unit: rework resource management API

This introduces a new static list of known attributes and their special
semantics. This means that cgroup attribute values can now be
automatically translated from user to kernel notation for command line
set settings, too.

This also adds proper support for multi-line attributes.

1 files changed, 91 insertions, 68 deletions

diff --git a/src/core/unit.c b/src/core/unit.c
index 3a88996eb7..370ad67e59 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -749,15 +749,13 @@ void unit_dump(Unit *u, FILE *f, const char *prefix) {
                                 prefix, b->controller, b->path);
 
                 LIST_FOREACH(by_unit, a, u->cgroup_attributes) {
-                        char *v = NULL;
+                        _cleanup_free_ char *v = NULL;
 
-                        if (a->map_callback)
-                                a->map_callback(a->controller, a->name, a->value, &v);
+                        if (a->semantics && a->semantics->map_write)
+                                a->semantics->map_write(a->semantics, a->value, &v);
 
                         fprintf(f, "%s\tControlGroupAttribute: %s %s \"%s\"\n",
                                 prefix, a->controller, a->name, v ? v : a->value);
-
-                        free(v);
                 }
 
                 if (UNIT_VTABLE(u)->dump)
@@ -1900,30 +1898,12 @@ finish:
 }
 
 int set_unit_path(const char *p) {
-        char *cwd, *c;
-        int r;
+        _cleanup_free_ char *c = NULL;
 
         /* This is mostly for debug purposes */
-
-        if (path_is_absolute(p)) {
-                if (!(c = strdup(p)))
-                        return -ENOMEM;
-        } else {
-                if (!(cwd = get_current_dir_name()))
-                        return -errno;
-
-                r = asprintf(&c, "%s/%s", cwd, p);
-                free(cwd);
-
-                if (r < 0)
-                        return -ENOMEM;
-        }
-
-        if (setenv("SYSTEMD_UNIT_PATH", c, 0) < 0) {
-                r = -errno;
-                free(c);
-                return r;
-        }
+        c = path_make_absolute_cwd(p);
+        if (setenv("SYSTEMD_UNIT_PATH", c, 0) < 0)
+                return -errno;
 
         return 0;
 }
@@ -2109,7 +2089,7 @@ static int unit_add_one_default_cgroup(Unit *u, const char *controller) {
         if (r < 0)
                 goto fail;
 
-        return 0;
+        return 1;
 
 fail:
         free(b->path);
@@ -2153,10 +2133,10 @@ CGroupBonding* unit_get_default_cgroup(Unit *u) {
 
 int unit_add_cgroup_attribute(
                 Unit *u,
+                const CGroupSemantics *semantics,
                 const char *controller,
                 const char *name,
                 const char *value,
-                CGroupAttributeMapCallback map_callback,
                 CGroupAttribute **ret) {
 
         _cleanup_free_ char *c = NULL;
@@ -2164,48 +2144,67 @@ int unit_add_cgroup_attribute(
         int r;
 
         assert(u);
-        assert(name);
         assert(value);
 
+        if (semantics) {
+                /* Semantics always take precedence */
+                if (semantics->name)
+                        name = semantics->name;
+
+                if (semantics->controller)
+                        controller = semantics->controller;
+        }
+
+        if (!name)
+                return -EINVAL;
+
         if (!controller) {
                 r = cg_controller_from_attr(name, &c);
                 if (r < 0)
                         return -EINVAL;
 
                 controller = c;
-        } else {
-                if (!filename_is_safe(name))
-                        return -EINVAL;
-
-                if (!filename_is_safe(controller))
-                        return -EINVAL;
         }
 
         if (!controller || streq(controller, SYSTEMD_CGROUP_CONTROLLER))
                 return -EINVAL;
 
+        if (!filename_is_safe(name))
+                return -EINVAL;
+
+        if (!filename_is_safe(controller))
+                return -EINVAL;
+
+        /* Check if this attribute already exists. Note that we will
+         * explicitly check for the value here too, as there are
+         * attributes which accept multiple values. */
         a = cgroup_attribute_find_list(u->cgroup_attributes, controller, name);
         if (a) {
-                char *v;
-
                 if (streq(value, a->value)) {
+                        /* Exactly the same value is always OK, let's ignore this */
                         if (ret)
                                 *ret = a;
 
                         return 0;
                 }
 
-                v = strdup(value);
-                if (!v)
-                        return -ENOMEM;
+                if (semantics && !semantics->multiple) {
+                        char *v;
 
-                free(a->value);
-                a->value = v;
+                        /* If this is a single-item entry, we can
+                         * simply patch the existing attribute */
+
+                        v = strdup(value);
+                        if (!v)
+                                return -ENOMEM;
 
-                if (ret)
-                        *ret = a;
+                        free(a->value);
+                        a->value = v;
 
-                return 1;
+                        if (ret)
+                                *ret = a;
+                        return 1;
+                }
         }
 
         a = new0(CGroupAttribute, 1);
@@ -2226,11 +2225,10 @@ int unit_add_cgroup_attribute(
                 free(a->name);
                 free(a->value);
                 free(a);
-
                 return -ENOMEM;
         }
 
-        a->map_callback = map_callback;
+        a->semantics = semantics;
         a->unit = u;
 
         LIST_PREPEND(CGroupAttribute, by_unit, u->cgroup_attributes, a);
@@ -2763,52 +2761,77 @@ ExecContext *unit_get_exec_context(Unit *u) {
         return (ExecContext*) ((uint8_t*) u + offset);
 }
 
-int unit_write_drop_in(Unit *u, bool runtime, const char *name, const char *data) {
-        _cleanup_free_ char *p = NULL, *q = NULL;
+static int drop_in_file(Unit *u, bool runtime, const char *name, char **_p, char **_q) {
+        char *p, *q;
+        int r;
+
         assert(u);
+        assert(name);
+        assert(_p);
+        assert(_q);
 
-        if (u->manager->running_as != SYSTEMD_SYSTEM)
+        if (u->manager->running_as == SYSTEMD_USER && runtime)
                 return -ENOTSUP;
 
         if (!filename_is_safe(name))
                 return -EINVAL;
 
-        p = strjoin(runtime ? "/run/systemd/system/" : "/etc/systemd/system/", u->id, ".d", NULL);
+        if (u->manager->running_as == SYSTEMD_USER) {
+                _cleanup_free_ char *c = NULL;
+
+                r = user_config_home(&c);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        return -ENOENT;
+
+                p = strjoin(c, "/", u->id, ".d", NULL);
+        } else  if (runtime)
+                p = strjoin("/run/systemd/system/", u->id, ".d", NULL);
+        else
+                p = strjoin("/etc/systemd/system/", u->id, ".d", NULL);
         if (!p)
                 return -ENOMEM;
 
         q = strjoin(p, "/50-", name, ".conf", NULL);
-        if (!q)
+        if (!q) {
+                free(p);
                 return -ENOMEM;
+        }
 
-        mkdir_p(p, 0755);
-        return write_one_line_file_atomic_label(q, data);
+        *_p = p;
+        *_q = q;
+        return 0;
 }
 
-int unit_remove_drop_in(Unit *u, bool runtime, const char *name) {
+int unit_write_drop_in(Unit *u, bool runtime, const char *name, const char *data) {
         _cleanup_free_ char *p = NULL, *q = NULL;
+        int r;
 
         assert(u);
 
-        if (u->manager->running_as != SYSTEMD_SYSTEM)
-                return -ENOTSUP;
+        r = drop_in_file(u, runtime, name, &p, &q);
+        if (r < 0)
+                return r;
 
-        if (!filename_is_safe(name))
-                return -EINVAL;
+        mkdir_p(p, 0755);
+        return write_one_line_file_atomic_label(q, data);
+}
 
-        p = strjoin(runtime ? "/run/systemd/system/" : "/etc/systemd/system/", u->id, ".d", NULL);
-        if (!p)
-                return -ENOMEM;
+int unit_remove_drop_in(Unit *u, bool runtime, const char *name) {
+        _cleanup_free_ char *p = NULL, *q = NULL;
+        int r;
 
-        q = strjoin(p, "/50-", name, ".conf", NULL);
-        if (!q)
-                return -ENOMEM;
+        assert(u);
 
+        r = drop_in_file(u, runtime, name, &p, &q);
         if (unlink(q) < 0)
-                return -errno;
+                r = -errno;
+        else
+                r = 0;
 
         rmdir(p);
-        return 0;
+        return r;
 }
 
 int unit_kill_context(