#include <u.h>#include <libc.h>#include "fmtdef.h" intvsnprint(char *buf, int len, char *fmt, va_list args){	Fmt f; 	if(len <= 0)		return -1;	f.runes = 0;	f.start = buf;	f.to = buf;	f.stop = buf + len - 1;	f.flush = 0;	f.farg = nil;	f.nfmt = 0;	VA_COPY(f.args,args);	dofmt(&f, fmt);	VA_END(f.args);	*(char*)f.to = '\0';	return (char*)f.to - buf;}