#include <u.h>#include <libc.h>#include <gio.h> longgwrite(int fd, void *buf, long len, vlong offset){	ReadWriter *rd;	long rval; 	rd = getrdstruct(fd);	if(rd == nil)		return -1;	if(rd->pwrite == nil)		return -2;	wlock(rd);	rval = rd->pwrite(rd, buf, len, offset);	wunlock(rd);	return rval;}