#include <u.h>#include <libc.h>voidusage(void){	fprint(2, "usage: fossil/last disk\n");	exits("usage");}voidmain(int argc, char **argv){	int fd, bs, addr;	char buf[20];	ARGBEGIN{	default:		usage();	}ARGEND	if(argc != 1)		usage();	if((fd = open(argv[0], OREAD)) < 0)		sysfatal("open %s: %r", argv[0]);	werrstr("end of file");	if(seek(fd, 131072, 0) < 0 || readn(fd, buf, 20) != 20)		sysfatal("error reading %s: %r", argv[0]);	fmtinstall('H', encodefmt);	if(memcmp(buf, "\x37\x76\xAE\x89", 4) != 0)		sysfatal("bad magic %.4H != 3776AE89", buf);	bs = buf[7]|(buf[6]<<8);	addr = (buf[8]<<24)|(buf[9]<<16)|(buf[10]<<8)|buf[11];	if(seek(fd, (vlong)bs*addr+34, 0) < 0 || readn(fd, buf, 20) != 20)		sysfatal("error reading %s: %r", argv[0]);	print("vac:%.20lH\n", buf);	exits(0);}