udf_vnops.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2001, 2002 Scott Long <[email protected]>
 * 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.
 */

/* udf_vnops.c */
/* Take care of the vnode side of things */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/stat.h>
#include <sys/bio.h>
#include <sys/conf.h>
#include <sys/buf.h>
#include <sys/iconv.h>
#include <sys/limits.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/dirent.h>
#include <sys/queue.h>
#include <sys/unistd.h>
#include <sys/endian.h>

#include <vm/uma.h>

#include <fs/udf/ecma167-udf.h>
#include <fs/udf/osta.h>
#include <fs/udf/udf.h>
#include <fs/udf/udf_mount.h>

extern struct iconv_functions *udf_iconv;

static vop_access_t	udf_access;
static vop_getattr_t	udf_getattr;
static vop_open_t	udf_open;
static vop_ioctl_t	udf_ioctl;
static vop_pathconf_t	udf_pathconf;
static vop_print_t	udf_print;
static vop_read_t	udf_read;
static vop_readdir_t	udf_readdir;
static vop_readlink_t	udf_readlink;
static vop_setattr_t	udf_setattr;
static vop_strategy_t	udf_strategy;
static vop_bmap_t	udf_bmap;
static vop_cachedlookup_t	udf_lookup;
static vop_reclaim_t	udf_reclaim;
static vop_vptofh_t	udf_vptofh;
static int udf_readatoffset(struct udf_node *node, int *size, off_t offset,
    struct buf **bp, uint8_t **data);
static int udf_bmap_internal(struct udf_node *node, off_t offset,
    daddr_t *sector, uint32_t *max_size);

static struct vop_vector udf_vnodeops = {
	.vop_default =		&default_vnodeops,

	.vop_access =		udf_access,
	.vop_bmap =		udf_bmap,
	.vop_cachedlookup =	udf_lookup,
	.vop_getattr =		udf_getattr,
	.vop_ioctl =		udf_ioctl,
	.vop_lookup =		vfs_cache_lookup,
	.vop_open =		udf_open,
	.vop_pathconf =		udf_pathconf,
	.vop_print =		udf_print,
	.vop_read =		udf_read,
	.vop_readdir =		udf_readdir,
	.vop_readlink =		udf_readlink,
	.vop_reclaim =		udf_reclaim,
	.vop_setattr =		udf_setattr,
	.vop_strategy =		udf_strategy,
	.vop_vptofh =		udf_vptofh,
};
VFS_VOP_VECTOR_REGISTER(udf_vnodeops);

struct vop_vector udf_fifoops = {
	.vop_default =		&fifo_specops,
	.vop_access =		udf_access,
	.vop_getattr =		udf_getattr,
	.vop_pathconf =		udf_pathconf,
	.vop_print =		udf_print,
	.vop_reclaim =		udf_reclaim,
	.vop_setattr =		udf_setattr,
	.vop_vptofh =		udf_vptofh,
};
VFS_VOP_VECTOR_REGISTER(udf_fifoops);

static MALLOC_DEFINE(M_UDFFID, "udf_fid", "UDF FileId structure");
static MALLOC_DEFINE(M_UDFDS, "udf_ds", "UDF Dirstream structure");

#define UDF_INVALID_BMAP	-1

int
udf_allocv(struct mount *mp, struct vnode **vpp, struct thread *td)
{
	int error;
	struct vnode *vp;

	error = getnewvnode("udf", mp, &udf_vnodeops, &vp);
	if (error) {
		printf("udf_allocv: failed to allocate new vnode\n");
		return (error);
	}

	*vpp = vp;
	return (0);
}

/* Convert file entry permission (5 bits per owner/group/user) to a mode_t */
static mode_t
udf_permtomode(struct udf_node *node)
{
	uint32_t perm;
	uint16_t flags;
	mode_t mode;

	perm = le32toh(node->fentry->perm);
	flags = le16toh(node->fentry->icbtag.flags);

	mode = perm & UDF_FENTRY_PERM_USER_MASK;
	mode |= ((perm & UDF_FENTRY_PERM_GRP_MASK) >> 2);
	mode |= ((perm & UDF_FENTRY_PERM_OWNER_MASK) >> 4);
	mode |= ((flags & UDF_ICB_TAG_FLAGS_STICKY) << 4);
	mode |= ((flags & UDF_ICB_TAG_FLAGS_SETGID) << 6);
	mode |= ((flags & UDF_ICB_TAG_FLAGS_SETUID) << 8);

	return (mode);
}

static int
udf_access(struct vop_access_args *a)
{
	struct vnode *vp;
	struct udf_node *node;
	accmode_t accmode;
	mode_t mode;

	vp = a->a_vp;
	node = VTON(vp);
	accmode = a->a_accmode;

	if (accmode & VWRITE) {
		switch (vp->v_type) {
		case VDIR:
		case VLNK:
		case VREG:
			return (EROFS);
			/* NOT REACHED */
		default:
			break;
		}
	}

	mode = udf_permtomode(node);

	return (vaccess(vp->v_type, mode, node->fentry->uid, node->fentry->gid,
	    accmode, a->a_cred));
}

static int
udf_open(struct vop_open_args *ap)
{
	struct udf_node *np = VTON(ap->a_vp);
	uint64_t fsize;

	fsize = le64toh(np->fentry->inf_len);
	if (fsize > OFF_MAX)
		return (EIO);
	vnode_create_vobject(ap->a_vp, fsize, ap->a_td);
	return 0;
}

static const int mon_lens[2][12] = {
	{0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334},
	{0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335}
};

static int
udf_isaleapyear(int year)
{
	int i;

	i = (year % 4) ? 0 : 1;
	i &= (year % 100) ? 1 : 0;
	i |= (year % 400) ? 0 : 1;

	return i;
}

/*
 * Timezone calculation compliments of Julian Elischer <[email protected]>.
 */
static void
udf_timetotimespec(struct timestamp *time, struct timespec *t)
{
	int i, lpyear, daysinyear, year, startyear;
	union {
		uint16_t	u_tz_offset;
		int16_t		s_tz_offset;
	} tz;

	/*
	 * DirectCD seems to like using bogus year values.
	 * Don't trust time->month as it will be used for an array index.
	 */
	year = le16toh(time->year);
	if (year < 1970 || time->month < 1 || time->month > 12) {
		t->tv_sec = 0;
		t->tv_nsec = 0;
		return;
	}

	/* Calculate the time and day */
	t->tv_sec = time->second;
	t->tv_sec += time->minute * 60;
	t->tv_sec += time->hour * 3600;
	t->tv_sec += (time->day - 1) * 3600 * 24;

	/* Calculate the month */
	lpyear = udf_isaleapyear(year);
	t->tv_sec += mon_lens[lpyear][time->month - 1] * 3600 * 24;

	/* Speed up the calculation */
	startyear = 1970;
	if (year > 2009) {
		t->tv_sec += 1262304000;
		startyear += 40;
	} else if (year > 1999) {
		t->tv_sec += 946684800;
		startyear += 30;
	} else if (year > 1989) {
		t->tv_sec += 631152000;
		startyear += 20;
	} else if (year > 1979) {
		t->tv_sec += 315532800;
		startyear += 10;
	}

	daysinyear = (year - startyear) * 365;
	for (i = startyear; i < year; i++)
		daysinyear += udf_isaleapyear(i);
	t->tv_sec += daysinyear * 3600 * 24;

	/* Calculate microseconds */
	t->tv_nsec = time->centisec * 10000 + time->hund_usec * 100 +
	    time->usec;

	/*
	 * Calculate the time zone.  The timezone is 12 bit signed 2's
	 * complement, so we gotta do some extra magic to handle it right.
	 */
	tz.u_tz_offset = le16toh(time->type_tz);
	tz.u_tz_offset &= 0x0fff;
	if (tz.u_tz_offset & 0x0800)
		tz.u_tz_offset |= 0xf000;	/* extend the sign to 16 bits */
	if ((le16toh(time->type_tz) & 0x1000) && (tz.s_tz_offset != -2047))
		t->tv_sec -= tz.s_tz_offset * 60;

	return;
}

static int
udf_getattr(struct vop_getattr_args *a)
{
	struct vnode *vp;
	struct udf_node *node;
	struct vattr *vap;
	struct file_entry *fentry;

	vp = a->a_vp;
	vap = a->a_vap;
	node = VTON(vp);
	fentry = node->fentry;

	vap->va_fsid = dev2udev(node->udfmp->im_dev);
	vap->va_fileid = node->hash_id;
	vap->va_mode = udf_permtomode(node);
	vap->va_nlink = le16toh(fentry->link_cnt);
	/*
	 * XXX The spec says that -1 is valid for uid/gid and indicates an
	 * invalid uid/gid.  How should this be represented?
	 */
	vap->va_uid = (le32toh(fentry->uid) == -1) ? 0 : le32toh(fentry->uid);
	vap->va_gid = (le32toh(fentry->gid) == -1) ? 0 : le32toh(fentry->gid);
	udf_timetotimespec(&fentry->atime, &vap->va_atime);
	udf_timetotimespec(&fentry->mtime, &vap->va_mtime);
	vap->va_ctime = vap->va_mtime; /* XXX Stored as an Extended Attribute */
	vap->va_rdev = NODEV;
	if (vp->v_type & VDIR) {
		/*
		 * Directories that are recorded within their ICB will show
		 * as having 0 blocks recorded.  Since tradition dictates
		 * that directories consume at least one logical block,
		 * make it appear so.
		 */
		vap->va_size = le64toh(fentry->logblks_rec);
		if (vap->va_size == 0)
			vap->va_size = node->udfmp->bsize;
		else if (vap->va_size > UINT64_MAX / node->udfmp->bsize)
			vap->va_size = UINT64_MAX;
		else
			vap->va_size *= node->udfmp->bsize;
	} else {
		vap->va_size = le64toh(fentry->inf_len);
	}
	vap->va_flags = 0;
	vap->va_gen = 1;
	vap->va_blocksize = node->udfmp->bsize;
	vap->va_bytes = le64toh(fentry->inf_len);
	vap->va_type = vp->v_type;
	vap->va_filerev = 0; /* XXX */
	return (0);
}

static int
udf_setattr(struct vop_setattr_args *a)
{
	struct vnode *vp;
	struct vattr *vap;

	vp = a->a_vp;
	vap = a->a_vap;
	if (vap->va_flags != (u_long)VNOVAL || vap->va_uid != (uid_t)VNOVAL ||
	    vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL ||
	    vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL)
		return (EROFS);
	if (vap->va_size != (u_quad_t)VNOVAL) {
		switch (vp->v_type) {
		case VDIR:
			return (EISDIR);
		case VLNK:
		case VREG:
			return (EROFS);
		case VCHR:
		case VBLK:
		case VSOCK:
		case VFIFO:
		case VNON:
		case VBAD:
		case VMARKER:
			return (0);
		}
	}
	return (0);
}

/*
 * File specific ioctls.
 */
static int
udf_ioctl(struct vop_ioctl_args *a)
{
	printf("%s called\n", __func__);
	return (ENOTTY);
}

/*
 * I'm not sure that this has much value in a read-only filesystem, but
 * cd9660 has it too.
 */
static int
udf_pathconf(struct vop_pathconf_args *a)
{

	switch (a->a_name) {
	case _PC_FILESIZEBITS:
		*a->a_retval = 64;
		return (0);
	case _PC_LINK_MAX:
		*a->a_retval = 65535;
		return (0);
	case _PC_NAME_MAX:
		*a->a_retval = NAME_MAX;
		return (0);
	case _PC_SYMLINK_MAX:
		*a->a_retval = MAXPATHLEN;
		return (0);
	case _PC_NO_TRUNC:
		*a->a_retval = 1;
		return (0);
	case _PC_PIPE_BUF:
		if (a->a_vp->v_type == VDIR || a->a_vp->v_type == VFIFO) {
			*a->a_retval = PIPE_BUF;
			return (0);
		}
		return (EINVAL);
	default:
		return (vop_stdpathconf(a));
	}
}

static int
udf_print(struct vop_print_args *ap)
{
	struct vnode *vp = ap->a_vp;
	struct udf_node *node = VTON(vp);

	printf("    ino %lu, on dev %s", (u_long)node->hash_id,
	    devtoname(node->udfmp->im_dev));
	if (vp->v_type == VFIFO)
		fifo_printinfo(vp);
	printf("\n");
	return (0);
}

#define lblkno(udfmp, loc)	((loc) >> (udfmp)->bshift)
#define blkoff(udfmp, loc)	((loc) & (udfmp)->bmask)
#define lblktosize(udfmp, blk)	((blk) << (udfmp)->bshift)

static inline int
is_data_in_fentry(const struct udf_node *node)
{
	const struct file_entry *fentry = node->fentry;

	return ((le16toh(fentry->icbtag.flags) & 0x7) == 3);
}

static int
udf_read(struct vop_read_args *ap)
{
	struct vnode *vp = ap->a_vp;
	struct uio *uio = ap->a_uio;
	struct udf_node *node = VTON(vp);
	struct udf_mnt *udfmp;
	struct file_entry *fentry;
	struct buf *bp;
	uint8_t *data;
	daddr_t lbn, rablock;
	uint64_t len;
	off_t diff, fsize;
	ssize_t n;
	int error = 0;
	long size, on;

	if (uio->uio_resid == 0)
		return (0);
	if (uio->uio_offset < 0)
		return (EINVAL);

	if (is_data_in_fentry(node)) {
		fentry = node->fentry;
		data = &fentry->data[le32toh(fentry->l_ea)];
		fsize = le32toh(fentry->l_ad);

		n = uio->uio_resid;
		diff = fsize - uio->uio_offset;
		if (diff <= 0)
			return (0);
		if (diff < n)
			n = diff;
		error = uiomove(data + uio->uio_offset, (int)n, uio);
		return (error);
	}

	len = le64toh(node->fentry->inf_len);
	if (len > OFF_MAX) {
		/* too big, just cap to the requested length */
		len = uio->uio_resid;
	}
	fsize = len;
	udfmp = node->udfmp;
	do {
		lbn = lblkno(udfmp, uio->uio_offset);
		on = blkoff(udfmp, uio->uio_offset);
		n = min((u_int)(udfmp->bsize - on),
			uio->uio_resid);
		diff = fsize - uio->uio_offset;
		if (diff <= 0)
			return (0);
		if (diff < n)
			n = diff;
		size = udfmp->bsize;
		rablock = lbn + 1;
		if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
			if (lblktosize(udfmp, rablock) < fsize) {
				error = cluster_read(vp, fsize, lbn, size,
				    NOCRED, uio->uio_resid,
				    (ap->a_ioflag >> 16), 0, &bp);
			} else {
				error = bread(vp, lbn, size, NOCRED, &bp);
			}
		} else {
			error = bread(vp, lbn, size, NOCRED, &bp);
		}
		if (error != 0) {
			brelse(bp);
			return (error);
		}
		n = min(n, size - bp->b_resid);

		error = uiomove(bp->b_data + on, (int)n, uio);
		brelse(bp);
	} while (error == 0 && uio->uio_resid > 0 && n != 0);
	return (error);
}

/*
 * Call the OSTA routines to translate the name from a CS0 dstring to a
 * 16-bit Unicode String.  Hooks need to be placed in here to translate from
 * Unicode to the encoding that the kernel/user expects.  Return the length
 * of the translated string.
 */
static int
udf_transname(char *cs0string, char *destname, int len, struct udf_mnt *udfmp)
{
	unicode_t *transname;
	char *unibuf, *unip;
	int i, destlen;
	ssize_t unilen = 0;
	size_t destleft = MAXNAMLEN;

	/* Convert 16-bit Unicode to destname */
	if (udfmp->im_flags & UDFMNT_KICONV && udf_iconv) {
		/* allocate a buffer big enough to hold an 8->16 bit expansion */
		unibuf = uma_zalloc(udf_zone_trans, M_WAITOK);
		unip = unibuf;
		if ((unilen = (ssize_t)udf_UncompressUnicodeByte(len, cs0string, unibuf)) == -1) {
			printf("udf: Unicode translation failed\n");
			uma_zfree(udf_zone_trans, unibuf);
			return 0;
		}

		while (unilen > 0 && destleft > 0) {
			udf_iconv->conv(udfmp->im_d2l, __DECONST(const char **,
			    &unibuf), (size_t *)&unilen, (char **)&destname,
			    &destleft);
			/* Unconverted character found */
			if (unilen > 0 && destleft > 0) {
				*destname++ = '?';
				destleft--;
				unibuf += 2;
				unilen -= 2;
			}
		}
		uma_zfree(udf_zone_trans, unip);
		*destname = '\0';
		destlen = MAXNAMLEN - (int)destleft;
	} else {
		/* allocate a buffer big enough to hold an 8->16 bit expansion */
		transname = uma_zalloc(udf_zone_trans, M_WAITOK);

		if ((unilen = (ssize_t)udf_UncompressUnicode(len, cs0string, transname)) == -1) {
			printf("udf: Unicode translation failed\n");
			uma_zfree(udf_zone_trans, transname);
			return 0;
		}

		for (i = 0; i < unilen ; i++) {
			if (transname[i] & 0xff00) {
				destname[i] = '.';	/* Fudge the 16bit chars */
			} else {
				destname[i] = transname[i] & 0xff;
			}
		}
		uma_zfree(udf_zone_trans, transname);
		destname[unilen] = 0;
		destlen = (int)unilen;
	}

	return (destlen);
}

/*
 * Compare a CS0 dstring with a name passed in from the VFS layer.  Return
 * 0 on a successful match, nonzero otherwise.  Unicode work may need to be done
 * here also.
 */
static int
udf_cmpname(char *cs0string, char *cmpname, int cs0len, int cmplen, struct udf_mnt *udfmp)
{
	char *transname;
	int error = 0;

	/* This is overkill, but not worth creating a new zone */
	transname = uma_zalloc(udf_zone_trans, M_WAITOK);

	cs0len = udf_transname(cs0string, transname, cs0len, udfmp);

	/* Easy check.  If they aren't the same length, they aren't equal */
	if ((cs0len == 0) || (cs0len != cmplen))
		error = -1;
	else
		error = bcmp(transname, cmpname, cmplen);

	uma_zfree(udf_zone_trans, transname);
	return (error);
}

struct udf_uiodir {
	struct dirent *dirent;
	uint64_t *cookies;
	int ncookies;
	int acookies;
	int eofflag;
};

static int
udf_uiodir(struct udf_uiodir *uiodir, int de_size, struct uio *uio, long cookie)
{
	if (uiodir->cookies != NULL) {
		if (++uiodir->acookies > uiodir->ncookies) {
			uiodir->eofflag = 0;
			return (-1);
		}
		*uiodir->cookies++ = cookie;
	}

	if (uio->uio_resid < de_size) {
		uiodir->eofflag = 0;
		return (-1);
	}

	return (uiomove(uiodir->dirent, de_size, uio));
}

static struct udf_dirstream *
udf_opendir(struct udf_node *node, int offset, int fsize, struct udf_mnt *udfmp)
{
	struct udf_dirstream *ds;

	ds = uma_zalloc(udf_zone_ds, M_WAITOK | M_ZERO);

	ds->node = node;
	ds->offset = offset;
	ds->udfmp = udfmp;
	ds->fsize = fsize;

	return (ds);
}

static struct fileid_desc *
udf_getfid(struct udf_dirstream *ds)
{
	struct fileid_desc *fid;
	int error, frag_size = 0, total_fid_size;

	/* End of directory? */
	if (ds->offset + ds->off >= ds->fsize) {
		ds->error = 0;
		return (NULL);
	}

	/* Grab the first extent of the directory */
	if (ds->off == 0) {
		ds->size = 0;
		error = udf_readatoffset(ds->node, &ds->size, ds->offset,
		    &ds->bp, &ds->data);
		if (error) {
			ds->error = error;
			if (ds->bp != NULL)
				brelse(ds->bp);
			return (NULL);
		}
	}

	/*
	 * Clean up from a previous fragmented FID.
	 * XXX Is this the right place for this?
	 */
	if (ds->fid_fragment && ds->buf != NULL) {
		ds->fid_fragment = 0;
		free(ds->buf, M_UDFFID);
	}

	fid = (struct fileid_desc*)&ds->data[ds->off];

	/*
	 * Check to see if the fid is fragmented. The first test
	 * ensures that we don't wander off the end of the buffer
	 * looking for the l_iu and l_fi fields.
	 */
	if (ds->off + UDF_FID_SIZE > ds->size ||
	    ds->off + le16toh(fid->l_iu) + fid->l_fi + UDF_FID_SIZE > ds->size){
		/* Copy what we have of the fid into a buffer */
		frag_size = ds->size - ds->off;
		if (frag_size >= ds->udfmp->bsize) {
			printf("udf: invalid FID fragment\n");
			ds->error = EINVAL;
			return (NULL);
		}

		/*
		 * File ID descriptors can only be at most one
		 * logical sector in size.
		 */
		ds->buf = malloc(ds->udfmp->bsize, M_UDFFID,
		     M_WAITOK | M_ZERO);
		bcopy(fid, ds->buf, frag_size);

		/* Reduce all of the casting magic */
		fid = (struct fileid_desc*)ds->buf;

		if (ds->bp != NULL)
			brelse(ds->bp);

		/* Fetch the next allocation */
		ds->offset += ds->size;
		ds->size = 0;
		error = udf_readatoffset(ds->node, &ds->size, ds->offset,
		    &ds->bp, &ds->data);
		if (error) {
			ds->error = error;
			return (NULL);
		}

		/*
		 * If the fragment was so small that we didn't get
		 * the l_iu and l_fi fields, copy those in.
		 */
		if (frag_size < UDF_FID_SIZE)
			bcopy(ds->data, &ds->buf[frag_size],
			    UDF_FID_SIZE - frag_size);

		/*
		 * Now that we have enough of the fid to work with,
		 * copy in the rest of the fid from the new
		 * allocation.
		 */
		total_fid_size = UDF_FID_SIZE + le16toh(fid->l_iu) + fid->l_fi;
		if (total_fid_size > ds->udfmp->bsize) {
			printf("udf: invalid FID\n");
			ds->error = EIO;
			return (NULL);
		}
		bcopy(ds->data, &ds->buf[frag_size],
		    total_fid_size - frag_size);

		ds->fid_fragment = 1;
	} else {
		total_fid_size = le16toh(fid->l_iu) + fid->l_fi + UDF_FID_SIZE;
	}

	/*
	 * Update the offset. Align on a 4 byte boundary because the
	 * UDF spec says so.
	 */
	ds->this_off = ds->offset + ds->off;
	if (!ds->fid_fragment) {
		ds->off += (total_fid_size + 3) & ~0x03;
	} else {
		ds->off = (total_fid_size - frag_size + 3) & ~0x03;
	}

	return (fid);
}

static void
udf_closedir(struct udf_dirstream *ds)
{

	if (ds->bp != NULL)
		brelse(ds->bp);

	if (ds->fid_fragment && ds->buf != NULL)
		free(ds->buf, M_UDFFID);

	uma_zfree(udf_zone_ds, ds);
}

static int
udf_readdir(struct vop_readdir_args *a)
{
	struct vnode *vp;
	struct uio *uio;
	struct dirent dir;
	struct udf_node *node;
	struct udf_mnt *udfmp;
	struct fileid_desc *fid;
	struct udf_uiodir uiodir;
	struct udf_dirstream *ds;
	uint64_t *cookies = NULL;
	uint64_t len;
	int ncookies;
	int error = 0;

	vp = a->a_vp;
	uio = a->a_uio;
	node = VTON(vp);
	udfmp = node->udfmp;
	uiodir.eofflag = 1;

	if (a->a_ncookies != NULL) {
		/*
		 * Guess how many entries are needed.  If we run out, this
		 * function will be called again and thing will pick up were
		 * it left off.
		 */
		ncookies = uio->uio_resid / 8;
		cookies = malloc(sizeof(*cookies) * ncookies, M_TEMP, M_WAITOK);
		uiodir.ncookies = ncookies;
		uiodir.cookies = cookies;
		uiodir.acookies = 0;
	} else {
		uiodir.cookies = NULL;
	}

	/*
	 * Iterate through the file id descriptors.  Give the parent dir
	 * entry special attention.
	 */
	len = le64toh(node->fentry->inf_len);
	if (len > INT_MAX) {
		/* too big, just cap to INT_MAX */
		len = INT_MAX;
	}
	ds = udf_opendir(node, uio->uio_offset, len, node->udfmp);

	while ((fid = udf_getfid(ds)) != NULL) {
		/* XXX Should we return an error on a bad fid? */
		if (udf_checktag(&fid->tag, TAGID_FID)) {
			printf("Invalid FID tag\n");
			hexdump(fid, UDF_FID_SIZE, NULL, 0);
			error = EIO;
			break;
		}

		/* Is this a deleted file? */
		if (fid->file_char & UDF_FILE_CHAR_DEL)
			continue;

		if ((fid->l_fi == 0) && (fid->file_char & UDF_FILE_CHAR_PAR)) {
			/* Do up the '.' and '..' entries.  Dummy values are
			 * used for the cookies since the offset here is
			 * usually zero, and NFS doesn't like that value
			 */
			dir.d_fileno = node->hash_id;
			dir.d_type = DT_DIR;
			dir.d_name[0] = '.';
			dir.d_namlen = 1;
			dir.d_reclen = GENERIC_DIRSIZ(&dir);
			dir.d_off = 1;
			dirent_terminate(&dir);
			uiodir.dirent = &dir;
			error = udf_uiodir(&uiodir, dir.d_reclen, uio, 1);
			if (error)
				break;

			dir.d_fileno = udf_getid(&fid->icb);
			dir.d_type = DT_DIR;
			dir.d_name[0] = '.';
			dir.d_name[1] = '.';
			dir.d_namlen = 2;
			dir.d_reclen = GENERIC_DIRSIZ(&dir);
			dir.d_off = 2;
			dirent_terminate(&dir);
			uiodir.dirent = &dir;
			error = udf_uiodir(&uiodir, dir.d_reclen, uio, 2);
		} else {
			dir.d_namlen = udf_transname(&fid->data[fid->l_iu],
			    &dir.d_name[0], fid->l_fi, udfmp);
			dir.d_fileno = udf_getid(&fid->icb);
			dir.d_type = (fid->file_char & UDF_FILE_CHAR_DIR) ?
			    DT_DIR : DT_UNKNOWN;
			dir.d_reclen = GENERIC_DIRSIZ(&dir);
			dir.d_off = ds->this_off;
			dirent_terminate(&dir);
			uiodir.dirent = &dir;
			error = udf_uiodir(&uiodir, dir.d_reclen, uio,
			    ds->this_off);
		}
		if (error)
			break;
		uio->uio_offset = ds->offset + ds->off;
	}

	/* tell the calling layer whether we need to be called again */
	*a->a_eofflag = uiodir.eofflag;

	if (error < 0)
		error = 0;
	if (!error)
		error = ds->error;

	udf_closedir(ds);

	if (a->a_ncookies != NULL) {
		if (error)
			free(cookies, M_TEMP);
		else {
			*a->a_ncookies = uiodir.acookies;
			*a->a_cookies = cookies;
		}
	}

	return (error);
}

static int
udf_readlink(struct vop_readlink_args *ap)
{
	struct path_component *pc, *end;
	struct vnode *vp;
	struct uio uio;
	struct iovec iov[1];
	struct udf_node *node;
	void *buf;
	char *cp;
	uint64_t len;
	int error, root;

	/*
	 * A symbolic link in UDF is a list of variable-length path
	 * component structures.  We build a pathname in the caller's
	 * uio by traversing this list.
	 */
	vp = ap->a_vp;
	node = VTON(vp);
	len = le64toh(node->fentry->inf_len);
	if (len > MAXPATHLEN)
		return (EIO);
	buf = malloc(len, M_DEVBUF, M_WAITOK);
	iov[0].iov_len = len;
	iov[0].iov_base = buf;
	uio.uio_iov = iov;
	uio.uio_iovcnt = 1;
	uio.uio_offset = 0;
	uio.uio_resid = iov[0].iov_len;
	uio.uio_segflg = UIO_SYSSPACE;
	uio.uio_rw = UIO_READ;
	uio.uio_td = curthread;
	error = VOP_READ(vp, &uio, 0, ap->a_cred);
	if (error)
		goto error;

	pc = buf;
	end = (void *)((char *)buf + len);
	root = 0;
	while (pc < end) {
		switch (pc->type) {
		case UDF_PATH_ROOT:
			/* Only allow this at the beginning of a path. */
			if ((void *)pc != buf) {
				error = EINVAL;
				goto error;
			}
			cp = "/";
			len = 1;
			root = 1;
			break;
		case UDF_PATH_DOT:
			cp = ".";
			len = 1;
			break;
		case UDF_PATH_DOTDOT:
			cp = "..";
			len = 2;
			break;
		case UDF_PATH_PATH:
			if (pc->length == 0) {
				error = EINVAL;
				goto error;
			}
			/*
			 * XXX: We only support CS8 which appears to map
			 * to ASCII directly.
			 */
			switch (pc->identifier[0]) {
			case 8:
				cp = pc->identifier + 1;
				len = pc->length - 1;
				break;
			default:
				error = EOPNOTSUPP;
				goto error;
			}
			break;
		default:
			error = EINVAL;
			goto error;
		}

		/*
		 * If this is not the first component, insert a path
		 * separator.
		 */
		if (pc != buf) {
			/* If we started with root we already have a "/". */
			if (root)
				goto skipslash;
			root = 0;
			if (ap->a_uio->uio_resid < 1) {
				error = ENAMETOOLONG;
				goto error;
			}
			error = uiomove("/", 1, ap->a_uio);
			if (error)
				break;
		}
	skipslash:

		/* Append string at 'cp' of length 'len' to our path. */
		if (len > ap->a_uio->uio_resid) {
			error = ENAMETOOLONG;
			goto error;
		}
		error = uiomove(cp, len, ap->a_uio);
		if (error)
			break;

		/* Advance to next component. */
		pc = (void *)((char *)pc + 4 + pc->length);
	}
error:
	free(buf, M_DEVBUF);
	return (error);
}

static int
udf_strategy(struct vop_strategy_args *a)
{
	struct buf *bp;
	struct vnode *vp;
	struct udf_node *node;
	struct bufobj *bo;
	off_t offset;
	uint32_t maxsize;
	daddr_t sector;
	int error;

	bp = a->a_bp;
	vp = a->a_vp;
	node = VTON(vp);

	if (bp->b_blkno == bp->b_lblkno) {
		offset = lblktosize(node->udfmp, bp->b_lblkno);
		error = udf_bmap_internal(node, offset, &sector, &maxsize);
		if (error) {
			clrbuf(bp);
			bp->b_blkno = -1;
			bufdone(bp);
			return (0);
		}
		/* bmap gives sector numbers, bio works with device blocks */
		bp->b_blkno = sector << (node->udfmp->bshift - DEV_BSHIFT);
	}
	bo = node->udfmp->im_bo;
	bp->b_iooffset = dbtob(bp->b_blkno);
	BO_STRATEGY(bo, bp);
	return (0);
}

static int
udf_bmap(struct vop_bmap_args *a)
{
	struct udf_node *node;
	uint32_t max_size;
	daddr_t lsector;
	int nblk;
	int error;

	node = VTON(a->a_vp);

	if (a->a_bop != NULL)
		*a->a_bop = &node->udfmp->im_devvp->v_bufobj;
	if (a->a_bnp == NULL)
		return (0);
	if (a->a_runb)
		*a->a_runb = 0;

	/*
	 * UDF_INVALID_BMAP means data embedded into fentry, this is an internal
	 * error that should not be propagated to calling code.
	 * Most obvious mapping for this error is EOPNOTSUPP as we can not truly
	 * translate block numbers in this case.
	 * Incidentally, this return code will make vnode pager to use VOP_READ
	 * to get data for mmap-ed pages and udf_read knows how to do the right
	 * thing for this kind of files.
	 */
	error = udf_bmap_internal(node, a->a_bn << node->udfmp->bshift,
	    &lsector, &max_size);
	if (error == UDF_INVALID_BMAP)
		return (EOPNOTSUPP);
	if (error)
		return (error);

	/* Translate logical to physical sector number */
	*a->a_bnp = lsector << (node->udfmp->bshift - DEV_BSHIFT);

	/*
	 * Determine maximum number of readahead blocks following the
	 * requested block.
	 */
	if (a->a_runp) {
		nblk = (max_size >> node->udfmp->bshift) - 1;
		if (nblk <= 0)
			*a->a_runp = 0;
		else if (nblk >= (MAXBSIZE >> node->udfmp->bshift))
			*a->a_runp = (MAXBSIZE >> node->udfmp->bshift) - 1;
		else
			*a->a_runp = nblk;
	}

	if (a->a_runb) {
		*a->a_runb = 0;
	}

	return (0);
}

/*
 * The all powerful VOP_LOOKUP().
 */
static int
udf_lookup(struct vop_cachedlookup_args *a)
{
	struct vnode *dvp;
	struct vnode *tdp = NULL;
	struct vnode **vpp = a->a_vpp;
	struct udf_node *node;
	struct udf_mnt *udfmp;
	struct fileid_desc *fid = NULL;
	struct udf_dirstream *ds;
	uint64_t fsize;
	u_long nameiop;
	u_long flags;
	char *nameptr;
	long namelen;
	ino_t id = 0;
	int offset, error = 0;
	int lkflags, ltype, numdirpasses;

	dvp = a->a_dvp;
	node = VTON(dvp);
	udfmp = node->udfmp;
	nameiop = a->a_cnp->cn_nameiop;
	flags = a->a_cnp->cn_flags;
	lkflags = a->a_cnp->cn_lkflags;
	nameptr = a->a_cnp->cn_nameptr;
	namelen = a->a_cnp->cn_namelen;
	fsize = le64toh(node->fentry->inf_len);
	if (fsize > INT_MAX) {
		/* too big, just cap to INT_MAX */
		fsize = INT_MAX;
	}

	/*
	 * If this is a LOOKUP and we've already partially searched through
	 * the directory, pick up where we left off and flag that the
	 * directory may need to be searched twice.  For a full description,
	 * see /sys/fs/cd9660/cd9660_lookup.c:cd9660_lookup()
	 */
	if (nameiop != LOOKUP || node->diroff == 0 || node->diroff > fsize) {
		offset = 0;
		numdirpasses = 1;
	} else {
		offset = node->diroff;
		numdirpasses = 2;
		nchstats.ncs_2passes++;
	}

lookloop:
	ds = udf_opendir(node, offset, fsize, udfmp);

	while ((fid = udf_getfid(ds)) != NULL) {
		/* XXX Should we return an error on a bad fid? */
		if (udf_checktag(&fid->tag, TAGID_FID)) {
			printf("udf_lookup: Invalid tag\n");
			error = EIO;
			break;
		}

		/* Is this a deleted file? */
		if (fid->file_char & UDF_FILE_CHAR_DEL)
			continue;

		if ((fid->l_fi == 0) && (fid->file_char & UDF_FILE_CHAR_PAR)) {
			if (flags & ISDOTDOT) {
				id = udf_getid(&fid->icb);
				break;
			}
		} else {
			if (!(udf_cmpname(&fid->data[fid->l_iu],
			    nameptr, fid->l_fi, namelen, udfmp))) {
				id = udf_getid(&fid->icb);
				break;
			}
		}
	}

	if (!error)
		error = ds->error;

	/* XXX Bail out here? */
	if (error) {
		udf_closedir(ds);
		return (error);
	}

	/* Did we have a match? */
	if (id) {
		/*
		 * Remember where this entry was if it's the final
		 * component.
		 */
		if ((flags & ISLASTCN) && nameiop == LOOKUP)
			node->diroff = ds->offset + ds->off;
		if (numdirpasses == 2)
			nchstats.ncs_pass2++;
		udf_closedir(ds);

		if (flags & ISDOTDOT) {
			error = vn_vget_ino(dvp, id, lkflags, &tdp);
		} else if (node->hash_id == id) {
			vref(dvp);	/* we want ourself, ie "." */
			/*
			 * When we lookup "." we still can be asked to lock it
			 * differently.
			 */
			ltype = lkflags & LK_TYPE_MASK;
			if (ltype != VOP_ISLOCKED(dvp)) {
				if (ltype == LK_EXCLUSIVE)
					vn_lock(dvp, LK_UPGRADE | LK_RETRY);
				else /* if (ltype == LK_SHARED) */
					vn_lock(dvp, LK_DOWNGRADE | LK_RETRY);
			}
			tdp = dvp;
		} else
			error = udf_vget(udfmp->im_mountp, id, lkflags, &tdp);
		if (!error) {
			*vpp = tdp;
			/* Put this entry in the cache */
			if (flags & MAKEENTRY)
				cache_enter(dvp, *vpp, a->a_cnp);
		}
	} else {
		/* Name wasn't found on this pass.  Do another pass? */
		if (numdirpasses == 2) {
			numdirpasses--;
			offset = 0;
			udf_closedir(ds);
			goto lookloop;
		}
		udf_closedir(ds);

		/* Enter name into cache as non-existant */
		if (flags & MAKEENTRY)
			cache_enter(dvp, *vpp, a->a_cnp);

		if ((flags & ISLASTCN) &&
		    (nameiop == CREATE || nameiop == RENAME)) {
			error = EROFS;
		} else {
			error = ENOENT;
		}
	}

	return (error);
}

static int
udf_reclaim(struct vop_reclaim_args *a)
{
	struct vnode *vp;
	struct udf_node *unode;

	vp = a->a_vp;
	unode = VTON(vp);

	if (unode != NULL) {
		vfs_hash_remove(vp);

		if (unode->fentry != NULL)
			free(unode->fentry, M_UDFFENTRY);
		uma_zfree(udf_zone_node, unode);
		vp->v_data = NULL;
	}

	return (0);
}

static int
udf_vptofh(struct vop_vptofh_args *a)
{
	struct udf_node *node;
	struct ifid *ifhp;
	_Static_assert(sizeof(struct ifid) <= sizeof(struct fid),
	    "struct ifid cannot be larger than struct fid");

	node = VTON(a->a_vp);
	ifhp = (struct ifid *)a->a_fhp;
	ifhp->ifid_len = sizeof(struct ifid);
	ifhp->ifid_ino = node->hash_id;

	return (0);
}

/*
 * Read the block and then set the data pointer to correspond with the
 * offset passed in.  Only read in at most 'size' bytes, and then set 'size'
 * to the number of bytes pointed to.  If 'size' is zero, try to read in a
 * whole extent.
 *
 * Note that *bp may be assigned error or not.
 *
 */
static int
udf_readatoffset(struct udf_node *node, int *size, off_t offset,
    struct buf **bp, uint8_t **data)
{
	struct udf_mnt *udfmp = node->udfmp;
	struct vnode *vp = node->i_vnode;
	struct file_entry *fentry;
	struct buf *bp1;
	uint32_t max_size;
	daddr_t sector;
	off_t off;
	int adj_size;
	int error;

	/*
	 * This call is made *not* only to detect UDF_INVALID_BMAP case,
	 * max_size is used as an ad-hoc read-ahead hint for "normal" case.
	 */
	error = udf_bmap_internal(node, offset, &sector, &max_size);
	if (error == UDF_INVALID_BMAP) {
		/*
		 * This error means that the file *data* is stored in the
		 * allocation descriptor field of the file entry.
		 */
		fentry = node->fentry;
		*data = &fentry->data[le32toh(fentry->l_ea)];
		*size = le32toh(fentry->l_ad);
		if (offset >= *size)
			*size = 0;
		else {
			*data += offset;
			*size -= offset;
		}
		return (0);
	} else if (error != 0) {
		return (error);
	}

	/* Adjust the size so that it is within range */
	if (*size == 0 || *size > max_size)
		*size = max_size;

	/*
	 * Because we will read starting at block boundary, we need to adjust
	 * how much we need to read so that all promised data is in.
	 * Also, we can't promise to read more than MAXBSIZE bytes starting
	 * from block boundary, so adjust what we promise too.
	 */
	off = blkoff(udfmp, offset);
	*size = min(*size, MAXBSIZE - off);
	adj_size = (*size + off + udfmp->bmask) & ~udfmp->bmask;
	*bp = NULL;
	if ((error = bread(vp, lblkno(udfmp, offset), adj_size, NOCRED, bp))) {
		printf("warning: udf_readlblks returned error %d\n", error);
		/* note: *bp may be non-NULL */
		return (error);
	}

	bp1 = *bp;
	*data = (uint8_t *)&bp1->b_data[offset & udfmp->bmask];
	return (0);
}

/*
 * Translate a file offset into a logical block and then into a physical
 * block.
 * max_size - maximum number of bytes that can be read starting from given
 * offset, rather than beginning of calculated sector number
 */
static int
udf_bmap_internal(struct udf_node *node, off_t offset, daddr_t *sector,
    uint32_t *max_size)
{
	struct udf_mnt *udfmp;
	struct file_entry *fentry;
	void *icb;
	struct icb_tag *tag;
	uint32_t icblen = 0;
	daddr_t lsector;
	int ad_offset, ad_num = 0;
	int i, p_offset;

	udfmp = node->udfmp;
	fentry = node->fentry;
	tag = &fentry->icbtag;

	switch (le16toh(tag->strat_type)) {
	case 4:
		break;

	case 4096:
		printf("Cannot deal with strategy4096 yet!\n");
		return (ENODEV);

	default:
		printf("Unknown strategy type %d\n", tag->strat_type);
		return (ENODEV);
	}

	switch (le16toh(tag->flags) & 0x7) {
	case 0:
		/*
		 * The allocation descriptor field is filled with short_ad's.
		 * If the offset is beyond the current extent, look for the
		 * next extent.
		 */
		do {
			offset -= icblen;
			ad_offset = sizeof(struct short_ad) * ad_num;
			if (ad_offset > le32toh(fentry->l_ad)) {
				printf("File offset out of bounds\n");
				return (EINVAL);
			}
			icb = GETICB(short_ad, fentry,
			    le32toh(fentry->l_ea) + ad_offset);
			icblen = GETICBLEN(short_ad, icb);
			ad_num++;
		} while(offset >= icblen);

		lsector = (offset  >> udfmp->bshift) +
		    le32toh(((struct short_ad *)(icb))->pos);

		*max_size = icblen - offset;

		break;
	case 1:
		/*
		 * The allocation descriptor field is filled with long_ad's
		 * If the offset is beyond the current extent, look for the
		 * next extent.
		 */
		do {
			offset -= icblen;
			ad_offset = sizeof(struct long_ad) * ad_num;
			if (ad_offset > le32toh(fentry->l_ad)) {
				printf("File offset out of bounds\n");
				return (EINVAL);
			}
			icb = GETICB(long_ad, fentry,
			    le32toh(fentry->l_ea) + ad_offset);
			icblen = GETICBLEN(long_ad, icb);
			ad_num++;
		} while(offset >= icblen);

		lsector = (offset >> udfmp->bshift) +
		    le32toh(((struct long_ad *)(icb))->loc.lb_num);

		*max_size = icblen - offset;

		break;
	case 3:
		/*
		 * This type means that the file *data* is stored in the
		 * allocation descriptor field of the file entry.
		 */
		*max_size = 0;
		*sector = node->hash_id + udfmp->part_start;

		return (UDF_INVALID_BMAP);
	case 2:
		/* DirectCD does not use extended_ad's */
	default:
		printf("Unsupported allocation descriptor %d\n",
		       tag->flags & 0x7);
		return (ENODEV);
	}

	*sector = lsector + udfmp->part_start;

	/*
	 * Check the sparing table.  Each entry represents the beginning of
	 * a packet.
	 */
	if (udfmp->s_table != NULL) {
		for (i = 0; i< udfmp->s_table_entries; i++) {
			p_offset =
			    lsector - le32toh(udfmp->s_table->entries[i].org);
			if ((p_offset < udfmp->p_sectors) && (p_offset >= 0)) {
				*sector =
				   le32toh(udfmp->s_table->entries[i].map) +
				    p_offset;
				break;
			}
		}
	}

	return (0);
}