code: mafs

ref: 7038b412045ad003366804789e7fecaf0552f77c
dir: /block.c/

#include <u.h>
#include <libc.h>
#include "dat.h"
#include "fns.h"

/*
	write out a single formatted block based on the tag
	TODO
		add a flag -r to show the recent block of metada
 */

int debug = 0;
char *devfile = nil;

static void
usage(void)
{
	fprint(2, "usage: block [-D] fsfile blkidx\n");
	exits("usage");
}

void
main(int argc, char *argv[])
{
	u8 tag;
	u64 size, blkno;
	u8 buf[Maxdatablocksize];
	Data *da;
	Errenv env = {0};

	envpp = privalloc();
	*envpp = &env;
	if(waserror()){
		panic(0, "err stack %d: %lux %lux %lux %lux %lux %lux",
			env.nlabel,
			env.label[0][JMPBUFPC], env.label[1][JMPBUFPC],
			env.label[2][JMPBUFPC], env.label[3][JMPBUFPC],
			env.label[4][JMPBUFPC], env.label[5][JMPBUFPC]);
	}

	ARGBEGIN{
	default:	usage();
	case 'D':	debug++; break;
	}ARGEND

	if(argc != 2)
		usage();

	devfile = argv[0];
	if(devfile == nil)
		sysfatal("no disk file");
	blkno = atoi(argv[1]);

	if (access(devfile, AREAD|AWRITE) == -1)
		sysfatal("%s cannot access device", devfile);

	size = devinit(devfile);
	if(size == 0)
		panic("null size %s", devfile);

	if(debug){
		print("Dentry size %d\n", sizeof(Dentry));
		print("Dentryhdr size %d Ddatasize %llud Servicelen %d\n",
				sizeof(Dentryhdr), Ddatasize, Servicelen);
	}

	// nunits = size/Blocksize;
	memset(buf, 0, Blocksize);
	devread(blkno, buf, 1);
	tag = buf[0];
	if(tag == Tdata){
		da = (Data*)buf;
		devread(blkno, buf, da->len);
		showblock(1, buf);
	}else
		showblock(1, buf);
	close(devfd);
	exits(0);
}