#include <u.h>
#include <libc.h>
#include <bio.h>
#include <flate.h>
#include "cram.h"

void
usage(void)
{
	fprint(2, "usage: %s file offset\n", argv0);
	exits("usage");
}

void
main(int argc, char **argv)
{
	Biobuf *disk;
	Dentry f;
	uchar cblock[2*Blocksz], dblock[Blocksz];
	u32int start, end;
	int nblocks, block, n;

	ARGBEGIN {
	default:
		usage();
	} ARGEND

	if(argc != 2)
		usage();

	if((disk = Bopen(argv[0], OREAD)) == nil)
		sysfatal("open: %r");
	if(readdentry(disk, &f, atoll(argv[1])) < 0)
		sysfatal("read dentry: %r");
	if(inflateinit() < 0)
		sysfatal("inflateinit");

	nblocks = (f.length + Blocksz-1) / Blocksz;
	for(block = 0, start = f.data; block < nblocks; block++, start = end) {
		if(Bpread(disk, cblock, 4, f.index + block*4) != 4)
			sysfatal("read index");
		end = get32(cblock);
		if(end < start || end-start > sizeof cblock)
			sysfatal("bad index: [%#ux %#ux)", start, end);
		n = end - start + 2;	/* why +2? */

		if(Bpread(disk, cblock, n, start) != n)
			sysfatal("read data");
		if((n = inflatezlibblock(dblock, Blocksz, cblock, n)) < 0)
			sysfatal("inflate: %s", flateerr(n));
		if(write(1, dblock, n) != n)
			sysfatal("write: %r");
	}

	exits(nil);
}