一，binder驱动源码分析，使用服务过程

uint32_t svcmgr_lookup(struct binder_state *bs, uint32_t target, const char *name)
{
    uint32_t handle;
    unsigned iodata[512/4];
    struct binder_io msg, reply;

    bio_init(&msg, iodata, sizeof(iodata), 4);
    bio_put_uint32(&msg, 0);  // strict mode header
    bio_put_string16_x(&msg, SVC_MGR_NAME);
    bio_put_string16_x(&msg, name);

    if (binder_call(bs, &msg, &reply, target, SVC_MGR_CHECK_SERVICE))
        return 0;

    handle = bio_get_ref(&reply);

    if (handle)
        binder_acquire(bs, handle);

    binder_done(bs, &msg, &reply);

    return handle;
}