scan for ffs2 slices

ffs2.lua

local ffi = require("ffi")
local io = require("io")
local bit = require("bit")

ffi.cdef[[

typedef unsigned char u_char;
typedef unsigned char u_int8_t;
typedef uint32_t u_int32_t;
typedef uint64_t u_int64_t;

enum { SBSIZE = 8192 };
enum { SBLOCK_UFS2 = 65536, };

enum { MAXMNTLEN = 468, };

enum { MAXVOLLEN = 32, };


enum { NOCSPTRS	= ((128 / sizeof(void *)) - 4), };


enum { FSMAXSNAP = 20, };


struct csum {
	int32_t	cs_ndir;		
	int32_t	cs_nbfree;		
	int32_t	cs_nifree;		
	int32_t	cs_nffree;		
};

struct csum_total {
	int64_t cs_ndir;		
	int64_t cs_nbfree;		
	int64_t cs_nifree;		
	int64_t cs_nffree;		
	int64_t cs_spare[4];		
};

struct fs {
	int32_t	 fs_firstfield;		
	int32_t	 fs_unused_1;		
	int32_t	 fs_sblkno;		
	int32_t	 fs_cblkno;		
	int32_t	 fs_iblkno;		
	int32_t	 fs_dblkno;		
	int32_t	 fs_cgoffset;		
	int32_t	 fs_cgmask;		
	int32_t	 fs_ffs1_time;		
	int32_t	 fs_ffs1_size;		
	int32_t	 fs_ffs1_dsize;		
	u_int32_t fs_ncg;		
	int32_t	 fs_bsize;		
	int32_t	 fs_fsize;		
	int32_t	 fs_frag;		

	int32_t	 fs_minfree;		
	int32_t	 fs_rotdelay;		
	int32_t	 fs_rps;		

	int32_t	 fs_bmask;		
	int32_t	 fs_fmask;		
	int32_t	 fs_bshift;		
	int32_t	 fs_fshift;		

	int32_t	 fs_maxcontig;		
	int32_t	 fs_maxbpg;		

	int32_t	 fs_fragshift;		
	int32_t	 fs_fsbtodb;		
	int32_t	 fs_sbsize;		
	int32_t	 fs_csmask;		
	int32_t	 fs_csshift;		
	int32_t	 fs_nindir;		
	u_int32_t fs_inopb;		
	int32_t	 fs_nspf;		

	int32_t	 fs_optim;		

	int32_t	 fs_npsect;		
	int32_t	 fs_interleave;		
	int32_t	 fs_trackskew;		

	int32_t  fs_id[2];		

	int32_t	 fs_ffs1_csaddr;	
	int32_t	 fs_cssize;		
	int32_t	 fs_cgsize;		

	int32_t	 fs_ntrak;		
	int32_t	 fs_nsect;		
	int32_t	 fs_spc;		

	int32_t	 fs_ncyl;		

	int32_t	 fs_cpg;		
	u_int32_t fs_ipg;		
	int32_t	 fs_fpg;		

	struct	csum fs_ffs1_cstotal;	

	int8_t	 fs_fmod;		
	int8_t	 fs_clean;		
	int8_t	 fs_ronly;		
	int8_t	 fs_ffs1_flags;		
	u_char	 fs_fsmnt[MAXMNTLEN];	
	u_char	 fs_volname[MAXVOLLEN];	
	u_int64_t fs_swuid;		
	int32_t	 fs_pad;		

	int32_t	 fs_cgrotor;		
	void    *fs_ocsp[NOCSPTRS];	
	u_int8_t *fs_contigdirs;	
	struct csum *fs_csp;		
	int32_t	*fs_maxcluster;		
	u_char	*fs_active;		
	int32_t	 fs_cpc;		

	int32_t	 fs_maxbsize;           
	int64_t	 fs_spareconf64[17];    
	int64_t	 fs_sblockloc;          
	struct	csum_total fs_cstotal;  
	int64_t	 fs_time;               
	int64_t	 fs_size;               
	int64_t	 fs_dsize;              
	int64_t	 fs_csaddr;             
	int64_t	 fs_pendingblocks;      
	u_int32_t fs_pendinginodes;     
	u_int32_t fs_snapinum[FSMAXSNAP];

	u_int32_t fs_avgfilesize;	
	u_int32_t fs_avgfpdir;		
	int32_t	 fs_sparecon[26];	
	u_int32_t fs_flags;		
	int32_t	 fs_fscktime;		
	int32_t	 fs_contigsumsize;	
	int32_t	 fs_maxsymlinklen;	
	int32_t	 fs_inodefmt;		
	u_int64_t fs_maxfilesize;	
	int64_t	 fs_qbmask;		
	int64_t	 fs_qfmask;		
	int32_t	 fs_state;		
	int32_t	 fs_postblformat;	
	int32_t	 fs_nrpos;		
	int32_t	 fs_postbloff;		
	int32_t	 fs_rotbloff;		
	int32_t	 fs_magic;		
	u_int8_t fs_space[1];		
};

enum { FS_UFS2_MAGIC = 0x19540119, };

]]

local sbtype = ffi.typeof("struct fs")
local sbsize = ffi.sizeof(sbtype)
local d = assert(io.open(arg[1] or "/dev/rsd0c", "r"))
local idx = 0

while true do
	local buf = d:read(ffi.C.SBSIZE)
	if not buf then break end
	local sb = ffi.new(sbtype)
	ffi.copy(sb, buf, sbsize)

	if sb.fs_magic == ffi.C.FS_UFS2_MAGIC and sb.fs_sbsize <= ffi.C.SBSIZE and bit.band(sb.fs_bsize, sb.fs_bsize-1) == 0 then
		local mnt = ffi.string(sb.fs_fsmnt)
		if string.sub(mnt, 1, 1) == "/" then
			print((idx*ffi.C.SBSIZE) / 512, "UFS2", ffi.string(sb.fs_fsmnt))
		end
	end

	idx = idx + 1
end

2112    UFS2    /
18966080        UFS2    /tmp
27354688        UFS2    /var
55071808        UFS2    /usr
67654720        UFS2    /usr/X11R6
69751872        UFS2    /usr/local
103641280       UFS2    /usr/src
109932736       UFS2    /usr/obj
122515648       UFS2    /home