/*      $OpenBSD: msdosfs_denode.c,v 1.68 2023/03/08 04:43:08 guenther Exp $    */
/*      $NetBSD: msdosfs_denode.c,v 1.23 1997/10/17 11:23:58 ws Exp $   */

/*-
 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
 * All rights reserved.
 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
 *
 * 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 TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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.
 */
/*
 * Written by Paul Popelka (paulp@uts.amdahl.com)
 *
 * You can do anything you want with this software, just don't say you wrote
 * it, and don't remove this notice.
 *
 * This software is provided "as is".
 *
 * The author supplies this software to be publicly redistributed on the
 * understanding that the author is not responsible for the correct
 * functioning of this software in any circumstances and is not liable for
 * any damages caused by this software.
 *
 * October 1992
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/lock.h>
#include <sys/kernel.h>         /* defines "time" */
#include <sys/dirent.h>
#include <sys/namei.h>

#include <crypto/siphash.h>

#include <msdosfs/bpb.h>
#include <msdosfs/msdosfsmount.h>
#include <msdosfs/direntry.h>
#include <msdosfs/denode.h>
#include <msdosfs/fat.h>

u_int msdosfs_dehash(dev_t, uint32_t, uint32_t);

struct denode **dehashtbl;
SIPHASH_KEY dehashkey;
u_long dehash;                  /* size of hash table - 1 */
#define DEHASH(dev, dcl, doff) msdosfs_dehash((dev), (dcl), (doff))

static struct denode *msdosfs_hashget(dev_t, uint32_t, uint32_t);
static int msdosfs_hashins(struct denode *);
static void msdosfs_hashrem(struct denode *);

int
msdosfs_init(struct vfsconf *vfsp)
{
        dehashtbl = hashinit(initialvnodes / 2, M_MSDOSFSMNT, M_WAITOK, &dehash);
        arc4random_buf(&dehashkey, sizeof(dehashkey));
        return (0);
}

u_int
msdosfs_dehash(dev_t dev, uint32_t dirclust, uint32_t diroff)
{
        SIPHASH_CTX ctx;

        SipHash24_Init(&ctx, &dehashkey);
        SipHash24_Update(&ctx, &dev, sizeof(dev));
        SipHash24_Update(&ctx, &dirclust, sizeof(dirclust));
        SipHash24_Update(&ctx, &diroff, sizeof(diroff));

        return (SipHash24_End(&ctx) & dehash);
}

static struct denode *
msdosfs_hashget(dev_t dev, uint32_t dirclust, uint32_t diroff)
{
        struct denode *dep;

        for (;;)
                for (dep = dehashtbl[DEHASH(dev, dirclust, diroff)]; ;
                     dep = dep->de_next) {
                        if (dep == NULL)
                                return (NULL);
                        if (dirclust == dep->de_dirclust &&
                            diroff == dep->de_diroffset &&
                            dev == dep->de_dev &&
                            dep->de_refcnt != 0) {
                                struct vnode *vp = DETOV(dep);

                                if (!vget(vp, LK_EXCLUSIVE))
                                        return (dep);
                                break;
                        }
                }
        /* NOTREACHED */
}

static int
msdosfs_hashins(struct denode *dep)
{
        struct denode **depp, *deq;

        depp = &dehashtbl[DEHASH(dep->de_dev, dep->de_dirclust,
                                 dep->de_diroffset)];

        for (deq = *depp; deq; deq = deq->de_next) {
                if (dep->de_dirclust == deq->de_dirclust &&
                    dep->de_diroffset == deq->de_diroffset &&
                    dep->de_dev == deq->de_dev &&
                    deq->de_refcnt != 0) {
                        return (EEXIST);
                }
        }

        if ((deq = *depp) != NULL)
                deq->de_prev = &dep->de_next;
        dep->de_next = deq;
        dep->de_prev = depp;
        *depp = dep;
        return (0);
}

static void
msdosfs_hashrem(struct denode *dep)
{
        struct denode *deq;

        if (dep->de_prev == NULL)
                return;

        if ((deq = dep->de_next) != NULL)
                deq->de_prev = dep->de_prev;
        *dep->de_prev = deq;
#ifdef DIAGNOSTIC
        dep->de_next = NULL;
        dep->de_prev = NULL;
#endif
}

/*
 * If deget() succeeds it returns with the gotten denode locked().
 *
 * pmp       - address of msdosfsmount structure of the filesystem containing
 *             the denode of interest.  The pm_dev field and the address of
 *             the msdosfsmount structure are used.
 * dirclust  - which cluster bp contains, if dirclust is 0 (root directory)
 *             diroffset is relative to the beginning of the root directory,
 *             otherwise it is cluster relative.
 * diroffset - offset past begin of cluster of denode we want
 * depp      - returns the address of the gotten denode.
 */
int
deget(struct msdosfsmount *pmp, uint32_t dirclust, uint32_t diroffset,
    struct denode **depp)
{
        int error;
        extern const struct vops msdosfs_vops;
        struct direntry *direntptr;
        struct denode *ldep;
        struct vnode *nvp;
        struct buf *bp;

#ifdef MSDOSFS_DEBUG
        printf("deget(pmp %p, dirclust %d, diroffset %x, depp %p)\n",
            pmp, dirclust, diroffset, depp);
#endif

        /*
         * On FAT32 filesystems, root is a (more or less) normal
         * directory
         */
        if (FAT32(pmp) && dirclust == MSDOSFSROOT)
                dirclust = pmp->pm_rootdirblk;

        /*
         * See if the denode is in the denode cache. Use the location of
         * the directory entry to compute the hash value. For subdir use
         * address of "." entry. For root dir (if not FAT32) use cluster
         * MSDOSFSROOT, offset MSDOSFSROOT_OFS
         *
         * NOTE: The check for de_refcnt > 0 below insures the denode being
         * examined does not represent an unlinked but still open file.
         * These files are not to be accessible even when the directory
         * entry that represented the file happens to be reused while the
         * deleted file is still open.
         */
retry:
        ldep = msdosfs_hashget(pmp->pm_dev, dirclust, diroffset);
        if (ldep) {
                *depp = ldep;
                return (0);
        }

        /*
         * Directory entry was not in cache, have to create a vnode and
         * copy it from the passed disk buffer.
         */
        /* getnewvnode() does a vref() on the vnode */
        error = getnewvnode(VT_MSDOSFS, pmp->pm_mountp, &msdosfs_vops, &nvp);
        if (error) {
                *depp = 0;
                return (error);
        }
        ldep = malloc(sizeof(*ldep), M_MSDOSFSNODE, M_WAITOK | M_ZERO);
        rrw_init_flags(&ldep->de_lock, "denode", RWL_DUPOK | RWL_IS_VNODE);
        nvp->v_data = ldep;
        ldep->de_vnode = nvp;
        ldep->de_flag = 0;
        ldep->de_devvp = 0;
        ldep->de_lockf = 0;
        ldep->de_dev = pmp->pm_dev;
        ldep->de_dirclust = dirclust;
        ldep->de_diroffset = diroffset;
        fc_purge(ldep, 0);      /* init the fat cache for this denode */

        /*
         * Insert the denode into the hash queue and lock the denode so it
         * can't be accessed until we've read it in and have done what we
         * need to it.
         */
        vn_lock(nvp, LK_EXCLUSIVE | LK_RETRY);
        error = msdosfs_hashins(ldep);

        if (error) {
                vput (nvp);

                if (error == EEXIST)
                        goto retry;

                return (error);
        }

        ldep->de_pmp = pmp;
        ldep->de_devvp = pmp->pm_devvp;
        ldep->de_refcnt = 1;
        /*
         * Copy the directory entry into the denode area of the vnode.
         */
        if ((dirclust == MSDOSFSROOT
             || (FAT32(pmp) && dirclust == pmp->pm_rootdirblk))
            && diroffset == MSDOSFSROOT_OFS) {
                /*
                 * Directory entry for the root directory. There isn't one,
                 * so we manufacture one. We should probably rummage
                 * through the root directory and find a label entry (if it
                 * exists), and then use the time and date from that entry
                 * as the time and date for the root denode.
                 */
                nvp->v_flag |= VROOT; /* should be further down         XXX */

                ldep->de_Attributes = ATTR_DIRECTORY;
                if (FAT32(pmp))
                        ldep->de_StartCluster = pmp->pm_rootdirblk;
                        /* de_FileSize will be filled in further down */
                else {
                        ldep->de_StartCluster = MSDOSFSROOT;
                        ldep->de_FileSize = pmp->pm_rootdirsize * pmp->pm_BytesPerSec;
                }
                /*
                 * fill in time and date so that dos2unixtime() doesn't
                 * spit up when called from msdosfs_getattr() with root
                 * denode
                 */
                ldep->de_CTime = 0x0000;        /* 00:00:00      */
                ldep->de_CTimeHundredth = 0;
                ldep->de_CDate = (0 << DD_YEAR_SHIFT) | (1 << DD_MONTH_SHIFT)
                    | (1 << DD_DAY_SHIFT);
                /* Jan 1, 1980   */
                ldep->de_ADate = ldep->de_CDate;
                ldep->de_MTime = ldep->de_CTime;
                ldep->de_MDate = ldep->de_CDate;
                /* leave the other fields as garbage */
        } else {
                error = readep(pmp, dirclust, diroffset, &bp, &direntptr);
                if (error)
                        return (error);
                DE_INTERNALIZE(ldep, direntptr);
                brelse(bp);
        }

        /*
         * Fill in a few fields of the vnode and finish filling in the
         * denode.  Then return the address of the found denode.
         */
        if (ldep->de_Attributes & ATTR_DIRECTORY) {
                /*
                 * Since DOS directory entries that describe directories
                 * have 0 in the filesize field, we take this opportunity
                 * to find out the length of the directory and plug it into
                 * the denode structure.
                 */
                uint32_t size;

                nvp->v_type = VDIR;
                if (ldep->de_StartCluster != MSDOSFSROOT) {
                        error = pcbmap(ldep, CLUST_END, 0, &size, 0);
                        if (error == E2BIG) {
                                ldep->de_FileSize = de_cn2off(pmp, size);
                                error = 0;
                        } else if (error) {
                                printf("deget(): pcbmap returned %d\n", error);
                                return (error);
                        }
                }
        } else
                nvp->v_type = VREG;
        vref(ldep->de_devvp);
        *depp = ldep;
        return (0);
}

int
deupdat(struct denode *dep, int waitfor)
{
        struct buf *bp;
        struct direntry *dirp;
        int error;
        struct timespec ts;

        if (DETOV(dep)->v_mount->mnt_flag & MNT_RDONLY)
                return (0);
        getnanotime(&ts);
        DETIMES(dep, &ts, &ts, &ts);
        if ((dep->de_flag & DE_MODIFIED) == 0)
                return (0);
        dep->de_flag &= ~DE_MODIFIED;
        if (dep->de_Attributes & ATTR_DIRECTORY)
                return (0);
        if (dep->de_refcnt <= 0)
                return (0);
        error = readde(dep, &bp, &dirp);
        if (error)
                return (error);
        DE_EXTERNALIZE(dirp, dep);
        if (waitfor)
                return (bwrite(bp));
        else {
                bdwrite(bp);
                return (0);
        }
}

/*
 * Truncate the file described by dep to the length specified by length.
 */
int
detrunc(struct denode *dep, uint32_t length, int flags, struct ucred *cred,
    struct proc *p)
{
        int error;
        int allerror;
        int vflags;
        uint32_t eofentry;
        uint32_t chaintofree = 0;
        daddr_t bn;
        int boff;
        int isadir = dep->de_Attributes & ATTR_DIRECTORY;
        struct buf *bp;
        struct msdosfsmount *pmp = dep->de_pmp;

#ifdef MSDOSFS_DEBUG
        printf("detrunc(): file %.11s, length %u, flags %d\n",
            dep->de_Name, length, flags);
#endif

        /*
         * Disallow attempts to truncate the root directory since it is of
         * fixed size.  That's just the way dos filesystems are.  We use
         * the VROOT bit in the vnode because checking for the directory
         * bit and a startcluster of 0 in the denode is not adequate to
         * recognize the root directory at this point in a file or
         * directory's life.
         */
        if ((DETOV(dep)->v_flag & VROOT) && !FAT32(pmp)) {
                printf("detrunc(): can't truncate root directory, clust %u, offset %u\n",
                    dep->de_dirclust, dep->de_diroffset);
                return (EINVAL);
        }

        uvm_vnp_setsize(DETOV(dep), length);

        if (dep->de_FileSize < length)
                return (deextend(dep, length, cred));

        /*
         * If the desired length is 0 then remember the starting cluster of
         * the file and set the StartCluster field in the directory entry
         * to 0.  If the desired length is not zero, then get the number of
         * the last cluster in the shortened file.  Then get the number of
         * the first cluster in the part of the file that is to be freed.
         * Then set the next cluster pointer in the last cluster of the
         * file to CLUST_EOFE.
         */
        if (length == 0) {
                chaintofree = dep->de_StartCluster;
                dep->de_StartCluster = 0;
                eofentry = ~0;
        } else {
                error = pcbmap(dep, de_clcount(pmp, length) - 1, 0,
                               &eofentry, 0);
                if (error) {
#ifdef MSDOSFS_DEBUG
                        printf("detrunc(): pcbmap fails %d\n", error);
#endif
                        return (error);
                }
        }

        fc_purge(dep, de_clcount(pmp, length));

        /*
         * If the new length is not a multiple of the cluster size then we
         * must zero the tail end of the new last cluster in case it
         * becomes part of the file again because of a seek.
         */
        if ((boff = length & pmp->pm_crbomask) != 0) {
                if (isadir) {
                        bn = cntobn(pmp, eofentry);
                        error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, &bp);
                } else {
                        bn = de_blk(pmp, length);
                        error = bread(DETOV(dep), bn, pmp->pm_bpcluster, &bp);
                }
                if (error) {
                        brelse(bp);
#ifdef MSDOSFS_DEBUG
                        printf("detrunc(): bread fails %d\n", error);
#endif
                        return (error);
                }
                uvm_vnp_uncache(DETOV(dep));
                /*
                 * is this the right place for it?
                 */
                bzero(bp->b_data + boff, pmp->pm_bpcluster - boff);
                if (flags & IO_SYNC)
                        bwrite(bp);
                else
                        bdwrite(bp);
        }

        /*
         * Write out the updated directory entry.  Even if the update fails
         * we free the trailing clusters.
         */
        dep->de_FileSize = length;
        if (!isadir)
                dep->de_flag |= DE_UPDATE|DE_MODIFIED;
        vflags = (length > 0 ? V_SAVE : 0) | V_SAVEMETA;
        vinvalbuf(DETOV(dep), vflags, cred, p, 0, INFSLP);
        allerror = deupdat(dep, 1);
#ifdef MSDOSFS_DEBUG
        printf("detrunc(): allerror %d, eofentry %d\n",
               allerror, eofentry);
#endif

        /*
         * If we need to break the cluster chain for the file then do it
         * now.
         */
        if (eofentry != ~0) {
                error = fatentry(FAT_GET_AND_SET, pmp, eofentry,
                                 &chaintofree, CLUST_EOFE);
                if (error) {
#ifdef MSDOSFS_DEBUG
                        printf("detrunc(): fatentry errors %d\n", error);
#endif
                        return (error);
                }
                fc_setcache(dep, FC_LASTFC, de_cluster(pmp, length - 1),
                            eofentry);
        }

        /*
         * Now free the clusters removed from the file because of the
         * truncation.
         */
        if (chaintofree != 0 && !MSDOSFSEOF(pmp, chaintofree))
                freeclusterchain(pmp, chaintofree);

        return (allerror);
}

/*
 * Extend the file described by dep to length specified by length.
 */
int
deextend(struct denode *dep, uint32_t length, struct ucred *cred)
{
        struct msdosfsmount *pmp = dep->de_pmp;
        uint32_t count;
        int error;

        /*
         * The root of a DOS filesystem cannot be extended.
         */
        if ((DETOV(dep)->v_flag & VROOT) && !FAT32(pmp))
                return (EINVAL);

        /*
         * Directories cannot be extended.
         */
        if (dep->de_Attributes & ATTR_DIRECTORY)
                return (EISDIR);

        if (length <= dep->de_FileSize)
                panic("deextend: file too large");

        /*
         * Compute the number of clusters to allocate.
         */
        count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
        if (count > 0) {
                if (count > pmp->pm_freeclustercount)
                        return (ENOSPC);
                error = extendfile(dep, count, NULL, NULL, DE_CLEAR);
                if (error) {
                        /* truncate the added clusters away again */
                        (void) detrunc(dep, dep->de_FileSize, 0, cred, curproc);
                        return (error);
                }
        }

        dep->de_FileSize = length;
        dep->de_flag |= DE_UPDATE|DE_MODIFIED;
        return (deupdat(dep, 1));
}

/*
 * Move a denode to its correct hash queue after the file it represents has
 * been moved to a new directory.
 */
void
reinsert(struct denode *dep)
{
        /*
         * Fix up the denode cache.  If the denode is for a directory,
         * there is nothing to do since the hash is based on the starting
         * cluster of the directory file and that hasn't changed.  If for a
         * file the hash is based on the location of the directory entry,
         * so we must remove it from the cache and re-enter it with the
         * hash based on the new location of the directory entry.
         */
        if (dep->de_Attributes & ATTR_DIRECTORY)
                return;
        msdosfs_hashrem(dep);
        msdosfs_hashins(dep);
}

int
msdosfs_reclaim(void *v)
{
        struct vop_reclaim_args *ap = v;
        struct vnode *vp = ap->a_vp;
        struct denode *dep = VTODE(vp);
#ifdef DIAGNOSTIC
        extern int prtactive;

        if (prtactive && vp->v_usecount != 0)
                vprint("msdosfs_reclaim(): pushing active", vp);
#endif

#ifdef MSDOSFS_DEBUG
        printf("msdosfs_reclaim(): dep %p, file %.11s, refcnt %ld\n",
            dep, dep->de_Name, dep->de_refcnt);
#endif

        /*
         * Remove the denode from its hash chain.
         */
        msdosfs_hashrem(dep);
        /*
         * Purge old data structures associated with the denode.
         */
        cache_purge(vp);
        if (dep->de_devvp) {
                vrele(dep->de_devvp);
                dep->de_devvp = 0;
        }
#if 0 /* XXX */
        dep->de_flag = 0;
#endif
        free(dep, M_MSDOSFSNODE, 0);
        vp->v_data = NULL;
        return (0);
}

int
msdosfs_inactive(void *v)
{
        struct vop_inactive_args *ap = v;
        struct vnode *vp = ap->a_vp;
        struct denode *dep = VTODE(vp);
        int error;
#ifdef DIAGNOSTIC
        extern int prtactive;

        if (prtactive && vp->v_usecount != 0)
                vprint("msdosfs_inactive(): pushing active", vp);
#endif

#ifdef MSDOSFS_DEBUG
        printf("msdosfs_inactive(): dep %p, de_Name[0] %x\n", dep,
            dep->de_Name[0]);
#endif

        error = 0;

        /*
         * Get rid of denodes related to stale file handles.
         */
        if (dep->de_Name[0] == SLOT_DELETED)
                goto out;

        /*
         * If the file has been deleted and it is on a read/write
         * filesystem, then truncate the file, and mark the directory slot
         * as empty.  (This may not be necessary for the dos filesystem.)
         */
#ifdef MSDOSFS_DEBUG
        printf("msdosfs_inactive(): dep %p, refcnt %ld, mntflag %x, "
            "MNT_RDONLY %x\n", dep, dep->de_refcnt, vp->v_mount->mnt_flag,
            MNT_RDONLY);
#endif
        if (dep->de_refcnt <= 0 && (vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
                error = detrunc(dep, (uint32_t)0, 0, NOCRED, ap->a_p);
                dep->de_Name[0] = SLOT_DELETED;
        }
        deupdat(dep, 0);

out:
        VOP_UNLOCK(vp);
        /*
         * If we are done with the denode, reclaim it
         * so that it can be reused immediately.
         */
#ifdef MSDOSFS_DEBUG
        printf("msdosfs_inactive(): v_usecount %d, de_Name[0] %x\n",
            vp->v_usecount, dep->de_Name[0]);
#endif
        if (dep->de_Name[0] == SLOT_DELETED)
                vrecycle(vp, ap->a_p);
        return (error);
}