/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1994 The Regents of the University of California.
 * Copyright (c) 1994 Jan-Simon Pendry.
 * Copyright (c) 2005, 2006 Masanori Ozawa <ozawa@ongs.co.jp>, ONGS Inc.
 * Copyright (c) 2006 Daichi Goto <daichi@freebsd.org>
 * All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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. 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.
 */

#ifdef _KERNEL

/* copy method of attr from lower to upper */
typedef enum _unionfs_copymode {
        UNIONFS_TRADITIONAL = 0,
        UNIONFS_TRANSPARENT,
        UNIONFS_MASQUERADE
} unionfs_copymode;

/* whiteout policy of upper layer */
typedef enum _unionfs_whitemode {
       UNIONFS_WHITE_ALWAYS = 0,
       UNIONFS_WHITE_WHENNEEDED
} unionfs_whitemode;

struct unionfs_mount {
        struct mount   *um_lowermp;     /* MNT_REFed lower mount object */
        struct mount   *um_uppermp;     /* MNT_REFed upper mount object */
        struct vnode   *um_lowervp;     /* VREFed once */
        struct vnode   *um_uppervp;     /* VREFed once */
        struct vnode   *um_rootvp;      /* ROOT vnode */
        struct mount_upper_node um_lower_link;  /* node in lower FS list of uppers */
        struct mount_upper_node um_upper_link;  /* node in upper FS list of uppers */
        unionfs_copymode um_copymode;
        unionfs_whitemode um_whitemode;
        uid_t           um_uid;
        gid_t           um_gid;
        u_short         um_udir;
        u_short         um_ufile;
};

/* unionfs status list */
struct unionfs_node_status {
        LIST_ENTRY(unionfs_node_status) uns_list;       /* Status list */
        pid_t           uns_pid;                /* current process id */
        int             uns_node_flag;          /* uns flag */
        int             uns_lower_opencnt;      /* open count of lower */
        int             uns_upper_opencnt;      /* open count of upper */
        int             uns_lower_openmode;     /* open mode of lower */
        int             uns_readdir_status;     /* read status of readdir */
};

/* union node status flags */
#define UNS_OPENL_4_READDIR     0x01    /* open lower layer for readdir */

/* A cache of vnode references */
struct unionfs_node {
        struct vnode   *un_lowervp;             /* lower side vnode */
        struct vnode   *un_uppervp;             /* upper side vnode */
        struct vnode   *un_dvp;                 /* parent unionfs vnode */
        struct vnode   *un_vnode;               /* Back pointer */
        LIST_HEAD(, unionfs_node_status) un_unshead;
                                                /* unionfs status head */
        LIST_HEAD(unionfs_node_hashhead, unionfs_node) *un_hashtbl;
                                                /* dir vnode hash table */
        union {
                LIST_ENTRY(unionfs_node) un_hash; /* hash list entry */
                STAILQ_ENTRY(unionfs_node) un_rele; /* deferred release list */
        };

        char           *un_path;                /* path */
        int             un_pathlen;             /* strlen of path */

        /*
         * unionfs node flags
         * Changing these flags requires the vnode to be locked exclusive.
         */
        #define UNIONFS_OPENEXTL                0x01    /* openextattr (lower) */
        #define UNIONFS_OPENEXTU                0x02    /* openextattr (upper) */
        #define UNIONFS_COPY_IN_PROGRESS        0x04    /* copy/dir shadow in progres */
        #define UNIONFS_LOOKUP_IN_PROGRESS      0x08
        unsigned int    un_flag;                /* unionfs node flag */
};

extern struct vop_vector unionfs_vnodeops;

static inline struct unionfs_node *
unionfs_check_vnode(struct vnode *vp, const char *file __unused,
    int line __unused)
{
        /*
         * unionfs_lock() needs the NULL check here, as it explicitly
         * handles the case in which the vnode has been vgonel()'ed.
         */
        KASSERT(vp->v_op == &unionfs_vnodeops || vp->v_data == NULL,
            ("%s:%d: non-unionfs vnode %p", file, line, vp));
        return ((struct unionfs_node *)vp->v_data);
}

#define MOUNTTOUNIONFSMOUNT(mp) ((struct unionfs_mount *)((mp)->mnt_data))
#define VTOUNIONFS(vp) unionfs_check_vnode(vp, __FILE__, __LINE__)
#define UNIONFSTOV(xp) ((xp)->un_vnode)

int     unionfs_init(struct vfsconf *);
int     unionfs_uninit(struct vfsconf *);
int     unionfs_nodeget(struct mount *, struct vnode *, struct vnode *,
            struct vnode *, struct vnode **, struct componentname *);
void    unionfs_noderem(struct vnode *);
struct unionfs_node_status *    unionfs_find_node_status(struct unionfs_node *,
            struct thread *td);
void    unionfs_get_node_status(struct unionfs_node *, struct thread *,
            struct unionfs_node_status **);
void    unionfs_tryrem_node_status(struct unionfs_node *,
            struct unionfs_node_status *);
int     unionfs_check_rmdir(struct vnode *, struct ucred *, struct thread *);
int     unionfs_copyfile(struct vnode *, int, struct ucred *, struct thread *);
int     unionfs_copylink(struct vnode *, struct ucred *, struct thread *);
void    unionfs_create_uppervattr_core(struct unionfs_mount *, struct vattr *,
            struct vattr *, struct thread *);
int     unionfs_create_uppervattr(struct unionfs_mount *, struct vnode *,
            struct vattr *, struct ucred *, struct thread *);
int     unionfs_mkshadowdir(struct vnode *, struct vnode *,
            struct componentname *, struct thread *);
int     unionfs_mkwhiteout(struct vnode *, struct vnode *,
            struct componentname *, struct thread *, char *, int);
int     unionfs_relookup(struct vnode *, struct vnode **,
            struct componentname *, struct componentname *, struct thread *,
            char *, int, u_long);
void    unionfs_forward_vop_start_pair(struct vnode *, int *,
            struct vnode *, int *);
bool    unionfs_forward_vop_finish_pair(struct vnode *, struct vnode *, int,
            struct vnode *, struct vnode *, int);
int     unionfs_set_in_progress_flag(struct vnode *, unsigned int);
void    unionfs_clear_in_progress_flag(struct vnode *, unsigned int);

static inline void
unionfs_forward_vop_start(struct vnode *basevp, int *lkflags)
{
        unionfs_forward_vop_start_pair(basevp, lkflags, NULL, NULL);
}

static inline bool
unionfs_forward_vop_finish(struct vnode *unionvp, struct vnode *basevp,
    int lkflags)
{
        return (unionfs_forward_vop_finish_pair(unionvp, basevp, lkflags,
            NULL, NULL, 0));
}

#define UNIONFSVPTOLOWERVP(vp) (VTOUNIONFS(vp)->un_lowervp)
#define UNIONFSVPTOUPPERVP(vp) (VTOUNIONFS(vp)->un_uppervp)

#ifdef MALLOC_DECLARE
MALLOC_DECLARE(M_UNIONFSNODE);
MALLOC_DECLARE(M_UNIONFSPATH);
#endif

#ifdef UNIONFS_DEBUG
#define UNIONFSDEBUG(format, args...) printf(format ,## args)
#else
#define UNIONFSDEBUG(format, args...)
#endif                          /* UNIONFS_DEBUG */

#endif                          /* _KERNEL */