xnu-1504.9.37.tar.gz

[apple/xnu.git] / bsd / hfs / hfs_xattr.c

/*
 * Copyright (c) 2004-2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/ubc.h>
#include <sys/utfconv.h>
#include <sys/vnode.h>
#include <sys/xattr.h>
#include <sys/fcntl.h>
#include <sys/vnode_internal.h>
#include <sys/kauth.h>

#include "hfs.h"
#include "hfs_cnode.h"
#include "hfs_mount.h"
#include "hfs_format.h"
#include "hfs_endian.h"
#include "hfs_btreeio.h"
#include "hfs_fsctl.h"

#include "hfscommon/headers/BTreesInternal.h"

#define HFS_XATTR_VERBOSE  0

#define  ATTRIBUTE_FILE_NODE_SIZE   8192


/* State information for the listattr_callback callback function. */
struct listattr_callback_state {
	u_int32_t   fileID;
	int         result;
	uio_t       uio;
	size_t      size;
#if HFS_COMPRESSION
	int         showcompressed;
	vfs_context_t ctx;
	vnode_t     vp;
#endif /* HFS_COMPRESSION */
};

#define HFS_MAXATTRIBUTESIZE    (128 * 1024)
#define HFS_MAXATTRBLKS         (32 * 1024)


/* HFS Internal Names */
#define	XATTR_EXTENDEDSECURITY_NAME   "system.extendedsecurity"
#define XATTR_XATTREXTENTS_NAME	      "system.xattrextents"

/* Faster version if we already know this is the data fork. */
#define RSRC_FORK_EXISTS(CP)   \
	(((CP)->c_attr.ca_blocks - (CP)->c_datafork->ff_data.cf_blocks) > 0)

static u_int32_t emptyfinfo[8] = {0};

const char hfs_attrdatafilename[] = "Attribute Data";

static int  listattr_callback(const HFSPlusAttrKey *key, const HFSPlusAttrData *data,
                       struct listattr_callback_state *state);

static int  remove_attribute_records(struct hfsmount *hfsmp, BTreeIterator * iterator);

static int  getnodecount(struct hfsmount *hfsmp, size_t nodesize);

static size_t  getmaxinlineattrsize(struct vnode * attrvp);

static int  read_attr_data(struct hfsmount *hfsmp, uio_t uio, size_t datasize, HFSPlusExtentDescriptor *extents);

static int  write_attr_data(struct hfsmount *hfsmp, uio_t uio, size_t datasize, HFSPlusExtentDescriptor *extents);

static int  alloc_attr_blks(struct hfsmount *hfsmp, size_t attrsize, size_t extentbufsize, HFSPlusExtentDescriptor *extents, int *blocks);

static void  free_attr_blks(struct hfsmount *hfsmp, int blkcnt, HFSPlusExtentDescriptor *extents);

static int  has_overflow_extents(HFSPlusForkData *forkdata);

static int  count_extent_blocks(int maxblks, HFSPlusExtentRecord extents);

#if NAMEDSTREAMS
/*
 * Obtain the vnode for a stream.
 */
int
hfs_vnop_getnamedstream(struct vnop_getnamedstream_args* ap)
{
	vnode_t vp = ap->a_vp;
	vnode_t *svpp = ap->a_svpp;
	struct cnode *cp;
	int error = 0;

	*svpp = NULL;

	/*
	 * We only support the "com.apple.ResourceFork" stream.
	 */
	if (bcmp(ap->a_name, XATTR_RESOURCEFORK_NAME, sizeof(XATTR_RESOURCEFORK_NAME)) != 0) {
		return (ENOATTR);
	}
	cp = VTOC(vp);
	if ( !S_ISREG(cp->c_mode) ) {
		return (EPERM);
	}
#if HFS_COMPRESSION
	int hide_rsrc = hfs_hides_rsrc(ap->a_context, VTOC(vp), 1);
#endif /* HFS_COMPRESSION */
	if ((error = hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK))) {
		return (error);
	}
	if ((!RSRC_FORK_EXISTS(cp)
#if HFS_COMPRESSION
	     || hide_rsrc
#endif /* HFS_COMPRESSION */
	     ) && (ap->a_operation != NS_OPEN)) {
		hfs_unlock(cp);
		return (ENOATTR);
	}
	error = hfs_vgetrsrc(VTOHFS(vp), vp, svpp, TRUE, FALSE);
	hfs_unlock(cp);

	return (error);
}

/*
 * Create a stream.
 */
int
hfs_vnop_makenamedstream(struct vnop_makenamedstream_args* ap)
{
	vnode_t vp = ap->a_vp;
	vnode_t *svpp = ap->a_svpp;
	struct cnode *cp;
	int error = 0;

	*svpp = NULL;

	/*
	 * We only support the "com.apple.ResourceFork" stream.
	 */
	if (bcmp(ap->a_name, XATTR_RESOURCEFORK_NAME, sizeof(XATTR_RESOURCEFORK_NAME)) != 0) {
		return (ENOATTR);
	}
	cp = VTOC(vp);
	if ( !S_ISREG(cp->c_mode) ) {
		return (EPERM);
	}
#if HFS_COMPRESSION
	if (hfs_hides_rsrc(ap->a_context, VTOC(vp), 1)) {
		if (VNODE_IS_RSRC(vp)) {
			return EINVAL;
		} else {
			error = decmpfs_decompress_file(vp, VTOCMP(vp), -1, 1, 0);
			if (error != 0)
				return error;
		}
	}
#endif /* HFS_COMPRESSION */
	if ((error = hfs_lock(cp, HFS_EXCLUSIVE_LOCK))) {
		return (error);
	}
	error = hfs_vgetrsrc(VTOHFS(vp), vp, svpp, TRUE, FALSE);
	hfs_unlock(cp);

	return (error);
}

/*
 * Remove a stream.
 */
int
hfs_vnop_removenamedstream(struct vnop_removenamedstream_args* ap)
{
	vnode_t svp = ap->a_svp;
	struct cnode *scp;
	int error = 0;

	/*
	 * We only support the "com.apple.ResourceFork" stream.
	 */
	if (bcmp(ap->a_name, XATTR_RESOURCEFORK_NAME, sizeof(XATTR_RESOURCEFORK_NAME)) != 0) {
		return (ENOATTR);
	}
#if HFS_COMPRESSION
	if (hfs_hides_rsrc(ap->a_context, VTOC(svp), 1)) {
		/* do nothing */
		return 0;
	}
#endif /* HFS_COMPRESSION */
	
	scp = VTOC(svp);

	/* Take truncate lock before taking cnode lock. */
	hfs_lock_truncate(scp, TRUE);
	if ((error = hfs_lock(scp, HFS_EXCLUSIVE_LOCK))) {
		goto out;
	}
	if (VTOF(svp)->ff_size != 0) {
		error = hfs_truncate(svp, 0, IO_NDELAY, 0, 0, ap->a_context);
	}
	hfs_unlock(scp);
out:
	hfs_unlock_truncate(scp, TRUE);
	return (error);
}
#endif


/*
 * Retrieve the data of an extended attribute.
 */
__private_extern__
int
hfs_vnop_getxattr(struct vnop_getxattr_args *ap)
/*
	struct vnop_getxattr_args {
		struct vnodeop_desc *a_desc;
		vnode_t a_vp;
		char * a_name;
		uio_t a_uio;
		size_t *a_size;
		int a_options;
		vfs_context_t a_context;
	};
*/
{
	struct vnode *vp = ap->a_vp;
	struct cnode *cp;
	struct hfsmount *hfsmp;
	uio_t uio = ap->a_uio;
	struct BTreeIterator * iterator = NULL;
	struct filefork *btfile;
	FSBufferDescriptor btdata;
	HFSPlusAttrRecord * recp = NULL;
	size_t bufsize;
	u_int16_t datasize;
	int lockflags;
	int result;

	cp = VTOC(vp);
	if (vp == cp->c_vp) {
#if HFS_COMPRESSION
		int decmpfs_hide = hfs_hides_xattr(ap->a_context, VTOC(vp), ap->a_name, 1); /* 1 == don't take the cnode lock */
		if (decmpfs_hide && !(ap->a_options & XATTR_SHOWCOMPRESSION))
				return ENOATTR;
#endif /* HFS_COMPRESSION */
		
		/* Get the Finder Info. */
		if (bcmp(ap->a_name, XATTR_FINDERINFO_NAME, sizeof(XATTR_FINDERINFO_NAME)) == 0) {
			u_int8_t finderinfo[32];
			bufsize = 32;

			if ((result = hfs_lock(cp, HFS_SHARED_LOCK))) {
				return (result);
			}
			/* Make a copy since we may not export all of it. */
			bcopy(cp->c_finderinfo, finderinfo, sizeof(finderinfo));
			hfs_unlock(cp);

			/* Don't expose a symlink's private type/creator. */
			if (vnode_islnk(vp)) {
				struct FndrFileInfo *fip;

				fip = (struct FndrFileInfo *)&finderinfo;
				fip->fdType = 0;
				fip->fdCreator = 0;
			}
			/* If Finder Info is empty then it doesn't exist. */
			if (bcmp(finderinfo, emptyfinfo, sizeof(emptyfinfo)) == 0) {
				return (ENOATTR);
			}
			if (uio == NULL) {
				*ap->a_size = bufsize;
				return (0);
			}
			if ((user_size_t)uio_resid(uio) < bufsize)
				return (ERANGE);

			result = uiomove((caddr_t)&finderinfo , bufsize, uio);

			return (result);
		}
		/* Read the Resource Fork. */
		if (bcmp(ap->a_name, XATTR_RESOURCEFORK_NAME, sizeof(XATTR_RESOURCEFORK_NAME)) == 0) {
			struct vnode *rvp = NULL;
			int openunlinked = 0;
			int namelen = 0;

			if ( !S_ISREG(cp->c_mode) ) {
				return (EPERM);
			}
			if ((result = hfs_lock(cp, HFS_EXCLUSIVE_LOCK))) {
				return (result);
			}
			namelen = cp->c_desc.cd_namelen;

			if ( !RSRC_FORK_EXISTS(cp)) {
				hfs_unlock(cp);
				return (ENOATTR);
			}
			hfsmp = VTOHFS(vp);
			if ((cp->c_flag & C_DELETED) && (namelen == 0)) {
				openunlinked = 1;
			}
			
			result = hfs_vgetrsrc(hfsmp, vp, &rvp, TRUE, FALSE);
			hfs_unlock(cp);
			if (result) {
				return (result);
			}
			if (uio == NULL) {
				*ap->a_size = (size_t)VTOF(rvp)->ff_size;
			} else {
#if HFS_COMPRESSION
				user_ssize_t uio_size = 0;
				if (decmpfs_hide)
					uio_size = uio_resid(uio);
#endif /* HFS_COMPRESSION */
				result = VNOP_READ(rvp, uio, 0, ap->a_context);
#if HFS_COMPRESSION
				if (decmpfs_hide &&
				    (result == 0) &&
				    (uio_resid(uio) == uio_size)) {
					/*
					 we intentionally make the above call to VNOP_READ so that
					 it can return an authorization/permission/etc. error
					 based on ap->a_context and thus deny this operation;
					 in that case, result != 0 and we won't proceed
					 
					 however, if result == 0, it will have returned no data
					 because hfs_vnop_read hid the resource fork
					 (hence uio_resid(uio) == uio_size, i.e. the uio is untouched)
					 
					 in that case, we try again with the decmpfs_ctx context
					 to get the actual data
					 */
					result = VNOP_READ(rvp, uio, 0, decmpfs_ctx);
				}
#endif /* HFS_COMPRESSION */
			}
			/* force the rsrc fork vnode to recycle right away */
			if (openunlinked) {
				int vref;
				vref = vnode_ref (rvp);
				if (vref == 0) {
					vnode_rele (rvp);
				}
				vnode_recycle(rvp);
			}
			vnode_put(rvp);
			return (result);
		}
	}
	hfsmp = VTOHFS(vp);
	/*
	 * Standard HFS only supports native FinderInfo and Resource Forks.
	 */
	if (hfsmp->hfs_flags & HFS_STANDARD) {
		return (EPERM);
	}

	if ((result = hfs_lock(cp, HFS_SHARED_LOCK))) {
		return (result);
	}
	/* Bail if we don't have any extended attributes. */
	if ((hfsmp->hfs_attribute_vp == NULL) ||
	    (cp->c_attr.ca_recflags & kHFSHasAttributesMask) == 0) {
	    	result = ENOATTR;
		goto exit;
	}
	btfile = VTOF(hfsmp->hfs_attribute_vp);

	MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		result = ENOMEM;
		goto exit;
	}
	bzero(iterator, sizeof(*iterator));

	bufsize = sizeof(HFSPlusAttrData) - 2;
	if (uio)
		bufsize += uio_resid(uio);
	bufsize = MAX(bufsize, sizeof(HFSPlusAttrRecord));
	MALLOC(recp, HFSPlusAttrRecord *, bufsize, M_TEMP, M_WAITOK);
	if (recp == NULL) {
		result = ENOMEM;
		goto exit;
	}
	btdata.bufferAddress = recp;
	btdata.itemSize = bufsize;
	btdata.itemCount = 1;

	result = hfs_buildattrkey(VTOC(vp)->c_fileid, ap->a_name, (HFSPlusAttrKey *)&iterator->key);
	if (result)
		goto exit;	

	/* Lookup the attribute. */
	lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE, HFS_SHARED_LOCK);
	result = BTSearchRecord(btfile, iterator, &btdata, &datasize, NULL);
	hfs_systemfile_unlock(hfsmp, lockflags);

	if (result) {
		if (result == btNotFound)
			result = ENOATTR;
		goto exit;
	}

	switch (recp->recordType) {
	case kHFSPlusAttrInlineData:
		/*
		 * Sanity check record size. It's not required to have any
		 * user data, so the minimum size is 2 bytes less that the
		 * size of HFSPlusAttrData (since HFSPlusAttrData struct
		 * has 2 bytes set aside for attribute data).
		 */
		if (datasize < (sizeof(HFSPlusAttrData) - 2)) {
			printf("hfs_getxattr: %d,%s invalid record size %d (expecting %lu)\n", 
				VTOC(vp)->c_fileid, ap->a_name, datasize, sizeof(HFSPlusAttrData));
			result = ENOATTR;
			break;
		}
		*ap->a_size = recp->attrData.attrSize;
		if (uio && recp->attrData.attrSize != 0) {
			if (*ap->a_size > (user_size_t)uio_resid(uio))
				result = ERANGE;
			else
				result = uiomove((caddr_t) &recp->attrData.attrData , recp->attrData.attrSize, uio);
		}
		break;

	case kHFSPlusAttrForkData:
		if (datasize < sizeof(HFSPlusAttrForkData)) {
			printf("hfs_getxattr: %d,%s invalid record size %d (expecting %lu)\n", 
				VTOC(vp)->c_fileid, ap->a_name, datasize, sizeof(HFSPlusAttrForkData));
			result = ENOATTR;
			break;
		}
		*ap->a_size = recp->forkData.theFork.logicalSize;
		if (uio == NULL) {
			break;
		}
		if (*ap->a_size > (user_size_t)uio_resid(uio)) {
			result = ERANGE;
			break;
		}
		/* Process overflow extents if necessary. */
		if (has_overflow_extents(&recp->forkData.theFork)) {
			HFSPlusExtentDescriptor *extentbuf;
			HFSPlusExtentDescriptor *extentptr;
			size_t extentbufsize;
			u_int32_t totalblocks;
			u_int32_t blkcnt;
			u_int32_t attrlen;

			totalblocks = recp->forkData.theFork.totalBlocks;
			/* Ignore bogus block counts. */
			if (totalblocks > HFS_MAXATTRBLKS) {
				result = ERANGE;
				break;
			}
			attrlen = recp->forkData.theFork.logicalSize;

			/* Get a buffer to hold the worst case amount of extents. */
			extentbufsize = totalblocks * sizeof(HFSPlusExtentDescriptor);
			extentbufsize = roundup(extentbufsize, sizeof(HFSPlusExtentRecord));
			MALLOC(extentbuf, HFSPlusExtentDescriptor *, extentbufsize, M_TEMP, M_WAITOK);
			if (extentbuf == NULL) {
				result = ENOMEM;
				break;
			}
			bzero(extentbuf, extentbufsize);
			extentptr = extentbuf;

			/* Grab the first 8 extents. */
			bcopy(&recp->forkData.theFork.extents[0], extentptr, sizeof(HFSPlusExtentRecord));
			extentptr += kHFSPlusExtentDensity;
			blkcnt = count_extent_blocks(totalblocks, recp->forkData.theFork.extents);

			/* Now lookup the overflow extents. */
			lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE, HFS_SHARED_LOCK);
			while (blkcnt < totalblocks) {
				((HFSPlusAttrKey *)&iterator->key)->startBlock = blkcnt;
				result = BTSearchRecord(btfile, iterator, &btdata, &datasize, NULL);
				if (result ||
				    (recp->recordType != kHFSPlusAttrExtents) ||
				    (datasize < sizeof(HFSPlusAttrExtents))) {
					printf("hfs_getxattr: %s missing extents, only %d blks of %d found\n",
						ap->a_name, blkcnt, totalblocks);
					result = ENOATTR;
					break;   /* break from while */
				}
				/* Grab the next 8 extents. */
				bcopy(&recp->overflowExtents.extents[0], extentptr, sizeof(HFSPlusExtentRecord));
				extentptr += kHFSPlusExtentDensity;
				blkcnt += count_extent_blocks(totalblocks, recp->overflowExtents.extents);
			}
			hfs_systemfile_unlock(hfsmp, lockflags);

			if (blkcnt < totalblocks) {
				result = ENOATTR;
			} else {
				result = read_attr_data(hfsmp, uio, attrlen, extentbuf);
			}
			FREE(extentbuf, M_TEMP);

		} else /* No overflow extents. */ {
			result = read_attr_data(hfsmp, uio, recp->forkData.theFork.logicalSize, recp->forkData.theFork.extents);
		}
		break;

	default:
		result = ENOATTR;
		break;		
	}
exit:
	hfs_unlock(cp);

	if (iterator) {
		FREE(iterator, M_TEMP);
	}
	if (recp) {
		FREE(recp, M_TEMP);
	}
	
	return MacToVFSError(result);
}

/*
 * Set the data of an extended attribute.
 */
__private_extern__
int
hfs_vnop_setxattr(struct vnop_setxattr_args *ap)
/*
	struct vnop_setxattr_args {
		struct vnodeop_desc *a_desc;
		vnode_t a_vp;
		char * a_name;
		uio_t a_uio;
		int a_options;
		vfs_context_t a_context;
	};
*/
{
	struct vnode *vp = ap->a_vp;
	struct cnode *cp = NULL;
	struct hfsmount *hfsmp;
	uio_t uio = ap->a_uio;
	struct BTreeIterator * iterator = NULL;
	struct filefork *btfile = NULL;
	size_t attrsize;
	FSBufferDescriptor btdata;
	HFSPlusAttrRecord *recp = NULL;
	HFSPlusExtentDescriptor *extentptr = NULL;
	HFSPlusAttrRecord attrdata;  /* 90 bytes */
	void * user_data_ptr = NULL;
	int started_transaction = 0;
	int lockflags = 0;
	int exists;
	int allocatedblks = 0;
	int result;

	if (ap->a_name == NULL || ap->a_name[0] == '\0') {
		return (EINVAL);  /* invalid name */
	}
	hfsmp = VTOHFS(vp);
	if (VNODE_IS_RSRC(vp)) {
		return (EPERM);
	}

#if HFS_COMPRESSION
	if (hfs_hides_xattr(ap->a_context, VTOC(vp), ap->a_name, 1) ) { /* 1 == don't take the cnode lock */
		result = decmpfs_decompress_file(vp, VTOCMP(vp), -1, 1, 0);
		if (result != 0)
			return result;
	}
#endif /* HFS_COMPRESSION */
	
	/* Set the Finder Info. */
	if (bcmp(ap->a_name, XATTR_FINDERINFO_NAME, sizeof(XATTR_FINDERINFO_NAME)) == 0) {
		u_int8_t finderinfo[32];
		struct FndrFileInfo *fip;
		void * finderinfo_start;
		u_int16_t fdFlags;

		attrsize = sizeof(VTOC(vp)->c_finderinfo);

		if ((user_size_t)uio_resid(uio) != attrsize) {
			return (ERANGE);
		}
		/* Grab the new Finder Info data. */
		if ((result = uiomove((caddr_t)&finderinfo , attrsize, uio))) {
			return (result);
		}
		fip = (struct FndrFileInfo *)&finderinfo;

		if ((result = hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK))) {
			return (result);
		}
		cp = VTOC(vp);

		/* Symlink's don't have an external type/creator. */
		if (vnode_islnk(vp)) {
			/* Skip over type/creator fields. */
			finderinfo_start = &cp->c_finderinfo[8];
			attrsize -= 8;
		} else {
			finderinfo_start = &cp->c_finderinfo[0];
			/*
			 * Don't allow the external setting of
			 * file type to kHardLinkFileType.
			 */
			if (fip->fdType == SWAP_BE32(kHardLinkFileType)) {
				hfs_unlock(cp);
				return (EPERM);
			} 
		}

		if (bcmp(finderinfo_start, emptyfinfo, attrsize)) {
			/* attr exists and "create" was specified. */
			if (ap->a_options & XATTR_CREATE) {
				hfs_unlock(cp);
				return (EEXIST);
			}
		} else /* empty */ {
			/* attr doesn't exists and "replace" was specified. */
			if (ap->a_options & XATTR_REPLACE) {
				hfs_unlock(cp);
				return (ENOATTR);
			}
		}
		/* Set the cnode's Finder Info. */
		if (attrsize == sizeof(cp->c_finderinfo))
			bcopy(&finderinfo[0], finderinfo_start, attrsize);
		else
			bcopy(&finderinfo[8], finderinfo_start, attrsize);

		/* Updating finderInfo updates change time and modified time */
		cp->c_touch_chgtime = TRUE;
		cp->c_flag |= C_MODIFIED;

		/*
		 * Mirror the invisible bit to the UF_HIDDEN flag.
		 *
		 * The fdFlags for files and frFlags for folders are both 8 bytes
		 * into the userInfo (the first 16 bytes of the Finder Info).  They
		 * are both 16-bit fields.
		 */
		fdFlags = *((u_int16_t *) &cp->c_finderinfo[8]);
		if (fdFlags & OSSwapHostToBigConstInt16(kFinderInvisibleMask))
			cp->c_flags |= UF_HIDDEN;
		else
			cp->c_flags &= ~UF_HIDDEN;

		result = hfs_update(vp, FALSE);

		hfs_unlock(cp);
		return (result);
	}
	/* Write the Resource Fork. */
	if (bcmp(ap->a_name, XATTR_RESOURCEFORK_NAME, sizeof(XATTR_RESOURCEFORK_NAME)) == 0) {
		struct vnode *rvp = NULL;
		int namelen = 0;
		int openunlinked = 0;

		if (!vnode_isreg(vp)) {
			return (EPERM);
		}
		if ((result = hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK))) {
			return (result);
		}
		cp = VTOC(vp);
		namelen = cp->c_desc.cd_namelen;

		if (RSRC_FORK_EXISTS(cp)) {
			/* attr exists and "create" was specified. */
			if (ap->a_options & XATTR_CREATE) {
				hfs_unlock(cp);
				return (EEXIST);
			}
		} else {
			/* attr doesn't exists and "replace" was specified. */
			if (ap->a_options & XATTR_REPLACE) {
				hfs_unlock(cp);
				return (ENOATTR);
			}
		}
		
		/*
		 * Note that we could be called on to grab the rsrc fork vnode
		 * for a file that has become open-unlinked.
		 */
		if ((cp->c_flag & C_DELETED) && (namelen == 0)) {
			openunlinked = 1;
		}

		result = hfs_vgetrsrc(hfsmp, vp, &rvp, TRUE, FALSE);
		hfs_unlock(cp);
		if (result) {
			return (result);
		}
		/* 
		 * VNOP_WRITE marks the vnode as needing a modtime update.
		 */
		result = VNOP_WRITE(rvp, uio, 0, ap->a_context);
		
		/* if open unlinked, force it inactive and recycle */
		if (openunlinked) {
			int vref;
			vref = vnode_ref (rvp);
			if (vref == 0) {
				vnode_rele(rvp);
			}
			vnode_recycle (rvp);
		}
		else {
			/* re-lock the cnode so we can update the modtimes */
			if ((result = hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK))) {
				vnode_recycle(rvp);
				vnode_put(rvp);
				return (result);
			}

			/* HFS fsync the resource fork to force it out to disk */
			result = hfs_fsync (rvp, MNT_NOWAIT, 0, vfs_context_proc(ap->a_context));

			hfs_unlock(cp);
		}

		vnode_put(rvp);
		return (result);
	}
	/*
	 * Standard HFS only supports native FinderInfo and Resource Forks.
	 */
	if (hfsmp->hfs_flags & HFS_STANDARD) {
		return (EPERM);
	}
	attrsize = uio_resid(uio);

	/* Enforce an upper limit. */
	if (attrsize > HFS_MAXATTRIBUTESIZE) {
		return (E2BIG);
	}

	/*
	 * Attempt to copy the users attr data before taking any locks.
	 */
	if (attrsize > 0 &&
	    hfsmp->hfs_max_inline_attrsize != 0 &&
	    attrsize < hfsmp->hfs_max_inline_attrsize) {
		MALLOC(user_data_ptr, void *, attrsize, M_TEMP, M_WAITOK);
		if (user_data_ptr == NULL) {
			result = ENOMEM;
			goto exit;
		}

		result = uiomove((caddr_t)user_data_ptr, attrsize, uio);
		if (result) {
			goto exit;
		}
	}

	result = hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK);
	if (result) {
		goto exit;
	}
	cp = VTOC(vp);

	/* Start a transaction for our changes. */
	if (hfs_start_transaction(hfsmp) != 0) {
	    result = EINVAL;
	    goto exit;
	}
	started_transaction = 1;

	/*
	 * Once we started the transaction, nobody can compete
	 * with us, so make sure this file is still there.
	 */
	if (cp->c_flag & C_NOEXISTS) {
		result = ENOENT;
		goto exit;
	}

	/*
	 * If there isn't an attributes b-tree then create one.
	 */
	if (hfsmp->hfs_attribute_vp == NULL) {
		result = hfs_create_attr_btree(hfsmp, ATTRIBUTE_FILE_NODE_SIZE,
		                               getnodecount(hfsmp, ATTRIBUTE_FILE_NODE_SIZE));
		if (result) {
			goto exit;
		}
	}
	if (hfsmp->hfs_max_inline_attrsize == 0) {
		hfsmp->hfs_max_inline_attrsize = getmaxinlineattrsize(hfsmp->hfs_attribute_vp);
	}

	/* Take exclusive access to the attributes b-tree. */
	lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE, HFS_EXCLUSIVE_LOCK);

	/* Build the b-tree key. */
	MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		result = ENOMEM;
		goto exit;
	}
	bzero(iterator, sizeof(*iterator));
	result = hfs_buildattrkey(VTOC(vp)->c_fileid, ap->a_name, (HFSPlusAttrKey *)&iterator->key);
	if (result) {
		goto exit;
	}

	/* Preflight for replace/create semantics. */
	btfile = VTOF(hfsmp->hfs_attribute_vp);
	btdata.bufferAddress = &attrdata;
	btdata.itemSize = sizeof(attrdata);
	btdata.itemCount = 1;
	exists = BTSearchRecord(btfile, iterator, &btdata, NULL, NULL) == 0;

	/* Replace requires that the attribute already exists. */
	if ((ap->a_options & XATTR_REPLACE) && !exists) {
		result = ENOATTR;
		goto exit;	
	}
	/* Create requires that the attribute doesn't exist. */
	if ((ap->a_options & XATTR_CREATE) && exists) {
		result = EEXIST;
		goto exit;	
	}
	/* If it won't fit inline then use extent-based attributes. */
	if (attrsize > hfsmp->hfs_max_inline_attrsize) {
		size_t extentbufsize;
		int blkcnt;
		int extentblks;
		u_int32_t *keystartblk;
		int i;

		/* Check if volume supports extent-based attributes */
		if ((hfsmp->hfs_flags & HFS_XATTR_EXTENTS) == 0) {
			result = E2BIG;
			goto exit;
		} 

		/* Get some blocks. */
		blkcnt = howmany(attrsize, hfsmp->blockSize);
		extentbufsize = blkcnt * sizeof(HFSPlusExtentDescriptor);
		extentbufsize = roundup(extentbufsize, sizeof(HFSPlusExtentRecord));
		MALLOC(extentptr, HFSPlusExtentDescriptor *, extentbufsize, M_TEMP, M_WAITOK);
		if (extentptr == NULL) {
			result = ENOMEM;
			goto exit;
		}
		bzero(extentptr, extentbufsize);
		result = alloc_attr_blks(hfsmp, attrsize, extentbufsize, extentptr, &allocatedblks);
		if (result) {
			allocatedblks = 0;
			goto exit;  /* no more space */
		}
		/* Copy data into the blocks. */
		result = write_attr_data(hfsmp, uio, attrsize, extentptr);
		if (result) {
			const char *name = vnode_getname(vp);
			printf("hfs_setxattr: write_attr_data err (%d) %s:%s\n",
				result,  name ? name : "", ap->a_name);
			if (name)
				vnode_putname(name);
			goto exit;
		}

		/* Now remove any previous attribute. */
		if (exists) {
			result = remove_attribute_records(hfsmp, iterator);
			if (result) {
				const char *name = vnode_getname(vp);
				printf("hfs_setxattr: remove_attribute_records err (%d) %s:%s\n",
					result, name ? name : "", ap->a_name);
				if (name)
					vnode_putname(name);
				goto exit; 
			}
		}

		/* Create attribute fork data record. */
		MALLOC(recp, HFSPlusAttrRecord *, sizeof(HFSPlusAttrRecord), M_TEMP, M_WAITOK);
		if (recp == NULL) {
			result = ENOMEM;
			goto exit;
		}
		btdata.bufferAddress = recp;
		btdata.itemCount = 1;
		btdata.itemSize = sizeof(HFSPlusAttrForkData);

		recp->recordType = kHFSPlusAttrForkData;
		recp->forkData.reserved = 0;
		recp->forkData.theFork.logicalSize = attrsize;
		recp->forkData.theFork.clumpSize = 0;
		recp->forkData.theFork.totalBlocks = blkcnt;
		bcopy(extentptr, recp->forkData.theFork.extents, sizeof(HFSPlusExtentRecord));

		(void) hfs_buildattrkey(VTOC(vp)->c_fileid, ap->a_name, (HFSPlusAttrKey *)&iterator->key);

		result = BTInsertRecord(btfile, iterator, &btdata, btdata.itemSize);
		if (result) {
#if HFS_XATTR_VERBOSE
			const char *name = vnode_getname(vp);
			printf("hfs_setxattr: BTInsertRecord err (%d) %s:%s\n",
			       MacToVFSError(result), name ? name : "", ap->a_name);
			if (name)
				vnode_putname(name);
#endif
			goto exit; 
		}
		extentblks = count_extent_blocks(blkcnt, recp->forkData.theFork.extents);
		blkcnt -= extentblks;
		keystartblk = &((HFSPlusAttrKey *)&iterator->key)->startBlock;
		i = 0;

		/* Create overflow extents as needed. */
		while (blkcnt > 0) {
			/* Initialize the key and record. */
			*keystartblk += (u_int32_t)extentblks;
			btdata.itemSize = sizeof(HFSPlusAttrExtents);
			recp->recordType = kHFSPlusAttrExtents;
			recp->overflowExtents.reserved = 0;

			/* Copy the next set of extents. */
			i += kHFSPlusExtentDensity;
			bcopy(&extentptr[i], recp->overflowExtents.extents, sizeof(HFSPlusExtentRecord));

			result = BTInsertRecord(btfile, iterator, &btdata, btdata.itemSize);
			if (result) {
				const char *name = vnode_getname(vp);
				printf("hfs_setxattr: BTInsertRecord err (%d) %s:%s\n",
					MacToVFSError(result), name ? name : "", ap->a_name);
				if (name)
					vnode_putname(name);
				goto exit;
			}
			extentblks = count_extent_blocks(blkcnt, recp->overflowExtents.extents);
			blkcnt -= extentblks;
		}
	} else /* Inline data */ {
		if (exists) {
			result = remove_attribute_records(hfsmp, iterator);
			if (result) {
				goto exit;
			}
		}

		/* Calculate size of record rounded up to multiple of 2 bytes. */
		btdata.itemSize = sizeof(HFSPlusAttrData) - 2 + attrsize + ((attrsize & 1) ? 1 : 0);
		MALLOC(recp, HFSPlusAttrRecord *, btdata.itemSize, M_TEMP, M_WAITOK);
		if (recp == NULL) {
			result = ENOMEM;
			goto exit;
		}
		recp->recordType = kHFSPlusAttrInlineData;
		recp->attrData.reserved[0] = 0;
		recp->attrData.reserved[1] = 0;
		recp->attrData.attrSize = attrsize;
	
		/* Copy in the attribute data (if any). */
		if (attrsize > 0) {
			if (user_data_ptr)
				bcopy(user_data_ptr, &recp->attrData.attrData, attrsize);
			else
				result = uiomove((caddr_t)&recp->attrData.attrData, attrsize, uio);
			if (result) {
				goto exit;
			}
		}

		(void) hfs_buildattrkey(VTOC(vp)->c_fileid, ap->a_name, (HFSPlusAttrKey *)&iterator->key);

		btdata.bufferAddress = recp;
		btdata.itemCount = 1;
		result = BTInsertRecord(btfile, iterator, &btdata, btdata.itemSize);
	}
exit:
	if (btfile && started_transaction) {
		(void) BTFlushPath(btfile);
	}
	if (lockflags) {
		hfs_systemfile_unlock(hfsmp, lockflags);
	}
	if (result == 0) {
		cp = VTOC(vp);
		/* Setting an attribute only updates change time and not 
		 * modified time of the file.
		 */
		cp->c_touch_chgtime = TRUE;
		cp->c_attr.ca_recflags |= kHFSHasAttributesMask;
		if ((bcmp(ap->a_name, KAUTH_FILESEC_XATTR, sizeof(KAUTH_FILESEC_XATTR)) == 0)) {
			cp->c_attr.ca_recflags |= kHFSHasSecurityMask;
		}
		(void) hfs_update(vp, 0);
	}
	if (started_transaction) {
		if (result && allocatedblks) {
			free_attr_blks(hfsmp, allocatedblks, extentptr);
		}
		hfs_end_transaction(hfsmp);
	}
	if (cp) {
		hfs_unlock(cp);
	}
	if (user_data_ptr) {
		FREE(user_data_ptr, M_TEMP);
	}
	if (recp) {
		FREE(recp, M_TEMP);
	}
	if (extentptr) {
		FREE(extentptr, M_TEMP);
	}
	if (iterator) {
		FREE(iterator, M_TEMP);
	}
	return (result == btNotFound ? ENOATTR : MacToVFSError(result));
}

/*
 * Remove an extended attribute.
 */
__private_extern__
int
hfs_vnop_removexattr(struct vnop_removexattr_args *ap)
/*
	struct vnop_removexattr_args {
		struct vnodeop_desc *a_desc;
		vnode_t a_vp;
		char * a_name;
		int a_options;
		vfs_context_t a_context;
	};
*/
{
	struct vnode *vp = ap->a_vp;
	struct cnode *cp = VTOC(vp);
	struct hfsmount *hfsmp;
	struct BTreeIterator * iterator = NULL;
	int lockflags;
	int result;

	if (ap->a_name == NULL || ap->a_name[0] == '\0') {
		return (EINVAL);  /* invalid name */
	}
	hfsmp = VTOHFS(vp);
	if (VNODE_IS_RSRC(vp)) {
		return (EPERM);
	}

#if HFS_COMPRESSION
	if (hfs_hides_xattr(ap->a_context, VTOC(vp), ap->a_name, 1) && !(ap->a_options & XATTR_SHOWCOMPRESSION))
		return ENOATTR;
#endif /* HFS_COMPRESSION */
	
	/* If Resource Fork is non-empty then truncate it. */
	if (bcmp(ap->a_name, XATTR_RESOURCEFORK_NAME, sizeof(XATTR_RESOURCEFORK_NAME)) == 0) {
		struct vnode *rvp = NULL;

		if ( !vnode_isreg(vp) ) {
			return (EPERM);
		}
		if ((result = hfs_lock(cp, HFS_EXCLUSIVE_LOCK))) {
			return (result);
		}
		if ( !RSRC_FORK_EXISTS(cp)) {
			hfs_unlock(cp);
			return (ENOATTR);
		}
		result = hfs_vgetrsrc(hfsmp, vp, &rvp, TRUE, FALSE);
		hfs_unlock(cp);
		if (result) {
			return (result);
		}

		hfs_lock_truncate(VTOC(rvp), TRUE);
		if ((result = hfs_lock(VTOC(rvp), HFS_EXCLUSIVE_LOCK))) {
			hfs_unlock_truncate(cp, TRUE);
			vnode_put(rvp);
			return (result);
		}

		/* Start a transaction for encapsulating changes in 
		 * hfs_truncate() and hfs_update()
		 */
		if ((result = hfs_start_transaction(hfsmp))) {
			hfs_unlock_truncate(cp, TRUE);
			hfs_unlock(cp);
			vnode_put(rvp);
			return (result);
		}

		result = hfs_truncate(rvp, (off_t)0, IO_NDELAY, 0, 0, ap->a_context);
		if (result == 0) {
			cp->c_touch_chgtime = TRUE;
			cp->c_flag |= C_MODIFIED;
			result = hfs_update(vp, FALSE);
		}

		hfs_end_transaction(hfsmp);
		hfs_unlock_truncate(VTOC(rvp), TRUE);
		hfs_unlock(VTOC(rvp));

		vnode_put(rvp);
		return (result);
	}
	/* Clear out the Finder Info. */
	if (bcmp(ap->a_name, XATTR_FINDERINFO_NAME, sizeof(XATTR_FINDERINFO_NAME)) == 0) {
		void * finderinfo_start;
		int finderinfo_size;

		if ((result = hfs_lock(cp, HFS_EXCLUSIVE_LOCK))) {
			return (result);
		}

		/* Symlink's don't have an external type/creator. */
		if (vnode_islnk(vp)) {
			/* Skip over type/creator fields. */
			finderinfo_start = &cp->c_finderinfo[8];
			finderinfo_size = sizeof(cp->c_finderinfo) - 8;
		} else {
			finderinfo_start = &cp->c_finderinfo[0];
			finderinfo_size = sizeof(cp->c_finderinfo);
		}
		if (bcmp(finderinfo_start, emptyfinfo, finderinfo_size) == 0) {
			hfs_unlock(cp);
			return (ENOATTR);
		}

		bzero(finderinfo_start, finderinfo_size);

		/* Updating finderInfo updates change time and modified time */
		cp->c_touch_chgtime = TRUE;
		cp->c_flag |= C_MODIFIED;
		hfs_update(vp, FALSE);

		hfs_unlock(cp);

		return (0);
	}
	/*
	 * Standard HFS only supports native FinderInfo and Resource Forks.
	 */
	if (hfsmp->hfs_flags & HFS_STANDARD) {
		return (EPERM);
	}
	if (hfsmp->hfs_attribute_vp == NULL) {
		return (ENOATTR);
	}

	MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		return (ENOMEM);
	}
	bzero(iterator, sizeof(*iterator));

	if ((result = hfs_lock(cp, HFS_EXCLUSIVE_LOCK))) {
		return (result);
	}

	result = hfs_buildattrkey(cp->c_fileid, ap->a_name, (HFSPlusAttrKey *)&iterator->key);
	if (result) {
		goto exit;	
	}

	if (hfs_start_transaction(hfsmp) != 0) {
	    result = EINVAL;
	    goto exit;
	}
	lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE | SFL_BITMAP, HFS_EXCLUSIVE_LOCK);
	
	result = remove_attribute_records(hfsmp, iterator);

	hfs_systemfile_unlock(hfsmp, lockflags);

	if (result == 0) {
		cp->c_touch_chgtime = TRUE;

		lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE, HFS_SHARED_LOCK);

		/* If no more attributes exist, clear attribute bit */
		result = file_attribute_exist(hfsmp, cp->c_fileid);
		if (result == 0) {
			cp->c_attr.ca_recflags &= ~kHFSHasAttributesMask;
		}
		if (result == EEXIST) {
			result = 0;
		}

		hfs_systemfile_unlock(hfsmp, lockflags);

		/* If ACL was removed, clear security bit */
		if ((bcmp(ap->a_name, KAUTH_FILESEC_XATTR, sizeof(KAUTH_FILESEC_XATTR)) == 0)) {
			cp->c_attr.ca_recflags &= ~kHFSHasSecurityMask;
		}
		(void) hfs_update(vp, 0);
	}

	hfs_end_transaction(hfsmp);
exit:
	hfs_unlock(cp);
	FREE(iterator, M_TEMP);
	return MacToVFSError(result);
}

/* Check if any attribute record exist for given fileID.  This function 
 * is called by hfs_vnop_removexattr to determine if it should clear the 
 * attribute bit in the catalog record or not.
 * 
 * Note - you must acquire a shared lock on the attribute btree before
 *        calling this function.
 * 
 * Output: 
 * 	EEXIST	- If attribute record was found
 *	0	- Attribute was not found
 *	(other)	- Other error (such as EIO) 
 */
int
file_attribute_exist(struct hfsmount *hfsmp, uint32_t fileID)
{
	HFSPlusAttrKey *key;
	struct BTreeIterator * iterator = NULL;
	struct filefork *btfile;
	int result = 0;

	// if there's no attribute b-tree we sure as heck
	// can't have any attributes!
	if (hfsmp->hfs_attribute_vp == NULL) {
	    return false;
	}

	MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		result = ENOMEM;
		goto out;
	} 
	bzero(iterator, sizeof(*iterator));
	key = (HFSPlusAttrKey *)&iterator->key;

	result = hfs_buildattrkey(fileID, NULL, key);
	if (result) {
		goto out;
	}

	btfile = VTOF(hfsmp->hfs_attribute_vp);
	result = BTSearchRecord(btfile, iterator, NULL, NULL, NULL);
	if (result && (result != btNotFound)) {
		goto out;
	}

	result = BTIterateRecord(btfile, kBTreeNextRecord, iterator, NULL, NULL);
	/* If no next record was found or fileID for next record did not match,
	 * no more attributes exist for this fileID
	 */
	if ((result && (result == btNotFound)) || (key->fileID != fileID)) {
		result = 0;	
	} else {
		result = EEXIST;
	}

out:
	if (iterator) {
		FREE(iterator, M_TEMP);
	}
	return result;
}


/*
 * Remove all the records for a given attribute.
 *
 * - Used by hfs_vnop_removexattr, hfs_vnop_setxattr and hfs_removeallattr.
 * - A transaction must have been started.
 * - The Attribute b-tree file must be locked exclusive.
 * - The Allocation Bitmap file must be locked exclusive.
 * - The iterator key must be initialized.
 */
static int
remove_attribute_records(struct hfsmount *hfsmp, BTreeIterator * iterator)
{
	struct filefork *btfile;
	FSBufferDescriptor btdata;
	HFSPlusAttrRecord attrdata;  /* 90 bytes */
	u_int16_t datasize;
	int result;

	btfile = VTOF(hfsmp->hfs_attribute_vp);

	btdata.bufferAddress = &attrdata;
	btdata.itemSize = sizeof(attrdata);
	btdata.itemCount = 1;
	result = BTSearchRecord(btfile, iterator, &btdata, &datasize, NULL);
	if (result) {
		goto exit; /* no records. */
	}
	/*
	 * Free the blocks from extent based attributes.
	 *
	 * Note that the block references (btree records) are removed
	 * before releasing the blocks in the allocation bitmap.
	 */
	if (attrdata.recordType == kHFSPlusAttrForkData) {
		int totalblks;
		int extentblks;
		u_int32_t *keystartblk;

#if HFS_XATTR_VERBOSE
		if (datasize < sizeof(HFSPlusAttrForkData)) {
			printf("hfs: remove_attribute_records: bad record size %d (expecting %d)\n", datasize, sizeof(HFSPlusAttrForkData));
		}
#endif
		totalblks = attrdata.forkData.theFork.totalBlocks;

		/* Process the first 8 extents. */
		extentblks = count_extent_blocks(totalblks, attrdata.forkData.theFork.extents);
		if (extentblks > totalblks)
			panic("hfs: remove_attribute_records: corruption...");
		if (BTDeleteRecord(btfile, iterator) == 0) {
			free_attr_blks(hfsmp, extentblks, attrdata.forkData.theFork.extents);
		}
		totalblks -= extentblks;
		keystartblk = &((HFSPlusAttrKey *)&iterator->key)->startBlock;

		/* Process any overflow extents. */
		while (totalblks) {
			*keystartblk += (u_int32_t)extentblks;

			result = BTSearchRecord(btfile, iterator, &btdata, &datasize, NULL);
			if (result ||
			    (attrdata.recordType != kHFSPlusAttrExtents) ||
			    (datasize < sizeof(HFSPlusAttrExtents))) {
				printf("hfs: remove_attribute_records: BTSearchRecord %d (%d), totalblks %d\n",
					MacToVFSError(result), attrdata.recordType != kHFSPlusAttrExtents, totalblks);
				result = ENOATTR;
				break;   /* break from while */
			}
			/* Process the next 8 extents. */
			extentblks = count_extent_blocks(totalblks, attrdata.overflowExtents.extents);
			if (extentblks > totalblks)
				panic("hfs: remove_attribute_records: corruption...");
			if (BTDeleteRecord(btfile, iterator) == 0) {
				free_attr_blks(hfsmp, extentblks, attrdata.overflowExtents.extents);
			}
			totalblks -= extentblks;
		}
	} else {
		result = BTDeleteRecord(btfile, iterator);
	}
	(void) BTFlushPath(btfile);
exit:
	return (result == btNotFound ? ENOATTR :  MacToVFSError(result));
}


/*
 * Retrieve the list of extended attribute names.
 */
__private_extern__
int
hfs_vnop_listxattr(struct vnop_listxattr_args *ap)
/*
	struct vnop_listxattr_args {
		struct vnodeop_desc *a_desc;
		vnode_t a_vp;
		uio_t a_uio;
		size_t *a_size;
		int a_options;
		vfs_context_t a_context;
*/
{
	struct vnode *vp = ap->a_vp;
	struct cnode *cp = VTOC(vp);
	struct hfsmount *hfsmp;
	uio_t uio = ap->a_uio;
	struct BTreeIterator * iterator = NULL;
	struct filefork *btfile;
	struct listattr_callback_state state;
	void * finderinfo_start;
	int finderinfo_size;
	user_addr_t user_start = 0;
	user_size_t user_len = 0;
	int lockflags;
	int result;

	if (VNODE_IS_RSRC(vp)) {
		return (EPERM);
	}
	
#if HFS_COMPRESSION
	int compressed = hfs_file_is_compressed(cp, 1); /* 1 == don't take the cnode lock */
#endif /* HFS_COMPRESSION */
	
	hfsmp = VTOHFS(vp);
	*ap->a_size = 0;

	if ((result = hfs_lock(cp, HFS_SHARED_LOCK))) {
		return (result);
	}

	/* Don't expose a symlink's private type/creator. */
	if (vnode_islnk(vp)) {
		/* Skip over type/creator fields. */
		finderinfo_start = &cp->c_finderinfo[8];
		finderinfo_size = sizeof(cp->c_finderinfo) - 8;
	} else {
		finderinfo_start = &cp->c_finderinfo[0];
		finderinfo_size = sizeof(cp->c_finderinfo);
	}
	/* If Finder Info is non-empty then export it's name. */
	if (bcmp(finderinfo_start, emptyfinfo, finderinfo_size) != 0) {
		if (uio == NULL) {
			*ap->a_size += sizeof(XATTR_FINDERINFO_NAME);
		} else if ((user_size_t)uio_resid(uio) < sizeof(XATTR_FINDERINFO_NAME)) {
			result = ERANGE;
			goto exit;
		} else {
			result = uiomove(XATTR_FINDERINFO_NAME,
			                  sizeof(XATTR_FINDERINFO_NAME), uio);
			if (result)
				goto exit;
		}
	}
	/* If Resource Fork is non-empty then export it's name. */
	if (S_ISREG(cp->c_mode) && RSRC_FORK_EXISTS(cp)) {
#if HFS_COMPRESSION
		if ((ap->a_options & XATTR_SHOWCOMPRESSION) ||
		    !compressed ||
		    !hfs_hides_rsrc(ap->a_context, VTOC(vp), 1) /* 1 == don't take the cnode lock */
		    )
#endif /* HFS_COMPRESSION */
		{
			if (uio == NULL) {
				*ap->a_size += sizeof(XATTR_RESOURCEFORK_NAME);
			} else if ((user_size_t)uio_resid(uio) < sizeof(XATTR_RESOURCEFORK_NAME)) {
				result = ERANGE;
				goto exit;
			} else {
				result = uiomove(XATTR_RESOURCEFORK_NAME,
								 sizeof(XATTR_RESOURCEFORK_NAME), uio);
				if (result)
					goto exit;
			}
		}
	}
	/*
	 * Standard HFS only supports native FinderInfo and Resource Forks.
	 * Return at this point.
	 */
	if (hfsmp->hfs_flags & HFS_STANDARD) {
		result = 0;
		goto exit;
	}
	/* Bail if we don't have any extended attributes. */
	if ((hfsmp->hfs_attribute_vp == NULL) ||
	    (cp->c_attr.ca_recflags & kHFSHasAttributesMask) == 0) {
		result = 0;
		goto exit;
	}
	btfile = VTOF(hfsmp->hfs_attribute_vp);

	MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		result = ENOMEM;
		goto exit;
	}
	bzero(iterator, sizeof(*iterator));
	result = hfs_buildattrkey(cp->c_fileid, NULL, (HFSPlusAttrKey *)&iterator->key);
	if (result)
		goto exit;	

	/*
	 * Lock the user's buffer here so that we won't fault on
	 * it in uiomove while holding the attributes b-tree lock.
	 */
	if (uio && uio_isuserspace(uio)) {
		user_start = uio_curriovbase(uio);
		user_len = uio_curriovlen(uio);

		if ((result = vslock(user_start, user_len)) != 0) {
			user_start = 0;
			goto exit;
		}
	}
	lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE, HFS_SHARED_LOCK);

	result = BTSearchRecord(btfile, iterator, NULL, NULL, NULL);
	if (result && result != btNotFound) {
		hfs_systemfile_unlock(hfsmp, lockflags);
		goto exit;
	}

	state.fileID = cp->c_fileid;
	state.result = 0;
	state.uio = uio;
	state.size = 0;
#if HFS_COMPRESSION
	state.showcompressed = !compressed || ap->a_options & XATTR_SHOWCOMPRESSION;
	state.ctx = ap->a_context;
	state.vp = vp;
#endif /* HFS_COMPRESSION */

	/*
	 * Process entries starting just after iterator->key.
	 */
	result = BTIterateRecords(btfile, kBTreeNextRecord, iterator,
	                          (IterateCallBackProcPtr)listattr_callback, &state);
	hfs_systemfile_unlock(hfsmp, lockflags);
	if (uio == NULL) {
		*ap->a_size += state.size;
	}

	if (state.result || result == btNotFound)
		result = state.result;

exit:
	if (user_start) {
		vsunlock(user_start, user_len, TRUE);
	}
	FREE(iterator, M_TEMP);

	hfs_unlock(cp);
	
	return MacToVFSError(result);
}


/*
 * Callback - called for each attribute
 */
static int
listattr_callback(const HFSPlusAttrKey *key, __unused const HFSPlusAttrData *data, struct listattr_callback_state *state)
{
	char attrname[XATTR_MAXNAMELEN + 1];
	ssize_t bytecount;
	int result;

	if (state->fileID != key->fileID) {
		state->result = 0;
		return (0);	/* stop */
	}
	/*
	 * Skip over non-primary keys
	 */
	if (key->startBlock != 0) {
		return (1);	/* continue */
	}

	/* Convert the attribute name into UTF-8. */
	result = utf8_encodestr(key->attrName, key->attrNameLen * sizeof(UniChar),
				(u_int8_t *)attrname, (size_t *)&bytecount, sizeof(attrname), '/', 0);
	if (result) {
		state->result = result;
		return (0);	/* stop */
	}
	bytecount++; /* account for null termination char */

	if (xattr_protected(attrname))
		return (1);     /* continue */

#if HFS_COMPRESSION
	if (!state->showcompressed && hfs_hides_xattr(state->ctx, VTOC(state->vp), attrname, 1) ) /* 1 == don't take the cnode lock */
		return 1; /* continue */
#endif /* HFS_COMPRESSION */
	
	if (state->uio == NULL) {
		state->size += bytecount;
	} else {
		if (bytecount > uio_resid(state->uio)) {
			state->result = ERANGE;
			return (0);	/* stop */
		}
		result = uiomove((caddr_t) attrname, bytecount, state->uio);
		if (result) {
			state->result = result;
			return (0);	/* stop */
		}
	}
	return (1); /* continue */
}

/*
 * Remove all the attributes from a cnode.
 *
 * This function creates/ends its own transaction so that each
 * attribute is deleted in its own transaction (to avoid having
 * a transaction grow too large).
 *
 * This function takes the necessary locks on the attribute
 * b-tree file and the allocation (bitmap) file.
 */
__private_extern__
int
hfs_removeallattr(struct hfsmount *hfsmp, u_int32_t fileid)
{
	BTreeIterator *iterator = NULL;
	HFSPlusAttrKey *key;
	struct filefork *btfile;
	int result, lockflags;

	if (hfsmp->hfs_attribute_vp == NULL) {
		return (0);
	}
	btfile = VTOF(hfsmp->hfs_attribute_vp);

	MALLOC(iterator, BTreeIterator *, sizeof(BTreeIterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		return (ENOMEM);
	}
	bzero(iterator, sizeof(BTreeIterator));
	key = (HFSPlusAttrKey *)&iterator->key;

	/* Loop until there are no more attributes for this file id */
	for(;;) {
		if (hfs_start_transaction(hfsmp) != 0) {
			result = EINVAL;
			goto exit;
		}

		/* Lock the attribute b-tree and the allocation (bitmap) files */
		lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE | SFL_BITMAP, HFS_EXCLUSIVE_LOCK);

		/*
		 * Go to first possible attribute key/record pair
		 */
		(void) hfs_buildattrkey(fileid, NULL, key);
		result = BTIterateRecord(btfile, kBTreeNextRecord, iterator, NULL, NULL);
		if (result || key->fileID != fileid) {
			hfs_systemfile_unlock(hfsmp, lockflags);
			hfs_end_transaction(hfsmp);
			goto exit;
		}
		result = remove_attribute_records(hfsmp, iterator);

#if HFS_XATTR_VERBOSE
		if (result) {
			printf("hfs_removeallattr: unexpected err %d\n", result);
		}
#endif
		hfs_systemfile_unlock(hfsmp, lockflags);
		hfs_end_transaction(hfsmp);
		if (result)
			break;
	}
exit:
	FREE(iterator, M_TEMP);
	return (result == btNotFound ? 0: MacToVFSError(result));
}

__private_extern__
void
hfs_xattr_init(struct hfsmount * hfsmp)
{
	/*
	 * If there isn't an attributes b-tree then create one.
	 */
	if (!(hfsmp->hfs_flags & HFS_STANDARD) &&
	    (hfsmp->hfs_attribute_vp == NULL) &&
	    !(hfsmp->hfs_flags & HFS_READ_ONLY)) {
		(void) hfs_create_attr_btree(hfsmp, ATTRIBUTE_FILE_NODE_SIZE,
		                             getnodecount(hfsmp, ATTRIBUTE_FILE_NODE_SIZE));
	}
	if (hfsmp->hfs_attribute_vp)
		hfsmp->hfs_max_inline_attrsize = getmaxinlineattrsize(hfsmp->hfs_attribute_vp);
}

/*
 * Enable/Disable volume attributes stored as EA for root file system.
 * Supported attributes are - 
 *	1. ACLs
 *	2. Extent-based Extended Attributes 
 */
__private_extern__
int
hfs_set_volxattr(struct hfsmount *hfsmp, unsigned int xattrtype, int state)
{
	struct BTreeIterator * iterator = NULL;
	struct filefork *btfile;
	int lockflags;
	int result;

	if (hfsmp->hfs_flags & HFS_STANDARD) {
		return (ENOTSUP);
	}

	/*
	 * If there isn't an attributes b-tree then create one.
	 */
	if (hfsmp->hfs_attribute_vp == NULL) {
		result = hfs_create_attr_btree(hfsmp, ATTRIBUTE_FILE_NODE_SIZE,
		                               getnodecount(hfsmp, ATTRIBUTE_FILE_NODE_SIZE));
		if (result) {
			return (result);
		}
	}

	MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		return (ENOMEM);
	} 
	bzero(iterator, sizeof(*iterator));

	/*
	 * Build a b-tree key.
	 * We use the root's parent id (1) to hold this volume attribute.
	 */
	if (xattrtype == HFS_SETACLSTATE) {
		/* ACL */
		(void) hfs_buildattrkey(kHFSRootParentID, XATTR_EXTENDEDSECURITY_NAME,
		                      (HFSPlusAttrKey *)&iterator->key);
	} else if (xattrtype == HFS_SET_XATTREXTENTS_STATE) {
		/* Extent-based extended attributes */
		(void) hfs_buildattrkey(kHFSRootParentID, XATTR_XATTREXTENTS_NAME,
		                      (HFSPlusAttrKey *)&iterator->key);
	} else {
		result = EINVAL;
		goto exit;
	}

	/* Start a transaction for our changes. */
	if (hfs_start_transaction(hfsmp) != 0) {
		result = EINVAL;
		goto exit;
	}
	btfile = VTOF(hfsmp->hfs_attribute_vp);

	lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE, HFS_EXCLUSIVE_LOCK);

	if (state == 0) {
		/* Remove the attribute. */
		result = BTDeleteRecord(btfile, iterator);
		if (result == btNotFound)
			result = 0;
	} else {
		FSBufferDescriptor btdata;
		HFSPlusAttrData attrdata;
		u_int16_t datasize;

		datasize = sizeof(attrdata);
		btdata.bufferAddress = &attrdata;
		btdata.itemSize = datasize;
		btdata.itemCount = 1;
		attrdata.recordType = kHFSPlusAttrInlineData;
		attrdata.reserved[0] = 0;
		attrdata.reserved[1] = 0;
		attrdata.attrSize    = 2;
		attrdata.attrData[0] = 0;
		attrdata.attrData[1] = 0;

		/* Insert the attribute. */
		result = BTInsertRecord(btfile, iterator, &btdata, datasize);
		if (result == btExists)
			result = 0;
	}
	(void) BTFlushPath(btfile);

	hfs_systemfile_unlock(hfsmp, lockflags);

	/* Finish the transaction of our changes. */
	hfs_end_transaction(hfsmp);
exit:
	if (iterator) {
		FREE(iterator, M_TEMP);
	}
	if (result == 0) {
		if (xattrtype == HFS_SETACLSTATE) {
			if (state == 0) {
				vfs_clearextendedsecurity(HFSTOVFS(hfsmp));
			} else {
				vfs_setextendedsecurity(HFSTOVFS(hfsmp));
			}
		} else { 
			/* HFS_SET_XATTREXTENTS_STATE */
			HFS_MOUNT_LOCK(hfsmp, TRUE);
			if (state == 0) {
				hfsmp->hfs_flags &= ~HFS_XATTR_EXTENTS; 
			} else {
				hfsmp->hfs_flags |= HFS_XATTR_EXTENTS; 
			}
			HFS_MOUNT_UNLOCK(hfsmp, TRUE); 
		}
	}

	return MacToVFSError(result);
}


 /*
 * Check for volume attributes stored as EA for root file system.
 * Supported attributes are - 
 *	1. ACLs
 *	2. Extent-based Extended Attributes 
 */
__private_extern__
void
hfs_check_volxattr(struct hfsmount *hfsmp, unsigned int xattrtype)
{
	struct BTreeIterator * iterator;
	struct filefork *btfile;
	int lockflags;
	int result;

	if (hfsmp->hfs_flags & HFS_STANDARD ||
	    hfsmp->hfs_attribute_vp == NULL) {
		return;
	}

	MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
	if (iterator == NULL) {
		return;
	}
	bzero(iterator, sizeof(*iterator));

	/*
	 * Build a b-tree key.
	 * We use the root's parent id (1) to hold this volume attribute.
	 */
	if (xattrtype == HFS_SETACLSTATE) {
		/* ACLs */
		(void) hfs_buildattrkey(kHFSRootParentID, XATTR_EXTENDEDSECURITY_NAME,
	        	              (HFSPlusAttrKey *)&iterator->key);
	} else {
		/* Extent-based extended attributes */
		(void) hfs_buildattrkey(kHFSRootParentID, XATTR_XATTREXTENTS_NAME,
	        	              (HFSPlusAttrKey *)&iterator->key);
	}
	btfile = VTOF(hfsmp->hfs_attribute_vp);

	lockflags = hfs_systemfile_lock(hfsmp, SFL_ATTRIBUTE, HFS_EXCLUSIVE_LOCK);

	/* Check for our attribute. */
	result = BTSearchRecord(btfile, iterator, NULL, NULL, NULL);

	hfs_systemfile_unlock(hfsmp, lockflags);
	FREE(iterator, M_TEMP);

	if (result == 0) {
		if (xattrtype == HFS_SETACLSTATE) {
			vfs_setextendedsecurity(HFSTOVFS(hfsmp));
		} else {
			HFS_MOUNT_LOCK(hfsmp, TRUE);
			hfsmp->hfs_flags |= HFS_XATTR_EXTENTS; 
			HFS_MOUNT_UNLOCK(hfsmp, TRUE); 
		}
	}
}


/*
 * hfs_attrkeycompare - compare two attribute b-tree keys.
 *
 * The name portion of the key is compared using a 16-bit binary comparison. 
 * This is called from the b-tree code.
 */
__private_extern__
int
hfs_attrkeycompare(HFSPlusAttrKey *searchKey, HFSPlusAttrKey *trialKey)
{
	u_int32_t searchFileID, trialFileID;
	int result;

	searchFileID = searchKey->fileID;
	trialFileID = trialKey->fileID;
	result = 0;
	
	if (searchFileID > trialFileID) {
		++result;
	} else if (searchFileID < trialFileID) {
		--result;
	} else {
		u_int16_t * str1 = &searchKey->attrName[0];
		u_int16_t * str2 = &trialKey->attrName[0];
		int length1 = searchKey->attrNameLen;
		int length2 = trialKey->attrNameLen;
		u_int16_t c1, c2;
		int length;
	
		if (length1 < length2) {
			length = length1;
			--result;
		} else if (length1 > length2) {
			length = length2;
			++result;
		} else {
			length = length1;
		}
	
		while (length--) {
			c1 = *(str1++);
			c2 = *(str2++);
	
			if (c1 > c2) {
				result = 1;
				break;
			}
			if (c1 < c2) {
				result = -1;
				break;
			}
		}
		if (result)
			return (result);
		/*
		 * Names are equal; compare startBlock
		 */
		if (searchKey->startBlock == trialKey->startBlock)
			return (0);
		else
			return (searchKey->startBlock < trialKey->startBlock ? -1 : 1);
		}

	return result;
}


/*
 * hfs_buildattrkey - build an Attribute b-tree key
 */
__private_extern__
int
hfs_buildattrkey(u_int32_t fileID, const char *attrname, HFSPlusAttrKey *key)
{
	int result = 0;
	size_t unicodeBytes = 0;

	if (attrname != NULL) {
		/*
		 * Convert filename from UTF-8 into Unicode
		 */	
		result = utf8_decodestr((const u_int8_t *)attrname, strlen(attrname), key->attrName,
					&unicodeBytes, sizeof(key->attrName), 0, 0);
		if (result) {
			if (result != ENAMETOOLONG)
				result = EINVAL;  /* name has invalid characters */
			return (result);
		}
		key->attrNameLen = unicodeBytes / sizeof(UniChar);
		key->keyLength = kHFSPlusAttrKeyMinimumLength + unicodeBytes;
	} else {
		key->attrNameLen = 0;
		key->keyLength = kHFSPlusAttrKeyMinimumLength;
	}
	key->pad = 0;
	key->fileID = fileID;
	key->startBlock = 0;

	return (0);
 }

/*
 * getnodecount - calculate starting node count for attributes b-tree.
 */
static int
getnodecount(struct hfsmount *hfsmp, size_t nodesize)
{
	u_int64_t freebytes;
	u_int64_t calcbytes;

	/*
	 * 10.4: Scale base on current catalog file size (20 %) up to 20 MB.
	 * 10.5: Attempt to be as big as the catalog clump size.
	 *
	 * Use no more than 10 % of the remaining free space.
	 */
	freebytes = (u_int64_t)hfs_freeblks(hfsmp, 0) * (u_int64_t)hfsmp->blockSize;

	calcbytes = MIN(hfsmp->hfs_catalog_cp->c_datafork->ff_size / 5, 20 * 1024 * 1024);

	calcbytes = MAX(calcbytes, hfsmp->hfs_catalog_cp->c_datafork->ff_clumpsize);
	
	calcbytes = MIN(calcbytes, freebytes / 10);

	return (MAX(2, (int)(calcbytes / nodesize)));
}


/*
 * getmaxinlineattrsize - calculate maximum inline attribute size.
 *
 * This yields 3,802 bytes for an 8K node size.
 */
static size_t
getmaxinlineattrsize(struct vnode * attrvp)
{
	struct BTreeInfoRec btinfo;
	size_t nodesize = ATTRIBUTE_FILE_NODE_SIZE;
	size_t maxsize;

	if (attrvp != NULL) {
		(void) hfs_lock(VTOC(attrvp), HFS_SHARED_LOCK);
		if (BTGetInformation(VTOF(attrvp), 0, &btinfo) == 0)
			nodesize = btinfo.nodeSize;
		hfs_unlock(VTOC(attrvp));
	}
	maxsize = nodesize;
	maxsize -= sizeof(BTNodeDescriptor);     /* minus node descriptor */
	maxsize -= 3 * sizeof(u_int16_t);        /* minus 3 index slots */
	maxsize /= 2;                            /* 2 key/rec pairs minumum */
	maxsize -= sizeof(HFSPlusAttrKey);       /* minus maximum key size */
	maxsize -= sizeof(HFSPlusAttrData) - 2;  /* minus data header */
	maxsize &= 0xFFFFFFFE;                   /* multiple of 2 bytes */
	
	return (maxsize);
}

/*
 * Get a referenced vnode for attribute data I/O.
 */
static int
get_attr_data_vnode(struct hfsmount *hfsmp, vnode_t *vpp)
{
	vnode_t vp;
	int result = 0;

	vp = hfsmp->hfs_attrdata_vp;
	if (vp == NULLVP) {
		struct cat_desc cat_desc;
		struct cat_attr cat_attr;
		struct cat_fork cat_fork;

		/* We don't tag it as a system file since we intend to use cluster I/O. */
		bzero(&cat_desc, sizeof(cat_desc));
		cat_desc.cd_parentcnid = kHFSRootParentID;
		cat_desc.cd_nameptr = (const u_int8_t *)hfs_attrdatafilename;
		cat_desc.cd_namelen = strlen(hfs_attrdatafilename);
		cat_desc.cd_cnid = kHFSAttributeDataFileID;

		bzero(&cat_attr, sizeof(cat_attr));
		cat_attr.ca_linkcount = 1;
		cat_attr.ca_mode = S_IFREG;
		cat_attr.ca_fileid = cat_desc.cd_cnid;
		cat_attr.ca_blocks = hfsmp->totalBlocks;

		/*
		 * The attribute data file is a virtual file that spans the
		 * entire file system space.
		 *
		 * Each extent-based attribute occupies a unique portion of
		 * in this virtual file.  The cluster I/O is done using actual
		 * allocation block offsets so no additional mapping is needed
		 * for the VNOP_BLOCKMAP call.
		 *
		 * This approach allows the attribute data to be cached without
		 * incurring the high cost of using a separate vnode per attribute.
		 *
		 * Since we need to acquire the attribute b-tree file lock anyways,
		 * the virtual file doesn't introduce any additional serialization.
		 */
		bzero(&cat_fork, sizeof(cat_fork));
		cat_fork.cf_size = (u_int64_t)hfsmp->totalBlocks * (u_int64_t)hfsmp->blockSize;
		cat_fork.cf_blocks = hfsmp->totalBlocks;
		cat_fork.cf_extents[0].startBlock = 0;
		cat_fork.cf_extents[0].blockCount = cat_fork.cf_blocks;
	
		result = hfs_getnewvnode(hfsmp, NULL, NULL, &cat_desc, 0, &cat_attr, &cat_fork, &vp);
		if (result == 0) {
			HFS_MOUNT_LOCK(hfsmp, 1);
			/* Check if someone raced us for creating this vnode. */
			if (hfsmp->hfs_attrdata_vp != NULLVP) {
				HFS_MOUNT_UNLOCK(hfsmp, 1);
				vnode_put(vp);
				vnode_recycle(vp);
				vp = hfsmp->hfs_attrdata_vp;
			} else {
				hfsmp->hfs_attrdata_vp = vp;
				HFS_MOUNT_UNLOCK(hfsmp, 1);
				/* Keep a reference on this vnode until unmount */
				vnode_ref_ext(vp, O_EVTONLY);
				hfs_unlock(VTOC(vp));
			}
		}
	} else {
		if ((result = vnode_get(vp)))
			vp = NULLVP;
	}
	*vpp = vp;
	return (result);
}

/*
 * Read an extent based attribute.
 */
static int
read_attr_data(struct hfsmount *hfsmp, uio_t uio, size_t datasize, HFSPlusExtentDescriptor *extents)
{
	vnode_t evp = NULLVP;
	int bufsize;
	int iosize;
	int attrsize;
	int blksize;
	int i;
	int result = 0;

	if ((result = get_attr_data_vnode(hfsmp, &evp))) {
		return (result);
	}
	hfs_lock_truncate(VTOC(evp), 0);

	bufsize = (int)uio_resid(uio);
	attrsize = (int)datasize;
	blksize = (int)hfsmp->blockSize;

	/*
	 * Read the attribute data one extent at a time.
	 * For the typical case there is only one extent.
	 */
	for (i = 0; (attrsize > 0) && (bufsize > 0) && (extents[i].startBlock != 0); ++i) {
		iosize = (int)extents[i].blockCount * blksize;
		iosize = MIN(iosize, attrsize);
		iosize = MIN(iosize, bufsize);
		uio_setresid(uio, iosize);
		uio_setoffset(uio, (u_int64_t)extents[i].startBlock * (u_int64_t)blksize);

		result = cluster_read(evp, uio, VTOF(evp)->ff_size, IO_SYNC | IO_UNIT);

#if HFS_XATTR_VERBOSE
		printf("hfs: read_attr_data: cr iosize %d [%d, %d] (%d)\n",
			iosize, extents[i].startBlock, extents[i].blockCount, result);
#endif
		if (result)
			break;
		attrsize -= iosize;
		bufsize -= iosize;
	}
	uio_setresid(uio, bufsize);
	uio_setoffset(uio, datasize);

	hfs_unlock_truncate(VTOC(evp), 0);
	vnode_put(evp);
	return (result);
}

/*
 * Write an extent based attribute.
 */
static int
write_attr_data(struct hfsmount *hfsmp, uio_t uio, size_t datasize, HFSPlusExtentDescriptor *extents)
{
	vnode_t evp = NULLVP;
	off_t filesize;
	int bufsize;
	int attrsize;
	int iosize;
	int blksize;
	int i;
	int result = 0;

	/* Get exclusive use of attribute data vnode. */
	if ((result = get_attr_data_vnode(hfsmp, &evp))) {
		return (result);
	}
	hfs_lock_truncate(VTOC(evp), 0);

	bufsize = uio_resid(uio);
	attrsize = (int) datasize;
	blksize = (int) hfsmp->blockSize;
	filesize = VTOF(evp)->ff_size;

	/*
	 * Write the attribute data one extent at a time.
	 */
	for (i = 0; (attrsize > 0) && (bufsize > 0) && (extents[i].startBlock != 0); ++i) {
		iosize = (int)extents[i].blockCount * blksize;
		iosize = MIN(iosize, attrsize);
		iosize = MIN(iosize, bufsize);
		uio_setresid(uio, iosize);
		uio_setoffset(uio, (u_int64_t)extents[i].startBlock * (u_int64_t)blksize);

		result = cluster_write(evp, uio, filesize, filesize, filesize,
		                       (off_t) 0, IO_SYNC | IO_UNIT);
#if HFS_XATTR_VERBOSE
		printf("hfs: write_attr_data: cw iosize %d [%d, %d] (%d)\n",
			iosize, extents[i].startBlock, extents[i].blockCount, result);
#endif
		if (result)
			break;
		attrsize -= iosize;
		bufsize -= iosize;
	}
	uio_setresid(uio, bufsize);
	uio_setoffset(uio, datasize);

	hfs_unlock_truncate(VTOC(evp), 0);
	vnode_put(evp);
	return (result);
}

/*
 * Allocate blocks for an extent based attribute.
 */
static int
alloc_attr_blks(struct hfsmount *hfsmp, size_t attrsize, size_t extentbufsize, HFSPlusExtentDescriptor *extents, int *blocks)
{
	int blkcnt;
	int startblk;
	int lockflags;
	int i;
	int maxextents;
	int result = 0;

	startblk = hfsmp->hfs_metazone_end;
	blkcnt = howmany(attrsize, hfsmp->blockSize);
	if (blkcnt > (int)hfs_freeblks(hfsmp, 0)) {
		return (ENOSPC);
	}
	*blocks = blkcnt;
	maxextents = extentbufsize / sizeof(HFSPlusExtentDescriptor);

	lockflags = hfs_systemfile_lock(hfsmp, SFL_BITMAP, HFS_EXCLUSIVE_LOCK);

	for (i = 0; (blkcnt > 0) && (i < maxextents); i++) {
		result = BlockAllocate(hfsmp, startblk, blkcnt, blkcnt, 0,
				       &extents[i].startBlock, &extents[i].blockCount);
#if HFS_XATTR_VERBOSE
		printf("hfs: alloc_attr_blks: BA blkcnt %d [%d, %d] (%d)\n",
			blkcnt, extents[i].startBlock, extents[i].blockCount, result);
#endif
		if (result) {
			extents[i].startBlock = 0;
			extents[i].blockCount = 0;
			break;
		}
		blkcnt -= extents[i].blockCount;
		startblk = extents[i].startBlock + extents[i].blockCount;
	}
	/*
	 * If it didn't fit in the extents buffer then bail.
	 */
	if (blkcnt) {
		result = ENOSPC;

#if HFS_XATTR_VERBOSE
		printf("hfs: alloc_attr_blks: unexpected failure, %d blocks unallocated\n", blkcnt);
#endif
		for (; i <= 0; i--) {
			if ((blkcnt = extents[i].blockCount) != 0) {
				(void) BlockDeallocate(hfsmp, extents[i].startBlock, blkcnt, 0);
				extents[i].startBlock = 0;
				extents[i].blockCount = 0;
		    }
		}
	}

	hfs_systemfile_unlock(hfsmp, lockflags);
	return MacToVFSError(result);
}

/*
 * Release blocks from an extent based attribute.
 */
static void
free_attr_blks(struct hfsmount *hfsmp, int blkcnt, HFSPlusExtentDescriptor *extents)
{
	vnode_t evp = NULLVP;
	int remblks = blkcnt;
	int lockflags;
	int i;

	if (get_attr_data_vnode(hfsmp, &evp) != 0) {
		evp = NULLVP;
	}
	lockflags = hfs_systemfile_lock(hfsmp, SFL_BITMAP, HFS_EXCLUSIVE_LOCK);

	for (i = 0; (remblks > 0) && (extents[i].blockCount != 0); i++) {
		if (extents[i].blockCount > (u_int32_t)blkcnt) {
#if HFS_XATTR_VERBOSE
			printf("hfs: free_attr_blks: skipping bad extent [%d, %d]\n",
				extents[i].startBlock, extents[i].blockCount);
#endif
			extents[i].blockCount = 0;
			continue;
		}
		if (extents[i].startBlock == 0) {
			break;
		}
		(void)BlockDeallocate(hfsmp, extents[i].startBlock, extents[i].blockCount, 0);
		remblks -= extents[i].blockCount;
		extents[i].startBlock = 0;
		extents[i].blockCount = 0;

#if HFS_XATTR_VERBOSE
		printf("hfs: free_attr_blks: BlockDeallocate [%d, %d]\n",
		       extents[i].startBlock, extents[i].blockCount);
#endif
		/* Discard any resident pages for this block range. */
		if (evp) {
			off_t  start, end;

			start = (u_int64_t)extents[i].startBlock * (u_int64_t)hfsmp->blockSize;
			end = start + (u_int64_t)extents[i].blockCount * (u_int64_t)hfsmp->blockSize;
			(void) ubc_msync(hfsmp->hfs_attrdata_vp, start, end, &start, UBC_INVALIDATE);
		}
	}

	hfs_systemfile_unlock(hfsmp, lockflags);
	if (evp) {
		vnode_put(evp);
	}
}

static int
has_overflow_extents(HFSPlusForkData *forkdata)
{
	u_int32_t blocks;

	if (forkdata->extents[7].blockCount == 0)
		return (0);

	blocks = forkdata->extents[0].blockCount +
		 forkdata->extents[1].blockCount +
		 forkdata->extents[2].blockCount +
		 forkdata->extents[3].blockCount +
		 forkdata->extents[4].blockCount +
		 forkdata->extents[5].blockCount +
		 forkdata->extents[6].blockCount +
		 forkdata->extents[7].blockCount;	

	return (forkdata->totalBlocks > blocks);
}

static int
count_extent_blocks(int maxblks, HFSPlusExtentRecord extents)
{
	int blocks;
	int i;

	for (i = 0, blocks = 0; i < kHFSPlusExtentDensity; ++i) {
		/* Ignore obvious bogus extents. */
		if (extents[i].blockCount > (u_int32_t)maxblks)
			continue;
		if (extents[i].startBlock == 0 || extents[i].blockCount == 0)
			break;
		blocks += extents[i].blockCount;
	}
	return (blocks);
}