/*      $NetBSD: dir.c,v 1.29 2017/04/28 11:33:00 christos Exp $        */

/*
 * Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
 * Copyright (c) 1995 Martin Husemann
 * Some structure declaration borrowed from Paul Popelka
 * (paulp@uts.amdahl.com), see /sys/msdosfs/ for reference.
 *
 * 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 AUTHORS ``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 AUTHORS 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>
#ifndef lint
__RCSID("$NetBSD: dir.c,v 1.29 2017/04/28 11:33:00 christos Exp $");
#endif /* not lint */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <assert.h>
#include <time.h>

#include <sys/param.h>

#include "ext.h"
#include "fsutil.h"

#define SLOT_EMPTY      0x00            /* slot has never been used */
#define SLOT_E5         0x05            /* the real value is 0xe5 */
#define SLOT_DELETED    0xe5            /* file in this slot deleted */

#define ATTR_NORMAL     0x00            /* normal file */
#define ATTR_READONLY   0x01            /* file is readonly */
#define ATTR_HIDDEN     0x02            /* file is hidden */
#define ATTR_SYSTEM     0x04            /* file is a system file */
#define ATTR_VOLUME     0x08            /* entry is a volume label */
#define ATTR_DIRECTORY  0x10            /* entry is a directory name */
#define ATTR_ARCHIVE    0x20            /* file is new or modified */

#define ATTR_WIN95      0x0f            /* long name record */

/*
 * This is the format of the contents of the deTime field in the direntry
 * structure.
 * We don't use bitfields because we don't know how compilers for
 * arbitrary machines will lay them out.
 */
#define DT_2SECONDS_MASK        0x1F    /* seconds divided by 2 */
#define DT_2SECONDS_SHIFT       0
#define DT_MINUTES_MASK         0x7E0   /* minutes */
#define DT_MINUTES_SHIFT        5
#define DT_HOURS_MASK           0xF800  /* hours */
#define DT_HOURS_SHIFT          11

/*
 * This is the format of the contents of the deDate field in the direntry
 * structure.
 */
#define DD_DAY_MASK             0x1F    /* day of month */
#define DD_DAY_SHIFT            0
#define DD_MONTH_MASK           0x1E0   /* month */
#define DD_MONTH_SHIFT          5
#define DD_YEAR_MASK            0xFE00  /* year - 1980 */
#define DD_YEAR_SHIFT           9


/* dir.c */
static struct dosDirEntry *newDosDirEntry(void);
static void freeDosDirEntry(struct dosDirEntry *);
static struct dirTodoNode *newDirTodo(void);
static void freeDirTodo(struct dirTodoNode *);
static char *fullpath(struct dosDirEntry *);
static u_char calcShortSum(u_char *);
static int delete(int, struct bootblock *, struct fatEntry *, cl_t, int,
    cl_t, int, int);
static int removede(int, struct bootblock *, struct fatEntry *, u_char *,
    u_char *, cl_t, cl_t, cl_t, char *, int);
static int checksize(struct bootblock *, struct fatEntry *, u_char *,
    struct dosDirEntry *);
static int readDosDirSection(int, struct bootblock *, struct fatEntry *,
    struct dosDirEntry *);

/*
 * Manage free dosDirEntry structures.
 */
static struct dosDirEntry *freede;

static struct dosDirEntry *
newDosDirEntry(void)
{
        struct dosDirEntry *de;

        if (!(de = freede)) {
                if (!(de = (struct dosDirEntry *)malloc(sizeof *de)))
                        return 0;
        } else
                freede = de->next;
        return de;
}

static void
freeDosDirEntry(struct dosDirEntry *de)
{
        de->next = freede;
        freede = de;
}

/*
 * The same for dirTodoNode structures.
 */
static struct dirTodoNode *freedt;

static struct dirTodoNode *
newDirTodo(void)
{
        struct dirTodoNode *dt;

        if (!(dt = freedt)) {
                if (!(dt = (struct dirTodoNode *)malloc(sizeof *dt)))
                        return 0;
        } else
                freedt = dt->next;
        return dt;
}

static void
freeDirTodo(struct dirTodoNode *dt)
{
        dt->next = freedt;
        freedt = dt;
}

/*
 * The stack of unread directories
 */
struct dirTodoNode *pendingDirectories = NULL;

/*
 * Return the full pathname for a directory entry.
 */
static char *
fullpath(struct dosDirEntry *dir)
{
        static char namebuf[MAXPATHLEN + 1];
        char *cp, *np;
        int nl;

        cp = namebuf + sizeof namebuf - 1;
        *cp = '\0';
        do {
                np = dir->lname[0] ? dir->lname : dir->name;
                nl = strlen(np);
                if ((cp -= nl) <= namebuf + 1)
                        break;
                memcpy(cp, np, nl);
                *--cp = '/';
        } while ((dir = dir->parent) != NULL);
        if (dir)
                *--cp = '?';
        else
                cp++;
        return cp;
}

/*
 * Calculate a checksum over an 8.3 alias name
 */
static u_char
calcShortSum(u_char *p)
{
        u_char sum = 0;
        int i;

        for (i = 0; i < 11; i++) {
                sum = (sum << 7)|(sum >> 1);    /* rotate right */
                sum += p[i];
        }

        return sum;
}

/*
 * Global variables temporarily used during a directory scan
 */
static char longName[DOSLONGNAMELEN] = "";
static char *eLongName = longName + sizeof(longName);
static u_char *buffer = NULL;
static u_char *delbuf = NULL;

struct dosDirEntry *rootDir;
static struct dosDirEntry *lostDir;

/*
 * Init internal state for a new directory scan.
 */
int
resetDosDirSection(struct bootblock *boot, struct fatEntry *fat)
{
        int b1, b2;
        cl_t cl;
        int ret = FSOK;
        size_t len;

        b1 = boot->RootDirEnts * 32;
        b2 = boot->SecPerClust * boot->BytesPerSec;

        if ((buffer = malloc(len = b1 > b2 ? b1 : b2)) == NULL) {
                perr("No space for directory buffer (%zu)", len);
                return FSFATAL;
        }

        if ((delbuf = malloc(len = b2)) == NULL) {
                free(buffer);
                perr("No space for directory delbuf (%zu)", len);
                return FSFATAL;
        }

        if ((rootDir = newDosDirEntry()) == NULL) {
                free(buffer);
                free(delbuf);
                perr("No space for directory entry");
                return FSFATAL;
        }

        memset(rootDir, 0, sizeof *rootDir);
        if (boot->flags & FAT32) {
                if (boot->RootCl < CLUST_FIRST || boot->RootCl >= boot->NumClusters) {
                        pfatal("Root directory starts with cluster out of range(%u)",
                               boot->RootCl);
                        return FSFATAL;
                }
                cl = fat[boot->RootCl].next;
                if (cl < CLUST_FIRST
                    || (cl >= CLUST_RSRVD && cl< CLUST_EOFS)
                    || fat[boot->RootCl].head != boot->RootCl) {
                        if (cl == CLUST_FREE)
                                pwarn("Root directory starts with free cluster\n");
                        else if (cl >= CLUST_RSRVD)
                                pwarn("Root directory starts with cluster marked %s\n",
                                      rsrvdcltype(cl));
                        else {
                                pfatal("Root directory doesn't start a cluster chain");
                                return FSFATAL;
                        }
                        if (ask(1, "Fix")) {
                                fat[boot->RootCl].next = CLUST_FREE;
                                ret = FSFATMOD;
                        } else
                                ret = FSFATAL;
                }

                fat[boot->RootCl].flags |= FAT_USED;
                rootDir->head = boot->RootCl;
        }

        return ret;
}

/*
 * Cleanup after a directory scan
 */
void
finishDosDirSection(void)
{
        struct dirTodoNode *p, *np;
        struct dosDirEntry *d, *nd;

        for (p = pendingDirectories; p; p = np) {
                np = p->next;
                freeDirTodo(p);
        }
        pendingDirectories = 0;
        for (d = rootDir; d; d = nd) {
                if ((nd = d->child) != NULL) {
                        d->child = 0;
                        continue;
                }
                if (!(nd = d->next))
                        nd = d->parent;
                freeDosDirEntry(d);
        }
        rootDir = lostDir = NULL;
        free(buffer);
        free(delbuf);
        buffer = NULL;
        delbuf = NULL;
}

/*
 * Delete directory entries between startcl, startoff and endcl, endoff.
 */
static int
delete(int f, struct bootblock *boot, struct fatEntry *fat, cl_t startcl, 
       int startoff, cl_t endcl, int endoff, int notlast)
{
        u_char *s, *e;
        off_t off;
        int clsz = boot->SecPerClust * boot->BytesPerSec;

        s = delbuf + startoff;
        e = delbuf + clsz;
        while (startcl >= CLUST_FIRST && startcl < boot->NumClusters) {
                if (startcl == endcl) {
                        if (notlast)
                                break;
                        e = delbuf + endoff;
                }
                off = (startcl - CLUST_FIRST) * boot->SecPerClust + boot->FirstCluster;
                off *= boot->BytesPerSec;
                if (lseek(f, off, SEEK_SET) != off
                    || read(f, delbuf, clsz) != clsz) {
                        perr("Unable to read directory");
                        return FSFATAL;
                }
                while (s < e) {
                        *s = SLOT_DELETED;
                        s += 32;
                }
                if (lseek(f, off, SEEK_SET) != off
                    || write(f, delbuf, clsz) != clsz) {
                        perr("Unable to write directory");
                        return FSFATAL;
                }
                if (startcl == endcl)
                        break;
                startcl = fat[startcl].next;
                s = delbuf;
        }
        return FSOK;
}

static int
removede(int f, struct bootblock *boot, struct fatEntry *fat, u_char *start, 
         u_char *end, cl_t startcl, cl_t endcl, cl_t curcl, char *path, 
         int type)
{
        switch (type) {
        case 0:
                pwarn("Invalid long filename entry for %s\n", path);
                break;
        case 1:
                pwarn("Invalid long filename entry at end of directory %s\n", path);
                break;
        case 2:
                pwarn("Invalid long filename entry for volume label\n");
                break;
        }
        if (ask(0, "Remove")) {
                if (startcl != curcl) {
                        if (delete(f, boot, fat,
                                   startcl, start - buffer,
                                   endcl, end - buffer,
                                   endcl == curcl) == FSFATAL)
                                return FSFATAL;
                        start = buffer;
                }
                /* startcl is < CLUST_FIRST for !fat32 root */
                if ((endcl == curcl) || (startcl < CLUST_FIRST))
                        for (; start < end; start += 32)
                                *start = SLOT_DELETED;
                return FSDIRMOD;
        }
        return FSERROR;
}

/*
 * Check an in-memory file entry
 */
static int
checksize(struct bootblock *boot, struct fatEntry *fat, u_char *p, 
          struct dosDirEntry *dir)
{
        /*
         * Check size on ordinary files
         */
        u_int32_t physicalSize;

        if (dir->head == CLUST_FREE)
                physicalSize = 0;
        else {
                if (dir->head < CLUST_FIRST || dir->head >= boot->NumClusters)
                        return FSERROR;
                physicalSize = fat[dir->head].length * boot->ClusterSize;
        }
        if (physicalSize < dir->size) {
                pwarn("size of %s is %u, should at most be %u\n",
                      fullpath(dir), dir->size, physicalSize);
                if (ask(1, "Truncate")) {
                        dir->size = physicalSize;
                        p[28] = (u_char)physicalSize;
                        p[29] = (u_char)(physicalSize >> 8);
                        p[30] = (u_char)(physicalSize >> 16);
                        p[31] = (u_char)(physicalSize >> 24);
                        return FSDIRMOD;
                } else
                        return FSERROR;
        } else if (physicalSize - dir->size >= boot->ClusterSize) {
                pwarn("%s has too many clusters allocated\n",
                      fullpath(dir));
                if (ask(1, "Drop superfluous clusters")) {
                        cl_t cl;
                        u_int32_t sz, len;

                        for (cl = dir->head, len = sz = 0;
                            (sz += boot->ClusterSize) < dir->size; len++)
                                cl = fat[cl].next;
                        clearchain(boot, fat, fat[cl].next);
                        fat[cl].next = CLUST_EOF;
                        fat[dir->head].length = len;
                        return FSFATMOD;
                } else
                        return FSERROR;
        }
        return FSOK;
}

static int
procName(int from, int to, char **dst, const u_char *src)
{
        int k;
        char *t = *dst;

        for (k = from; k < to && t < eLongName; k += 2) {
                if (!src[k] && !src[k + 1])
                        break;
                *t++ = src[k];
                /*
                 * Warn about those unusable chars in msdosfs here?     XXX
                 */
                if (src[k + 1])
                    t[-1] = '?';
        }
        *dst = t;
        return k;
}

/*
 * Read a directory and
 *   - resolve long name records
 *   - enter file and directory records into the parent's list
 *   - push directories onto the todo-stack
 */
static int
readDosDirSection(int f, struct bootblock *boot, struct fatEntry *fat, 
                  struct dosDirEntry *dir)
{
        struct dosDirEntry dirent, *d;
        u_char *p, *vallfn, *invlfn, *empty;
        off_t off;
        int i, j, k, last;
        cl_t cl, valcl = ~0, invcl = ~0, empcl = ~0;
        char *t;
        u_int lidx = 0;
        int shortSum;
        int mod = FSOK;
#define THISMOD 0x8000                  /* Only used within this routine */

        cl = dir->head;
        if (dir->parent && (cl < CLUST_FIRST || cl >= boot->NumClusters)) {
                /*
                 * Already handled somewhere else.
                 */
                return FSOK;
        }
        shortSum = -1;
        vallfn = invlfn = empty = NULL;
        do {
                if (!(boot->flags & FAT32) && !dir->parent) {
                        last = boot->RootDirEnts * 32;
                        off = boot->ResSectors + boot->FATs * boot->FATsecs;
                } else {
                        last = boot->SecPerClust * boot->BytesPerSec;
                        off = (cl - CLUST_FIRST) * boot->SecPerClust + boot->FirstCluster;
                }

                off *= boot->BytesPerSec;
                if (lseek(f, off, SEEK_SET) != off
                    || read(f, buffer, last) != last) {
                        perr("Unable to read directory");
                        return FSFATAL;
                }
                last /= 32;
                /*
                 * Check `.' and `..' entries here?                     XXX
                 */
                for (p = buffer, i = 0; i < last; i++, p += 32) {
                        if (dir->fsckflags & DIREMPWARN) {
                                *p = SLOT_EMPTY;
                                continue;
                        }

                        if (*p == SLOT_EMPTY || *p == SLOT_DELETED) {
                                if (*p == SLOT_EMPTY) {
                                        dir->fsckflags |= DIREMPTY;
                                        empty = p;
                                        empcl = cl;
                                }
                                continue;
                        }

                        if (dir->fsckflags & DIREMPTY) {
                                if (!(dir->fsckflags & DIREMPWARN)) {
                                        pwarn("%s has entries after end of directory\n",
                                              fullpath(dir));
                                        if (ask(1, "Extend")) {
                                                u_char *q;

                                                dir->fsckflags &= ~DIREMPTY;
                                                if (delete(f, boot, fat,
                                                           empcl, empty - buffer,
                                                           cl, p - buffer, 1) == FSFATAL)
                                                        return FSFATAL;
                                                q = empcl == cl ? empty : buffer;
                                                assert(q != NULL);
                                                for (; q < p; q += 32)
                                                        *q = SLOT_DELETED;
                                                mod |= THISMOD|FSDIRMOD;
                                        } else if (ask(0, "Truncate"))
                                                dir->fsckflags |= DIREMPWARN;
                                }
                                if (dir->fsckflags & DIREMPWARN) {
                                        *p = SLOT_DELETED;
                                        mod |= THISMOD|FSDIRMOD;
                                        continue;
                                } else if (dir->fsckflags & DIREMPTY)
                                        mod |= FSERROR;
                                empty = NULL;
                        }

                        if (p[11] == ATTR_WIN95) {
                                u_int lrnomask = *p & LRNOMASK;
                                if (*p & LRFIRST) {
                                        if (shortSum != -1) {
                                                if (!invlfn) {
                                                        invlfn = vallfn;
                                                        invcl = valcl;
                                                }
                                        }
                                        memset(longName, 0, sizeof longName);
                                        shortSum = p[13];
                                        vallfn = p;
                                        valcl = cl;
                                } else if (shortSum != p[13]
                                   || lidx != lrnomask) {
                                        if (!invlfn) {
                                                invlfn = vallfn;
                                                invcl = valcl;
                                        }
                                        if (!invlfn) {
                                                invlfn = p;
                                                invcl = cl;
                                        }
                                        vallfn = NULL;
                                }
                                lidx = lrnomask;
                                if (lidx != 0) {
                                        t = longName + --lidx * 13;
                                        k = procName(1, 11, &t, p);
                                        if (k >= 11)
                                                k = procName(14, 26, &t, p);
                                        if (k >= 26)
                                                k = procName(28, 32, &t, p);
                                        if (t >= eLongName) {
                                                pwarn(
                                                    "long filename too long\n");
                                                if (!invlfn) {
                                                        invlfn = vallfn;
                                                        invcl = valcl;
                                                }
                                                vallfn = NULL;
                                        }
                                }
                                if (p[26] | (p[27] << 8)) {
                                        pwarn("long filename record cluster "
                                            "start != 0\n");
                                        if (!invlfn) {
                                                invlfn = vallfn;
                                                invcl = cl;
                                        }
                                        vallfn = NULL;
                                }
                                continue;       /* long records don't carry
                                                 * further information */
                        }

                        /*
                         * This is a standard msdosfs directory entry.
                         */
                        memset(&dirent, 0, sizeof dirent);

                        /*
                         * it's a short name record, but we need to know
                         * more, so get the flags first.
                         */
                        dirent.flags = p[11];

                        /*
                         * Translate from 850 to ISO here               XXX
                         */
                        for (j = 0; j < 8; j++)
                                dirent.name[j] = p[j];
                        dirent.name[8] = '\0';
                        for (k = 7; k >= 0 && dirent.name[k] == ' '; k--)
                                dirent.name[k] = '\0';
                        if (k < 0 || dirent.name[k] != '\0')
                                k++;
                        if (dirent.name[0] == SLOT_E5)
                                dirent.name[0] = 0xe5;

                        if (dirent.flags & ATTR_VOLUME) {
                                if (vallfn || invlfn) {
                                        mod |= removede(f, boot, fat,
                                                        invlfn ? invlfn : vallfn, p,
                                                        invlfn ? invcl : valcl, -1, 0,
                                                        fullpath(dir), 2);
                                        vallfn = NULL;
                                        invlfn = NULL;
                                }
                                continue;
                        }

                        if (p[8] != ' ')
                                dirent.name[k++] = '.';
                        for (j = 0; j < 3; j++)
                                dirent.name[k++] = p[j+8];
                        dirent.name[k] = '\0';
                        for (k--; k >= 0 && dirent.name[k] == ' '; k--)
                                dirent.name[k] = '\0';

                        if (vallfn && shortSum != calcShortSum(p)) {
                                if (!invlfn) {
                                        invlfn = vallfn;
                                        invcl = valcl;
                                }
                                vallfn = NULL;
                        }
                        dirent.head = p[26] | (p[27] << 8);
                        if (boot->ClustMask == CLUST32_MASK)
                                dirent.head |= (p[20] << 16) | (p[21] << 24);
                        dirent.size = p[28] | (p[29] << 8) | (p[30] << 16) | (p[31] << 24);
                        if (vallfn) {
                                strlcpy(dirent.lname, longName,
                                    sizeof(dirent.lname));
                                longName[0] = '\0';
                                shortSum = -1;
                        }

                        dirent.parent = dir;
                        dirent.next = dir->child;

                        if (invlfn) {
                                mod |= k = removede(f, boot, fat,
                                                    invlfn, vallfn ? vallfn : p,
                                                    invcl, vallfn ? valcl : cl, cl,
                                                    fullpath(&dirent), 0);
                                if (mod & FSFATAL)
                                        return FSFATAL;
                                if (vallfn
                                    ? (valcl == cl && vallfn != buffer)
                                    : p != buffer)
                                        if (k & FSDIRMOD)
                                                mod |= THISMOD;
                        }

                        vallfn = NULL; /* not used any longer */
                        invlfn = NULL;

                        if (dirent.size == 0 && !(dirent.flags & ATTR_DIRECTORY)) {
                                if (dirent.head != 0) {
                                        pwarn("%s has clusters, but size 0\n",
                                              fullpath(&dirent));
                                        if (ask(1, "Drop allocated clusters")) {
                                                p[26] = p[27] = 0;
                                                if (boot->ClustMask == CLUST32_MASK)
                                                        p[20] = p[21] = 0;
                                                clearchain(boot, fat, dirent.head);
                                                dirent.head = 0;
                                                mod |= THISMOD|FSDIRMOD|FSFATMOD;
                                        } else
                                                mod |= FSERROR;
                                }
                        } else if (dirent.head == 0
                                   && !strcmp(dirent.name, "..")
                                   && dir->parent                       /* XXX */
                                   && !dir->parent->parent) {
                                /*
                                 *  Do nothing, the parent is the root
                                 */
                        } else if (dirent.head < CLUST_FIRST
                                   || dirent.head >= boot->NumClusters
                                   || fat[dirent.head].next == CLUST_FREE
                                   || (fat[dirent.head].next >= CLUST_RSRVD
                                       && fat[dirent.head].next < CLUST_EOFS)
                                   || fat[dirent.head].head != dirent.head) {
                                if (dirent.head == 0)
                                        pwarn("%s has no clusters\n",
                                              fullpath(&dirent));
                                else if (dirent.head < CLUST_FIRST
                                         || dirent.head >= boot->NumClusters)
                                        pwarn("%s starts with cluster out of range(%u)\n",
                                              fullpath(&dirent),
                                              dirent.head);
                                else if (fat[dirent.head].next == CLUST_FREE)
                                        pwarn("%s starts with free cluster\n",
                                              fullpath(&dirent));
                                else if (fat[dirent.head].next >= CLUST_RSRVD)
                                        pwarn("%s starts with cluster marked %s\n",
                                              fullpath(&dirent),
                                              rsrvdcltype(fat[dirent.head].next));
                                else
                                        pwarn("%s doesn't start a cluster chain\n",
                                              fullpath(&dirent));
                                if (dirent.flags & ATTR_DIRECTORY) {
                                        if (ask(0, "Remove")) {
                                                *p = SLOT_DELETED;
                                                mod |= THISMOD|FSDIRMOD;
                                        } else
                                                mod |= FSERROR;
                                        continue;
                                } else {
                                        if (ask(1, "Truncate")) {
                                                p[28] = p[29] = p[30] = p[31] = 0;
                                                p[26] = p[27] = 0;
                                                if (boot->ClustMask == CLUST32_MASK)
                                                        p[20] = p[21] = 0;
                                                dirent.size = 0;
                                                mod |= THISMOD|FSDIRMOD;
                                        } else
                                                mod |= FSERROR;
                                }
                        }

                        if (dirent.head >= CLUST_FIRST && dirent.head < boot->NumClusters)
                                fat[dirent.head].flags |= FAT_USED;

                        if (dirent.flags & ATTR_DIRECTORY) {
                                /*
                                 * gather more info for directories
                                 */
                                struct dirTodoNode *n;

                                if (dirent.size) {
                                        pwarn("Directory %s has size != 0\n",
                                              fullpath(&dirent));
                                        if (ask(1, "Correct")) {
                                                p[28] = p[29] = p[30] = p[31] = 0;
                                                dirent.size = 0;
                                                mod |= THISMOD|FSDIRMOD;
                                        } else
                                                mod |= FSERROR;
                                }
                                /*
                                 * handle `.' and `..' specially
                                 */
                                if (strcmp(dirent.name, ".") == 0) {
                                        if (dirent.head != dir->head) {
                                                pwarn("`.' entry in %s has incorrect start cluster\n",
                                                      fullpath(dir));
                                                if (ask(1, "Correct")) {
                                                        dirent.head = dir->head;
                                                        p[26] = (u_char)dirent.head;
                                                        p[27] = (u_char)(dirent.head >> 8);
                                                        if (boot->ClustMask == CLUST32_MASK) {
                                                                p[20] = (u_char)(dirent.head >> 16);
                                                                p[21] = (u_char)(dirent.head >> 24);
                                                        }
                                                        mod |= THISMOD|FSDIRMOD;
                                                } else
                                                        mod |= FSERROR;
                                        }
                                        continue;
                                }
                                if (strcmp(dirent.name, "..") == 0) {
                                        if (dir->parent) {              /* XXX */
                                                if (!dir->parent->parent) {
                                                        if (dirent.head) {
                                                                pwarn("`..' entry in %s has non-zero start cluster\n",
                                                                      fullpath(dir));
                                                                if (ask(1, "Correct")) {
                                                                        dirent.head = 0;
                                                                        p[26] = p[27] = 0;
                                                                        if (boot->ClustMask == CLUST32_MASK)
                                                                                p[20] = p[21] = 0;
                                                                        mod |= THISMOD|FSDIRMOD;
                                                                } else
                                                                        mod |= FSERROR;
                                                        }
                                                } else if (dirent.head != dir->parent->head) {
                                                        pwarn("`..' entry in %s has incorrect start cluster\n",
                                                              fullpath(dir));
                                                        if (ask(1, "Correct")) {
                                                                dirent.head = dir->parent->head;
                                                                p[26] = (u_char)dirent.head;
                                                                p[27] = (u_char)(dirent.head >> 8);
                                                                if (boot->ClustMask == CLUST32_MASK) {
                                                                        p[20] = (u_char)(dirent.head >> 16);
                                                                        p[21] = (u_char)(dirent.head >> 24);
                                                                }
                                                                mod |= THISMOD|FSDIRMOD;
                                                        } else
                                                                mod |= FSERROR;
                                                }
                                        }
                                        continue;
                                }

                                /* create directory tree node */
                                if (!(d = newDosDirEntry())) {
                                        perr("No space for directory");
                                        return FSFATAL;
                                }
                                memcpy(d, &dirent, sizeof(struct dosDirEntry));
                                /* link it into the tree */
                                dir->child = d;

                                /* Enter this directory into the todo list */
                                if (!(n = newDirTodo())) {
                                        perr("No space for todo list");
                                        return FSFATAL;
                                }
                                n->next = pendingDirectories;
                                n->dir = d;
                                pendingDirectories = n;
                        } else {
                                mod |= k = checksize(boot, fat, p, &dirent);
                                if (k & FSDIRMOD)
                                        mod |= THISMOD;
                        }
                        boot->NumFiles++;
                }

                if (!(boot->flags & FAT32) && !dir->parent)
                        break;

                if (mod & THISMOD) {
                        last *= 32;
                        if (lseek(f, off, SEEK_SET) != off
                            || write(f, buffer, last) != last) {
                                perr("Unable to write directory");
                                return FSFATAL;
                        }
                        mod &= ~THISMOD;
                }
        } while ((cl = fat[cl].next) >= CLUST_FIRST && cl < boot->NumClusters);
        if (invlfn || vallfn)
                mod |= removede(f, boot, fat,
                                invlfn ? invlfn : vallfn, p,
                                invlfn ? invcl : valcl, -1, 0,
                                fullpath(dir), 1);

        /* The root directory of non fat32 filesystems is in a special
         * area and may have been modified above without being written out.
         */
        if ((mod & FSDIRMOD) && !(boot->flags & FAT32) && !dir->parent) {
                last *= 32;
                if (lseek(f, off, SEEK_SET) != off
                    || write(f, buffer, last) != last) {
                        perr("Unable to write directory");
                        return FSFATAL;
                }
                mod &= ~THISMOD;
        }
        return mod & ~THISMOD;
}

int
handleDirTree(int dosfs, struct bootblock *boot, struct fatEntry *fat)
{
        int mod;

        mod = readDosDirSection(dosfs, boot, fat, rootDir);
        if (mod & FSFATAL)
                return FSFATAL;

        /*
         * process the directory todo list
         */
        while (pendingDirectories) {
                struct dosDirEntry *dir = pendingDirectories->dir;
                struct dirTodoNode *n = pendingDirectories->next;

                /*
                 * remove TODO entry now, the list might change during
                 * directory reads
                 */
                freeDirTodo(pendingDirectories);
                pendingDirectories = n;

                /*
                 * handle subdirectory
                 */
                mod |= readDosDirSection(dosfs, boot, fat, dir);
                if (mod & FSFATAL)
                        return FSFATAL;
        }

        return mod;
}

/*
 * Try to reconnect a FAT chain into dir
 */
static u_char *lfbuf;
static cl_t lfcl;
static off_t lfoff;

int
reconnect(int dosfs, struct bootblock *boot, struct fatEntry *fat, cl_t head)
{
        struct dosDirEntry d;
        int len;
        u_char *p;

        if (!ask(1, "Reconnect"))
                return FSERROR;

        if (!lostDir) {
                for (lostDir = rootDir->child; lostDir; lostDir = lostDir->next) {
                        if (!strcmp(lostDir->name, LOSTDIR))
                                break;
                }
                if (!lostDir) {         /* Create LOSTDIR?              XXX */
                        pwarn("No %s directory\n", LOSTDIR);
                        return FSERROR;
                }
        }
        if (!lfbuf) {
                lfbuf = malloc(boot->ClusterSize);
                if (!lfbuf) {
                        perr("No space for buffer");
                        return FSFATAL;
                }
                p = NULL;
        } else
                p = lfbuf;
        while (1) {
                if (p)
                        for (; p < lfbuf + boot->ClusterSize; p += 32)
                                if (*p == SLOT_EMPTY
                                    || *p == SLOT_DELETED)
                                        break;
                if (p && p < lfbuf + boot->ClusterSize)
                        break;
                lfcl = p ? fat[lfcl].next : lostDir->head;
                if (lfcl < CLUST_FIRST || lfcl >= boot->NumClusters) {
                        /* Extend LOSTDIR?                              XXX */
                        pwarn("No space in %s\n", LOSTDIR);
                        return FSERROR;
                }
                lfoff = (lfcl - CLUST_FIRST) * boot->ClusterSize
                    + boot->FirstCluster * boot->BytesPerSec;
                if (lseek(dosfs, lfoff, SEEK_SET) != lfoff
                    || (size_t)read(dosfs, lfbuf, boot->ClusterSize) != boot->ClusterSize) {
                        perr("could not read LOST.DIR");
                        return FSFATAL;
                }
                p = lfbuf;
        }

        boot->NumFiles++;
        /* Ensure uniqueness of entry here!                             XXX */
        memset(&d, 0, sizeof d);
        /* worst case -1 = 4294967295, 10 digits */
        len = snprintf(d.name, sizeof(d.name), "%u", head);
        d.flags = 0;
        d.head = head;
        d.size = fat[head].length * boot->ClusterSize;

        memcpy(p, d.name, len);
        memset(p + len, ' ', 11 - len);
        memset(p + 11, 0, 32 - 11);
        p[26] = (u_char)d.head;
        p[27] = (u_char)(d.head >> 8);
        if (boot->ClustMask == CLUST32_MASK) {
                p[20] = (u_char)(d.head >> 16);
                p[21] = (u_char)(d.head >> 24);
        }
        p[28] = (u_char)d.size;
        p[29] = (u_char)(d.size >> 8);
        p[30] = (u_char)(d.size >> 16);
        p[31] = (u_char)(d.size >> 24);
        fat[head].flags |= FAT_USED;
        if (lseek(dosfs, lfoff, SEEK_SET) != lfoff
            || (size_t)write(dosfs, lfbuf, boot->ClusterSize) != boot->ClusterSize) {
                perr("could not write LOST.DIR");
                return FSFATAL;
        }
        return FSDIRMOD;
}

void
finishlf(void)
{
        if (lfbuf)
                free(lfbuf);
        lfbuf = NULL;
}