コード例 #1
0
ファイル: cd9660_lookup.c プロジェクト: Hooman3/minix
/*
 * Convert a component of a pathname into a pointer to a locked inode.
 * This is a very central and rather complicated routine.
 * If the file system is not maintained in a strict tree hierarchy,
 * this can result in a deadlock situation (see comments in code below).
 *
 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
 * whether the name is to be looked up, created, renamed, or deleted.
 * When CREATE, RENAME, or DELETE is specified, information usable in
 * creating, renaming, or deleting a directory entry may be calculated.
 * If the target of the pathname exists, lookup returns both the target
 * and its parent directory locked.
 * When creating or renaming, the target may * not be ".".
 * When deleting , the target may be "."., but the caller must check
 * to ensure it does an vrele and vput instead of two vputs.
 *
 * Overall outline of ufs_lookup:
 *
 *	check accessibility of directory
 *	look for name in cache, if found, then if at end of path
 *	  and deleting or creating, drop it, else return name
 *	search for name in directory, to found or notfound
 * notfound:
 *	if creating, return locked directory, leaving info on available slots
 *	else return error
 * found:
 *	if at end of path and deleting, return information to allow delete
 *	if at end of path and rewriting (RENAME), lock target
 *	  inode and return info to allow rewrite
 *	if not at end, add name to cache; if at end and neither creating
 *	  nor deleting, add name to cache
 */
int
cd9660_lookup(void *v)
{
	struct vop_lookup_args /* {
		struct vnode *a_dvp;
		struct vnode **a_vpp;
		struct componentname *a_cnp;
	} */ *ap = v;
	struct vnode *vdp;		/* vnode for directory being searched */
	struct iso_node *dp;		/* inode for directory being searched */
	struct iso_mnt *imp;		/* file system that directory is in */
	struct buf *bp;			/* a buffer of directory entries */
	struct iso_directory_record *ep = NULL;
					/* the current directory entry */
	int entryoffsetinblock;		/* offset of ep in bp's buffer */
	int saveoffset = -1;		/* offset of last directory entry in dir */
	int numdirpasses;		/* strategy for directory search */
	doff_t endsearch;		/* offset to end directory search */
	struct vnode *pdp;		/* saved dp during symlink work */
	struct vnode *tdp;		/* returned by cd9660_vget_internal */
	u_long bmask;			/* block offset mask */
	int error;
	ino_t ino = 0;
	int reclen;
	u_short namelen;
	char altname[ISO_MAXNAMLEN];
	int res;
	int assoc, len;
	const char *name;
	struct vnode **vpp = ap->a_vpp;
	struct componentname *cnp = ap->a_cnp;
	kauth_cred_t cred = cnp->cn_cred;
	int flags;
	int nameiop = cnp->cn_nameiop;

	flags = cnp->cn_flags;

	bp = NULL;
	*vpp = NULL;
	vdp = ap->a_dvp;
	dp = VTOI(vdp);
	imp = dp->i_mnt;

	/*
	 * Check accessiblity of directory.
	 */
	if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 0)
		return (error);

	if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
		return (EROFS);

	/*
	 * We now have a segment name to search for, and a directory to search.
	 *
	 * Before tediously performing a linear scan of the directory,
	 * check the name cache to see if the directory/name pair
	 * we are looking for is known already.
	 */
	if (cache_lookup(vdp, cnp->cn_nameptr, cnp->cn_namelen,
			 cnp->cn_nameiop, cnp->cn_flags, NULL, vpp)) {
		return *vpp == NULLVP ? ENOENT : 0;
	}

	len = cnp->cn_namelen;
	name = cnp->cn_nameptr;
	/*
	 * A leading `=' means, we are looking for an associated file
	 */
	assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR);
	if (assoc) {
		len--;
		name++;
	}

	/*
	 * If there is cached information on a previous search of
	 * this directory, pick up where we last left off.
	 * We cache only lookups as these are the most common
	 * and have the greatest payoff. Caching CREATE has little
	 * benefit as it usually must search the entire directory
	 * to determine that the entry does not exist. Caching the
	 * location of the last DELETE or RENAME has not reduced
	 * profiling time and hence has been removed in the interest
	 * of simplicity.
	 */
	bmask = imp->im_bmask;
	if (nameiop != LOOKUP || dp->i_diroff == 0 ||
	    dp->i_diroff > dp->i_size) {
		entryoffsetinblock = 0;
		dp->i_offset = 0;
		numdirpasses = 1;
	} else {
		dp->i_offset = dp->i_diroff;
		if ((entryoffsetinblock = dp->i_offset & bmask) &&
		    (error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL,
		    &bp)))
				return (error);
		numdirpasses = 2;
		iso_nchstats.ncs_2passes++;
	}
	endsearch = dp->i_size;

searchloop:
	while (dp->i_offset < endsearch) {
		/*
		 * If offset is on a block boundary,
		 * read the next directory block.
		 * Release previous if it exists.
		 */
		if ((dp->i_offset & bmask) == 0) {
			if (bp != NULL)
				brelse(bp, 0);
			error = cd9660_blkatoff(vdp, (off_t)dp->i_offset,
					     NULL, &bp);
			if (error)
				return (error);
			entryoffsetinblock = 0;
		}
		/*
		 * Get pointer to next entry.
		 */
		KASSERT(bp != NULL);
		ep = (struct iso_directory_record *)
			((char *)bp->b_data + entryoffsetinblock);

		reclen = isonum_711(ep->length);
		if (reclen == 0) {
			/* skip to next block, if any */
			dp->i_offset =
			    (dp->i_offset & ~bmask) + imp->logical_block_size;
			continue;
		}

		if (reclen < ISO_DIRECTORY_RECORD_SIZE)
			/* illegal entry, stop */
			break;

		if (entryoffsetinblock + reclen > imp->logical_block_size)
			/* entries are not allowed to cross boundaries */
			break;

		namelen = isonum_711(ep->name_len);

		if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
			/* illegal entry, stop */
			break;

		/*
		 * Check for a name match.
		 */
		switch (imp->iso_ftype) {
		default:
			if ((!(isonum_711(ep->flags)&4)) == !assoc) {
				if ((len == 1
				     && *name == '.')
				    || (flags & ISDOTDOT)) {
					if (namelen == 1
					    && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
						/*
						 * Save directory entry's inode number and
						 * release directory buffer.
						 */
						dp->i_ino = isodirino(ep, imp);
						goto found;
					}
					if (namelen != 1
					    || ep->name[0] != 0)
						goto notfound;
				} else if (!(res = isofncmp(name,len,
						   ep->name,namelen,
						   imp->im_joliet_level))) {
					if (isonum_711(ep->flags)&2)
						ino = isodirino(ep, imp);
					else
						ino = dbtob(bp->b_blkno)
							+ entryoffsetinblock;
					saveoffset = dp->i_offset;
				} else if (ino)
					goto foundino;
#ifdef	NOSORTBUG	/* On some CDs directory entries are not sorted correctly */
				else if (res < 0)
					goto notfound;
				else if (res > 0 && numdirpasses == 2)
					numdirpasses++;
#endif
			}
			break;
		case ISO_FTYPE_RRIP:
			if (isonum_711(ep->flags)&2)
				ino = isodirino(ep, imp);
			else
				ino = dbtob(bp->b_blkno) + entryoffsetinblock;
			dp->i_ino = ino;
			cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
			if (namelen == cnp->cn_namelen) {
				if (imp->im_flags & ISOFSMNT_RRCASEINS) {
					if (strncasecmp(name, altname, namelen) == 0)
						goto found;
				} else {
					if (memcmp(name, altname, namelen) == 0)
						goto found;
				}
			}
			ino = 0;
			break;
		}
		dp->i_offset += reclen;
		entryoffsetinblock += reclen;
	}
	if (ino) {
foundino:
		dp->i_ino = ino;
		if (saveoffset != dp->i_offset) {
			if (cd9660_lblkno(imp, dp->i_offset) !=
			    cd9660_lblkno(imp, saveoffset)) {
				if (bp != NULL)
					brelse(bp, 0);
				if ((error = cd9660_blkatoff(vdp,
					    (off_t)saveoffset, NULL, &bp)) != 0)
					return (error);
			}
			entryoffsetinblock = saveoffset & bmask;
			ep = (struct iso_directory_record *)
				((char *)bp->b_data + entryoffsetinblock);
			dp->i_offset = saveoffset;
		}
		goto found;
	}
notfound:
	/*
	 * If we started in the middle of the directory and failed
	 * to find our target, we must check the beginning as well.
	 */
	if (numdirpasses == 2) {
		numdirpasses--;
		dp->i_offset = 0;
		endsearch = dp->i_diroff;
		goto searchloop;
	}
	if (bp != NULL)
		brelse(bp, 0);

	/*
	 * Insert name into cache (as non-existent) if appropriate.
	 */
	cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags);
	return (nameiop == CREATE || nameiop == RENAME) ? EROFS : ENOENT;

found:
	if (numdirpasses == 2)
		iso_nchstats.ncs_pass2++;

	/*
	 * Found component in pathname.
	 * If the final component of path name, save information
	 * in the cache as to where the entry was found.
	 */
	if ((flags & ISLASTCN) && nameiop == LOOKUP)
		dp->i_diroff = dp->i_offset;

	/*
	 * Step through the translation in the name.  We do not `iput' the
	 * directory because we may need it again if a symbolic link
	 * is relative to the current directory.  Instead we save it
	 * unlocked as "pdp".  We must get the target inode before unlocking
	 * the directory to insure that the inode will not be removed
	 * before we get it.  We prevent deadlock by always fetching
	 * inodes from the root, moving down the directory tree. Thus
	 * when following backward pointers ".." we must unlock the
	 * parent directory before getting the requested directory.
	 * There is a potential race condition here if both the current
	 * and parent directories are removed before the `iget' for the
	 * inode associated with ".." returns.  We hope that this occurs
	 * infrequently since we cannot avoid this race condition without
	 * implementing a sophisticated deadlock detection algorithm.
	 * Note also that this simple deadlock detection scheme will not
	 * work if the file system has any hard links other than ".."
	 * that point backwards in the directory structure.
	 */
	pdp = vdp;

	/*
	 * If ino is different from dp->i_ino,
	 * it's a relocated directory.
	 */
	brelse(bp, 0);
	if (flags & ISDOTDOT) {
		VOP_UNLOCK(pdp);	/* race to get the inode */
		error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
					     dp->i_ino != ino, ep);
		vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY);
		if (error)
			return error;
		*vpp = tdp;
	} else if (dp->i_number == dp->i_ino) {
		vref(vdp);	/* we want ourself, ie "." */
		*vpp = vdp;
	} else {
		error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
					     dp->i_ino != ino, ep);
		if (error)
			return (error);
		*vpp = tdp;
	}

	/*
	 * Insert name into cache if appropriate.
	 */
	cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags);
	return 0;
}
コード例 #2
0
/*
 * Convert a component of a pathname into a pointer to a locked inode.
 * This is a very central and rather complicated routine.
 * If the file system is not maintained in a strict tree hierarchy,
 * this can result in a deadlock situation (see comments in code below).
 *
 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
 * whether the name is to be looked up, created, renamed, or deleted.
 * When CREATE, RENAME, or DELETE is specified, information usable in
 * creating, renaming, or deleting a directory entry may be calculated.
 * If flag has LOCKPARENT or'ed into it and the target of the pathname
 * exists, lookup returns both the target and its parent directory locked.
 * When creating or renaming and LOCKPARENT is specified, the target may
 * not be ".".  When deleting and LOCKPARENT is specified, the target may
 * be "."., but the caller must check to ensure it does an vrele and iput
 * instead of two iputs.
 *
 * Overall outline of ufs_lookup:
 *
 *	check accessibility of directory
 *	look for name in cache, if found, then if at end of path
 *	  and deleting or creating, drop it, else return name
 *	search for name in directory, to found or notfound
 * notfound:
 *	if creating, return locked directory, leaving info on available slots
 *	else return error
 * found:
 *	if at end of path and deleting, return information to allow delete
 *	if at end of path and rewriting (RENAME and LOCKPARENT), lock target
 *	  inode and return info to allow rewrite
 *	if not at end, add name to cache; if at end and neither creating
 *	  nor deleting, add name to cache
 *
 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
 */
int
cd9660_lookup(struct vnop_lookup_args *ap)
{
	register struct vnode *vdp;	/* vnode for directory being searched */
	register struct iso_node *dp;	/* inode for directory being searched */
	register struct iso_mnt *imp;	/* file system that directory is in */
	struct buf *bp;			/* a buffer of directory entries */
	struct iso_directory_record *ep = NULL;/* the current directory entry */
	int entryoffsetinblock;		/* offset of ep in bp's buffer */
	int saveoffset = 0;		/* offset of last directory entry in dir */
	int numdirpasses;		/* strategy for directory search */
	doff_t endsearch;		/* offset to end directory search */
	struct vnode *pdp;		/* saved dp during symlink work */
	struct vnode *tdp;		/* returned by cd9660_vget_internal */
	u_long bmask;			/* block offset mask */
	int lockparent;			/* 1 => lockparent flag is set */
	int wantparent;			/* 1 => wantparent or lockparent flag */
	int wantassoc;
	int error;
	ino_t ino = 0;
	int reclen;
	u_short namelen;
	int isoflags;
	char altname[ISO_RRIP_NAMEMAX];
	int res;
	int len;
	char *name;
	struct vnode **vpp = ap->a_vpp;
	struct componentname *cnp = ap->a_cnp;
	int flags = cnp->cn_flags;
	int nameiop = cnp->cn_nameiop;
	vfs_context_t ctx = cnp->cn_context;
	size_t altlen;
	
	bp = NULL;
	*vpp = NULL;
	vdp = ap->a_dvp;
	dp = VTOI(vdp);
	imp = dp->i_mnt;
	lockparent = flags & LOCKPARENT;
	wantparent = flags & (LOCKPARENT|WANTPARENT);
	wantassoc = 0;

	
	/*
	 * We now have a segment name to search for, and a directory to search.
	 *
	 * Before tediously performing a linear scan of the directory,
	 * check the name cache to see if the directory/name pair
	 * we are looking for is known already.
	 */
	if ((error = cache_lookup(vdp, vpp, cnp))) {
		if (error == ENOENT)
			return (error);
		return (0);
	}
	
	len = cnp->cn_namelen;
	name = cnp->cn_nameptr;
	altname[0] = '\0';
	/*
	 * A "._" prefix means, we are looking for an associated file
	 */
	if (imp->iso_ftype != ISO_FTYPE_RRIP &&
	    *name == ASSOCCHAR1 && *(name+1) == ASSOCCHAR2) {
		wantassoc = 1;
		len -= 2;
		name += 2;
	}
	/*
	 * Decode search name into UCS-2 (Unicode)
	 */
	if ((imp->iso_ftype == ISO_FTYPE_JOLIET) &&
	    !((len == 1 && *name == '.') || (flags & ISDOTDOT))) {
		int flags1 = UTF_PRECOMPOSED;

		(void) utf8_decodestr(name, len, (u_int16_t*) altname, &altlen,
					sizeof(altname), 0, flags1);
		name = altname;
		len = altlen;
	}
	/*
	 * If there is cached information on a previous search of
	 * this directory, pick up where we last left off.
	 * We cache only lookups as these are the most common
	 * and have the greatest payoff. Caching CREATE has little
	 * benefit as it usually must search the entire directory
	 * to determine that the entry does not exist. Caching the
	 * location of the last DELETE or RENAME has not reduced
	 * profiling time and hence has been removed in the interest
	 * of simplicity.
	 */
	bmask = imp->im_sector_size - 1;
	if (nameiop != LOOKUP || dp->i_diroff == 0 ||
	    dp->i_diroff > dp->i_size) {
		entryoffsetinblock = 0;
		dp->i_offset = 0;
		numdirpasses = 1;
	} else {
		dp->i_offset = dp->i_diroff;
		
		if ((entryoffsetinblock = dp->i_offset & bmask) &&
		    (error = cd9660_blkatoff(vdp, SECTOFF(imp, dp->i_offset), NULL, &bp)))
				return (error);
		numdirpasses = 2;
		iso_nchstats.ncs_2passes++;
	}
	endsearch = dp->i_size;
	
searchloop:
	while (dp->i_offset < endsearch) {
		/*
		 * If offset is on a block boundary,
		 * read the next directory block.
		 * Release previous if it exists.
		 */
		if ((dp->i_offset & bmask) == 0) {
			if (bp != NULL)
				buf_brelse(bp);
			if ( (error = cd9660_blkatoff(vdp, SECTOFF(imp,dp->i_offset), NULL, &bp)) )
				return (error);
			entryoffsetinblock = 0;
		}
		/*
		 * Get pointer to next entry.
		 */
		ep = (struct iso_directory_record *)
			((char *)0 + buf_dataptr(bp) + entryoffsetinblock);
		
		reclen = isonum_711(ep->length);
		if (reclen == 0) {
			/* skip to next block, if any */
			dp->i_offset =
			    (dp->i_offset & ~bmask) + imp->im_sector_size;
			continue;
		}
		
		if (reclen < ISO_DIRECTORY_RECORD_SIZE) {
			/* illegal entry, stop */
			break;
		}
		if (entryoffsetinblock + reclen > imp->im_sector_size) {
			/* entries are not allowed to cross sector boundaries */
			break;
		}
		namelen = isonum_711(ep->name_len);
		isoflags = isonum_711(ep->flags);
		
		if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
			/* illegal entry, stop */
			break;
		/*
		 * Check for a name match.
		 */
		if (imp->iso_ftype == ISO_FTYPE_RRIP) {
			if (isoflags & directoryBit)
				ino = isodirino(ep, imp);
			else
				ino = ((daddr_t)buf_blkno(bp) << imp->im_bshift) + entryoffsetinblock;
			dp->i_ino = ino;
			cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
			if (namelen == cnp->cn_namelen
			    && !bcmp(name,altname,namelen))
				goto found;
			ino = 0;
		} else {
			if ((!(isoflags & associatedBit)) == !wantassoc) {
				if ((len == 1
				     && *name == '.')
				    || (flags & ISDOTDOT)) {
					if (namelen == 1
					    && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
						/*
						 * Save directory entry's inode number and
						 * release directory buffer.
						 */
						dp->i_ino = isodirino(ep, imp);
						goto found;
					}
					if (namelen != 1
					    || ep->name[0] != 0)
						goto notfound;
				} else if (imp->iso_ftype != ISO_FTYPE_JOLIET && !(res = isofncmp(name, len, ep->name, namelen))) {
					if ( isoflags & directoryBit )
						ino = isodirino(ep, imp);
					else
						ino = ((daddr_t)buf_blkno(bp) << imp->im_bshift) + entryoffsetinblock;
					saveoffset = dp->i_offset;
				} else if (imp->iso_ftype == ISO_FTYPE_JOLIET && !(res = ucsfncmp((u_int16_t*)name, len,
							    (u_int16_t*) ep->name, namelen))) {
					if ( isoflags & directoryBit )
						ino = isodirino(ep, imp);
					else
						ino = ((daddr_t)buf_blkno(bp) << imp->im_bshift) + entryoffsetinblock;
					saveoffset = dp->i_offset;
				} else if (ino)
					goto foundino;
#ifdef	NOSORTBUG	/* On some CDs directory entries are not sorted correctly */
				else if (res < 0)
					goto notfound;
				else if (res > 0 && numdirpasses == 2)
					numdirpasses++;
#endif
			}
		}
		dp->i_offset += reclen;
		entryoffsetinblock += reclen;
	} /* endwhile */
	
	if (ino) {
foundino:
		dp->i_ino = ino;
		if (saveoffset != dp->i_offset) {
			if (lblkno(imp, dp->i_offset) !=
			    lblkno(imp, saveoffset)) {
				if (bp != NULL)
					buf_brelse(bp);
				if ( (error = cd9660_blkatoff(vdp, SECTOFF(imp, saveoffset), NULL, &bp)) )
					return (error);
			}
			entryoffsetinblock = saveoffset & bmask;
			ep = (struct iso_directory_record *)
				((char *)0 + buf_dataptr(bp) + entryoffsetinblock);
			dp->i_offset = saveoffset;
		}
		goto found;
	}
notfound:
	/*
	 * If we started in the middle of the directory and failed
	 * to find our target, we must check the beginning as well.
	 */
	if (numdirpasses == 2) {
		numdirpasses--;
		dp->i_offset = 0;
		endsearch = dp->i_diroff;
		goto searchloop;
	}
	if (bp != NULL)
		buf_brelse(bp);

	/*
	 * Insert name into cache (as non-existent) if appropriate.
	 */
	if (cnp->cn_flags & MAKEENTRY)
		cache_enter(vdp, *vpp, cnp);
	return (ENOENT);
	
found:
	if (numdirpasses == 2)
		iso_nchstats.ncs_pass2++;
	
	/*
	 * Found component in pathname.
	 * If the final component of path name, save information
	 * in the cache as to where the entry was found.
	 */
	if ((flags & ISLASTCN) && nameiop == LOOKUP)
		dp->i_diroff = dp->i_offset;
	
	/*
	 * Step through the translation in the name.  We do not `iput' the
	 * directory because we may need it again if a symbolic link
	 * is relative to the current directory.  Instead we save it
	 * unlocked as "pdp".  We must get the target inode before unlocking
	 * the directory to insure that the inode will not be removed
	 * before we get it.  We prevent deadlock by always fetching
	 * inodes from the root, moving down the directory tree. Thus
	 * when following backward pointers ".." we must unlock the
	 * parent directory before getting the requested directory.
	 * There is a potential race condition here if both the current
	 * and parent directories are removed before the `iget' for the
	 * inode associated with ".." returns.  We hope that this occurs
	 * infrequently since we cannot avoid this race condition without
	 * implementing a sophisticated deadlock detection algorithm.
	 * Note also that this simple deadlock detection scheme will not
	 * work if the file system has any hard links other than ".."
	 * that point backwards in the directory structure.
	 */
	pdp = vdp;
	/*
	 * If ino is different from dp->i_ino,
	 * it's a relocated directory.
	 */
	if (flags & ISDOTDOT) {
		error = cd9660_vget_internal(vnode_mount(vdp), dp->i_ino, &tdp, NULL, NULL,
					     dp->i_ino != ino, ep,
					     vfs_context_proc(ctx));
		VTOI(tdp)->i_parent = VTOI(pdp)->i_number;
		buf_brelse(bp);

		*vpp = tdp;
	} else if (dp->i_number == dp->i_ino) {
		buf_brelse(bp);
		vnode_get(vdp);	/* we want ourself, ie "." */
		*vpp = vdp;
	} else {
	        error = cd9660_vget_internal(vnode_mount(vdp), dp->i_ino, &tdp, vdp, cnp,
			     dp->i_ino != ino, ep, vfs_context_proc(ctx));
		/* save parent inode number */
		VTOI(tdp)->i_parent = VTOI(pdp)->i_number;
		buf_brelse(bp);
		if (error)
			return (error);
		*vpp = tdp;
	}
	return (0);
}
コード例 #3
0
int
cd9660_findstage2(ib_params *params, uint32_t *maxblk, ib_block *blocks)
{
	uint8_t buf[ISO_DEFAULT_BLOCK_SIZE];
	char name[MAXNAMLEN];
	char *ofwboot;
	off_t loc;
	int rv, blocksize, found, i;
	struct iso_primary_descriptor ipd;
	struct iso_directory_record *idr;

	assert(params != NULL);
	assert(params->stage2 != NULL);
	assert(maxblk != NULL);
	assert(blocks != NULL);

#if 0
	if (params->flags & IB_STAGE2START)
		return hardcode_stage2(params, maxblk, blocks);
#endif

	/* The secondary bootstrap must be clearly in /. */
	strlcpy(name, params->stage2, MAXNAMLEN);
	ofwboot = name;
	if (ofwboot[0] == '/')
		ofwboot++;
	if (strchr(ofwboot, '/') != NULL) {
		warnx("The secondary bootstrap `%s' must be in / "
		    "on filesystem `%s'", params->stage2, params->filesystem);
		return 0;
	}
	if (strchr(ofwboot, '.') == NULL) {
		/*
		 * XXX should fix isofncmp()?
		 */
		strlcat(ofwboot, ".", MAXNAMLEN);
	}

	rv = pread(params->fsfd, &ipd, sizeof(ipd),
	    ISO_DEFAULT_BLOCK_SIZE * 16);
	if (rv == -1) {
		warn("Reading primary descriptor in `%s'", params->filesystem);
		return 0;
	} else if (rv != sizeof(ipd)) {
		warnx("Reading primary descriptor in `%s': short read",
		   params->filesystem);
		return 0;
	}
	blocksize = isonum_723((char *)ipd.logical_block_size);

	idr = (void *)ipd.root_directory_record;
	loc = (off_t)isonum_733(idr->extent) * blocksize;
	rv = pread(params->fsfd, buf, blocksize, loc);
	if (rv == -1) {
		warn("Reading root directory record in `%s'",
		    params->filesystem);
		return 0;
	} else if (rv != sizeof(ipd)) {
		warnx("Reading root directory record in `%s': short read",
		   params->filesystem);
		return 0;
	}

	found = 0;
	for (i = 0; i < blocksize - sizeof(struct iso_directory_record);
	    i += (u_char)idr->length[0]) {
		idr = (void *)&buf[i];

#ifdef DEBUG
		printf("i = %d, idr->length[0] = %3d\n",
		    i, (u_char)idr->length[0]);
#endif
		/* check end of entries */
		if (idr->length[0] == 0) {
#ifdef DEBUG
		printf("end of entries\n");
#endif
			break;
		}

		if (idr->flags[0] & 2) {
			/* skip directory entries */
#ifdef DEBUG
			printf("skip directory entry\n");
#endif
			continue;
		}
		if (idr->name_len[0] == 1 &&
		    (idr->name[0] == 0 || idr->name[0] == 1)) {
			/* skip "." and ".." */
#ifdef DEBUG
			printf("skip dot dot\n");
#endif
			continue;
		}
#ifdef DEBUG
		{
			int j;

			printf("filename:");
			for (j = 0; j < isonum_711(idr->name_len); j++)
				printf("%c", idr->name[j]);
			printf("\n");
		}
#endif
		if (isofncmp(ofwboot, strlen(ofwboot),
		    idr->name, isonum_711(idr->name_len), 0) == 0) {
			found = 1;
			/* ISO filesystem always has contiguous file blocks */
			blocks[0].block = (int64_t)isonum_733(idr->extent);
			/* XXX bootxx assumes blocksize is 512 */
			blocks[0].block *= blocksize / 512;
			blocks[0].blocksize =
			    roundup(isonum_733(idr->size), blocksize);
			*maxblk = 1;
#ifdef DEBUG
			printf("block = %ld, blocksize = %ld\n",
			    (long)blocks[0].block, blocks[0].blocksize);
#endif
			break;
		}
	}

	if (found == 0) {
		warnx("Can't find secondary bootstrap `%s' in filesystem `%s'",
		    params->stage2, params->filesystem);
		return 0;
	}

	return 1;
}