add none check for buf to write
add none check for buf to write

RyanTech/tchannel,benfleis/tchannel,sasa233/tchannel,sasa233/tchannel,savaki/tchannel,bunnyblue/tchannel,bunnyblue/tchannel,sasa233/tchannel,Zirpon/tchannel,hustxiaoc/tchannel,benfleis/tchannel,chenwenbin928/tchannel,i/tchannel,i/tchannel,vanloswang/tchannel,savaki/tchannel,savaki/tchannel,chenwenbin928/tchannel,hustxiaoc/tchannel,benfleis/tchannel,hustxiaoc/tchannel,vanloswang/tchannel,chenwenbin928/tchannel,RyanTech/tchannel,vanloswang/tchannel,i/tchannel,bunnyblue/tchannel,Zirpon/tchannel,RyanTech/tchannel,Zirpon/tchannel