From a25f206a49d8a3111ac42791b2eca8a3c9af4991 Mon Sep 17 00:00:00 2001
From: licunlong <licunlong1@huawei.com>
Date: Thu, 6 May 2021 09:38:55 +0800
Subject: [PATCH] core-cgroup: support default slice for all units.

With this patch, users can specify a default slice for all units by
adding DefaultUnitSlice=xxx.slice in /etc/systemd/system.conf.
---
 src/core/main.c    | 22 +++++++++++
 src/core/manager.h |  3 ++
 src/core/unit.c    | 98 ++++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 115 insertions(+), 8 deletions(-)

diff --git a/src/core/main.c b/src/core/main.c
index c4379cf..e9f56fa 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -147,6 +147,7 @@ static sd_id128_t arg_machine_id;
 static EmergencyAction arg_cad_burst_action;
 static CPUSet arg_cpu_affinity;
 static NUMAPolicy arg_numa_policy;
+static char *arg_default_unit_slice = NULL;
 static usec_t arg_clock_usec;
 static void *arg_random_seed;
 static size_t arg_random_seed_size;
@@ -688,6 +689,7 @@ static int parse_config_file(void) {
                 { "Manager", "CtrlAltDelBurstAction",        config_parse_emergency_action,      arg_runtime_scope,        &arg_cad_burst_action             },
                 { "Manager", "DefaultOOMPolicy",             config_parse_oom_policy,            0,                        &arg_defaults.oom_policy          },
                 { "Manager", "DefaultOOMScoreAdjust",        config_parse_oom_score_adjust,      0,                        NULL                              },
+                { "Manager", "DefaultUnitSlice",             config_parse_string,                0,                        &arg_default_unit_slice           },
                 { "Manager", "ReloadLimitIntervalSec",       config_parse_sec,                   0,                        &arg_reload_limit_interval_sec    },
                 { "Manager", "ReloadLimitBurst",             config_parse_unsigned,              0,                        &arg_reload_limit_burst           },
 #if ENABLE_SMACK
@@ -756,6 +758,26 @@ static void set_manager_defaults(Manager *m) {
         r = manager_transient_environment_add(m, arg_default_environment);
         if (r < 0)
                 log_warning_errno(r, "Failed to add to transient environment, ignoring: %m");
+        if (m->default_unit_slice)
+        {
+                free(m->default_unit_slice);
+                m->default_unit_slice = NULL;
+        }
+
+        if (arg_default_unit_slice)
+        {
+                char *default_unit_slice_tmp = NULL;
+
+                default_unit_slice_tmp = strdup(arg_default_unit_slice);
+                if (!default_unit_slice_tmp)
+                        log_oom();
+
+                m->default_unit_slice = default_unit_slice_tmp;
+
+                /* free */
+                free(arg_default_unit_slice);
+                arg_default_unit_slice = NULL;
+        }
 }
 
 static void set_manager_settings(Manager *m) {
diff --git a/src/core/manager.h b/src/core/manager.h
index 6dd1a18..3c954af 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -23,6 +23,7 @@ typedef struct Unit Unit;
 
 /* Enforce upper limit how many names we allow */
 #define MANAGER_MAX_NAMES 131072 /* 128K */
+#define DEFAULT_UNIT_NAME_LEN_MAX 32
 
 /* On sigrtmin+18, private commands */
 enum {
@@ -481,6 +482,8 @@ struct Manager {
         unsigned sigchldgen;
         unsigned notifygen;
 
+        char *default_unit_slice;
+
         VarlinkServer *varlink_server;
         /* When we're a system manager, this object manages the subscription from systemd-oomd to PID1 that's
          * used to report changes in ManagedOOM settings (systemd server - oomd client). When
diff --git a/src/core/unit.c b/src/core/unit.c
index c069018..24d7060 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -3545,6 +3545,58 @@ int unit_set_slice(Unit *u, Unit *slice) {
         return 1;
 }
 
+/* system-xxx.slice, xxx must be (a b c/A B C...and 0 1 2...) */
+static bool slicename_is_valid(const char *slicename) {
+        const char *str_start  = "system-";
+        const char *str_end    = ".slice";
+        const char *str_tmp    = NULL;
+        size_t len_in    = 0;
+        size_t len_start = 0;
+        size_t len_end   = 0;
+        size_t i         = 0;
+
+        if (isempty(slicename))
+                return false;
+
+        len_in    = strlen(slicename);
+        len_start = strlen(str_start);
+        len_end   = strlen(str_end);
+
+        if (len_in > DEFAULT_UNIT_NAME_LEN_MAX)
+                return false;
+
+        if (len_in <= len_start + len_end)
+                return false;
+
+        /* system- */
+        if (strncmp(slicename, str_start, len_start) != 0)
+                return false;
+
+        str_tmp = slicename + len_start;
+
+        len_in = strlen(str_tmp);
+        if (len_in <= len_end)
+                return false;
+
+        /* .slice */
+        if (!strneq(str_tmp + len_in - len_end, str_end, len_end))
+                return false;
+
+        /* a b c/A B C...and 0 1 2... */
+        for (i = 0; i < (len_in - len_end); i++) {
+                char c = *(str_tmp + i);
+
+                if ((c >= 'a' && c <= 'z') ||
+                    (c >= 'A' && c <= 'Z') ||
+                    (c >= '0' && c <= '9'))
+                        continue;
+                else
+                        return false;
+        }
+
+        return true;
+}
+
 int unit_set_default_slice(Unit *u) {
         const char *slice_name;
         Unit *slice;
@@ -3558,6 +3610,20 @@ int unit_set_default_slice(Unit *u) {
         if (UNIT_GET_SLICE(u))
                 return 0;
 
+        bool isdefaultslice = false;
+        char *default_unit_slice = u->manager->default_unit_slice;
+
+        if (default_unit_slice) {
+                isdefaultslice = true;
+
+                if (streq(default_unit_slice, SPECIAL_SYSTEM_SLICE))
+                        isdefaultslice = false;
+                else if (!slicename_is_valid(default_unit_slice)) {
+                        log_error("default unit slice is error. slice name '%s' is invalid.", default_unit_slice);
+                        isdefaultslice = false;
+                }
+        }
+
         if (u->instance) {
                 _cleanup_free_ char *prefix = NULL, *escaped = NULL;
 
@@ -3575,24 +3641,40 @@ int unit_set_default_slice(Unit *u) {
                 if (!escaped)
                         return -ENOMEM;
 
-                if (MANAGER_IS_SYSTEM(u->manager))
-                        slice_name = strjoina("system-", escaped, ".slice");
-                else
+                if (MANAGER_IS_SYSTEM(u->manager)) {
+                        if (isdefaultslice) {
+                                _cleanup_free_ char *default_unit_slice_tmp = NULL;
+
+                                default_unit_slice_tmp = strreplace(default_unit_slice, ".slice", "-");
+                                if (!default_unit_slice_tmp)
+                                        return -ENOMEM;
+
+                                slice_name = strjoina(default_unit_slice_tmp, escaped, ".slice");
+                        } else
+                                slice_name = strjoina("system-", escaped, ".slice");
+                } else
                         slice_name = strjoina("app-", escaped, ".slice");
 
-        } else if (unit_is_extrinsic(u))
+        } else if (unit_is_extrinsic(u)) {
                 /* Keep all extrinsic units (e.g. perpetual units and swap and mount units in user mode) in
                  * the root slice. They don't really belong in one of the subslices. */
                 slice_name = SPECIAL_ROOT_SLICE;
-
-        else if (MANAGER_IS_SYSTEM(u->manager))
-                slice_name = SPECIAL_SYSTEM_SLICE;
-        else
+                isdefaultslice = false;
+        } else if (MANAGER_IS_SYSTEM(u->manager)) {
+                if (isdefaultslice)
+                        slice_name = default_unit_slice;
+                else
+                        slice_name = SPECIAL_SYSTEM_SLICE;
+        } else {
                 slice_name = SPECIAL_APP_SLICE;
+                isdefaultslice = false;
+        }
 
         r = manager_load_unit(u->manager, slice_name, NULL, NULL, &slice);
         if (r < 0)
                 return r;
+        if (isdefaultslice)
+                slice->default_dependencies=false;
 
         return unit_set_slice(u, slice);
 }
-- 
2.33.0

