以rmmod为例，在init.rc中添加命令支持

diff --git a/system/core/init/builtins.cpp b/system/core/init/builtins.cpp
index 01db4f5dabd..72cc41612ba 100644
--- a/system/core/init/builtins.cpp
+++ b/system/core/init/builtins.cpp
@@ -364,6 +364,17 @@ static Result<void> do_insmod(const BuiltinArguments& args) {
     return {};
 }
 
+static Result<void> do_rmmod(const BuiltinArguments& args) {
+    auto it = args.begin() + 1;
+
+    std::string filename = *it;
+
+    int rc = syscall(__NR_delete_module, filename.c_str(), O_NONBLOCK | O_EXCL);
+    if (rc == -1) return ErrnoError() << "delete_module for " << filename << " failed";
+
+    return {};
+}
+
 static Result<void> do_interface_restart(const BuiltinArguments& args) {
     Service* svc = ServiceList::GetInstance().FindInterface(args[1]);
     if (!svc) return Error() << "interface " << args[1] << " not found";
@@ -1398,6 +1409,7 @@ const BuiltinFunctionMap& GetBuiltinFunctionMap() {
         {"ifup",                    {1,     1,    {true,   do_ifup}}},
         {"init_user0",              {0,     0,    {false,  do_init_user0}}},
         {"insmod",                  {1,     kMax, {true,   do_insmod}}},
+        {"rmmod",                   {1,     1,    {true,   do_rmmod}}},
         {"installkey",              {1,     1,    {false,  do_installkey}}},
         {"interface_restart",       {1,     1,    {false,  do_interface_restart}}},
         {"interface_start",         {1,     1,    {false,  do_interface_start}}},