xnu-1699.26.8.tar.gz

[apple/xnu.git] / bsd / sys / vnode.h

/*
 * Copyright (c) 2000-2010 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,
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 * Please see the License for the specific language governing rights and
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 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *      @(#)vnode.h     8.17 (Berkeley) 5/20/95
 */
 
#ifndef _VNODE_H_
#define _VNODE_H_

#include <sys/appleapiopts.h>
#include <sys/cdefs.h>
#ifdef KERNEL
#include <sys/kernel_types.h>
#include <sys/signal.h>
#endif

/*
 * The vnode is the focus of all file activity in UNIX.  There is a
 * unique vnode allocated for each active file, each current directory,
 * each mounted-on file, text file, and the root.
 */

/*
 * Vnode types.  VNON means no type.
 */
enum vtype      { VNON, VREG, VDIR, VBLK, VCHR, VLNK, VSOCK, VFIFO, VBAD, VSTR,
                          VCPLX };

/*
 * Vnode tag types.
 * These are for the benefit of external programs only (e.g., pstat)
 * and should NEVER be inspected by the kernel.
 */
enum vtagtype   {
        VT_NON, VT_UFS, VT_NFS, VT_MFS, VT_MSDOSFS, VT_LFS, VT_LOFS, VT_FDESC,
        VT_PORTAL, VT_NULL, VT_UMAP, VT_KERNFS, VT_PROCFS, VT_AFS, VT_ISOFS,
        VT_UNION, VT_HFS, VT_ZFS, VT_DEVFS, VT_WEBDAV, VT_UDF, VT_AFP,
        VT_CDDA, VT_CIFS, VT_OTHER};


/*
 * flags for VNOP_BLOCKMAP
 */
#define VNODE_READ      0x01
#define VNODE_WRITE     0x02



/* flags for VNOP_ALLOCATE */
#define PREALLOCATE             0x00000001      /* preallocate allocation blocks */
#define ALLOCATECONTIG  0x00000002      /* allocate contigious space */
#define ALLOCATEALL             0x00000004      /* allocate all requested space */
                                                                        /* or no space at all */
#define FREEREMAINDER   0x00000008      /* deallocate allocated but */
                                                                        /* unfilled blocks */
#define ALLOCATEFROMPEOF        0x00000010      /* allocate from the physical eof */
#define ALLOCATEFROMVOL         0x00000020      /* allocate from the volume offset */

/*
 * Token indicating no attribute value yet assigned. some user source uses this
 */
#define VNOVAL  (-1)


#ifdef KERNEL

/*
 * Flags for ioflag.
 */
#define IO_UNIT         0x0001          /* do I/O as atomic unit */
#define IO_APPEND       0x0002          /* append write to end */
#define IO_SYNC         0x0004          /* do I/O synchronously */
#define IO_NODELOCKED   0x0008          /* underlying node already locked */
#define IO_NDELAY       0x0010          /* FNDELAY flag set in file table */
#define IO_NOZEROFILL   0x0020          /* F_SETSIZE fcntl uses to prevent zero filling */
#ifdef XNU_KERNEL_PRIVATE
#define IO_REVOKE       IO_NOZEROFILL   /* revoked close for tty, will Not be used in conjunction */
#endif /* XNU_KERNEL_PRIVATE */
#define IO_TAILZEROFILL 0x0040          /* zero fills at the tail of write */
#define IO_HEADZEROFILL 0x0080          /* zero fills at the head of write */
#define IO_NOZEROVALID  0x0100          /* do not zero fill if valid page */
#define IO_NOZERODIRTY  0x0200          /* do not zero fill if page is dirty */
#define IO_CLOSE        0x0400          /* I/O issued from close path */
#define IO_NOCACHE      0x0800          /* same effect as VNOCACHE_DATA, but only for this 1 I/O */
#define IO_RAOFF        0x1000          /* same effect as VRAOFF, but only for this 1 I/O */
#define IO_DEFWRITE     0x2000          /* defer write if vfs.defwrite is set */
#define IO_PASSIVE      0x4000          /* this I/O is marked as background I/O so it won't throttle Throttleable I/O */
#define IO_BACKGROUND IO_PASSIVE /* used for backward compatibility.  to be removed after IO_BACKGROUND is no longer
                                                                  * used by DiskImages in-kernel mode */
#define IO_NOAUTH       0x8000          /* No authorization checks. */
#define IO_NODIRECT    0x10000          /* don't use direct synchronous writes if IO_NOCACHE is specified */


/*
 * Component Name: this structure describes the pathname
 * information that is passed through the VNOP interface.
 */
struct componentname {
        /*
         * Arguments to lookup.
         */
        uint32_t        cn_nameiop;     /* lookup operation */
        uint32_t        cn_flags;       /* flags (see below) */
#ifdef BSD_KERNEL_PRIVATE
        vfs_context_t   cn_context;
        struct nameidata *cn_ndp;       /* pointer back to nameidata */

/* XXX use of these defines are deprecated */
#define cn_proc         (cn_context->vc_proc + 0)       /* non-lvalue */
#define cn_cred         (cn_context->vc_ucred + 0)      /* non-lvalue */

#else
        void * cn_reserved1;    /* use vfs_context_t */
        void * cn_reserved2;    /* use vfs_context_t */
#endif
        /*
         * Shared between lookup and commit routines.
         */
        char    *cn_pnbuf;      /* pathname buffer */
        int     cn_pnlen;       /* length of allocated buffer */
        char    *cn_nameptr;    /* pointer to looked up name */
        int     cn_namelen;     /* length of looked up component */
        uint32_t        cn_hash;        /* hash value of looked up name */
        uint32_t        cn_consume;     /* chars to consume in lookup() */
};

/*
 * component name operations (for VNOP_LOOKUP)
 */
#define LOOKUP          0       /* perform name lookup only */
#define CREATE          1       /* setup for file creation */
#define DELETE          2       /* setup for file deletion */
#define RENAME          3       /* setup for file renaming */
#define OPMASK          3       /* mask for operation */

/*
 * component name operational modifier flags
 */
#define FOLLOW          0x00000040 /* follow symbolic links */
#define NOTRIGGER       0x10000000 /* don't trigger automounts */

/*
 * component name parameter descriptors.
 */
#define ISDOTDOT        0x00002000 /* current component name is .. */
#define MAKEENTRY       0x00004000 /* entry is to be added to name cache */
#define ISLASTCN        0x00008000 /* this is last component of pathname */
#define ISWHITEOUT      0x00020000 /* OBSOLETE: found whiteout */
#define DOWHITEOUT      0x00040000 /* OBSOLETE: do whiteouts */


/* The following structure specifies a vnode for creation */
struct vnode_fsparam {
        struct mount * vnfs_mp;         /* mount point to which this vnode_t is part of */
        enum vtype      vnfs_vtype;             /* vnode type */
        const char * vnfs_str;          /* File system Debug aid */
        struct vnode * vnfs_dvp;                        /* The parent vnode */
        void * vnfs_fsnode;                     /* inode */
        int (**vnfs_vops)(void *);              /* vnode dispatch table */
        int vnfs_markroot;                      /* is this a root vnode in FS (not a system wide one) */
        int vnfs_marksystem;            /* is  a system vnode */
        dev_t vnfs_rdev;                        /* dev_t  for block or char vnodes */
        off_t vnfs_filesize;            /* that way no need for getattr in UBC */
        struct componentname * vnfs_cnp; /* component name to add to namecache */
        uint32_t vnfs_flags;            /* flags */
};

#define VNFS_NOCACHE    0x01    /* do not add to name cache at this time */
#define VNFS_CANTCACHE  0x02    /* never add this instance to the name cache */
#define VNFS_ADDFSREF   0x04    /* take fs (named) reference */

#define VNCREATE_FLAVOR 0
#define VCREATESIZE sizeof(struct vnode_fsparam)


#ifdef KERNEL_PRIVATE
/*
 * Resolver callback SPI for trigger vnodes
 *
 * Only available from kernels built with CONFIG_TRIGGERS option
 */

/*!
 @enum Pathname Lookup Operations
 @abstract Constants defining pathname operations (passed to resolver callbacks)
 */
enum path_operation     {
        OP_LOOKUP,
        OP_MOUNT,
        OP_UNMOUNT,
        OP_STATFS,
        OP_OPEN,
        OP_LINK,
        OP_UNLINK,
        OP_RENAME,
        OP_CHDIR,
        OP_CHROOT,
        OP_MKNOD,
        OP_MKFIFO,
        OP_SYMLINK,
        OP_ACCESS,
        OP_PATHCONF,
        OP_READLINK,
        OP_GETATTR,
        OP_SETATTR,
        OP_TRUNCATE,
        OP_COPYFILE,
        OP_MKDIR,
        OP_RMDIR,
        OP_REVOKE,
        OP_EXCHANGEDATA,
        OP_SEARCHFS,
        OP_FSCTL,
        OP_GETXATTR,
        OP_SETXATTR,
        OP_REMOVEXATTR,
        OP_LISTXATTR,
        OP_MAXOP        /* anything beyond previous entry is invalid */
};

/*
 * is operation a traditional trigger (autofs)?
 * 1 if trigger, 0 if no trigger
 */
extern int vfs_istraditionaltrigger(enum path_operation op, const struct componentname *cnp);

/*!
 @enum resolver status
 @abstract Constants defining resolver status
 @constant RESOLVER_RESOLVED  the resolver has finished (typically means a successful mount)
 @constant RESOLVER_NOCHANGE  the resolver status didn't change
 @constant RESOLVER_UNRESOLVED  the resolver has finished (typically means a successful unmount)
 @constant RESOLVER_ERROR  the resolver encountered an error (errno passed in aux value)
 @constant RESOLVER_STOP  a request to destroy trigger XXX do we need this???
 */
enum resolver_status {
        RESOLVER_RESOLVED,
        RESOLVER_NOCHANGE,
        RESOLVER_UNRESOLVED,
        RESOLVER_ERROR,
        RESOLVER_STOP
};

typedef uint64_t resolver_result_t;

/*
 * Compound resolver result
 *
 * The trigger vnode callbacks use a compound result value. In addition
 * to the resolver status, it contains a sequence number and an auxiliary
 * value.
 *
 * The sequence value is used by VFS to sequence-stamp trigger vnode
 * state transitions. It is expected to be incremented each time a
 * resolver changes state (ie resolved or unresolved). A result
 * containing a stale sequence (older than a trigger vnode's current
 * value) will be ignored by VFS.
 *
 * The auxiliary value is currently only used to deliver the errno
 * value for RESOLVER_ERROR status conditions. When a RESOLVER_ERROR
 * occurs, VFS will propagate this error back to the syscall that
 * encountered the trigger vnode.
 */
extern resolver_result_t vfs_resolver_result(uint32_t seq, enum resolver_status stat, int aux);

/*
 * Extract values from a compound resolver result
 */
extern enum resolver_status vfs_resolver_status(resolver_result_t);
extern uint32_t vfs_resolver_sequence(resolver_result_t);
extern int vfs_resolver_auxiliary(resolver_result_t);


/*!
 @typedef trigger_vnode_resolve_callback_t
 @abstract function prototype for a trigger vnode resolve callback
 @discussion This function is associated with a trigger vnode during a vnode create.  It is
 typically called when a lookup operation occurs for a trigger vnode
 @param vp The trigger vnode which needs resolving
 @param cnp Various data about lookup, e.g. filename and state flags
 @param pop The pathname operation that initiated the lookup (see enum path_operation).
 @param flags
 @param data Arbitrary data supplied by vnode trigger creator
 @param ctx Context for authentication.
 @return RESOLVER_RESOLVED, RESOLVER_NOCHANGE, RESOLVER_UNRESOLVED or RESOLVER_ERROR
*/
typedef resolver_result_t (* trigger_vnode_resolve_callback_t)(
        vnode_t                         vp,
        const struct componentname *    cnp,
        enum path_operation             pop,
        int                             flags,
        void *                          data,
        vfs_context_t                   ctx);

/*!
 @typedef trigger_vnode_unresolve_callback_t
 @abstract function prototype for a trigger vnode unresolve callback
 @discussion This function is associated with a trigger vnode during a vnode create.  It is
 called to unresolve a trigger vnode (typically this means unmount).
 @param vp The trigger vnode which needs unresolving
 @param flags Unmount flags
 @param data Arbitrary data supplied by vnode trigger creator
 @param ctx Context for authentication.
 @return RESOLVER_NOCHANGE, RESOLVER_UNRESOLVED or RESOLVER_ERROR
*/
typedef resolver_result_t (* trigger_vnode_unresolve_callback_t)(
        vnode_t         vp,
        int             flags,
        void *          data,
        vfs_context_t   ctx);

/*!
 @typedef trigger_vnode_rearm_callback_t
 @abstract function prototype for a trigger vnode rearm callback
 @discussion This function is associated with a trigger vnode during a vnode create.  It is
 called to verify a rearm from VFS (i.e. should VFS rearm the trigger?).
 @param vp The trigger vnode which needs rearming
 @param flags
 @param data Arbitrary data supplied by vnode trigger creator
 @param ctx Context for authentication.
 @return RESOLVER_NOCHANGE or RESOLVER_ERROR
*/
typedef resolver_result_t (* trigger_vnode_rearm_callback_t)(
        vnode_t         vp,
        int             flags,
        void *          data,
        vfs_context_t   ctx);

/*!
 @typedef trigger_vnode_reclaim_callback_t
 @abstract function prototype for a trigger vnode reclaim callback
 @discussion This function is associated with a trigger vnode during a vnode create.  It is
 called to deallocate private callback argument data
 @param vp The trigger vnode associated with the data
 @param data The arbitrary data supplied by vnode trigger creator
*/
typedef void (* trigger_vnode_reclaim_callback_t)(
        vnode_t         vp,
        void *          data);

/*!
 @function vnode_trigger_update
 @abstract Update a trigger vnode's state.
 @discussion This allows a resolver to notify VFS of a state change in a trigger vnode.
 @param vp The trigger vnode whose information to update.
 @param result A compound resolver result value
 @return EINVAL if result value is invalid or vp isn't a trigger vnode
 */
extern int vnode_trigger_update(vnode_t vp, resolver_result_t result);

struct vnode_trigger_info {
        trigger_vnode_resolve_callback_t        vti_resolve_func;
        trigger_vnode_unresolve_callback_t      vti_unresolve_func;
        trigger_vnode_rearm_callback_t          vti_rearm_func;
        trigger_vnode_reclaim_callback_t        vti_reclaim_func;
        void *                                  vti_data;   /* auxiliary data (optional) */
        uint32_t                                vti_flags;  /* optional flags (see below) */
};

/*
 * SPI for creating a trigger vnode
 *
 * Uses the VNCREATE_TRIGGER flavor with existing vnode_create() KPI
 *
 * Only one resolver per vnode.
 *
 * ERRORS (in addition to vnode_create errors):
 *      EINVAL (invalid resolver info, like invalid flags)
 *      ENOTDIR (only directories can have a resolver)
 *      EPERM (vnode cannot be a trigger - eg root dir of a file system)
 *      ENOMEM
 */
struct vnode_trigger_param {
        struct vnode_fsparam                    vnt_params; /* same as for VNCREATE_FLAVOR */
        trigger_vnode_resolve_callback_t        vnt_resolve_func;
        trigger_vnode_unresolve_callback_t      vnt_unresolve_func;
        trigger_vnode_rearm_callback_t          vnt_rearm_func;
        trigger_vnode_reclaim_callback_t        vnt_reclaim_func;
        void *                                  vnt_data;   /* auxiliary data (optional) */
        uint32_t                                vnt_flags;  /* optional flags (see below) */
};

#define VNCREATE_TRIGGER        (('T' << 8) + ('V'))
#define VNCREATE_TRIGGER_SIZE   sizeof(struct vnode_trigger_param)

/*
 * vnode trigger flags (vnt_flags)
 *
 * VNT_AUTO_REARM:
 * On unmounts of a trigger mount, automatically re-arm the trigger.
 *
 * VNT_NO_DIRECT_MOUNT:
 * A trigger vnode instance that doesn't directly trigger a mount,
 * instead it triggers the mounting of sub-trigger nodes.
 */
#define VNT_AUTO_REARM          (1 << 0)        
#define VNT_NO_DIRECT_MOUNT     (1 << 1)        
#define VNT_VALID_MASK          (VNT_AUTO_REARM | VNT_NO_DIRECT_MOUNT)

#endif /* KERNEL_PRIVATE */


/*
 * Vnode attributes, new-style.
 *
 * The vnode_attr structure is used to transact attribute changes and queries
 * with the filesystem.
 *
 * Note that this structure may be extended, but existing fields must not move.
 */

#define VATTR_INIT(v)                   do {(v)->va_supported = (v)->va_active = 0ll; (v)->va_vaflags = 0;} while(0)
#define VATTR_SET_ACTIVE(v, a)          ((v)->va_active |= VNODE_ATTR_ ## a)
#define VATTR_SET_SUPPORTED(v, a)       ((v)->va_supported |= VNODE_ATTR_ ## a)
#define VATTR_IS_SUPPORTED(v, a)        ((v)->va_supported & VNODE_ATTR_ ## a)
#define VATTR_CLEAR_ACTIVE(v, a)        ((v)->va_active &= ~VNODE_ATTR_ ## a)
#define VATTR_CLEAR_SUPPORTED(v, a)     ((v)->va_supported &= ~VNODE_ATTR_ ## a)
#define VATTR_IS_ACTIVE(v, a)           ((v)->va_active & VNODE_ATTR_ ## a)
#define VATTR_ALL_SUPPORTED(v)          (((v)->va_active & (v)->va_supported) == (v)->va_active)
#define VATTR_INACTIVE_SUPPORTED(v)     do {(v)->va_active &= ~(v)->va_supported; (v)->va_supported = 0;} while(0)
#define VATTR_SET(v, a, x)              do { (v)-> a = (x); VATTR_SET_ACTIVE(v, a);} while(0)
#define VATTR_WANTED(v, a)              VATTR_SET_ACTIVE(v, a)
#define VATTR_RETURN(v, a, x)           do { (v)-> a = (x); VATTR_SET_SUPPORTED(v, a);} while(0)
#define VATTR_NOT_RETURNED(v, a)        (VATTR_IS_ACTIVE(v, a) && !VATTR_IS_SUPPORTED(v, a))

/*
 * Two macros to simplify conditional checking in kernel code.
 */
#define VATTR_IS(v, a, x)               (VATTR_IS_SUPPORTED(v, a) && (v)-> a == (x))
#define VATTR_IS_NOT(v, a, x)           (VATTR_IS_SUPPORTED(v, a) && (v)-> a != (x))

#define VNODE_ATTR_va_rdev              (1LL<< 0)       /* 00000001 */
#define VNODE_ATTR_va_nlink             (1LL<< 1)       /* 00000002 */
#define VNODE_ATTR_va_total_size        (1LL<< 2)       /* 00000004 */
#define VNODE_ATTR_va_total_alloc       (1LL<< 3)       /* 00000008 */
#define VNODE_ATTR_va_data_size         (1LL<< 4)       /* 00000010 */
#define VNODE_ATTR_va_data_alloc        (1LL<< 5)       /* 00000020 */
#define VNODE_ATTR_va_iosize            (1LL<< 6)       /* 00000040 */
#define VNODE_ATTR_va_uid               (1LL<< 7)       /* 00000080 */
#define VNODE_ATTR_va_gid               (1LL<< 8)       /* 00000100 */
#define VNODE_ATTR_va_mode              (1LL<< 9)       /* 00000200 */
#define VNODE_ATTR_va_flags             (1LL<<10)       /* 00000400 */
#define VNODE_ATTR_va_acl               (1LL<<11)       /* 00000800 */
#define VNODE_ATTR_va_create_time       (1LL<<12)       /* 00001000 */
#define VNODE_ATTR_va_access_time       (1LL<<13)       /* 00002000 */
#define VNODE_ATTR_va_modify_time       (1LL<<14)       /* 00004000 */
#define VNODE_ATTR_va_change_time       (1LL<<15)       /* 00008000 */
#define VNODE_ATTR_va_backup_time       (1LL<<16)       /* 00010000 */
#define VNODE_ATTR_va_fileid            (1LL<<17)       /* 00020000 */
#define VNODE_ATTR_va_linkid            (1LL<<18)       /* 00040000 */
#define VNODE_ATTR_va_parentid          (1LL<<19)       /* 00080000 */
#define VNODE_ATTR_va_fsid              (1LL<<20)       /* 00100000 */
#define VNODE_ATTR_va_filerev           (1LL<<21)       /* 00200000 */
#define VNODE_ATTR_va_gen               (1LL<<22)       /* 00400000 */
#define VNODE_ATTR_va_encoding          (1LL<<23)       /* 00800000 */
#define VNODE_ATTR_va_type              (1LL<<24)       /* 01000000 */
#define VNODE_ATTR_va_name              (1LL<<25)       /* 02000000 */
#define VNODE_ATTR_va_uuuid             (1LL<<26)       /* 04000000 */
#define VNODE_ATTR_va_guuid             (1LL<<27)       /* 08000000 */
#define VNODE_ATTR_va_nchildren         (1LL<<28)       /* 10000000 */
#define VNODE_ATTR_va_dirlinkcount      (1LL<<29)       /* 20000000 */
#define VNODE_ATTR_va_addedtime         (1LL<<30)               /* 40000000 */

#define VNODE_ATTR_BIT(n)       (VNODE_ATTR_ ## n)
/*
 * Read-only attributes.
 */
#define VNODE_ATTR_RDONLY       (VNODE_ATTR_BIT(va_rdev) |              \
                                VNODE_ATTR_BIT(va_nlink) |              \
                                VNODE_ATTR_BIT(va_total_size) |         \
                                VNODE_ATTR_BIT(va_total_alloc) |        \
                                VNODE_ATTR_BIT(va_data_alloc) |         \
                                VNODE_ATTR_BIT(va_iosize) |             \
                                VNODE_ATTR_BIT(va_fileid) |             \
                                VNODE_ATTR_BIT(va_linkid) |             \
                                VNODE_ATTR_BIT(va_parentid) |           \
                                VNODE_ATTR_BIT(va_fsid) |               \
                                VNODE_ATTR_BIT(va_filerev) |            \
                                VNODE_ATTR_BIT(va_gen) |                \
                                VNODE_ATTR_BIT(va_name) |               \
                                VNODE_ATTR_BIT(va_type) |               \
                                VNODE_ATTR_BIT(va_nchildren) |          \
                                VNODE_ATTR_BIT(va_dirlinkcount)|                \
                VNODE_ATTR_BIT(va_addedtime)) 
/*
 * Attributes that can be applied to a new file object.
 */
#define VNODE_ATTR_NEWOBJ       (VNODE_ATTR_BIT(va_rdev) |              \
                                VNODE_ATTR_BIT(va_uid)  |               \
                                VNODE_ATTR_BIT(va_gid) |                \
                                VNODE_ATTR_BIT(va_mode) |               \
                                VNODE_ATTR_BIT(va_flags) |              \
                                VNODE_ATTR_BIT(va_acl) |                \
                                VNODE_ATTR_BIT(va_create_time) |        \
                                VNODE_ATTR_BIT(va_modify_time) |        \
                                VNODE_ATTR_BIT(va_change_time) |        \
                                VNODE_ATTR_BIT(va_encoding) |           \
                                VNODE_ATTR_BIT(va_type) |               \
                                VNODE_ATTR_BIT(va_uuuid) |              \
                                VNODE_ATTR_BIT(va_guuid))


struct vnode_attr {
        /* bitfields */
        uint64_t        va_supported;
        uint64_t        va_active;

        /*
         * Control flags.  The low 16 bits are reserved for the
         * ioflags being passed for truncation operations.
         */
        int             va_vaflags;
        
        /* traditional stat(2) parameter fields */
        dev_t           va_rdev;        /* device id (device nodes only) */
        uint64_t        va_nlink;       /* number of references to this file */
        uint64_t        va_total_size;  /* size in bytes of all forks */
        uint64_t        va_total_alloc; /* disk space used by all forks */
        uint64_t        va_data_size;   /* size in bytes of the fork managed by current vnode */
        uint64_t        va_data_alloc;  /* disk space used by the fork managed by current vnode */
        uint32_t        va_iosize;      /* optimal I/O blocksize */

        /* file security information */
        uid_t           va_uid;         /* owner UID */
        gid_t           va_gid;         /* owner GID */
        mode_t          va_mode;        /* posix permissions */
        uint32_t        va_flags;       /* file flags */
        struct kauth_acl *va_acl;       /* access control list */

        /* timestamps */
        struct timespec va_create_time; /* time of creation */
        struct timespec va_access_time; /* time of last access */
        struct timespec va_modify_time; /* time of last data modification */
        struct timespec va_change_time; /* time of last metadata change */
        struct timespec va_backup_time; /* time of last backup */
        
        /* file parameters */
        uint64_t        va_fileid;      /* file unique ID in filesystem */
        uint64_t        va_linkid;      /* file link unique ID */
        uint64_t        va_parentid;    /* parent ID */
        uint32_t        va_fsid;        /* filesystem ID */
        uint64_t        va_filerev;     /* file revision counter */     /* XXX */
        uint32_t        va_gen;         /* file generation count */     /* XXX - relationship of
                                                                        * these two? */
        /* misc parameters */
        uint32_t        va_encoding;    /* filename encoding script */

        enum vtype      va_type;        /* file type (create only) */
        char *          va_name;        /* Name for ATTR_CMN_NAME; MAXPATHLEN bytes */
        guid_t          va_uuuid;       /* file owner UUID */
        guid_t          va_guuid;       /* file group UUID */
        
        /* Meaningful for directories only */
        uint64_t        va_nchildren;     /* Number of items in a directory */
        uint64_t        va_dirlinkcount;  /* Real references to dir (i.e. excluding "." and ".." refs) */

        /* add new fields here only */
#ifdef BSD_KERNEL_PRIVATE
        struct kauth_acl *va_base_acl;
#else
        void *          va_reserved1;
#endif /* BSD_KERNEL_PRIVATE */
    struct timespec va_addedtime;       /* timestamp when item was added to parent directory */

                
};

/*
 * Flags for va_vaflags.
 */
#define VA_UTIMES_NULL          0x010000        /* utimes argument was NULL */
#define VA_EXCLUSIVE            0x020000        /* exclusive create request */
#define VA_NOINHERIT            0x040000        /* Don't inherit ACLs from parent */
#define VA_NOAUTH               0x080000        

/*
 *  Modes.  Some values same as Ixxx entries from inode.h for now.
 */
#define VSUID   0x800 /*04000*/ /* set user id on execution */
#define VSGID   0x400 /*02000*/ /* set group id on execution */
#define VSVTX   0x200 /*01000*/ /* save swapped text even after use */
#define VREAD   0x100 /*00400*/ /* read, write, execute permissions */
#define VWRITE  0x080 /*00200*/
#define VEXEC   0x040 /*00100*/

/*
 * Convert between vnode types and inode formats (since POSIX.1
 * defines mode word of stat structure in terms of inode formats).
 */
extern enum vtype       iftovt_tab[];
extern int              vttoif_tab[];
#define IFTOVT(mode)    (iftovt_tab[((mode) & S_IFMT) >> 12])
#define VTTOIF(indx)    (vttoif_tab[(int)(indx)])
#define MAKEIMODE(indx, mode)   (int)(VTTOIF(indx) | (mode))

/*
 * Flags to various vnode functions.
 */
#define SKIPSYSTEM      0x0001          /* vflush: skip vnodes marked VSYSTEM */
#define FORCECLOSE      0x0002          /* vflush: force file closeure */
#define WRITECLOSE      0x0004          /* vflush: only close writeable files */
#define SKIPSWAP        0x0008          /* vflush: skip vnodes marked VSWAP */
#define SKIPROOT        0x0010          /* vflush: skip root vnodes marked VROOT */

#define DOCLOSE         0x0008          /* vclean: close active files */

#define V_SAVE          0x0001          /* vinvalbuf: sync file first */
#define V_SAVEMETA      0x0002          /* vinvalbuf: leave indirect blocks */

#define REVOKEALL       0x0001          /* vnop_revoke: revoke all aliases */

/* VNOP_REMOVE: do not delete busy files (Carbon remove file semantics) */
#define VNODE_REMOVE_NODELETEBUSY  0x0001  

/* VNOP_READDIR flags: */
#define VNODE_READDIR_EXTENDED    0x0001   /* use extended directory entries */
#define VNODE_READDIR_REQSEEKOFF  0x0002   /* requires seek offset (cookies) */
#define VNODE_READDIR_SEEKOFF32   0x0004   /* seek offset values should fit in 32 bits */


#define NULLVP  ((struct vnode *)NULL)

#ifndef BSD_KERNEL_PRIVATE
struct vnodeop_desc;
#endif

extern  int desiredvnodes;              /* number of vnodes desired */


/*
 * This structure is used to configure the new vnodeops vector.
 */
struct vnodeopv_entry_desc {
        struct vnodeop_desc *opve_op;   /* which operation this is */
        int (*opve_impl)(void *);               /* code implementing this operation */
};
struct vnodeopv_desc {
                        /* ptr to the ptr to the vector where op should go */
        int (***opv_desc_vector_p)(void *);
        struct vnodeopv_entry_desc *opv_desc_ops;   /* null terminated list */
};

/*!
 @function vn_default_error
 @abstract Default vnode operation to fill unsupported slots in vnode operation vectors.
 @return ENOTSUP
 */
int vn_default_error(void);

/*
 * A generic structure.
 * This can be used by bypass routines to identify generic arguments.
 */
struct vnop_generic_args {
        struct vnodeop_desc *a_desc;
        /* other random data follows, presumably */
};

#ifndef _KAUTH_ACTION_T
typedef int kauth_action_t;
# define _KAUTH_ACTION_T
#endif

#include <sys/vnode_if.h>

__BEGIN_DECLS

/*!
 @function vnode_create
 @abstract Create and initialize a vnode.
 @discussion Returns wth an iocount held on the vnode which must eventually be dropped with vnode_put().
 @param flavor Should be VNCREATE_FLAVOR.
 @param size  Size of the struct vnode_fsparam in "data".
 @param data  Pointer to a struct vnode_fsparam containing initialization information.
 @param vpp  Pointer to a vnode pointer, to be filled in with newly created vnode.
 @return 0 for success, error code otherwise.
 */
errno_t vnode_create(uint32_t, uint32_t, void  *, vnode_t *);

/*!
 @function vnode_addfsref
 @abstract Mark a vnode as being stored in a filesystem hash.
 @discussion Should only be called once on a vnode, and never if that vnode was created with VNFS_ADDFSREF.
 There should be a corresponding call to vnode_removefsref() when the vnode is reclaimed; VFS assumes that a
 n unused vnode will not be marked as referenced by a filesystem.
 @param vp The vnode to mark.
 @return Always 0.
 */
int     vnode_addfsref(vnode_t);

/*!
 @function vnode_removefsref
 @abstract Mark a vnode as no longer being stored in a filesystem hash.
 @discussion Should only be called once on a vnode (during a reclaim), and only after the vnode has either been created with VNFS_ADDFSREF or marked by vnode_addfsref().
 @param vp The vnode to unmark.
 @return Always 0.
 */
int     vnode_removefsref(vnode_t);

/*!
 @function vnode_hasdirtyblks 
 @abstract Check if a vnode has dirty data waiting to be written to disk.
 @discussion Note that this routine is unsynchronized; it is only a snapshot and its result may cease to be true at the moment it is returned..
 @param vp The vnode to test.
 @return Nonzero if there are dirty blocks, 0 otherwise
 */
int     vnode_hasdirtyblks(vnode_t);

/*!
 @function vnode_hascleanblks
 @abstract Check if a vnode has clean buffers associated with it.
 @discussion Note that this routine is unsynchronized; it is only a snapshot and its result may cease to be true at the moment it is returned..
 @param vp The vnode to test.
 @return Nonzero if there are clean blocks, 0 otherwise.
 */
int     vnode_hascleanblks(vnode_t);

#define VNODE_ASYNC_THROTTLE    15
/*!
 @function vnode_waitforwrites
 @abstract Wait for the number of pending writes on a vnode to drop below a target.
 @param vp The vnode to monitor.
 @param output_target Max pending write count with which to return.
 @param slpflag Flags for msleep().
 @param slptimeout Frequency with which to force a check for completion; increments of 10 ms.
 @param msg String to pass  msleep() .
 @return 0 for success, or an error value from msleep().
 */
int     vnode_waitforwrites(vnode_t, int, int, int, const char *);

/*!
 @function vnode_startwrite
 @abstract Increment the count of pending writes on a vnode.
 @param vp The vnode whose count to increment.
 @return void.
 */
void    vnode_startwrite(vnode_t);

/*!
 @function vnode_startwrite
 @abstract Decrement the count of pending writes on a vnode .
 @discussion Also wakes up threads waiting for the write count to drop, as in vnode_waitforwrites.
 @param vp The vnode whose count to decrement.
 @return void.
 */
void    vnode_writedone(vnode_t);

/*!
 @function vnode_vtype
 @abstract Return a vnode's type.
 @param vp The vnode whose type to grab.
 @return The vnode's type.
 */
enum vtype      vnode_vtype(vnode_t);

/*!
 @function vnode_vid
 @abstract Return a vnode's vid (generation number), which is constant from creation until reclaim. 
 @param vp The vnode whose vid to grab.
 @return The vnode's vid.
 */
uint32_t        vnode_vid(vnode_t);

/*!
 @function vnode_mountedhere
 @abstract Returns a pointer to a mount placed on top of a vnode, should it exist.
 @param vp The vnode from whom to take the covering mount.
 @return Pointer to mount covering a vnode, or NULL if none exists.
 */
mount_t vnode_mountedhere(vnode_t vp);

/*!
 @function vnode_mount
 @abstract Get the mount structure for the filesystem that a vnode belongs to.
 @param vp The vnode whose mount to grab.
 @return The mount, directly.
 */
mount_t vnode_mount(vnode_t);

/*!
 @function vnode_specrdev
 @abstract Return the device id of the device associated with a special file.
 @param vp The vnode whose device id to extract--vnode must be a special file.
 @return The device id.
 */
dev_t   vnode_specrdev(vnode_t);

/*!
 @function vnode_fsnode
 @abstract Gets the filesystem-specific data associated with a vnode.
 @param vp The vnode whose data to grab.
 @return The filesystem-specific data, directly.
 */
void *  vnode_fsnode(vnode_t);

/*!
 @function vnode_clearfsnode
 @abstract Sets a vnode's filesystem-specific data to be NULL.
 @discussion This routine should only be called when a vnode is no longer in use, i.e. during a VNOP_RECLAIM.
 @param vp The vnode whose data to clear out.
 @return void.
 */
void    vnode_clearfsnode(vnode_t);

/*!
 @function vnode_isvroot
 @abstract Determine if a vnode is the root of its filesystem.
 @param vp The vnode to test.
 @return Nonzero if the vnode is the root, 0 if it is not.
 */
int     vnode_isvroot(vnode_t);

/*!
 @function vnode_issystem
 @abstract Determine if a vnode is marked as a System vnode.
 @param vp The vnode to test.
 @return Nonzero if the vnode is a system vnode, 0 if it is not.
 */
int     vnode_issystem(vnode_t);

/*!
 @function vnode_ismount
 @abstract Determine if there is currently a mount occurring which will cover this vnode.
 @discussion Note that this is only a snapshot; a mount may begin or end at any time.
 @param vp The vnode to test.
 @return Nonzero if there is a mount in progress, 0 otherwise.
 */
int     vnode_ismount(vnode_t);

/*!
 @function vnode_isreg
 @abstract Determine if a vnode is a regular file.
 @param vp The vnode to test.
 @return Nonzero if the vnode is of type VREG, 0 otherwise.
 */
int     vnode_isreg(vnode_t);

/*!
 @function vnode_isdir
 @abstract Determine if a vnode is a directory.
 @param vp The vnode to test.
 @return Nonzero if the vnode is of type VDIR, 0 otherwise.
 */
int     vnode_isdir(vnode_t);

/*!
 @function vnode_islnk
 @abstract Determine if a vnode is a symbolic link.
 @param vp The vnode to test.
 @return Nonzero if the vnode is of type VLNK, 0 otherwise.
 */
int     vnode_islnk(vnode_t);

/*!
 @function vnode_isfifo
 @abstract Determine if a vnode is a named pipe.
 @param vp The vnode to test.
 @return Nonzero if the vnode is of type VFIFO, 0 otherwise.
 */
int     vnode_isfifo(vnode_t);

/*!
 @function vnode_isblk
 @abstract Determine if a vnode is a block device special file.
 @param vp The vnode to test.
 @return Nonzero if the vnode is of type VBLK, 0 otherwise.
 */
int     vnode_isblk(vnode_t);

/*!
 @function vnode_ischr
 @abstract Determine if a vnode is a character device special file.
 @param vp The vnode to test.
 @return Nonzero if the vnode is of type VCHR, 0 otherwise.
 */
int     vnode_ischr(vnode_t);

/*!
 @function vnode_isswap
 @abstract Determine if a vnode is being used as a swap file.
 @param vp The vnode to test.
 @return Nonzero if the vnode is being used as swap, 0 otherwise.
 */
int     vnode_isswap(vnode_t vp);

#ifdef __APPLE_API_UNSTABLE
/*!
 @function vnode_isnamedstream
 @abstract Determine if a vnode is a named stream.
 @param vp The vnode to test.
 @return Nonzero if the vnode is a named stream, 0 otherwise.
 */
int     vnode_isnamedstream(vnode_t);
#endif

/*!
 @function vnode_ismountedon
 @abstract Determine if a vnode is a block device on which a filesystem has been mounted.
 @discussion A block device marked as being mounted on cannot be opened.
 @param vp The vnode to test.
 @return Nonzero if the vnode is a block device on which an filesystem is mounted, 0 otherwise.
 */
int     vnode_ismountedon(vnode_t);

/*!
 @function vnode_setmountedon
 @abstract Set flags indicating that a block device vnode has been mounted as a filesystem.
 @discussion A block device marked as being mounted on cannot be opened.
 @param vp The vnode to set flags on, a block device.
 @return void.
 */
void    vnode_setmountedon(vnode_t);

/*!
 @function vnode_clearmountedon
 @abstract Clear flags indicating that a block device vnode has been mounted as a filesystem.
 @param vp The vnode to clear flags on, a block device.
 @return void.
 */
void    vnode_clearmountedon(vnode_t);

/*!
 @function vnode_isrecycled
 @abstract Check if a vnode is dead or in the process of being killed (recycled).
 @discussion This is only a snapshot: a vnode may start to be recycled, or go from dead to in use, at any time.
 @param vp The vnode to test.
 @return Nonzero if vnode is dead or being recycled, 0 otherwise.
 */
int     vnode_isrecycled(vnode_t);

/*!
 @function vnode_isnocache
 @abstract Check if a vnode is set to not have its data cached in memory  (i.e. we write-through to disk and always read from disk).
 @param vp The vnode to test.
 @return Nonzero if vnode is set to not have data chached, 0 otherwise.
 */
int     vnode_isnocache(vnode_t);

/*!
 @function vnode_israge
 @abstract Check if a vnode is marked for rapid aging
 @param vp The vnode to test.
 @return Nonzero if vnode is marked for rapid aging, 0 otherwise
 */
int     vnode_israge(vnode_t);

/*!
 @function vnode_needssnapshots
 @abstract Check if a vnode needs snapshots events (regardless of its ctime status)
 @param vp The vnode to test.
 @return Nonzero if vnode needs snapshot events, 0 otherwise
 */
int     vnode_needssnapshots(vnode_t);

/*!
 @function vnode_setnocache
 @abstract Set a vnode to not have its data cached in memory (i.e. we write-through to disk and always read from disk).
 @param vp The vnode whose flags to set.
 @return void.
 */
void    vnode_setnocache(vnode_t);

/*!
 @function vnode_clearnocache
 @abstract Clear the flag on a vnode indicating that data should not be cached in memory (i.e. we write-through to disk and always read from disk).
 @param vp The vnode whose flags to clear.
 @return void.
 */
void    vnode_clearnocache(vnode_t);

/*!
 @function vnode_isnoreadahead
 @abstract Check if a vnode is set to not have data speculatively read in in hopes of future cache hits.
 @param vp The vnode to test.
 @return Nonzero if readahead is disabled, 0 otherwise.
 */
int     vnode_isnoreadahead(vnode_t);

/*!
 @function vnode_setnoreadahead
 @abstract Set a vnode to not have data speculatively read in in hopes of hitting in cache.
 @param vp The vnode on which to prevent readahead.
 @return void.
 */
void    vnode_setnoreadahead(vnode_t);

/*!
 @function vnode_clearnoreadahead
 @abstract Clear the flag indicating that a vnode should not have data speculatively read in.
 @param vp The vnode whose flag to clear.
 @return void.
 */
void    vnode_clearnoreadahead(vnode_t);

/* left only for compat reasons as User code depends on this from getattrlist, for ex */

/*!
 @function vnode_settag
 @abstract Set a vnode filesystem-specific "tag."
 @discussion Sets a tag indicating which filesystem a vnode belongs to, e.g. VT_HFS, VT_UDF, VT_ZFS.  The kernel never inspects this data, though the filesystem tags are defined in vnode.h; it is for the benefit of user programs via getattrlist.
 @param vp The vnode whose tag to set.
 @return void.
 */
void    vnode_settag(vnode_t, int);

/*!
 @function vnode_tag
 @abstract Get the vnode filesystem-specific "tag."
 @discussion Gets the tag indicating which filesystem a vnode belongs to, e.g. VT_HFS, VT_UDF, VT_ZFS.  The kernel never inspects this data, though the filesystem tags are defined in vnode.h; it is for the benefit of user programs via getattrlist.
 @param vp The vnode whose tag to grab.
 @return The tag.
 */
int     vnode_tag(vnode_t);

/*!
 @function vnode_getattr
 @abstract Get vnode attributes.
 @discussion Desired attributes are set with VATTR_SET_ACTIVE and VNODE_ATTR* macros.  Supported attributes are determined after call with VATTR_IS_SUPPORTED.
 @param vp The vnode whose attributes to grab.
 @param vap Structure containing: 1) A list of requested attributes 2) Space to indicate which attributes are supported and being returned 3) Space to return attributes.
 @param ctx Context for authentication.
 @return 0 for success or an error code.
 */
int     vnode_getattr(vnode_t vp, struct vnode_attr *vap, vfs_context_t ctx);

/*!
 @function vnode_setattr
 @abstract Set vnode attributes.
 @discussion Attributes to set are marked with VATTR_SET_ACTIVE and VNODE_ATTR* macros.  Attributes successfully set are determined after call with VATTR_IS_SUPPORTED.
 @param vp The vnode whose attributes to set.
 @param vap Structure containing: 1) A list of attributes to set 2) Space for values for those attributes 3) Space to indicate which attributes were set.
 @param ctx Context for authentication.
 @return 0 for success or an error code.
 */
int     vnode_setattr(vnode_t vp, struct vnode_attr *vap, vfs_context_t ctx);

/*!
 @function vfs_rootvnode
 @abstract Returns the root vnode with an iocount.
 @discussion Caller must vnode_put() the root node when done.
 @return Pointer to root vnode if successful; error code if there is a problem taking an iocount.
 */
vnode_t vfs_rootvnode(void);

/*!
 @function vnode_uncache_credentials
 @abstract Clear out cached credentials on a vnode.
 @discussion When we authorize an action on a vnode, we cache the credential that was authorized and the actions it was authorized for in case a similar request follows.  This function destroys that caching.
 @param vp The vnode whose cache to clear.
 @return void.
 */
void    vnode_uncache_credentials(vnode_t vp);

/*!
 @function vnode_setmultipath
 @abstract Mark a vnode as being reachable by multiple paths, i.e. as a hard link.
 @discussion "Multipath" vnodes can be reached through more than one entry in the filesystem, and so must be handled differently for caching and event notification purposes.  A filesystem should mark a vnode with multiple hardlinks this way.
 @param vp The vnode to mark.
 @return void.
 */
void    vnode_setmultipath(vnode_t vp);

/*!
 @function vnode_vfsmaxsymlen
 @abstract Determine the maximum length of a symbolic link for the filesystem on which a vnode resides.
 @param vp The vnode for which to get filesystem symlink size cap.
 @return Max symlink length.
 */
uint32_t  vnode_vfsmaxsymlen(vnode_t);

/*!
 @function vnode_vfsisrdonly
 @abstract Determine if the filesystem to which a vnode belongs is mounted read-only.
 @param vp The vnode for which to get filesystem writeability.
 @return Nonzero if the filesystem is read-only, 0 otherwise.
 */
int     vnode_vfsisrdonly(vnode_t);

/*!
 @function vnode_vfstypenum
 @abstract Get the "type number" of the filesystem to which a vnode belongs.
 @discussion This is an archaic construct; most filesystems are assigned a type number based on the order in which they are registered with the system.
 @param vp The vnode whose filesystem to examine.
 @return The type number of the fileystem to which the vnode belongs.
 */
int     vnode_vfstypenum(vnode_t);

/*!
 @function vnode_vfsname
 @abstract Get the name of the filesystem to which a vnode belongs.
 @param vp The vnode whose filesystem to examine.
 @param buf Destination for vfs name: should have size MFSNAMELEN or greater.
 @return The name of the fileystem to which the vnode belongs.
 */
void    vnode_vfsname(vnode_t, char *);

/*!
 @function vnode_vfs64bitready
 @abstract Determine if the filesystem to which a vnode belongs is marked as ready to interact with 64-bit user processes.
 @param vp The vnode whose filesystem to examine.
 @return Nonzero if filesystem is marked ready for 64-bit interactions; 0 otherwise.
 */
int     vnode_vfs64bitready(vnode_t);

/* These should move to private ... not documenting for now */
int     vfs_context_get_special_port(vfs_context_t, int, ipc_port_t *);
int     vfs_context_set_special_port(vfs_context_t, int, ipc_port_t);

/*!
 @function vfs_context_proc
 @abstract Get the BSD process structure associated with a vfs_context_t.
 @param ctx Context whose associated process to find.
 @return Process if available, NULL otherwise.
 */
proc_t  vfs_context_proc(vfs_context_t);

/*!
 @function vfs_context_ucred
 @abstract Get the credential associated with a vfs_context_t.
 @discussion Succeeds if and only if the context has a thread, the thread has a task, and the task has a BSD proc.
 @param ctx Context whose associated process to find.
 @return Process if available, NULL otherwise.
 */
kauth_cred_t    vfs_context_ucred(vfs_context_t);

/*!
 @function vfs_context_pid
 @abstract Get the process id of the BSD process associated with a vfs_context_t.
 @param ctx Context whose associated process to find.
 @return Process id.
 */
int     vfs_context_pid(vfs_context_t);

/*!
 @function vfs_context_issignal
 @abstract Get a bitfield of pending signals for the BSD process associated with a vfs_context_t.
 @discussion The bitfield is constructed using the sigmask() macro, in the sense of bits |= sigmask(SIGSEGV).
 @param ctx Context whose associated process to find.
 @return Bitfield of pending signals.
 */
int     vfs_context_issignal(vfs_context_t, sigset_t);

/*!
 @function vfs_context_suser
 @abstract Determine if a vfs_context_t corresponds to the superuser.
 @param ctx Context to examine.
 @return Nonzero if context belongs to superuser, 0 otherwise.
 */
int     vfs_context_suser(vfs_context_t);

/*!
 @function vfs_context_is64bit
 @abstract Determine if a vfs_context_t corresponds to a 64-bit user process.
 @param ctx Context to examine.
 @return Nonzero if context is of 64-bit process, 0 otherwise.
 */
int     vfs_context_is64bit(vfs_context_t);

/*!
 @function vfs_context_create
 @abstract Create a new vfs_context_t with appropriate references held.
 @discussion The context must be released with vfs_context_rele() when no longer in use.
 @param ctx Context to copy, or NULL to use information from running thread.
 @return The new context, or NULL in the event of failure.
 */
vfs_context_t vfs_context_create(vfs_context_t);

/*!
 @function vfs_context_rele
 @abstract Release references on components of a context and deallocate it.
 @discussion A context should not be referenced after vfs_context_rele has been called.
 @param ctx Context to release.
 @return Always 0.
 */
int vfs_context_rele(vfs_context_t);

/*!
 @function vfs_context_current
 @abstract Get the vfs_context for the current thread, or the kernel context if there is no context for current thread.
 @discussion Kexts should not use this function--it is preferred to use vfs_context_create(NULL) and vfs_context_rele(), which ensure proper reference counting of underlying structures.
 @return Context for current thread, or kernel context if thread context is unavailable.
 */
vfs_context_t vfs_context_current(void);
#ifdef KERNEL_PRIVATE
int     vfs_context_bind(vfs_context_t);

/*!
 @function vfs_ctx_skipatime
 @abstract Check to see if this context should skip updating a vnode's access times.
 @discussion  This is currently tied to the vnode rapid aging process.  If the process is marked for rapid aging, 
 then the kernel should not update vnodes it touches for access time purposes.  This will check to see if the
 specified process and/or thread is marked for rapid aging when it manipulates vnodes. 
 @param ctx The context being investigated. 
 @return 1 if we should skip access time updates.  
 @return 0 if we should NOT skip access time updates.
 */

int     vfs_ctx_skipatime(vfs_context_t ctx);

#endif

/*!
 @function vflush
 @abstract Reclaim the vnodes associated with a mount.
 @param mp The mount whose vnodes to kill.
 @param skipvp A specific vnode to not reclaim or to let interrupt an un-forced flush
 @param flags  Control which 
 @discussion This function is used to clear out the vnodes associated with a mount as part of the unmount process.  
 Its parameters can determine which vnodes to skip in the process and whether in-use vnodes should be forcibly reclaimed.
 Filesystems should call this function from their unmount code, because VFS code will always call it with SKIPROOT | SKIPSWAP | SKIPSYSTEM; filesystems
 must take care of such vnodes themselves.
        SKIPSYSTEM skip vnodes marked VSYSTEM 
        FORCECLOSE force file closeure 
        WRITECLOSE only close writeable files 
        SKIPSWAP   skip vnodes marked VSWAP 
        SKIPROOT   skip root vnodes marked VROOT 
 @return 0 for success, EBUSY if vnodes were busy and FORCECLOSE was not set.
 */
int     vflush(struct mount *mp, struct vnode *skipvp, int flags);

/*!
 @function vnode_get
 @abstract Increase the iocount on a vnode.
 @discussion If vnode_get() succeeds, the resulting io-reference must be dropped with vnode_put().
 This function succeeds unless the vnode in question is dead or in the process of dying AND the current iocount is zero.  
 This means that it can block an ongoing reclaim which is blocked behind some other iocount.

 On success, vnode_get() returns with an iocount held on the vnode; this type of reference is intended to be held only for short periods of time (e.g.
 across a function call) and provides a strong guarantee about the life of the vnode; vnodes with positive iocounts cannot be
 recycled, and an iocount is required for any  operation on a vnode.  However, vnode_get() does not provide any guarantees 
 about the identity of the vnode it is called on; unless there is a known existing iocount on the vnode at time the call is made,
 it could be recycled and put back in use before the vnode_get() succeeds, so the caller may be referencing a 
 completely different vnode than was intended.  vnode_getwithref() and vnode_getwithvid()
 provide guarantees about vnode identity.

 @return 0 for success, ENOENT if the vnode is dead and without existing io-reference.
 */
int     vnode_get(vnode_t);

/*!
 @function vnode_getwithvid
 @abstract Increase the iocount on a vnode, checking that the vnode is alive and has not changed vid (i.e. been recycled)
 @discussion If vnode_getwithvid() succeeds, the resulting io-reference must be dropped with vnode_put().
 This function succeeds unless the vnode in question is dead, in the process of dying, or has been recycled (and given a different vnode id).
 The intended usage is that a vnode is stored and its vid (vnode_vid(vp)) recorded while an iocount is held (example: a filesystem hash).  The
 iocount is then dropped, and time passes (perhaps locks are dropped and picked back up). Subsequently, vnode_getwithvid() is called to get an iocount, 
 but we are alerted if the vnode has been recycled.

 On success, vnode_getwithvid()  returns with an iocount held on the vnode; this type of reference is intended to be held only for short periods of time (e.g.
 across a function call) and provides a strong guarantee about the life of the vnode. vnodes with positive iocounts cannot be
 recycled. An iocount is required for any operation on a vnode.
 @return 0 for success, ENOENT if the vnode is dead, in the process of being reclaimed, or has been recycled and reused.
 */
int     vnode_getwithvid(vnode_t, uint32_t);

#ifdef BSD_KERNEL_PRIVATE
int vnode_getwithvid_drainok(vnode_t, uint32_t);
#endif /* BSD_KERNEL_PRIVATE */

/*!
 @function vnode_getwithref
 @abstract Increase the iocount on a vnode on which a usecount (persistent reference) is held.
 @discussion If vnode_getwithref() succeeds, the resulting io-reference must be dropped with vnode_put().
 vnode_getwithref() will succeed on dead vnodes; it should fail with ENOENT on vnodes which are in the process of being reclaimed.  
 Because it is only called with a usecount on the vnode, the caller is guaranteed that the vnode has not been 
 reused for a different file, though it may now be dead and have deadfs vnops (which return errors like EIO, ENXIO, ENOTDIR).
 On success, vnode_getwithref() returns with an iocount held on the vnode; this type of reference is intended to be held only for short periods of time (e.g.
 across a function call) and provides a strong guarantee about the life of the vnode. vnodes with positive iocounts cannot be
 recycled. An iocount is required for any operation on a vnode.
 @return 0 for success, ENOENT if the vnode is dead, in the process of being reclaimed, or has been recycled and reused.
 */
int     vnode_getwithref(vnode_t);

/*!
 @function vnode_put
 @abstract Decrement the iocount on a vnode.
 @discussion vnode_put() is called to indicate that a vnode is no longer in active use.  It removes the guarantee that a
 vnode will not be recycled.  This routine should be used to release io references no matter how they were obtained.
 @param vp The vnode whose iocount to drop.
 @return Always 0.
 */
int     vnode_put(vnode_t);

/*!
 @function vnode_ref
 @abstract Increment the usecount on a vnode.
 @discussion If vnode_ref() succeeds, the resulting usecount must be released with vnode_rele(). vnode_ref() is called to obtain 
 a persistent reference on a vnode.  This type of reference does not provide the same strong guarantee that a vnode will persist
 as does an iocount--it merely ensures that a vnode will not be reused to represent a different file.  However, a usecount may be
 held for extended periods of time, whereas an iocount is intended to be obtained and released quickly as part of performing a
 vnode operation.  A holder of a usecount must call vnode_getwithref()/vnode_put() in order to perform any operations on that vnode.
 @param vp The vnode on which to obtain a persistent reference.
 @return 0 for success; ENOENT if the vnode is dead or in the process of being recycled AND the calling thread is not the vnode owner.
 */
int     vnode_ref(vnode_t);

/*!
 @function vnode_rele
 @abstract Decrement the usecount on a vnode.
 @discussion vnode_rele() is called to relese a persistent reference on a vnode.  Releasing the last usecount 
 opens the door for a vnode to be reused as a new file; it also triggers a VNOP_INACTIVE call to the filesystem,
 though that will not happen immediately if there are outstanding iocount references.
 @param vp The vnode whose usecount to drop.
 @return void.
 */
void    vnode_rele(vnode_t);

/*!
 @function vnode_isinuse
 @abstract Determine if the number of persistent (usecount) references on a vnode is greater than a given count.
 @discussion vnode_isinuse() compares a vnode's  usecount (corresponding to vnode_ref() calls) to its refcnt parameter 
 (the number of references the caller expects to be on the vnode).  Note that "kusecount" references, corresponding
 to parties interested only in event notifications, e.g. open(..., O_EVTONLY), are not counted towards the total; the comparison is
 (usecount - kusecount > recnt).  It is
 also important to note that the result is only a snapshot; usecounts can change from moment to moment, and the result of vnode_isinuse
 may no longer be correct the very moment that the caller receives it.
 @param vp The vnode whose use-status to check.
 @param refcnt The threshold for saying that a vnode is in use.
 @return void.
 */
int     vnode_isinuse(vnode_t, int);

/*!
 @function vnode_recycle
 @abstract Cause a vnode to be reclaimed and prepared for reuse.
 @discussion Like all vnode KPIs, must be called with an iocount on the target vnode.
 vnode_recycle() will mark that vnode for reclaim when all existing references are dropped.
 @param vp The vnode to recycle.
 @return 1 if the vnode was reclaimed (i.e. there were no existing references), 0 if it was only marked for future reclaim.
 */
int     vnode_recycle(vnode_t);

#ifdef KERNEL_PRIVATE

#define VNODE_EVENT_DELETE              0x00000001      /* file was removed */
#define VNODE_EVENT_WRITE               0x00000002      /* file or directory contents changed */
#define VNODE_EVENT_EXTEND              0x00000004      /* ubc size increased */
#define VNODE_EVENT_ATTRIB              0x00000008      /* attributes changed (suitable for permission changes if type unknown)*/
#define VNODE_EVENT_LINK                0x00000010      /* link count changed */
#define VNODE_EVENT_RENAME              0x00000020      /* vnode was renamed */
#define VNODE_EVENT_PERMS               0x00000040      /* permissions changed: will cause a NOTE_ATTRIB */
#define VNODE_EVENT_FILE_CREATED        0x00000080      /* file created in directory: will cause NOTE_WRITE */
#define VNODE_EVENT_DIR_CREATED         0x00000100      /* directory created inside this directory: will cause NOTE_WRITE */
#define VNODE_EVENT_FILE_REMOVED        0x00000200      /* file removed from this directory: will cause NOTE_WRITE */
#define VNODE_EVENT_DIR_REMOVED         0x00000400      /* subdirectory from this directory: will cause NOTE_WRITE */

#ifdef BSD_KERNEL_PRIVATE 
#define VNODE_NOTIFY_ATTRS              (VNODE_ATTR_BIT(va_fsid) | \
                                        VNODE_ATTR_BIT(va_fileid)| \
                                        VNODE_ATTR_BIT(va_mode)  | \
                                        VNODE_ATTR_BIT(va_uid)   | \
                                        VNODE_ATTR_BIT(va_gid)   | \
                                        VNODE_ATTR_BIT(va_dirlinkcount) | \
                                        VNODE_ATTR_BIT(va_nlink))

                                        

#endif /* BSD_KERNEL_PRIVATE  */

/*!
 @function vnode_notify
 @abstract Send a notification up to VFS.  
 @param vp Vnode for which to provide notification.
 @param vap Attributes for that vnode, to be passed to fsevents.
 @discussion Filesystem determines which attributes to pass up using 
 vfs_get_notify_attributes(&vap).  The most specific events possible should be passed,
 e.g. VNODE_EVENT_FILE_CREATED on a directory rather than just VNODE_EVENT_WRITE, but
 a less specific event can be passed up if more specific information is not available.
 Will not reenter the filesystem.
 @return 0 for success, else an error code.
 */ 
int     vnode_notify(vnode_t, uint32_t, struct vnode_attr*);

/*!
 @function vnode_ismonitored
 @abstract Check whether a file has watchers that would make it useful to query a server
 for file changes.
 @param vp Vnode to examine.
 @discussion Will not reenter the filesystem.
 @return Zero if not monitored, nonzero if monitored.
 */ 
int     vnode_ismonitored(vnode_t);


/*!
 @function vnode_isdyldsharedcache
 @abstract Check whether a file is a dyld shared cache file.
 @param vp Vnode to examine.
 @discussion Will not reenter the filesystem.
 @return nonzero if a dyld shared cache file, zero otherwise.
 */ 
int     vnode_isdyldsharedcache(vnode_t);


/*!
 @function vfs_get_notify_attributes
 @abstract Determine what attributes are required to send up a notification with vnode_notify().
 @param vap Structure to initialize and activate required attributes on.
 @discussion Will not reenter the filesystem.
 @return 0 for success, nonzero for error (currently always succeeds).
 */ 
int     vfs_get_notify_attributes(struct vnode_attr *vap);

/*!
 @function vn_getpath_fsenter
 @abstract Attempt to get a vnode's path, willing to enter the filesystem.
 @discussion Paths to vnodes are not always straightforward: a file with multiple hard-links will have multiple pathnames,
 and it is sometimes impossible to determine a vnode's full path.  vn_getpath_fsenter() may enter the filesystem
 to try to construct a path, so filesystems should be wary of calling it.
 @param vp Vnode whose path to get
 @param pathbuf Buffer in which to store path.
 @param len Destination for length of resulting path string.  Result will include NULL-terminator in count--that is, "len"
 will be strlen(pathbuf) + 1.
 @return 0 for success or an error.
 */
int     vn_getpath_fsenter(struct vnode *vp, char *pathbuf, int *len);

#endif /* KERNEL_PRIVATE */

#define VNODE_UPDATE_PARENT     0x01
#define VNODE_UPDATE_NAME       0x02
#define VNODE_UPDATE_CACHE      0x04
#define VNODE_UPDATE_PURGE      0x08
/*!
 @function vnode_update_identity
 @abstract Update vnode data associated with the vfs cache.
 @discussion The vfs namecache is central to tracking vnode-identifying data and to locating files on the system.  vnode_update_identity()
 is used to update vnode data associated with the cache. It can set a vnode's parent and/or name (also potentially set by vnode_create())
 or flush cache data.
 @param vp The vnode whose information to update.
 @param dvp Parent to set on the vnode if VNODE_UPDATE_PARENT is used.
 @param name Name to set in the cache for the vnode if VNODE_UPDATE_NAME is used.  The buffer passed in can be subsequently freed, as the cache
 does its own name storage.  String should be NULL-terminated unless length and hash value are specified.
 @param name_len Length of name, if known.  Passing 0 causes the cache to determine the length itself.
 @param name_hashval Hash value of name, if known.  Passing 0 causes the cache to hash the name itself.
 @param flags VNODE_UPDATE_PARENT: set parent.  VNODE_UPDATE_NAME: set name.  VNODE_UPDATE_CACHE: flush cache entries for hard links
 associated with this file.  VNODE_UPDATE_PURGE: flush cache entries for hard links and children of this file.
 @return void.
 */
void    vnode_update_identity(vnode_t vp, vnode_t dvp, const char *name, int name_len, uint32_t name_hashval, int flags);

/*!
 @function vn_bwrite
 @abstract System-provided implementation of "bwrite" vnop.
 @discussion This routine is available for filesystems which do not want to implement their own "bwrite" vnop.  It just calls
 buf_bwrite() without modifying its arguments.
 @param ap Standard parameters to a bwrite vnop.
 @return Results of buf_bwrite directly.
 */
int     vn_bwrite(struct vnop_bwrite_args *ap);

/*!
 @function vnode_authorize
 @abstract Authorize a kauth-style action on a vnode.
 @discussion Operations on dead vnodes are always allowed (though never do anything).
 @param vp Vnode on which to authorize action.
 @param dvp Parent of "vp," can be NULL.
 @param action Action to authorize, e.g. KAUTH_VNODE_READ_DATA.  See bsd/sys/kauth.h.
 @param ctx Context for which to authorize actions.
 @return EACCESS if permission is denied.  0 if operation allowed.  Various errors from lower layers.
 */
int     vnode_authorize(vnode_t /*vp*/, vnode_t /*dvp*/, kauth_action_t, vfs_context_t);

/*!
 @function vnode_authattr
 @abstract Given a vnode_attr structure, determine what kauth-style actions must be authorized in order to set those attributes.
 @discussion vnode_authorize requires kauth-style actions; if we want to set a vnode_attr structure on a vnode, we need to translate
 the set of attributes to a set of kauth-style actions.  This routine will return errors for certain obviously disallowed, or 
 incoherent, actions.
 @param vp The vnode on which to authorize action.
 @param vap Pointer to vnode_attr struct containing desired attributes to set and their values.
 @param actionp Destination for set of actions to authorize
 @param ctx Context for which to authorize actions.
 @return 0 (and a result in "actionp" for success.  Otherwise, an error code.
 */
int     vnode_authattr(vnode_t, struct vnode_attr *, kauth_action_t *, vfs_context_t);

/*!
 @function vnode_authattr_new
 @abstract Initialize and validate file creation parameters with respect to the current context.
 @discussion vnode_authattr_new() will fill in unitialized values in the vnode_attr struct with defaults, and will validate the structure
 with respect to the current context for file creation.
 @param dvp The directory in which creation will occur.
 @param vap Pointer to vnode_attr struct containing desired attributes to set and their values.
 @param noauth If 1, treat the caller as the superuser, i.e. do not check permissions.
 @param ctx Context for which to authorize actions.
 @return KAUTH_RESULT_ALLOW for success, an error to indicate invalid or disallowed attributes.
 */
int     vnode_authattr_new(vnode_t /*dvp*/, struct vnode_attr *, int /*noauth*/, vfs_context_t);

/*!
 @function vnode_close
 @abstract Close a file as opened with vnode_open().
 @discussion vnode_close() drops the refcount (persistent reference) picked up in vnode_open() and calls down to the filesystem with VNOP_CLOSE.  It should
 be called with both an iocount and a refcount on the vnode and will drop both.
 @param vp The vnode to close.
 @param flags Flags to close: FWASWRITTEN indicates that the file was written to.
 @param ctx Context against which to validate operation.
 @return 0 for success or an error from the filesystem.
 */
errno_t vnode_close(vnode_t, int, vfs_context_t);

/*!
 @function vn_getpath
 @abstract Construct the path to a vnode.
 @discussion Paths to vnodes are not always straightforward: a file with multiple hard-links will have multiple pathnames,
 and it is sometimes impossible to determine a vnode's full path.  vn_getpath() will not enter the filesystem.
 @param vp The vnode whose path to obtain.
 @param pathbuf Destination for pathname; should be of size MAXPATHLEN
 @param len Destination for length of resulting path string.  Result will include NULL-terminator in count--that is, "len"
 will be strlen(pathbuf) + 1.
 @return 0 for success or an error code.
 */
int vn_getpath(struct vnode *vp, char *pathbuf, int *len);

/*
 * Flags for the vnode_lookup and vnode_open
 */
#define VNODE_LOOKUP_NOFOLLOW           0x01
#define VNODE_LOOKUP_NOCROSSMOUNT       0x02
#define VNODE_LOOKUP_DOWHITEOUT         0x04    /* OBSOLETE */
/*!
 @function vnode_lookup
 @abstract Convert a path into a vnode.
 @discussion This routine is a thin wrapper around xnu-internal lookup routines; if successful, 
 it returns with an iocount held on the resulting vnode which must be dropped with vnode_put().
 @param path Path to look up.
 @param flags VNODE_LOOKUP_NOFOLLOW: do not follow symbolic links.  VNODE_LOOKUP_NOCROSSMOUNT: do not cross mount points.
 @return Results 0 for success or an error code.
 */
errno_t vnode_lookup(const char *, int, vnode_t *, vfs_context_t);

/*!
 @function vnode_open
 @abstract Open a file identified by a path--roughly speaking an in-kernel open(2).
 @discussion If vnode_open() succeeds, it returns with both an iocount and a usecount on the returned vnode.  These must 
 be released eventually; the iocount should be released with vnode_put() as soon as any initial operations
 on the vnode are over, whereas the usecount should be released via vnode_close().
 @param path Path to look up.
 @param fmode e.g. O_NONBLOCK, O_APPEND; see bsd/sys/fcntl.h.
 @param cmode Permissions with which to create file if it does not exist.
 @param flags Same as vnode_lookup().
 @param vpp Destination for vnode.
 @param ctx Context with which to authorize open/creation.
 @return 0 for success or an error code.
 */
errno_t vnode_open(const char *, int, int, int, vnode_t *, vfs_context_t);

/*
 * exported vnode operations
 */

/*!
 @function vnode_iterate
 @abstract Perform an operation on (almost) all vnodes from a given mountpoint.
 @param mp Mount whose vnodes to operate on.
 @param flags
 VNODE_RELOAD                   Mark inactive vnodes for recycle.
 VNODE_WAIT                     
 VNODE_WRITEABLE                Only examine vnodes with writes in progress.
 VNODE_WITHID                   No effect.
 VNODE_NOLOCK_INTERNAL  No effect.
 VNODE_NODEAD                   No effect.
 VNODE_NOSUSPEND                No effect.
 VNODE_ITERATE_ALL              No effect.
 VNODE_ITERATE_ACTIVE   No effect.
 VNODE_ITERATE_INACTIVE No effect.
 
 @param callout Function to call on each vnode.
 @param arg Argument which will be passed to callout along with each vnode.
 @return Zero for success, else an error code.  Will return 0 immediately if there are no vnodes hooked into the mount.
 @discussion Skips vnodes which are dead, in the process of reclaim, suspended, or of type VNON.
 */
int     vnode_iterate(struct mount *, int, int (*)(struct vnode *, void *), void *);

/*
 * flags passed into vnode_iterate
 */
#define VNODE_RELOAD                    0x01
#define VNODE_WAIT                              0x02
#define VNODE_WRITEABLE                 0x04
#define VNODE_WITHID                    0x08
#define VNODE_NOLOCK_INTERNAL   0x10
#define VNODE_NODEAD                    0x20
#define VNODE_NOSUSPEND                 0x40
#define VNODE_ITERATE_ALL               0x80
#define VNODE_ITERATE_ACTIVE    0x100
#define VNODE_ITERATE_INACTIVE  0x200
#ifdef BSD_KERNEL_PRIVATE
#define VNODE_ALWAYS            0x400
#define VNODE_DRAINO            0x800
#endif /* BSD_KERNEL_PRIVATE */

/*
 * return values from callback
 */
#define VNODE_RETURNED          0       /* done with vnode, reference can be dropped */
#define VNODE_RETURNED_DONE     1       /* done with vnode, reference can be dropped, terminate iteration */
#define VNODE_CLAIMED           2       /* don't drop reference */
#define VNODE_CLAIMED_DONE      3       /* don't drop reference, terminate iteration */

/*!
 @function vn_revoke
 @abstract Invalidate all references to a vnode.
 @discussion Reclaims the vnode, giving it deadfs vnops (though not halting operations which are already in progress).  
 Also reclaims all aliased vnodes (important for devices).  People holding usecounts on the vnode, e.g. processes
 with the file open, will find that all subsequent operations but closing the file fail.
 @param vp The vnode to revoke.
 @param flags Unused.
 @param ctx Context against which to validate operation.
 @return 0 always.
 */
int     vn_revoke(vnode_t vp, int flags, vfs_context_t);

/* namecache function prototypes */
/*!
 @function cache_lookup
 @abstract Check for a filename in a directory using the VFS name cache.
 @discussion cache_lookup() will flush negative cache entries and return 0 if the operation of the cn_nameiop is CREATE or RENAME.
 Often used from the filesystem during a lookup vnop.  The filesystem will be called to if there is a negative cache entry for a file,
 so it can make sense to initially check for negative entries (and possibly lush them).
 @param dvp Directory in which lookup is occurring.
 @param vpp Destination for vnode pointer.
 @param cnp Various data about lookup, e.g. filename and intended operation.
 @return ENOENT: the filesystem has previously added a negative entry with cache_enter() to indicate that there is no
 file of the given name in "dp."  -1: successfully found a cached vnode (vpp is set).  0: No data in the cache, or operation is CRETE/RENAME.
 */
int     cache_lookup(vnode_t dvp, vnode_t *vpp, struct componentname *cnp);

/*!
 @function cache_enter
 @abstract Add a (name,vnode) entry to the VFS namecache.
 @discussion Generally used to add a cache entry after a successful filesystem-level lookup or to add a 
 negative entry after one which did not find its target.
 @param dvp Directory in which file lives.
 @param vp File to add to cache. A non-NULL vp is stored for rapid access; a NULL vp indicates 
 that there is no such file in the directory and speeds future failed lookups.
 @param cnp Various data about lookup, e.g. filename and intended operation.
 @return void.  
 */
void    cache_enter(vnode_t dvp, vnode_t vp, struct componentname *cnp);

/*!
 @function cache_purge
 @abstract Remove all data relating to a vnode from the namecache.
 @discussion Will flush all hardlinks to the vnode as well as all children (should any exist).  Logical 
 to use when cached data about a vnode becomes invalid, for instance in an unlink.
 @param vp The vnode to purge.
 @return void.  
 */
void    cache_purge(vnode_t vp);

/*!
 @function cache_purge_negatives
 @abstract Remove all negative cache entries which are children of a given vnode.
 @discussion Appropriate to use when negative cache information for a directory could have
 become invalid, e.g. after file creation.
 @param vp The vnode whose negative children to purge.
 @return void.  
 */
void    cache_purge_negatives(vnode_t vp);


/*
 * Global string-cache routines.  You can pass zero for nc_hash
 * if you don't know it (add_name() will then compute the hash).
 * There are no flags for now but maybe someday.
 */
/*!
 @function vfs_addname
 @abstract Deprecated
 @discussion vnode_update_identity() and vnode_create() make vfs_addname() unnecessary for kexts.
 */
const char *vfs_addname(const char *name, uint32_t len, uint32_t nc_hash, uint32_t flags);

/*!
 @function vfs_removename
 @abstract Deprecated
 @discussion vnode_update_identity() and vnode_create() make vfs_addname() unnecessary for kexts.
 */
int   vfs_removename(const char *name);

/*!
 @function vcount
 @abstract Count total references to a given file, disregarding "kusecount" (event listener, as with O_EVTONLY) references.
 @discussion For a regular file, just return (usecount-kusecount); for device files, return the sum over all
 vnodes 'v' which reference that device of (usecount(v) - kusecount(v)).  Note that this is merely a snapshot and could be
 invalid by the time the caller checks the result.
 @param vp The vnode whose references to count.
 @return Count of references.
 */
int     vcount(vnode_t vp);

/*!
 @function vn_path_package_check
 @abstract Figure out if a path corresponds to a Mac OS X package.
 @discussion  Determines if the extension on a path is a known OS X extension type.
 @param vp Unused.
 @param path Path to check.
 @param pathlen Size of path buffer.
 @param component Set to index of start of last path component if the path is found to be a package. Set to -1 if
 the path is not a known package type.
 @return 0 unless some parameter was invalid, in which case EINVAL is returned.  Determine package-ness by checking
 what *component is set to.
 */
int vn_path_package_check(vnode_t vp, char *path, int pathlen, int *component);

#ifdef KERNEL_PRIVATE
/*!
  @function vn_searchfs_inappropriate_name
  @abstract Figure out if the component is inappropriate for a SearchFS query.
  @param name component to check
  @param len length of component.
  @return 0 if no match, 1 if inappropriate. 
 */
int vn_searchfs_inappropriate_name(const char *name, int len); 
#endif 

/*!
 @function vn_rdwr
 @abstract Read from or write to a file.
 @discussion vn_rdwr() abstracts the details of constructing a uio and picking a vnode operation to allow
 simple in-kernel file I/O.
 @param rw UIO_READ for a read, UIO_WRITE for a write.
 @param vp The vnode on which to perform I/O.
 @param base Start of buffer into which to read or from which to write data.
 @param len Length of buffer.
 @param offset Offset within the file at which to start I/O.
 @param segflg What kind of address "base" is.   See uio_seg definition in sys/uio.h.  UIO_SYSSPACE for kernelspace, UIO_USERSPACE for userspace.
 UIO_USERSPACE32 and UIO_USERSPACE64 are in general preferred, but vn_rdwr will make sure that has the correct address sizes.
 @param ioflg Defined in vnode.h, e.g. IO_NOAUTH, IO_NOCACHE.
 @param cred Credential to pass down to filesystem for authentication.
 @param aresid Destination for amount of requested I/O which was not completed, as with uio_resid().
 @param p Process requesting I/O.
 @return 0 for success; errors from filesystem, and EIO if did not perform all requested I/O and the "aresid" parameter is NULL.
 */
int     vn_rdwr(enum uio_rw, vnode_t, caddr_t, int, off_t, enum uio_seg, int, kauth_cred_t, int *, proc_t);

/*!
 @function vnode_getname
 @abstract Get the name of a vnode from the VFS namecache.
 @discussion Not all vnodes have names, and vnode names can change (notably, hardlinks).  Use this routine at your own risk.
 The string is returned with a refcount incremented in the cache; callers must call vnode_putname() to release that reference.
 @param vp The vnode whose name to grab.
 @return The name, or NULL if unavailable.
 */
const char      *vnode_getname(vnode_t vp);

/*!
 @function vnode_putname
 @abstract Release a reference on a name from the VFS cache.
 @discussion Should be called on a string obtained with vnode_getname().
 @param name String to release.
 @return void.
 */
void    vnode_putname(const char *name);

/*!
 @function vnode_getparent
 @abstract Get an iocount on the parent of a vnode.
 @discussion A vnode's parent may change over time or be reclaimed, so vnode_getparent() may return different
 results at different times (e.g. a multiple-hardlink file). The parent is returned with an iocount which must
 subsequently be dropped with vnode_put().
 @param vp The vnode whose parent to grab.
 @return Parent if available, else NULL.
 */
vnode_t vnode_getparent(vnode_t vp);

#ifdef KERNEL_PRIVATE
/*! 
 @function vnode_lookup_continue_needed
 @abstract Determine whether vnode needs additional processing in VFS before being opened.
 @discussion If result is zero, filesystem can open this vnode.  If result is nonzero,
 additional processing is needed in VFS (e.g. symlink, mountpoint).  Nonzero results should
 be passed up to VFS.
 @param vp Vnode to consider opening (found by filesystem).
 @param cnp Componentname as passed to filesystem from VFS.
 @result 0 to indicate that a vnode can be opened, or an error that should be passed up to VFS.
 */
int vnode_lookup_continue_needed(vnode_t vp, struct componentname *cnp);
#endif /* KERNEL_PRIVATE */

#ifdef BSD_KERNEL_PRIVATE
/* Not in export list so can be private */
struct stat;
int     vn_stat(struct vnode *vp, void * sb, kauth_filesec_t *xsec, int isstat64, vfs_context_t ctx);
int     vn_stat_noauth(struct vnode *vp, void * sb, kauth_filesec_t *xsec, int isstat64, vfs_context_t ctx);
int     vaccess(mode_t file_mode, uid_t uid, gid_t gid,
                        mode_t acc_mode, kauth_cred_t cred);
int     check_mountedon(dev_t dev, enum vtype type, int  *errorp);
int vn_getcdhash(struct vnode *vp, off_t offset, unsigned char *cdhash);
void    vnode_reclaim(vnode_t);
vfs_context_t vfs_context_kernel(void);         /* get from 1st kernel thread */
int     vfs_context_issuser(vfs_context_t);
vnode_t vfs_context_cwd(vfs_context_t);
vnode_t current_rootdir(void);
vnode_t current_workingdir(void);
void    *vnode_vfsfsprivate(vnode_t);
struct vfsstatfs *vnode_vfsstatfs(vnode_t);
uint32_t vnode_vfsvisflags(vnode_t);
uint32_t vnode_vfscmdflags(vnode_t);
int     vnode_is_openevt(vnode_t);
void    vnode_set_openevt(vnode_t);
void    vnode_clear_openevt(vnode_t);
int     vnode_isstandard(vnode_t);
int     vnode_makeimode(int, int);
enum vtype      vnode_iftovt(int);
int     vnode_vttoif(enum vtype);
int     vnode_isshadow(vnode_t);
int     vnode_istty(vnode_t vp);
/*
 * Indicate that a file has multiple hard links.  VFS will always call
 * VNOP_LOOKUP on this vnode.  Volfs will always ask for it's parent
 * object ID (instead of using the v_parent pointer).
 */
vnode_t vnode_parent(vnode_t);
void vnode_setparent(vnode_t, vnode_t);
const char * vnode_name(vnode_t);
void vnode_setname(vnode_t, char *);
int vnode_isnoflush(vnode_t);
void vnode_setnoflush(vnode_t);
void vnode_clearnoflush(vnode_t);
/* XXX temporary until we can arrive at a KPI for NFS, Seatbelt */
thread_t vfs_context_thread(vfs_context_t);

#endif /* BSD_KERNEL_PRIVATE */

__END_DECLS

#endif /* KERNEL */

#endif /* !_VNODE_H_ */