/*      $NetBSD: chfs_subr.c,v 1.15 2020/09/05 16:30:12 riastradh Exp $ */

/*-
 * Copyright (c) 2010 Department of Software Engineering,
 *                    University of Szeged, Hungary
 * Copyright (C) 2010 Tamas Toth <ttoth@inf.u-szeged.hu>
 * Copyright (C) 2010 Adam Hoka <ahoka@NetBSD.org>
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by the Department of Software Engineering, University of Szeged, Hungary
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR 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.
 */

#include <sys/cdefs.h>

#include <sys/param.h>
#include <sys/dirent.h>
#include <sys/event.h>
#include <sys/kmem.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/systm.h>
#include <sys/swap.h>
#include <sys/vnode.h>
#include <sys/kauth.h>
#include <sys/proc.h>
#include <sys/atomic.h>

#include <uvm/uvm_extern.h>

#include <miscfs/specfs/specdev.h>
#include <miscfs/genfs/genfs.h>
#include "chfs.h"


/*
 * chfs_mem_info -
 * Returns information about the number of available memory pages,
 * including physical and virtual ones.
 *
 * If 'total' is true, the value returned is the total amount of memory
 * pages configured for the system (either in use or free).
 * If it is FALSE, the value returned is the amount of free memory pages.
 *
 * Remember to remove DUMMYFS_PAGES_RESERVED from the returned value to avoid
 * excessive memory usage.
 *
 */
size_t
chfs_mem_info(bool total)
{
        size_t size;

        size = 0;
        size += uvmexp.swpgavail;
        if (!total) {
                size -= uvmexp.swpgonly;
        }
        size += uvm_availmem(true);
        size += uvmexp.filepages;
        if (size > uvmexp.wired) {
                size -= uvmexp.wired;
        } else {
                size = 0;
        }

        return size;
}


/*
 * chfs_dir_lookup -
 * Looks for a directory entry in the directory represented by node.
 * 'cnp' describes the name of the entry to look for.  Note that the .
 * and .. components are not allowed as they do not physically exist
 * within directories.
 *
 * Returns a pointer to the entry when found, otherwise NULL.
 */
struct chfs_dirent *
chfs_dir_lookup(struct chfs_inode *ip, struct componentname *cnp)
{
        bool found;
        struct chfs_dirent *fd;
        dbg("dir_lookup()\n");

        KASSERT(IMPLIES(cnp->cn_namelen == 1, cnp->cn_nameptr[0] != '.'));
        KASSERT(IMPLIES(cnp->cn_namelen == 2, !(cnp->cn_nameptr[0] == '.' &&
                    cnp->cn_nameptr[1] == '.')));

        found = false;
        TAILQ_FOREACH(fd, &ip->dents, fds) {
                KASSERT(cnp->cn_namelen < 0xffff);
                if (fd->vno == 0)
                        continue;
                if (fd->nsize == (uint16_t)cnp->cn_namelen &&
                    memcmp(fd->name, cnp->cn_nameptr, fd->nsize) == 0) {
                        found = true;
                        break;
                }
        }

        return found ? fd : NULL;
}

/*
 * chfs_filldir - 
 * Creates a (kernel) dirent and moves it to the given memory address.
 * Used during readdir.
 */
int
chfs_filldir(struct uio* uio, ino_t ino, const char *name,
    int namelen, enum chtype type)
{
        struct dirent dent;
        int error;

        memset(&dent, 0, sizeof(dent));

        dent.d_fileno = ino;
        switch (type) {
        case CHT_BLK:
                dent.d_type = DT_BLK;
                break;

        case CHT_CHR:
                dent.d_type = DT_CHR;
                break;

        case CHT_DIR:
                dent.d_type = DT_DIR;
                break;

        case CHT_FIFO:
                dent.d_type = DT_FIFO;
                break;

        case CHT_LNK:
                dent.d_type = DT_LNK;
                break;

        case CHT_REG:
                dent.d_type = DT_REG;
                break;

        case CHT_SOCK:
                dent.d_type = DT_SOCK;
                break;

        default:
                KASSERT(0);
        }
        dent.d_namlen = namelen;
        (void)memcpy(dent.d_name, name, dent.d_namlen);
        dent.d_reclen = _DIRENT_SIZE(&dent);

        if (dent.d_reclen > uio->uio_resid) {
                error = -1;
        } else {
                error = uiomove(&dent, dent.d_reclen, uio);
        }

        return error;
}

/*
 * chfs_chsize - change size of the given vnode
 * Caller should execute chfs_update on vp after a successful execution.
 * The vnode must be locked on entry and remain locked on exit.
 */
int
chfs_chsize(struct vnode *vp, u_quad_t size, kauth_cred_t cred)
{
        struct chfs_mount *chmp;
        struct chfs_inode *ip;

        ip = VTOI(vp);
        chmp = ip->chmp;

        dbg("chfs_chsize\n");

        switch (ip->ch_type) {
        case CHT_DIR:
                return EISDIR;
        case CHT_LNK:
        case CHT_REG:
                if (vp->v_mount->mnt_flag & MNT_RDONLY)
                        return EROFS;
                break;
        case CHT_BLK:
        case CHT_CHR:
        case CHT_FIFO:
                return 0;
        default:
                return EOPNOTSUPP; /* XXX why not ENODEV? */
        }

        vflushbuf(vp, 0);

        mutex_enter(&chmp->chm_lock_mountfields);

        if (ip->size < size) {
                uvm_vnp_setsize(vp, size);
                chfs_set_vnode_size(vp, size);
                ip->iflag |= IN_CHANGE | IN_UPDATE;

                mutex_exit(&chmp->chm_lock_mountfields);
                return 0;
        }

        if (size != 0) {
                ubc_zerorange(&vp->v_uobj, size, ip->size - size, UBC_VNODE_FLAGS(vp));
        }
        
        /* drop unused fragments */
        chfs_truncate_fragtree(ip->chmp, &ip->fragtree, size);

        uvm_vnp_setsize(vp, size);
        chfs_set_vnode_size(vp, size);
        ip->iflag |= IN_CHANGE | IN_UPDATE;
        mutex_exit(&chmp->chm_lock_mountfields);
        return 0;
}

/*
 * chfs_chflags - change flags of the given vnode
 * Caller should execute chfs_update on vp after a successful execution.
 * The vnode must be locked on entry and remain locked on exit.
 */
int
chfs_chflags(struct vnode *vp, int flags, kauth_cred_t cred)
{
        struct chfs_inode *ip;
        int error = 0;
        kauth_action_t action = KAUTH_VNODE_WRITE_FLAGS;
        bool changing_sysflags = false;

        ip = VTOI(vp);

        if (vp->v_mount->mnt_flag & MNT_RDONLY)
                return EROFS;

        if ((flags & SF_SNAPSHOT) != (ip->flags & SF_SNAPSHOT))
                return EPERM;

        /* Indicate we're changing system flags if we are. */
        if ((ip->flags & SF_SETTABLE) != (flags & SF_SETTABLE) ||
            (flags & UF_SETTABLE) != flags) {
                action |= KAUTH_VNODE_WRITE_SYSFLAGS;
                changing_sysflags = true;
        }

        /* Indicate the node has system flags if it does. */
        if (ip->flags & (SF_IMMUTABLE | SF_APPEND)) {
                action |= KAUTH_VNODE_HAS_SYSFLAGS;
        }

        error = kauth_authorize_vnode(cred, action, vp, NULL,
            genfs_can_chflags(vp, cred, ip->uid, changing_sysflags));
        if (error)
                return error;

        if (changing_sysflags) {
                ip->flags = flags;
        } else {
                ip->flags &= SF_SETTABLE;
                ip->flags |= (flags & UF_SETTABLE);
        }
        ip->iflag |= IN_CHANGE;
        error = chfs_update(vp, NULL, NULL, UPDATE_WAIT);
        if (error)
                return error;

        if (flags & (IMMUTABLE | APPEND))
                return 0;

        return error;
}


/* chfs_itimes - updates a vnode times to the given data */
void
chfs_itimes(struct chfs_inode *ip, const struct timespec *acc,
    const struct timespec *mod, const struct timespec *cre)
{
        struct timespec now;

        if (!(ip->iflag & (IN_ACCESS | IN_CHANGE | IN_UPDATE | IN_MODIFY))) {
                return;
        }

        vfs_timestamp(&now);
        if (ip->iflag & IN_ACCESS) {
                if (acc == NULL)
                        acc = &now;
                ip->atime = acc->tv_sec;
        }
        if (ip->iflag & (IN_UPDATE | IN_MODIFY)) {
                if (mod == NULL)
                        mod = &now;
                ip->mtime = mod->tv_sec;
        }
        if (ip->iflag & (IN_CHANGE | IN_MODIFY)) {
                if (cre == NULL)
                        cre = &now;
                ip->ctime = cre->tv_sec;
        }
        if (ip->iflag & (IN_ACCESS | IN_MODIFY))
                ip->iflag |= IN_ACCESSED;
        if (ip->iflag & (IN_UPDATE | IN_CHANGE))
                ip->iflag |= IN_MODIFIED;
        ip->iflag &= ~(IN_ACCESS | IN_CHANGE | IN_UPDATE | IN_MODIFY);
}

/* chfs_update - updates a vnode times */
int
chfs_update(struct vnode *vp, const struct timespec *acc,
    const struct timespec *mod, int flags)
{
        struct chfs_inode *ip;

        /* XXX ufs_reclaim calls this function unlocked! */

        ip = VTOI(vp);
        chfs_itimes(ip, acc, mod, NULL);

        return (0);
}