/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include "stdinc.h"#include "dat.h"#include "fns.h" uchar buf[65536]; voidusage(void){	fprint(2, "usage: fossil/epoch fs [new-low-epoch]\n");	exits("usage");} voidmain(int argc, char **argv){	int fd;	Header h;	Super s; 	ARGBEGIN{	default:		usage();	}ARGEND 	if(argc == 0 || argc > 2)		usage(); 	if((fd = open(argv[0], argc==2 ? ORDWR : OREAD)) < 0)		sysfatal("open %s: %r", argv[0]); 	if(pread(fd, buf, HeaderSize, HeaderOffset) != HeaderSize)		sysfatal("reading header: %r");	if(!headerUnpack(&h, buf))		sysfatal("unpacking header: %r"); 	if(pread(fd, buf, h.blockSize, (vlong)h.super*h.blockSize) != h.blockSize)		sysfatal("reading super block: %r"); 	if(!superUnpack(&s, buf))		sysfatal("unpacking super block: %r"); 	print("epoch %d\n", s.epochLow);	if(argc == 2){		s.epochLow = strtoul(argv[1], 0, 0);		superPack(&s, buf);		if(pwrite(fd, buf, h.blockSize, (vlong)h.super*h.blockSize) != h.blockSize)			sysfatal("writing super block: %r");	}	exits(0);}