text: /*-
   * Copyright (c) 2004 Max Khon
   * Copyright (c) 2014 Juniper Networks, Inc.
   * Copyright (c) 2006-2016 Maxim Sobolev <sobomax@FreeBSD.org>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: releng/11.0/sys/geom/uzip/g_uzip.c 302284 2016-06-29 18:19:05Z sobomax $");
  
  #include <sys/param.h>
  #include <sys/bio.h>
  #include <sys/endian.h>
  #include <sys/errno.h>
  #include <sys/kernel.h>
  #include <sys/lock.h>
  #include <sys/mutex.h>
  #include <sys/malloc.h>
  #include <sys/sysctl.h>
  #include <sys/systm.h>
  #include <sys/kthread.h>
  
  #include <geom/geom.h>
  
  #include <geom/uzip/g_uzip.h>
  #include <geom/uzip/g_uzip_cloop.h>
  #include <geom/uzip/g_uzip_softc.h>
  #include <geom/uzip/g_uzip_dapi.h>
  #include <geom/uzip/g_uzip_zlib.h>
  #include <geom/uzip/g_uzip_lzma.h>
  #include <geom/uzip/g_uzip_wrkthr.h>
  
  #include "opt_geom.h"
  
  MALLOC_DEFINE(M_GEOM_UZIP, "geom_uzip", "GEOM UZIP data structures");
  
  FEATURE(geom_uzip, "GEOM read-only compressed disks support");
  
  struct g_uzip_blk {
          uint64_t offset;
          uint32_t blen;
          unsigned char last:1;
          unsigned char padded:1;
  #define BLEN_UNDEF      UINT32_MAX
  };
  
  #ifndef ABS
  #define	ABS(a)			((a) < 0 ? -(a) : (a))
  #endif
  
  #define BLK_IN_RANGE(mcn, bcn, ilen)	\
      (((bcn) != BLEN_UNDEF) && ( \
  	((ilen) >= 0 && (mcn >= bcn) && (mcn <= ((intmax_t)(bcn) + (ilen)))) || \
  	((ilen) < 0 && (mcn <= bcn) && (mcn >= ((intmax_t)(bcn) + (ilen)))) \
      ))
  
  #ifdef GEOM_UZIP_DEBUG
  # define GEOM_UZIP_DBG_DEFAULT	3
  #else
  # define GEOM_UZIP_DBG_DEFAULT	0
  #endif
  
  #define	GUZ_DBG_ERR	1
  #define	GUZ_DBG_INFO	2
  #define	GUZ_DBG_IO	3
  #define	GUZ_DBG_TOC	4
  
  #define	GUZ_DEV_SUFX	".uzip"
  #define	GUZ_DEV_NAME(p)	(p GUZ_DEV_SUFX)
  
  static char g_uzip_attach_to[MAXPATHLEN] = {"*"};
  static char g_uzip_noattach_to[MAXPATHLEN] = {GUZ_DEV_NAME("*")};
  TUNABLE_STR("kern.geom.uzip.attach_to", g_uzip_attach_to,
      sizeof(g_uzip_attach_to));
  TUNABLE_STR("kern.geom.uzip.noattach_to", g_uzip_noattach_to,
      sizeof(g_uzip_noattach_to));
  
  SYSCTL_DECL(_kern_geom);
  SYSCTL_NODE(_kern_geom, OID_AUTO, uzip, CTLFLAG_RW, 0, "GEOM_UZIP stuff");
  static u_int g_uzip_debug = GEOM_UZIP_DBG_DEFAULT;
  SYSCTL_UINT(_kern_geom_uzip, OID_AUTO, debug, CTLFLAG_RWTUN, &g_uzip_debug, 0,
      "Debug level (0-4)");
  static u_int g_uzip_debug_block = BLEN_UNDEF;
  SYSCTL_UINT(_kern_geom_uzip, OID_AUTO, debug_block, CTLFLAG_RWTUN,
      &g_uzip_debug_block, 0, "Debug operations around specific cluster#");
  
  #define	DPRINTF(lvl, a)		\
  	if ((lvl) <= g_uzip_debug) { \
  		printf a; \
  	}
  #define	DPRINTF_BLK(lvl, cn, a)	\
  	if ((lvl) <= g_uzip_debug || \
  	    BLK_IN_RANGE(cn, g_uzip_debug_block, 8) || \
  	    BLK_IN_RANGE(cn, g_uzip_debug_block, -8)) { \
  		printf a; \
  	}
  #define	DPRINTF_BRNG(lvl, bcn, ecn, a) \
  	KASSERT(bcn < ecn, ("DPRINTF_BRNG: invalid range (%ju, %ju)", \
  	    (uintmax_t)bcn, (uintmax_t)ecn)); \
  	if (((lvl) <= g_uzip_debug) || \
  	    BLK_IN_RANGE(g_uzip_debug_block, bcn, \
  	     (intmax_t)ecn - (intmax_t)bcn)) { \
  		printf a; \
  	}
  
  #define	UZIP_CLASS_NAME	"UZIP"
  
  /*
   * Maximum allowed valid block size (to prevent foot-shooting)
   */
  #define	MAX_BLKSZ	(MAXPHYS)
  
  static char CLOOP_MAGIC_START[] = "#!/bin/sh\n";
  
  static void g_uzip_read_done(struct bio *bp);
  static void g_uzip_do(struct g_uzip_softc *, struct bio *bp);
  
  static void
  g_uzip_softc_free(struct g_uzip_softc *sc, struct g_geom *gp)
  {
  
  	if (gp != NULL) {
  		DPRINTF(GUZ_DBG_INFO, ("%s: %d requests, %d cached\n",
  		    gp->name, sc->req_total, sc->req_cached));
  	}
  
  	mtx_lock(&sc->queue_mtx);
  	sc->wrkthr_flags |= GUZ_SHUTDOWN;
  	wakeup(sc);
  	while (!(sc->wrkthr_flags & GUZ_EXITING)) {
  		msleep(sc->procp, &sc->queue_mtx, PRIBIO, "guzfree",
  		    hz / 10);
  	}
  	mtx_unlock(&sc->queue_mtx);
  
  	sc->dcp->free(sc->dcp);
  	free(sc->toc, M_GEOM_UZIP);
  	mtx_destroy(&sc->queue_mtx);
  	mtx_destroy(&sc->last_mtx);
  	free(sc->last_buf, M_GEOM_UZIP);
  	free(sc, M_GEOM_UZIP);
  }
  
  static int
  g_uzip_cached(struct g_geom *gp, struct bio *bp)
  {
  	struct g_uzip_softc *sc;
  	off_t ofs;
  	size_t blk, blkofs, usz;
  
  	sc = gp->softc;
  	ofs = bp->bio_offset + bp->bio_completed;
  	blk = ofs / sc->blksz;
  	mtx_lock(&sc->last_mtx);
  	if (blk == sc->last_blk) {
  		blkofs = ofs % sc->blksz;
  		usz = sc->blksz - blkofs;
  		if (bp->bio_resid < usz)
  			usz = bp->bio_resid;
  		memcpy(bp->bio_data + bp->bio_completed, sc->last_buf + blkofs,
  		    usz);
  		sc->req_cached++;
  		mtx_unlock(&sc->last_mtx);
  
  		DPRINTF(GUZ_DBG_IO, ("%s/%s: %p: offset=%jd: got %jd bytes "
  		    "from cache\n", __func__, gp->name, bp, (intmax_t)ofs,
  		    (intmax_t)usz));
  
  		bp->bio_completed += usz;
  		bp->bio_resid -= usz;
  
  		if (bp->bio_resid == 0) {
  			g_io_deliver(bp, 0);
  			return (1);
  		}
  	} else
  		mtx_unlock(&sc->last_mtx);
  
  	return (0);
  }
  
  #define BLK_ENDS(sc, bi)	((sc)->toc[(bi)].offset + \
      (sc)->toc[(bi)].blen)
  
  #define BLK_IS_CONT(sc, bi)	(BLK_ENDS((sc), (bi) - 1) == \
      (sc)->toc[(bi)].offset)
  #define	BLK_IS_NIL(sc, bi)	((sc)->toc[(bi)].blen == 0)
  
  #define TOFF_2_BOFF(sc, pp, bi)	    ((sc)->toc[(bi)].offset - \
      (sc)->toc[(bi)].offset % (pp)->sectorsize)
  #define	TLEN_2_BLEN(sc, pp, bp, ei) roundup(BLK_ENDS((sc), (ei)) - \
      (bp)->bio_offset, (pp)->sectorsize)
  
  static int
  g_uzip_request(struct g_geom *gp, struct bio *bp)
  {
  	struct g_uzip_softc *sc;
  	struct bio *bp2;
  	struct g_consumer *cp;
  	struct g_provider *pp;
  	off_t ofs, start_blk_ofs;
  	size_t i, start_blk, end_blk, zsize;
  
  	if (g_uzip_cached(gp, bp) != 0)
  		return (1);
  
  	sc = gp->softc;
  
  	cp = LIST_FIRST(&gp->consumer);
  	pp = cp->provider;
  
  	ofs = bp->bio_offset + bp->bio_completed;
  	start_blk = ofs / sc->blksz;
  	KASSERT(start_blk < sc->nblocks, ("start_blk out of range"));
  	end_blk = howmany(ofs + bp->bio_resid, sc->blksz);
  	KASSERT(end_blk <= sc->nblocks, ("end_blk out of range"));
  
  	for (; BLK_IS_NIL(sc, start_blk) && start_blk < end_blk; start_blk++) {
  		/* Fill in any leading Nil blocks */
  		start_blk_ofs = ofs % sc->blksz;
  		zsize = MIN(sc->blksz - start_blk_ofs, bp->bio_resid);
  		DPRINTF_BLK(GUZ_DBG_IO, start_blk, ("%s/%s: %p/%ju: "
  		    "filling %ju zero bytes\n", __func__, gp->name, gp,
  		    (uintmax_t)bp->bio_completed, (uintmax_t)zsize));
  		bzero(bp->bio_data + bp->bio_completed, zsize);
  		bp->bio_completed += zsize;
  		bp->bio_resid -= zsize;
  		ofs += zsize;
  	}
  
  	if (start_blk == end_blk) {
  		KASSERT(bp->bio_resid == 0, ("bp->bio_resid is invalid"));
  		/*
  		 * No non-Nil data is left, complete request immediately.
  		 */
  		DPRINTF(GUZ_DBG_IO, ("%s/%s: %p: all done returning %ju "
  		    "bytes\n", __func__, gp->name, gp,
  		    (uintmax_t)bp->bio_completed));
  		g_io_deliver(bp, 0);
  		return (1);
  	}
  
  	for (i = start_blk + 1; i < end_blk; i++) {
  		/* Trim discontinuous areas if any */
  		if (!BLK_IS_CONT(sc, i)) {
  			end_blk = i;
  			break;
  		}
  	}
  
  	DPRINTF_BRNG(GUZ_DBG_IO, start_blk, end_blk, ("%s/%s: %p: "
  	    "start=%u (%ju[%jd]), end=%u (%ju)\n", __func__, gp->name, bp,
  	    (u_int)start_blk, (uintmax_t)sc->toc[start_blk].offset,
  	    (intmax_t)sc->toc[start_blk].blen,
  	    (u_int)end_blk, (uintmax_t)BLK_ENDS(sc, end_blk - 1)));
  
  	bp2 = g_clone_bio(bp);
  	if (bp2 == NULL) {
  		g_io_deliver(bp, ENOMEM);
  		return (1);
  	}
  	bp2->bio_done = g_uzip_read_done;
  
  	bp2->bio_offset = TOFF_2_BOFF(sc, pp, start_blk);
  	while (1) {
  		bp2->bio_length = TLEN_2_BLEN(sc, pp, bp2, end_blk - 1);
  		if (bp2->bio_length <= MAXPHYS) {
  			break;
  		}
  		if (end_blk == (start_blk + 1)) {
  			break;
  		}
  		end_blk--;
  	}
  
  	DPRINTF(GUZ_DBG_IO, ("%s/%s: bp2->bio_length = %jd, "
  	    "bp2->bio_offset = %jd\n", __func__, gp->name,
  	    (intmax_t)bp2->bio_length, (intmax_t)bp2->bio_offset));
  
  	bp2->bio_data = malloc(bp2->bio_length, M_GEOM_UZIP, M_NOWAIT);
  	if (bp2->bio_data == NULL) {
  		g_destroy_bio(bp2);
  		g_io_deliver(bp, ENOMEM);
  		return (1);
  	}
  
  	DPRINTF_BRNG(GUZ_DBG_IO, start_blk, end_blk, ("%s/%s: %p: "
  	    "reading %jd bytes from offset %jd\n", __func__, gp->name, bp,
  	    (intmax_t)bp2->bio_length, (intmax_t)bp2->bio_offset));
  
  	g_io_request(bp2, cp);
  	return (0);
  }
  
  static void
  g_uzip_read_done(struct bio *bp)
  {
  	struct bio *bp2;
  	struct g_geom *gp;
  	struct g_uzip_softc *sc;
  
  	bp2 = bp->bio_parent;
  	gp = bp2->bio_to->geom;
  	sc = gp->softc;
  
  	mtx_lock(&sc->queue_mtx);
  	bioq_disksort(&sc->bio_queue, bp);
  	mtx_unlock(&sc->queue_mtx);
  	wakeup(sc);
  }
  
  static int
  g_uzip_memvcmp(const void *memory, unsigned char val, size_t size)
  {
  	const u_char *mm;
  
  	mm = (const u_char *)memory;
  	return (*mm == val) && memcmp(mm, mm + 1, size - 1) == 0;
  }
  
  static void
  g_uzip_do(struct g_uzip_softc *sc, struct bio *bp)
  {
  	struct bio *bp2;
  	struct g_provider *pp;
  	struct g_consumer *cp;
  	struct g_geom *gp;
  	char *data, *data2;
  	off_t ofs;
  	size_t blk, blkofs, len, ulen, firstblk;
  	int err;
  
  	bp2 = bp->bio_parent;
  	gp = bp2->bio_to->geom;
  
  	cp = LIST_FIRST(&gp->consumer);
  	pp = cp->provider;
  
  	bp2->bio_error = bp->bio_error;
  	if (bp2->bio_error != 0)
  		goto done;
  
  	/* Make sure there's forward progress. */
  	if (bp->bio_completed == 0) {
  		bp2->bio_error = ECANCELED;
  		goto done;
  	}
  
  	ofs = bp2->bio_offset + bp2->bio_completed;
  	firstblk = blk = ofs / sc->blksz;
  	blkofs = ofs % sc->blksz;
  	data = bp->bio_data + sc->toc[blk].offset % pp->sectorsize;
  	data2 = bp2->bio_data + bp2->bio_completed;
  	while (bp->bio_completed && bp2->bio_resid) {
  		if (blk > firstblk && !BLK_IS_CONT(sc, blk)) {
  			DPRINTF_BLK(GUZ_DBG_IO, blk, ("%s/%s: %p: backref'ed "
  			    "cluster #%u requested, looping around\n",
  			    __func__, gp->name, bp2, (u_int)blk));
  			goto done;
  		}
  		ulen = MIN(sc->blksz - blkofs, bp2->bio_resid);
  		len = sc->toc[blk].blen;
  		DPRINTF(GUZ_DBG_IO, ("%s/%s: %p/%ju: data2=%p, ulen=%u, "
  		    "data=%p, len=%u\n", __func__, gp->name, gp,
  		    bp->bio_completed, data2, (u_int)ulen, data, (u_int)len));
  		if (len == 0) {
  			/* All zero block: no cache update */
  zero_block:
  			bzero(data2, ulen);
  		} else if (len <= bp->bio_completed) {
  			mtx_lock(&sc->last_mtx);
  			err = sc->dcp->decompress(sc->dcp, gp->name, data,
  			    len, sc->last_buf);
  			if (err != 0 && sc->toc[blk].last != 0) {
  				/*
  				 * Last block decompression has failed, check
  				 * if it's just zero padding.
  				 */
  				if (g_uzip_memvcmp(data, '\0', len) == 0) {
  					sc->toc[blk].blen = 0;
  					sc->last_blk = -1;
  					mtx_unlock(&sc->last_mtx);
  					len = 0;
  					goto zero_block;
  				}
  			}
  			if (err != 0) {
  				sc->last_blk = -1;
  				mtx_unlock(&sc->last_mtx);
  				bp2->bio_error = EILSEQ;
  				DPRINTF(GUZ_DBG_ERR, ("%s/%s: decompress"
  				    "(%p, %ju, %ju) failed\n", __func__,
  				    gp->name, sc->dcp, (uintmax_t)blk,
  				    (uintmax_t)len));
  				goto done;
  			}
  			sc->last_blk = blk;
  			memcpy(data2, sc->last_buf + blkofs, ulen);
  			mtx_unlock(&sc->last_mtx);
  			err = sc->dcp->rewind(sc->dcp, gp->name);
  			if (err != 0) {
  				bp2->bio_error = EILSEQ;
  				DPRINTF(GUZ_DBG_ERR, ("%s/%s: rewind(%p) "
  				    "failed\n", __func__, gp->name, sc->dcp));
  				goto done;
  			}
  			data += len;
  		} else
  			break;
  
  		data2 += ulen;
  		bp2->bio_completed += ulen;
  		bp2->bio_resid -= ulen;
  		bp->bio_completed -= len;
  		blkofs = 0;
  		blk++;
  	}
  
  done:
  	/* Finish processing the request. */
  	free(bp->bio_data, M_GEOM_UZIP);
  	g_destroy_bio(bp);
  	if (bp2->bio_error != 0 || bp2->bio_resid == 0)
  		g_io_deliver(bp2, bp2->bio_error);
  	else
  		g_uzip_request(gp, bp2);
  }
  
  static void
  g_uzip_start(struct bio *bp)
  {
  	struct g_provider *pp;
  	struct g_geom *gp;
  	struct g_uzip_softc *sc;
  
  	pp = bp->bio_to;
  	gp = pp->geom;
  
  	DPRINTF(GUZ_DBG_IO, ("%s/%s: %p: cmd=%d, offset=%jd, length=%jd, "
  	    "buffer=%p\n", __func__, gp->name, bp, bp->bio_cmd,
  	    (intmax_t)bp->bio_offset, (intmax_t)bp->bio_length, bp->bio_data));
  
  	sc = gp->softc;
  	sc->req_total++;
  
  	if (bp->bio_cmd != BIO_READ) {
  		g_io_deliver(bp, EOPNOTSUPP);
  		return;
  	}
  
  	bp->bio_resid = bp->bio_length;
  	bp->bio_completed = 0;
  
  	g_uzip_request(gp, bp);
  }
  
  static void
  g_uzip_orphan(struct g_consumer *cp)
  {
  	struct g_geom *gp;
  
  	g_trace(G_T_TOPOLOGY, "%s(%p/%s)", __func__, cp, cp->provider->name);
  	g_topology_assert();
  
  	gp = cp->geom;
  	g_uzip_softc_free(gp->softc, gp);
  	gp->softc = NULL;
  	g_wither_geom(gp, ENXIO);
  }
  
  static int
  g_uzip_access(struct g_provider *pp, int dr, int dw, int de)
  {
  	struct g_geom *gp;
  	struct g_consumer *cp;
  
  	gp = pp->geom;
  	cp = LIST_FIRST(&gp->consumer);
  	KASSERT (cp != NULL, ("g_uzip_access but no consumer"));
  
  	if (cp->acw + dw > 0)
  		return (EROFS);
  
  	return (g_access(cp, dr, dw, de));
  }
  
  static void
  g_uzip_spoiled(struct g_consumer *cp)
  {
  	struct g_geom *gp;
  
  	G_VALID_CONSUMER(cp);
  	gp = cp->geom;
  	g_trace(G_T_TOPOLOGY, "%s(%p/%s)", __func__, cp, gp->name);
  	g_topology_assert();
  
  	g_uzip_softc_free(gp->softc, gp);
  	gp->softc = NULL;
  	g_wither_geom(gp, ENXIO);
  }
  
  static int
  g_uzip_parse_toc(struct g_uzip_softc *sc, struct g_provider *pp,
      struct g_geom *gp)
  {
  	uint32_t i, j, backref_to;
  	uint64_t max_offset, min_offset;
  	struct g_uzip_blk *last_blk;
  
  	min_offset = sizeof(struct cloop_header) +
  	    (sc->nblocks + 1) * sizeof(uint64_t);
  	max_offset = sc->toc[0].offset - 1;
  	last_blk = &sc->toc[0];
  	for (i = 0; i < sc->nblocks; i++) {
  		/* First do some bounds checking */
  		if ((sc->toc[i].offset < min_offset) ||
  		    (sc->toc[i].offset > pp->mediasize)) {
  			goto error_offset;
  		}
  		DPRINTF_BLK(GUZ_DBG_IO, i, ("%s: cluster #%u "
  		    "offset=%ju max_offset=%ju\n", gp->name,
  		    (u_int)i, (uintmax_t)sc->toc[i].offset,
  		    (uintmax_t)max_offset));
  		backref_to = BLEN_UNDEF;
  		if (sc->toc[i].offset < max_offset) {
  			/*
  			 * For the backref'ed blocks search already parsed
  			 * TOC entries for the matching offset and copy the
  			 * size from matched entry.
  			 */
  			for (j = 0; j <= i; j++) {
                                  if (sc->toc[j].offset == sc->toc[i].offset &&
  				    !BLK_IS_NIL(sc, j)) {
                                          break;
                                  }
                                  if (j != i) {
  					continue;
  				}
  				DPRINTF(GUZ_DBG_ERR, ("%s: cannot match "
  				    "backref'ed offset at cluster #%u\n",
  				    gp->name, i));
  				return (-1);
  			}
  			sc->toc[i].blen = sc->toc[j].blen;
  			backref_to = j;
  		} else {
  			last_blk = &sc->toc[i];
  			/*
  			 * For the "normal blocks" seek forward until we hit
  			 * block whose offset is larger than ours and assume
  			 * it's going to be the next one.
  			 */
  			for (j = i + 1; j < sc->nblocks; j++) {
  				if (sc->toc[j].offset > max_offset) {
  					break;
  				}
  			}
  			sc->toc[i].blen = sc->toc[j].offset -
  			    sc->toc[i].offset;
  			if (BLK_ENDS(sc, i) > pp->mediasize) {
  				DPRINTF(GUZ_DBG_ERR, ("%s: cluster #%u "
  				    "extends past media boundary (%ju > %ju)\n",
  				    gp->name, (u_int)i,
  				    (uintmax_t)BLK_ENDS(sc, i),
  				    (intmax_t)pp->mediasize));
  				return (-1);
  			}
  			KASSERT(max_offset <= sc->toc[i].offset, (
  			    "%s: max_offset is incorrect: %ju",
  			    gp->name, (uintmax_t)max_offset));
  			max_offset = BLK_ENDS(sc, i) - 1;
  		}
  		DPRINTF_BLK(GUZ_DBG_TOC, i, ("%s: cluster #%u, original %u "
  		    "bytes, in %u bytes", gp->name, i, sc->blksz,
  		    sc->toc[i].blen));
  		if (backref_to != BLEN_UNDEF) {
  			DPRINTF_BLK(GUZ_DBG_TOC, i, (" (->#%u)",
  			    (u_int)backref_to));
  		}
  		DPRINTF_BLK(GUZ_DBG_TOC, i, ("\n"));
  	}
  	last_blk->last = 1;
  	/* Do a second pass to validate block lengths */
  	for (i = 0; i < sc->nblocks; i++) {
  		if (sc->toc[i].blen > sc->dcp->max_blen) {
  			if (sc->toc[i].last == 0) {
  				DPRINTF(GUZ_DBG_ERR, ("%s: cluster #%u "
  				    "length (%ju) exceeds "
  				    "max_blen (%ju)\n", gp->name, i,
  				    (uintmax_t)sc->toc[i].blen,
  				    (uintmax_t)sc->dcp->max_blen));
  				return (-1);
  			}
  			DPRINTF(GUZ_DBG_INFO, ("%s: cluster #%u extra "
  			    "padding is detected, trimmed to %ju\n",
  			    gp->name, i, (uintmax_t)sc->dcp->max_blen));
  			    sc->toc[i].blen = sc->dcp->max_blen;
  			sc->toc[i].padded = 1;
  		}
  	}
  	return (0);
  
  error_offset:
  	DPRINTF(GUZ_DBG_ERR, ("%s: cluster #%u: invalid offset %ju, "
  	    "min_offset=%ju mediasize=%jd\n", gp->name, (u_int)i,
  	    sc->toc[i].offset, min_offset, pp->mediasize));
  	return (-1);
  }
  
  static struct g_geom *
  g_uzip_taste(struct g_class *mp, struct g_provider *pp, int flags)
  {
  	int error;
  	uint32_t i, total_offsets, offsets_read, blk;
  	void *buf;
  	struct cloop_header *header;
  	struct g_consumer *cp;
  	struct g_geom *gp;
  	struct g_provider *pp2;
  	struct g_uzip_softc *sc;
  	enum {
  		G_UZIP = 1,
  		G_ULZMA
  	} type;
  
  	g_trace(G_T_TOPOLOGY, "%s(%s,%s)", __func__, mp->name, pp->name);
  	g_topology_assert();
  
  	/* Skip providers that are already open for writing. */
  	if (pp->acw > 0)
  		return (NULL);
  
  	if ((fnmatch(g_uzip_attach_to, pp->name, 0) != 0) ||
  	    (fnmatch(g_uzip_noattach_to, pp->name, 0) == 0)) {
  		DPRINTF(GUZ_DBG_INFO, ("%s(%s,%s), ignoring\n", __func__,
  		    mp->name, pp->name));
  		return (NULL);
  	}
  
  	buf = NULL;
  
  	/*
  	 * Create geom instance.
  	 */
  	gp = g_new_geomf(mp, GUZ_DEV_NAME("%s"), pp->name);
  	cp = g_new_consumer(gp);
  	error = g_attach(cp, pp);
  	if (error == 0)
  		error = g_access(cp, 1, 0, 0);
  	if (error) {
  		goto e1;
  	}
  	g_topology_unlock();
  
  	/*
  	 * Read cloop header, look for CLOOP magic, perform
  	 * other validity checks.
  	 */
  	DPRINTF(GUZ_DBG_INFO, ("%s: media sectorsize %u, mediasize %jd\n",
  	    gp->name, pp->sectorsize, (intmax_t)pp->mediasize));
  	buf = g_read_data(cp, 0, pp->sectorsize, NULL);
  	if (buf == NULL)
  		goto e2;
  	header = (struct cloop_header *) buf;
  	if (strncmp(header->magic, CLOOP_MAGIC_START,
  	    sizeof(CLOOP_MAGIC_START) - 1) != 0) {
  		DPRINTF(GUZ_DBG_ERR, ("%s: no CLOOP magic\n", gp->name));
  		goto e3;
  	}
  
  	switch (header->magic[CLOOP_OFS_COMPR]) {
  	case CLOOP_COMP_LZMA:
  	case CLOOP_COMP_LZMA_DDP:
  		type = G_ULZMA;
  		if (header->magic[CLOOP_OFS_VERSN] < CLOOP_MINVER_LZMA) {
  			DPRINTF(GUZ_DBG_ERR, ("%s: image version too old\n",
  			    gp->name));
  			goto e3;
  		}
  		DPRINTF(GUZ_DBG_INFO, ("%s: GEOM_UZIP_LZMA image found\n",
  		    gp->name));
  		break;
  	case CLOOP_COMP_LIBZ:
  	case CLOOP_COMP_LIBZ_DDP:
  		type = G_UZIP;
  		if (header->magic[CLOOP_OFS_VERSN] < CLOOP_MINVER_ZLIB) {
  			DPRINTF(GUZ_DBG_ERR, ("%s: image version too old\n",
  			    gp->name));
  			goto e3;
  		}
  		DPRINTF(GUZ_DBG_INFO, ("%s: GEOM_UZIP_ZLIB image found\n",
  		    gp->name));
  		break;
  	default:
  		DPRINTF(GUZ_DBG_ERR, ("%s: unsupported image type\n",
  		    gp->name));
                  goto e3;
          }
  
  	/*
  	 * Initialize softc and read offsets.
  	 */
  	sc = malloc(sizeof(*sc), M_GEOM_UZIP, M_WAITOK | M_ZERO);
  	gp->softc = sc;
  	sc->blksz = ntohl(header->blksz);
  	sc->nblocks = ntohl(header->nblocks);
  	if (sc->blksz % 512 != 0) {
  		printf("%s: block size (%u) should be multiple of 512.\n",
  		    gp->name, sc->blksz);
  		goto e4;
  	}
  	if (sc->blksz > MAX_BLKSZ) {
  		printf("%s: block size (%u) should not be larger than %d.\n",
  		    gp->name, sc->blksz, MAX_BLKSZ);
  	}
  	total_offsets = sc->nblocks + 1;
  	if (sizeof(struct cloop_header) +
  	    total_offsets * sizeof(uint64_t) > pp->mediasize) {
  		printf("%s: media too small for %u blocks\n",
  		    gp->name, sc->nblocks);
  		goto e4;
  	}
  	sc->toc = malloc(total_offsets * sizeof(struct g_uzip_blk),
  	    M_GEOM_UZIP, M_WAITOK | M_ZERO);
  	offsets_read = MIN(total_offsets,
  	    (pp->sectorsize - sizeof(*header)) / sizeof(uint64_t));
  	for (i = 0; i < offsets_read; i++) {
  		sc->toc[i].offset = be64toh(((uint64_t *) (header + 1))[i]);
  		sc->toc[i].blen = BLEN_UNDEF;
  	}
  	DPRINTF(GUZ_DBG_INFO, ("%s: %u offsets in the first sector\n",
  	       gp->name, offsets_read));
  	for (blk = 1; offsets_read < total_offsets; blk++) {
  		uint32_t nread;
  
  		free(buf, M_GEOM);
  		buf = g_read_data(
  		    cp, blk * pp->sectorsize, pp->sectorsize, NULL);
  		if (buf == NULL)
  			goto e5;
  		nread = MIN(total_offsets - offsets_read,
  		     pp->sectorsize / sizeof(uint64_t));
  		DPRINTF(GUZ_DBG_TOC, ("%s: %u offsets read from sector %d\n",
  		    gp->name, nread, blk));
  		for (i = 0; i < nread; i++) {
  			sc->toc[offsets_read + i].offset =
  			    be64toh(((uint64_t *) buf)[i]);
  			sc->toc[offsets_read + i].blen = BLEN_UNDEF;
  		}
  		offsets_read += nread;
  	}
  	free(buf, M_GEOM);
  	buf = NULL;
  	offsets_read -= 1;
  	DPRINTF(GUZ_DBG_INFO, ("%s: done reading %u block offsets from %u "
  	    "sectors\n", gp->name, offsets_read, blk));
  	if (sc->nblocks != offsets_read) {
  		DPRINTF(GUZ_DBG_ERR, ("%s: read %s offsets than expected "
  		    "blocks\n", gp->name,
  		    sc->nblocks < offsets_read ? "more" : "less"));
  		goto e5;
  	}
  
  	if (type == G_UZIP) {
  		sc->dcp = g_uzip_zlib_ctor(sc->blksz);
  	} else {
  		sc->dcp = g_uzip_lzma_ctor(sc->blksz);
  	}
  	if (sc->dcp == NULL) {
  		goto e5;
  	}
  
  	/*
  	 * "Fake" last+1 block, to make it easier for the TOC parser to
  	 * iterate without making the last element a special case.
  	 */
  	sc->toc[sc->nblocks].offset = pp->mediasize;
  	/* Massage TOC (table of contents), make sure it is sound */
  	if (g_uzip_parse_toc(sc, pp, gp) != 0) {
  		DPRINTF(GUZ_DBG_ERR, ("%s: TOC error\n", gp->name));
  		goto e6;
  	}
  	mtx_init(&sc->last_mtx, "geom_uzip cache", NULL, MTX_DEF);
  	mtx_init(&sc->queue_mtx, "geom_uzip wrkthread", NULL, MTX_DEF);
  	bioq_init(&sc->bio_queue);
  	sc->last_blk = -1;
  	sc->last_buf = malloc(sc->blksz, M_GEOM_UZIP, M_WAITOK);
  	sc->req_total = 0;
  	sc->req_cached = 0;
  
  	sc->uzip_do = &g_uzip_do;
  
  	error = kproc_create(g_uzip_wrkthr, sc, &sc->procp, 0, 0, "%s",
  	    gp->name);
  	if (error != 0) {
  		goto e7;
  	}
  
  	g_topology_lock();
  	pp2 = g_new_providerf(gp, "%s", gp->name);
  	pp2->sectorsize = 512;
  	pp2->mediasize = (off_t)sc->nblocks * sc->blksz;
  	pp2->stripesize = pp->stripesize;
  	pp2->stripeoffset = pp->stripeoffset;
  	g_error_provider(pp2, 0);
  	g_access(cp, -1, 0, 0);
  
  	DPRINTF(GUZ_DBG_INFO, ("%s: taste ok (%d, %jd), (%d, %d), %x\n",
  	    gp->name, pp2->sectorsize, (intmax_t)pp2->mediasize,
  	    pp2->stripeoffset, pp2->stripesize, pp2->flags));
  	DPRINTF(GUZ_DBG_INFO, ("%s: %u x %u blocks\n", gp->name, sc->nblocks,
  	    sc->blksz));
  	return (gp);
  
  e7:
  	free(sc->last_buf, M_GEOM);
  	mtx_destroy(&sc->queue_mtx);
  	mtx_destroy(&sc->last_mtx);
  e6:
  	sc->dcp->free(sc->dcp);
  e5:
  	free(sc->toc, M_GEOM);
  e4:
  	free(gp->softc, M_GEOM_UZIP);
  e3:
  	if (buf != NULL) {
  		free(buf, M_GEOM);
  	}
  e2:
  	g_topology_lock();
  	g_access(cp, -1, 0, 0);
  e1:
  	g_detach(cp);
  	g_destroy_consumer(cp);
  	g_destroy_geom(gp);
  
  	return (NULL);
  }
  
  static int
  g_uzip_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp)
  {
  	struct g_provider *pp;
  
  	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, gp->name);
  	g_topology_assert();
  
  	if (gp->softc == NULL) {
  		DPRINTF(GUZ_DBG_ERR, ("%s(%s): gp->softc == NULL\n", __func__,
  		    gp->name));
  		return (ENXIO);
  	}
  
  	KASSERT(gp != NULL, ("NULL geom"));
  	pp = LIST_FIRST(&gp->provider);
  	KASSERT(pp != NULL, ("NULL provider"));
  	if (pp->acr > 0 || pp->acw > 0 || pp->ace > 0)
  		return (EBUSY);
  
  	g_uzip_softc_free(gp->softc, gp);
  	gp->softc = NULL;
  	g_wither_geom(gp, ENXIO);
  
  	return (0);
  }
  
  static struct g_class g_uzip_class = {
  	.name = UZIP_CLASS_NAME,
  	.version = G_VERSION,
  	.taste = g_uzip_taste,
  	.destroy_geom = g_uzip_destroy_geom,
  
  	.start = g_uzip_start,
  	.orphan = g_uzip_orphan,
  	.access = g_uzip_access,
  	.spoiled = g_uzip_spoiled,
  };
  
  DECLARE_GEOM_CLASS(g_uzip_class, g_uzip);
  MODULE_DEPEND(g_uzip, zlib, 1, 1, 1);
  