/*      $OpenBSD: msdosfs_vfsops.c,v 1.14 2023/12/01 16:23:03 miod 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>  /* MAXBSIZE */
#include <sys/types.h>

#include "ffs/buf.h"

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

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <util.h>

#include "makefs.h"
#include "msdos.h"
#include "msdos/mkfs_msdos.h"

#ifdef MSDOSFS_DEBUG
#define DPRINTF(a) printf a
#else
#define DPRINTF(a)
#endif

struct msdosfsmount *
msdosfs_mount(struct mkfsvnode *devvp, int flags)
{
        struct msdosfsmount *pmp = NULL;
        struct mkfsbuf *bp;
        union bootsector *bsp;
        struct byte_bpb33 *b33;
        struct byte_bpb50 *b50;
        struct byte_bpb710 *b710;
        uint8_t SecPerClust;
        int     ronly = 0, error;
        int     bsize;
        unsigned secsize = 512;

        DPRINTF(("%s(bread 0)\n", __func__));
        if ((error = bread(devvp, 0, secsize, 0, &bp)) != 0)
                goto error_exit;

        bsp = (union bootsector *)bp->b_data;
        b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
        b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
        b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;

        if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
            || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
                DPRINTF(("bootsig0 %d bootsig1 %d\n",
                    bsp->bs50.bsBootSectSig0,
                    bsp->bs50.bsBootSectSig1));
                error = EINVAL;
                goto error_exit;
        }
        bsize = 0;

        pmp = ecalloc(1, sizeof *pmp);
        /*
         * Compute several useful quantities from the bpb in the
         * bootsector.  Copy in the dos 5 variant of the bpb then fix up
         * the fields that are different between dos 5 and dos 3.3.
         */
        SecPerClust = b50->bpbSecPerClust;
        pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
        pmp->pm_ResSectors = getushort(b50->bpbResSectors);
        pmp->pm_FATs = b50->bpbFATs;
        pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
        pmp->pm_Sectors = getushort(b50->bpbSectors);
        pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
        pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
        pmp->pm_Heads = getushort(b50->bpbHeads);
        pmp->pm_Media = b50->bpbMedia;
        pmp->pm_minuteswest = 0;

        DPRINTF(("%s(BytesPerSec=%u, ResSectors=%u, FATs=%d, RootDirEnts=%u, "
            "Sectors=%u, FATsecs=%lu, SecPerTrack=%u, Heads=%u, Media=%u)\n",
            __func__, pmp->pm_BytesPerSec, pmp->pm_ResSectors, pmp->pm_FATs,
            pmp->pm_RootDirEnts, pmp->pm_Sectors, pmp->pm_FATsecs,
            pmp->pm_SecPerTrack, pmp->pm_Heads, pmp->pm_Media));
        /* XXX - We should probably check more values here */
        if (!pmp->pm_BytesPerSec || !SecPerClust
                || pmp->pm_SecPerTrack > 63) {
                DPRINTF(("bytespersec %d secperclust %d "
                    "secpertrack %d\n",
                    pmp->pm_BytesPerSec, SecPerClust,
                    pmp->pm_SecPerTrack));
                error = EINVAL;
                goto error_exit;
        }

        pmp->pm_flags = flags & MSDOSFSMNT_MNTOPT;
        if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
                pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;

        if (pmp->pm_Sectors == 0) {
                pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
                pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
        } else {
                pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
                pmp->pm_HugeSectors = pmp->pm_Sectors;
        }

        if (pmp->pm_RootDirEnts == 0) {
                unsigned short vers = getushort(b710->bpbFSVers);
                /*
                 * Some say that bsBootSectSig[23] must be zero, but
                 * Windows does not require this and some digital cameras
                 * do not set these to zero.  Therefore, do not insist.
                 */
                if (pmp->pm_Sectors || pmp->pm_FATsecs || vers) {
                        DPRINTF(("sectors %d fatsecs %lu vers %d\n",
                            pmp->pm_Sectors, pmp->pm_FATsecs, vers));
                        error = EINVAL;
                        goto error_exit;
                }
                pmp->pm_fatmask = FAT32_MASK;
                pmp->pm_fatmult = 4;
                pmp->pm_fatdiv = 1;
                pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);

                /* mirrorring is enabled if the FATMIRROR bit is not set */
                if ((getushort(b710->bpbExtFlags) & FATMIRROR) == 0)
                        pmp->pm_flags |= MSDOSFS_FATMIRROR;
                else
                        pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
        } else
                pmp->pm_flags |= MSDOSFS_FATMIRROR;

        /* Check that fs has nonzero FAT size */
        if (pmp->pm_FATsecs == 0) {
                DPRINTF(("FATsecs is 0\n"));
                error = EINVAL;
                goto error_exit;
        }

        pmp->pm_fatblk = pmp->pm_ResSectors;
        if (FAT32(pmp)) {
                pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
                pmp->pm_firstcluster = pmp->pm_fatblk
                        + (pmp->pm_FATs * pmp->pm_FATsecs);
                pmp->pm_fsinfo = getushort(b710->bpbFSInfo);
        } else {
                pmp->pm_rootdirblk = pmp->pm_fatblk +
                        (pmp->pm_FATs * pmp->pm_FATsecs);
                pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
                                       + pmp->pm_BytesPerSec - 1)
                        / pmp->pm_BytesPerSec;/* in sectors */
                pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
        }

        pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
            SecPerClust;
        pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
        pmp->pm_fatsize = pmp->pm_FATsecs * pmp->pm_BytesPerSec;

        if (pmp->pm_fatmask == 0) {
                if (pmp->pm_maxcluster
                    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
                        /*
                         * This will usually be a floppy disk. This size makes
                         * sure that one FAT entry will not be split across
                         * multiple blocks.
                         */
                        pmp->pm_fatmask = FAT12_MASK;
                        pmp->pm_fatmult = 3;
                        pmp->pm_fatdiv = 2;
                } else {
                        pmp->pm_fatmask = FAT16_MASK;
                        pmp->pm_fatmult = 2;
                        pmp->pm_fatdiv = 1;
                }
        }
        if (FAT12(pmp))
                pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
        else
                pmp->pm_fatblocksize = MAXBSIZE;

        pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec;
        pmp->pm_bnshift = ffs(pmp->pm_BytesPerSec) - 1;

        /*
         * Compute mask and shift value for isolating cluster relative byte
         * offsets and cluster numbers from a file offset.
         */
        pmp->pm_bpcluster = SecPerClust * pmp->pm_BytesPerSec;
        pmp->pm_crbomask = pmp->pm_bpcluster - 1;
        pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;

        DPRINTF(("%s(fatmask=%lu, fatmult=%u, fatdiv=%u, fatblocksize=%lu, "
            "fatblocksec=%lu, bnshift=%lu, pbcluster=%lu, crbomask=%lu, "
            "cnshift=%lu)\n",
            __func__, pmp->pm_fatmask, pmp->pm_fatmult, pmp->pm_fatdiv,
            pmp->pm_fatblocksize, pmp->pm_fatblocksec, pmp->pm_bnshift,
            pmp->pm_bpcluster, pmp->pm_crbomask, pmp->pm_cnshift));
        /*
         * Check for valid cluster size
         * must be a power of 2
         */
        if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
                DPRINTF(("bpcluster %lu cnshift %lu\n",
                    pmp->pm_bpcluster, pmp->pm_cnshift));
                error = EINVAL;
                goto error_exit;
        }

        /*
         * Release the bootsector buffer.
         */
        brelse(bp, BC_AGE);
        bp = NULL;

        /*
         * Check FSInfo.
         */
        if (pmp->pm_fsinfo) {
                struct fsinfo *fp;

                /*
                 * XXX  If the fsinfo block is stored on media with
                 *      2KB or larger sectors, is the fsinfo structure
                 *      padded at the end or in the middle?
                 */
                DPRINTF(("%s(bread %lu)\n", __func__,
                    (unsigned long)de_bn2kb(pmp, pmp->pm_fsinfo)));
                if ((error = bread(devvp, de_bn2kb(pmp, pmp->pm_fsinfo),
                    roundup(sizeof(struct fsinfo), pmp->pm_BytesPerSec),
                    0, &bp)) != 0)
                        goto error_exit;
                fp = (struct fsinfo *)bp->b_data;
                if (!memcmp(fp->fsisig1, "RRaA", 4)
                    && !memcmp(fp->fsisig2, "rrAa", 4)
                    && !memcmp(fp->fsisig3, "\0\0\125\252", 4)
                    && !memcmp(fp->fsisig4, "\0\0\125\252", 4))
                        pmp->pm_nxtfree = getulong(fp->fsinxtfree);
                else
                        pmp->pm_fsinfo = 0;
                brelse(bp, 0);
                bp = NULL;
        }

        /*
         * Check and validate (or perhaps invalidate?) the fsinfo structure?
         * XXX
         */
        if (pmp->pm_fsinfo) {
                if ((pmp->pm_nxtfree == 0xffffffffUL) ||
                    (pmp->pm_nxtfree > pmp->pm_maxcluster))
                        pmp->pm_fsinfo = 0;
        }

        /*
         * Allocate memory for the bitmap of allocated clusters, and then
         * fill it in.
         */
        pmp->pm_inusemap = ecalloc(sizeof(*pmp->pm_inusemap),
            ((pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS));
        /*
         * fillinusemap() needs pm_devvp.
         */
        pmp->pm_dev = 0;
        pmp->pm_devvp = devvp;

        /*
         * Have the inuse map filled in.
         */
        if ((error = fillinusemap(pmp)) != 0) {
                DPRINTF(("fillinusemap %d\n", error));
                goto error_exit;
        }

        /*
         * Finish up.
         */
        if (ronly)
                pmp->pm_flags |= MSDOSFSMNT_RONLY;
        else
                pmp->pm_fmod = 1;

        return pmp;

error_exit:
        if (bp)
                brelse(bp, BC_AGE);
        if (pmp) {
                if (pmp->pm_inusemap)
                        free(pmp->pm_inusemap);
                free(pmp);
        }
        errno = error;
        return NULL;
}

int
msdosfs_root(struct msdosfsmount *pmp, struct mkfsvnode *vp) {
        struct denode *ndep;
        int error;

        *vp = *pmp->pm_devvp;
        if ((error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep)) != 0) {
                errno = error;
                return -1;
        }
        vp->v_data = ndep;
        return 0;
}