine all hierarchies (by reading /proc/self/cgroup),
* since mount points don't specify hierarchy number and
* /proc/cgroups does not contain named hierarchies
*/
static bool find_cgroup_hierarchies(struct cgroup_meta_data *meta_data,
bool all_kernel_subsystems, bool all_named_subsystems,
const char **subsystem_whitelist)
{
FILE *proc_self_cgroup;
char *line = NULL;
size_t sz = 0;
int r;
bool bret = false;
size_t hierarchy_capacity = 0;
/* Step 2: determine all hierarchies (by reading /proc/self/cgroup),
* since mount points don't specify hierarchy number and
* /proc/cgroups does not contain named hierarchies
*/
process_lock();
proc_self_cgroup = fopen_cloexec("/proc/self/cgroup", "r");
/* if for some reason (because of setns() and pid namespace for example),
......@@ -206,7 +189,7 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
proc_self_cgroup = fopen_cloexec("/proc/1/cgroup", "r");
process_unlock();
if (!proc_self_cgroup)
goto out_error;
return false;
while (getline(&line, &sz, proc_self_cgroup) != -1) {
/* file format: hierarchy:subsystems:group,
......@@ -241,25 +224,25 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
*/
r = lxc_grow_array((void ***)&meta_data->hierarchies, &hierarchy_capacity, hierarchy_number + 1, 12);
if (r < 0)
goto out_error;
goto out;
meta_data->maximum_hierarchy = hierarchy_number;
}
/* this shouldn't happen, we had this already */
if (meta_data->hierarchies[hierarchy_number])
goto out_error;
goto out;
h = calloc(1, sizeof(struct cgroup_hierarchy));
if (!h)
goto out_error;
goto out;
meta_data->hierarchies[hierarchy_number] = h;
h->index = hierarchy_number;
h->subsystems = lxc_string_split_and_trim(colon1, ',');
if (!h->subsystems)
goto out_error;
goto out;
/* see if this hierarchy should be considered */
if (!all_kernel_subsystems || !all_named_subsystems) {
for (p = h->subsystems; *p; p++) {
......@@ -280,13 +263,28 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
h->used = true;
}
}
bret = true;
out:
process_lock();
fclose(proc_self_cgroup);
process_unlock();
proc_self_cgroup = NULL;
/* Step 3: determine all mount points of each hierarchy */
return bret;
}
/* Step 3: determine all mount points of each hierarchy */
static bool find_hierarchy_mountpts( struct cgroup_meta_data *meta_data, char **kernel_subsystems)
{
bool bret = false;
FILE *proc_self_mountinfo;
char *line = NULL;
size_t sz = 0;
char **tokens = NULL;
size_t mount_point_count = 0;
size_t mount_point_capacity = 0;
size_t token_capacity = 0;
int r;
process_lock();
proc_self_mountinfo = fopen_cloexec("/proc/self/mountinfo", "r");
/* if for some reason (because of setns() and pid namespace for example),
......@@ -295,7 +293,7 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
proc_self_mountinfo = fopen_cloexec("/proc/1/mountinfo", "r");
process_unlock();
if (!proc_self_mountinfo)
goto out_error;
return false;
while (getline(&line, &sz, proc_self_mountinfo) != -1) {
char *token, *saveptr = NULL;
......@@ -310,7 +308,7 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
for (i = 0; (token = strtok_r(line, " ", &saveptr)); line = NULL) {
r = lxc_grow_array((void ***)&tokens, &token_capacity, i + 1, 64);
if (r < 0)
goto out_error;
goto out;
tokens[i++] = token;
}
......@@ -346,7 +344,7 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
subsystems = subsystems_from_mount_options(tokens[j + 3], kernel_subsystems);
if (!subsystems)
goto out_error;
goto out;
h = NULL;
for (k = 1; k <= meta_data->maximum_hierarchy; k++) {
......@@ -363,12 +361,12 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
r = lxc_grow_array((void ***)&meta_data->mount_points, &mount_point_capacity, mount_point_count + 1, 12);
if (r < 0)
goto out_error;
goto out;
/* create mount point object */
mount_point = calloc(1, sizeof(*mount_point));
if (!mount_point)
goto out_error;
goto out;
meta_data->mount_points[mount_point_count++] = mount_point;
......@@ -376,7 +374,7 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
mount_point->mount_point = strdup(tokens[4]);
mount_point->mount_prefix = strdup(tokens[3]);
if (!mount_point->mount_point || !mount_point->mount_prefix)
goto out_error;
goto out;
mount_point->read_only = !lxc_string_in_list("rw", tokens[5], ',');
if (!strcmp(mount_point->mount_prefix, "/")) {
......@@ -392,9 +390,57 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
k = lxc_array_len((void **)h->all_mount_points);
r = lxc_grow_array((void ***)&h->all_mount_points, &h->all_mount_point_capacity, k + 1, 4);
if (r < 0)
goto out_error;
goto out;
h->all_mount_points[k] = mount_point;
}
bret = true;
out:
process_lock();
fclose(proc_self_mountinfo);
process_unlock();
free(tokens);
return bret;
}
struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
{
bool all_kernel_subsystems = true;
bool all_named_subsystems = false;
struct cgroup_meta_data *meta_data = NULL;
char **kernel_subsystems = NULL;
int saved_errno = 0;
/* if the subsystem whitelist is not specified, include all
* hierarchies that contain kernel subsystems by default but
* no hierarchies that only contain named subsystems
*
* if it is specified, the specifier @all will select all
* hierarchies, @kernel will select all hierarchies with
* kernel subsystems and @named will select all named
* hierarchies
*/
all_kernel_subsystems = subsystem_whitelist ?
(lxc_string_in_array("@kernel", subsystem_whitelist) || lxc_string_in_array("@all", subsystem_whitelist)) :
true;
all_named_subsystems = subsystem_whitelist ?
(lxc_string_in_array("@named", subsystem_whitelist) || lxc_string_in_array("@all", subsystem_whitelist)) :
false;
meta_data = calloc(1, sizeof(struct cgroup_meta_data));
if (!meta_data)
return NULL;
meta_data->ref = 1;
if (!find_cgroup_subsystems(&kernel_subsystems))
goto out_error;
if (!find_cgroup_hierarchies(meta_data, all_kernel_subsystems,
all_named_subsystems, subsystem_whitelist))
goto out_error;
if (!find_hierarchy_mountpts(meta_data, kernel_subsystems))
goto out_error;
/* oops, we couldn't find anything */
if (!meta_data->hierarchies || !meta_data->mount_points) {
......@@ -406,16 +452,6 @@ struct cgroup_meta_data *lxc_cgroup_load_meta2(const char **subsystem_whitelist)
out_error:
saved_errno = errno;
process_lock();
if (proc_cgroups)
fclose(proc_cgroups);
if (proc_self_cgroup)
fclose(proc_self_cgroup);
if (proc_self_mountinfo)
fclose(proc_self_mountinfo);
process_unlock();
free(line);
free(tokens);
lxc_free_array((void **)kernel_subsystems, free);
lxc_cgroup_put_meta(meta_data);
errno = saved_errno;
......
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