cgroups: rework return values of some functions

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/cgroups/cgfsng.c b/src/lxc/cgroups/cgfsng.c
index 79f2a38b5cdb6b49265a7dfa0dbb79dd2ffb5b3c..0def4700108bc961bd4512a2e48ad0b66465c929 100644 (file)
--- a/src/lxc/cgroups/cgfsng.c
+++ b/src/lxc/cgroups/cgfsng.c
@@ -2887,8 +2887,7 @@ static void cg_unified_delegate(char ***delegate)
 /* At startup, parse_hierarchies finds all the info we need about cgroup
  * mountpoints and current cgroups, and stores it in @d.
  */
-static bool cg_hybrid_init(struct cgroup_ops *ops, bool relative,
-                          bool unprivileged)
+static int cg_hybrid_init(struct cgroup_ops *ops, bool relative, bool unprivileged)
 {
        __do_free char *basecginfo = NULL;
        __do_free char *line = NULL;
@@ -2905,19 +2904,15 @@ static bool cg_hybrid_init(struct cgroup_ops *ops, bool relative,
        else
                basecginfo = read_file("/proc/self/cgroup");
        if (!basecginfo)
-               return false;
+               return ret_set_errno(-1, ENOMEM);
 
        ret = get_existing_subsystems(&klist, &nlist);
-       if (ret < 0) {
-               ERROR("Failed to retrieve available legacy cgroup controllers");
-               return false;
-       }
+       if (ret < 0)
+               return log_error_errno(-1, errno, "Failed to retrieve available legacy cgroup controllers");
 
        f = fopen("/proc/self/mountinfo", "r");
-       if (!f) {
-               ERROR("Failed to open \"/proc/self/mountinfo\"");
-               return false;
-       }
+       if (!f)
+               return log_error_errno(-1, errno, "Failed to open \"/proc/self/mountinfo\"");
 
        lxc_cgfsng_print_basecg_debuginfo(basecginfo, klist, nlist);
 
@@ -2954,22 +2949,18 @@ static bool cg_hybrid_init(struct cgroup_ops *ops, bool relative,
 
                if (type == CGROUP_SUPER_MAGIC)
                        if (controller_list_is_dup(ops->hierarchies, controller_list))
-                               goto next;
+                               log_trace_errno(goto next, EEXIST, "Skipping duplicating controller");
 
                mountpoint = cg_hybrid_get_mountpoint(line);
-               if (!mountpoint) {
-                       ERROR("Failed parsing mountpoint from \"%s\"", line);
-                       goto next;
-               }
+               if (!mountpoint)
+                       log_error_errno(goto next, EINVAL, "Failed parsing mountpoint from \"%s\"", line);
 
                if (type == CGROUP_SUPER_MAGIC)
                        base_cgroup = cg_hybrid_get_current_cgroup(basecginfo, controller_list[0], CGROUP_SUPER_MAGIC);
                else
                        base_cgroup = cg_hybrid_get_current_cgroup(basecginfo, NULL, CGROUP2_SUPER_MAGIC);
-               if (!base_cgroup) {
-                       ERROR("Failed to find current cgroup");
-                       goto next;
-               }
+               if (!base_cgroup)
+                       log_error_errno(goto next, EINVAL, "Failed to find current cgroup");
 
                trim(base_cgroup);
                prune_init_scope(base_cgroup);
@@ -2978,7 +2969,7 @@ static bool cg_hybrid_init(struct cgroup_ops *ops, bool relative,
                else
                        writeable = test_writeable_v1(mountpoint, base_cgroup);
                if (!writeable)
-                       goto next;
+                       log_trace_errno(goto next, EROFS, "The %s group is not writeable", base_cgroup);
 
                if (type == CGROUP2_SUPER_MAGIC) {
                        char *cgv2_ctrl_path;
@@ -2998,7 +2989,7 @@ static bool cg_hybrid_init(struct cgroup_ops *ops, bool relative,
 
                /* Exclude all controllers that cgroup use does not want. */
                if (!cgroup_use_wants_controllers(ops, controller_list))
-                       goto next;
+                       log_trace_errno(goto next, EINVAL, "Skipping controller");
 
                new = add_hierarchy(&ops->hierarchies, controller_list, mountpoint, base_cgroup, type);
                if (type == CGROUP2_SUPER_MAGIC && !ops->unified) {
@@ -3025,9 +3016,9 @@ static bool cg_hybrid_init(struct cgroup_ops *ops, bool relative,
         * controllers are accounted for
         */
        if (!all_controllers_found(ops))
-               return false;
+               return log_error_errno(-1, ENOENT, "Failed to find all required controllers");
 
-       return true;
+       return 0;
 }
 
 /* Get current cgroup from /proc/self/cgroup for the cgroupfs v2 hierarchy. */
@@ -3114,7 +3105,7 @@ static int cg_unified_init(struct cgroup_ops *ops, bool relative,
        return CGROUP2_SUPER_MAGIC;
 }
 
-static bool cg_init(struct cgroup_ops *ops, struct lxc_conf *conf)
+static int cg_init(struct cgroup_ops *ops, struct lxc_conf *conf)
 {
        int ret;
        const char *tmp;
@@ -3134,29 +3125,32 @@ static bool cg_init(struct cgroup_ops *ops, struct lxc_conf *conf)
 
        ret = cg_unified_init(ops, relative, !lxc_list_empty(&conf->id_map));
        if (ret < 0)
-               return false;
+               return -1;
 
        if (ret == CGROUP2_SUPER_MAGIC)
-               return true;
+               return 0;
 
        return cg_hybrid_init(ops, relative, !lxc_list_empty(&conf->id_map));
 }
 
-__cgfsng_ops static bool cgfsng_data_init(struct cgroup_ops *ops)
+__cgfsng_ops static int cgfsng_data_init(struct cgroup_ops *ops)
 {
        const char *cgroup_pattern;
 
+       if (!ops)
+               return ret_set_errno(-1, ENOENT);
+
        /* copy system-wide cgroup information */
        cgroup_pattern = lxc_global_config_value("lxc.cgroup.pattern");
        if (!cgroup_pattern) {
                /* lxc.cgroup.pattern is only NULL on error. */
                ERROR("Failed to retrieve cgroup pattern");
-               return false;
+               return ret_set_errno(-1, ENOMEM);
        }
        ops->cgroup_pattern = must_copy_string(cgroup_pattern);
        ops->monitor_pattern = MONITOR_CGROUP;
 
-       return true;
+       return 0;
 }
 
 struct cgroup_ops *cgfsng_ops_init(struct lxc_conf *conf)
@@ -3165,12 +3159,12 @@ struct cgroup_ops *cgfsng_ops_init(struct lxc_conf *conf)
 
        cgfsng_ops = malloc(sizeof(struct cgroup_ops));
        if (!cgfsng_ops)
-               return NULL;
+               return ret_set_errno(NULL, ENOMEM);
 
        memset(cgfsng_ops, 0, sizeof(struct cgroup_ops));
        cgfsng_ops->cgroup_layout = CGROUP_LAYOUT_UNKNOWN;
 
-       if (!cg_init(cgfsng_ops, conf))
+       if (cg_init(cgfsng_ops, conf))
                return NULL;
 
        cgfsng_ops->unified_fd = -EBADF;

diff --git a/src/lxc/cgroups/cgroup.h b/src/lxc/cgroups/cgroup.h
index 80d2c315a3c45b108a17da0544f3323ee7806d73..dce506aa20d807e66699279b1110564bad29ea92 100644 (file)
--- a/src/lxc/cgroups/cgroup.h
+++ b/src/lxc/cgroups/cgroup.h
@@ -132,7 +132,7 @@ struct cgroup_ops {
         */
        cgroup_layout_t cgroup_layout;
 
-       bool (*data_init)(struct cgroup_ops *ops);
+       int (*data_init)(struct cgroup_ops *ops);
        void (*payload_destroy)(struct cgroup_ops *ops, struct lxc_handler *handler);
        void (*monitor_destroy)(struct cgroup_ops *ops, struct lxc_handler *handler);
        bool (*monitor_create)(struct cgroup_ops *ops, struct lxc_handler *handler);