shared: move exec_command_list_build_json() to varlink-common

exec_command_list_build_json() serializes a linked list of ExecCommand into a JSON array. It was static in varlink-unit.c (used by service_context_build_json) but is also needed by the upcoming socket context builder. Move it next to exec_command_build_json() in varlink-common where it can be shared.

src/core/varlink-common.c

@@ -136,3 +136,26 @@ int exec_command_build_json(sd_json_variant **ret, const char *name, void *userd
                         SD_JSON_BUILD_PAIR_BOOLEAN("noEnvExpand", FLAGS_SET(cmd->flags, EXEC_COMMAND_NO_ENV_EXPAND)),
                         SD_JSON_BUILD_PAIR_BOOLEAN("viaShell", FLAGS_SET(cmd->flags, EXEC_COMMAND_VIA_SHELL)));
 }
+
+int exec_command_list_build_json(sd_json_variant **ret, const char *name, void *userdata) {
+        _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL;
+        ExecCommand *list = userdata;
+        int r;
+
+        assert(ret);
+
+        LIST_FOREACH(command, c, list) {
+                _cleanup_(sd_json_variant_unrefp) sd_json_variant *entry = NULL;
+
+                r = exec_command_build_json(&entry, /* name= */ NULL, c);
+                if (r < 0)
+                        return r;
+
+                r = sd_json_variant_append_array(&v, entry);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = TAKE_PTR(v);
+        return 0;
+}

src/core/varlink-common.h

@@ -8,4 +8,5 @@ int rlimit_table_build_json(sd_json_variant **ret, const char *name, void *userd
 int cpuset_build_json(sd_json_variant **ret, const char *name, void *userdata);
 const char* varlink_error_id_from_bus_error(const sd_bus_error *e);
 int exec_command_build_json(sd_json_variant **ret, const char *name, void *userdata);
+int exec_command_list_build_json(sd_json_variant **ret, const char *name, void *userdata);
 int varlink_reply_bus_error(sd_varlink *link, int r, const sd_bus_error *e);

src/core/varlink-unit.c

@@ -118,29 +118,6 @@ static int unit_conditions_build_json(sd_json_variant **ret, const char *name, v
         return 0;
 }
 
-static int exec_command_list_build_json(sd_json_variant **ret, const char *name, void *userdata) {
-        _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL;
-        ExecCommand *list = userdata;
-        int r;
-
-        assert(ret);
-
-        LIST_FOREACH(command, c, list) {
-                _cleanup_(sd_json_variant_unrefp) sd_json_variant *entry = NULL;
-
-                r = exec_command_build_json(&entry, /* name= */ NULL, c);
-                if (r < 0)
-                        return r;
-
-                r = sd_json_variant_append_array(&v, entry);
-                if (r < 0)
-                        return r;
-        }
-
-        *ret = TAKE_PTR(v);
-        return 0;
-}
-
 /* TODO: This covers only a small subset of a service object's properties. Extend to make more available to
  * consumers like Unit.StartTransient */
 static int service_context_build_json(sd_json_variant **ret, const char *name, void *userdata) {