#include <u.h>#include <libc.h>#include <bio.h>#include "authcmdlib.h" /* *  read exactly len bytes */intreadn(int fd, char *buf, int len){	int m, n; 	for(n = 0; n < len; n += m){		m = read(fd, buf+n, len-n);		if(m <= 0)			return -1;	}	return n;}