ref: a542e25da704455c6ac9397e4dbc94d4ab7e17d9
dir: /sys/src/cmd/auth/lib/readn.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include "authcmdlib.h"
/*
* read exactly len bytes
*/
int
readn(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;
}