源代码

sds sdsgrowzero(sds s,size_t len){   struct sdshdr *sh = (void*)(s-(sizeof(struct sdshdr)));   size_t totlen,curlen = sh->len;   if(len <= curlen) return s;   s = sdsMakeRoomFor(s,len-curlen);   if(s = NULL) return NULL;   /*Make sure added region doesn't contain garbage*/   sh = (void*)(s-(sizeof(struct sdshdr)));   memset(s+curlen,0,(len-curlen+1));//also set trailing \0 byte   totlen = sh->len+sh->free;   sh->len = len;   sh->free = totlen-sh->len;   return s;}

函数功能

将sds字符串的长度指定为len，不是原来字符串长度部分的sds将被统一设置为0.