/*      $OpenBSD: msdosfs_lookup.c,v 1.4 2021/10/06 00:40:41 deraadt Exp $      */
/*      $NetBSD: msdosfs_lookup.c,v 1.35 2016/01/30 09:59:27 mlelstv 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 "ffs/buf.h"

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



/*
 * dep  - directory entry to copy into the directory
 * ddep - directory to add to
 * depp - return the address of the denode for the created directory entry
 *        if depp != 0
 * cnp  - componentname needed for Win95 long filenames
 */
int
createde(struct denode *dep, struct denode *ddep, struct denode **depp, struct componentname *cnp)
{
        int error, rberror;
        u_long dirclust, clusoffset;
        u_long fndoffset, havecnt = 0, wcnt = 1, i;
        struct direntry *ndep;
        struct msdosfsmount *pmp = ddep->de_pmp;
        struct mkfsbuf *bp;
        daddr_t bn;
        int blsize;
#define async 0

#ifdef MSDOSFS_DEBUG
        printf("createde(dep %p, ddep %p, depp %p, cnp %p)\n",
            dep, ddep, depp, cnp);
#endif

        /*
         * If no space left in the directory then allocate another cluster
         * and chain it onto the end of the file.  There is one exception
         * to this.  That is, if the root directory has no more space it
         * can NOT be expanded.  extendfile() checks for and fails attempts
         * to extend the root directory.  We just return an error in that
         * case.
         */
        if (ddep->de_fndoffset >= ddep->de_FileSize) {
                u_long needlen = ddep->de_fndoffset + sizeof(struct direntry)
                    - ddep->de_FileSize;
                dirclust = de_clcount(pmp, needlen);
                if ((error = extendfile(ddep, dirclust, 0, 0, DE_CLEAR)) != 0) {
                        (void)detrunc(ddep, ddep->de_FileSize, 0);
                        goto err_norollback;
                }

                /*
                 * Update the size of the directory
                 */
                ddep->de_FileSize += de_cn2off(pmp, dirclust);
        }

        /*
         * We just read in the cluster with space.  Copy the new directory
         * entry in.  Then write it to disk. NOTE:  DOS directories
         * do not get smaller as clusters are emptied.
         */
        error = pcbmap(ddep, de_cluster(pmp, ddep->de_fndoffset),
                       &bn, &dirclust, &blsize);
        if (error)
                goto err_norollback;
        clusoffset = ddep->de_fndoffset;
        if (dirclust != MSDOSFSROOT)
                clusoffset &= pmp->pm_crbomask;
        if ((error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), blsize,
            B_MODIFY, &bp)) != 0) {
                goto err_norollback;
        }
        ndep = bptoep(pmp, bp, clusoffset);

        DE_EXTERNALIZE(ndep, dep);

        /*
         * Now write the Win95 long name
         */
        if (ddep->de_fndcnt > 0) {
                u_int8_t chksum = winChksum(ndep->deName);
                u_char *un = cnp->cn_nameptr;
                int unlen = cnp->cn_namelen;
                u_long xhavecnt;

                fndoffset = ddep->de_fndoffset;
                xhavecnt = ddep->de_fndcnt + 1;

                for(; wcnt < xhavecnt; wcnt++) {
                        if ((fndoffset & pmp->pm_crbomask) == 0) {
                                /* we should never get here if ddep is root
                                 * directory */

                                if (async)
                                        (void) bdwrite(bp);
                                else if ((error = bwrite(bp)) != 0)
                                        goto rollback;

                                fndoffset -= sizeof(struct direntry);
                                error = pcbmap(ddep,
                                               de_cluster(pmp, fndoffset),
                                               &bn, 0, &blsize);
                                if (error)
                                        goto rollback;

                                error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn),
                                    blsize, B_MODIFY, &bp);
                                if (error) {
                                        goto rollback;
                                }
                                ndep = bptoep(pmp, bp,
                                                fndoffset & pmp->pm_crbomask);
                        } else {
                                ndep--;
                                fndoffset -= sizeof(struct direntry);
                        }
                        if (!unix2winfn(un, unlen, (struct winentry *)ndep,
                                        wcnt, chksum))
                                break;
                }
        }

        if (async)
                bdwrite(bp);
        else if ((error = bwrite(bp)) != 0)
                goto rollback;

        /*
         * If they want us to return with the denode gotten.
         */
        if (depp) {
                u_long diroffset = clusoffset;

                if (dep->de_Attributes & ATTR_DIRECTORY) {
                        dirclust = dep->de_StartCluster;
                        if (FAT32(pmp) && dirclust == pmp->pm_rootdirblk)
                                dirclust = MSDOSFSROOT;
                        if (dirclust == MSDOSFSROOT)
                                diroffset = MSDOSFSROOT_OFS;
                        else
                                diroffset = 0;
                }
                error = deget(pmp, dirclust, diroffset, depp);
                return error;
        }

        return 0;

    rollback:
        /*
         * Mark all slots modified so far as deleted. Note that we
         * can't just call removede(), since directory is not in
         * consistent state.
         */
        fndoffset = ddep->de_fndoffset;
        rberror = pcbmap(ddep, de_cluster(pmp, fndoffset),
               &bn, NULL, &blsize);
        if (rberror)
                goto err_norollback;
        if ((rberror = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), blsize,
            B_MODIFY, &bp)) != 0) {
                goto err_norollback;
        }
        ndep = bptoep(pmp, bp, clusoffset);

        havecnt = ddep->de_fndcnt + 1;
        for(i = wcnt; i <= havecnt; i++) {
                /* mark entry as deleted */
                ndep->deName[0] = SLOT_DELETED;

                if ((fndoffset & pmp->pm_crbomask) == 0) {
                        /* we should never get here if ddep is root
                         * directory */

                        if (async)
                                bdwrite(bp);
                        else if ((rberror = bwrite(bp)) != 0)
                                goto err_norollback;

                        fndoffset -= sizeof(struct direntry);
                        rberror = pcbmap(ddep,
                                       de_cluster(pmp, fndoffset),
                                       &bn, 0, &blsize);
                        if (rberror)
                                goto err_norollback;

                        rberror = bread(pmp->pm_devvp, de_bn2kb(pmp, bn),
                            blsize, B_MODIFY, &bp);
                        if (rberror) {
                                goto err_norollback;
                        }
                        ndep = bptoep(pmp, bp, fndoffset);
                } else {
                        ndep--;
                        fndoffset -= sizeof(struct direntry);
                }
        }

        /* ignore any further error */
        if (async)
                (void) bdwrite(bp);
        else
                (void) bwrite(bp);

    err_norollback:
        return error;
}

/*
 * Read in the disk block containing the directory entry (dirclu, dirofs)
 * and return the address of the buf header, and the address of the
 * directory entry within the block.
 */
int
readep(struct msdosfsmount *pmp, u_long dirclust, u_long diroffset, struct mkfsbuf **bpp, struct direntry **epp)
{
        int error;
        daddr_t bn;
        int blsize;

        blsize = pmp->pm_bpcluster;
        if (dirclust == MSDOSFSROOT
            && de_blk(pmp, diroffset + blsize) > pmp->pm_rootdirsize)
                blsize = de_bn2off(pmp, pmp->pm_rootdirsize) & pmp->pm_crbomask;
        bn = detobn(pmp, dirclust, diroffset);
        if ((error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), blsize,
            0, bpp)) != 0) {
                *bpp = NULL;
                return (error);
        }
        if (epp)
                *epp = bptoep(pmp, *bpp, diroffset);
        return (0);
}

/*
 * Read in the disk block containing the directory entry dep came from and
 * return the address of the buf header, and the address of the directory
 * entry within the block.
 */
int
readde(struct denode *dep, struct mkfsbuf **bpp, struct direntry **epp)
{
        return (readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
                        bpp, epp));
}

/*
 * Create a unique DOS name in dvp
 */
int
uniqdosname(struct denode *dep, struct componentname *cnp, u_char *cp)
{
        struct msdosfsmount *pmp = dep->de_pmp;
        struct direntry *dentp;
        int gen;
        int blsize;
        u_long cn;
        daddr_t bn;
        struct mkfsbuf *bp;
        int error;

        for (gen = 1;; gen++) {
                /*
                 * Generate DOS name with generation number
                 */
                if (!unix2dosfn(cnp->cn_nameptr, cp, cnp->cn_namelen, gen))
                        return gen == 1 ? EINVAL : EEXIST;

                /*
                 * Now look for a dir entry with this exact name
                 */
                for (cn = error = 0; !error; cn++) {
                        if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
                                if (error == E2BIG)     /* EOF reached and not found */
                                        return 0;
                                return error;
                        }
                        error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), blsize,
                            0, &bp);
                        if (error) {
                                return error;
                        }
                        for (dentp = (struct direntry *)bp->b_data;
                             (char *)dentp < (char *)bp->b_data + blsize;
                             dentp++) {
                                if (dentp->deName[0] == SLOT_EMPTY) {
                                        /*
                                         * Last used entry and not found
                                         */
                                        brelse(bp, 0);
                                        return 0;
                                }
                                /*
                                 * Ignore volume labels and Win95 entries
                                 */
                                if (dentp->deAttributes & ATTR_VOLUME)
                                        continue;
                                if (!memcmp(dentp->deName, cp, 11)) {
                                        error = EEXIST;
                                        break;
                                }
                        }
                        brelse(bp, 0);
                }
        }
}