Bochs/bochs/iodev/vvfat.cc

/////////////////////////////////////////////////////////////////////////
// $Id$
/////////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2010/2011  The Bochs Project
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
/////////////////////////////////////////////////////////////////////////

// Virtual VFAT image support (shadows a local directory)
// ported from the Qemu block driver (written by Johannes E. Schindelin)

// ADDITIONS:
// - win32 specific directory functions (required for MSVC)
// - configurable disk geometry
// - read MBR and boot sector from file
// - FAT32 support
// - volatile runtime write support using the hdimage redolog_t class
// - ask user on Bochs exit if directory and file changes should be committed
// - save and restore FAT file attributes using a separate file
// - set file modification date and time after committing file changes
// - vvfat floppy support (1.44 MB media only)

// Define BX_PLUGGABLE in files that can be compiled into plugins.  For
// platforms that require a special tag on exported symbols, BX_PLUGGABLE
// is used to know when we are exporting symbols and when we are importing.
#define BX_PLUGGABLE

#ifndef WIN32
#include <dirent.h>
#include <utime.h>
#endif

#include "iodev.h"
#include "hdimage.h"
#include "vvfat.h"

#define LOG_THIS bx_devices.pluginHDImageCtl->

#define VVFAT_MBR  "vvfat_mbr.bin"
#define VVFAT_BOOT "vvfat_boot.bin"
#define VVFAT_ATTR "vvfat_attr.cfg"

#if defined (BX_LITTLE_ENDIAN)
#define htod16(val) (val)
#else
#define htod16(val) ( (((val)&0xff00)>>8) | (((val)&0xff)<<8) )
#endif
#define dtoh16 htod16

#ifndef F_OK
#define F_OK 0
#endif

// portable mkdir / rmdir
static int bx_mkdir(const char *path)
{
#ifndef WIN32
  return mkdir(path, 0755);
#else
  return (CreateDirectory(path, NULL) != 0) ? 0 : -1;
#endif
}

static int bx_rmdir(const char *path)
{
#ifndef WIN32
  return rmdir(path);
#else
  return (RemoveDirectory(path) != 0) ? 0 : -1;
#endif
}

// dynamic array functions
static inline void array_init(array_t* array,unsigned int item_size)
{
  array->pointer = NULL;
  array->size = 0;
  array->next = 0;
  array->item_size = item_size;
}

static inline void array_free(array_t* array)
{
  if (array->pointer)
    free(array->pointer);
  array->size=array->next = 0;
}

// does not automatically grow
static inline void* array_get(array_t* array,unsigned int index)
{
  assert(index < array->next);
  return array->pointer + index * array->item_size;
}

static inline int array_ensure_allocated(array_t* array, int index)
{
  if ((index + 1) * array->item_size > array->size) {
    int new_size = (index + 32) * array->item_size;
    array->pointer = (char*)realloc(array->pointer, new_size);
    if (!array->pointer)
      return -1;
    array->size = new_size;
    array->next = index + 1;
  }
  return 0;
}

static inline void* array_get_next(array_t* array)
{
  unsigned int next = array->next;
  void* result;

  if (array_ensure_allocated(array, next) < 0)
    return NULL;

  array->next = next + 1;
  result = array_get(array, next);

  return result;
}

static inline void* array_insert(array_t* array,unsigned int index,unsigned int count)
{
  if ((array->next+count)*array->item_size > array->size) {
    int increment = count*array->item_size;
    array->pointer = (char*)realloc(array->pointer, array->size+increment);
    if (!array->pointer)
      return NULL;
    array->size += increment;
  }
  memmove(array->pointer+(index+count)*array->item_size,
          array->pointer+index*array->item_size,
          (array->next-index)*array->item_size);
  array->next += count;
  return array->pointer+index*array->item_size;
}

/* this performs a "roll", so that the element which was at index_from becomes
 * index_to, but the order of all other elements is preserved. */
static inline int array_roll(array_t* array, int index_to, int index_from, int count)
{
  char* buf;
  char* from;
  char* to;
  int is;

  if (!array ||
      (index_to < 0) || (index_to >= (int)array->next) ||
      (index_from < 0 || (index_from >= (int)array->next)))
    return -1;

  if (index_to == index_from)
    return 0;

  is = array->item_size;
  from = array->pointer+index_from*is;
  to = array->pointer+index_to*is;
  buf = (char*)malloc(is*count);
  memcpy(buf, from, is*count);

  if (index_to < index_from)
    memmove(to+is*count, to, from-to);
  else
    memmove(from, from+is*count, to-from);

  memcpy(to, buf, is*count);

  free(buf);

  return 0;
}

#if 0
static inline int array_remove_slice(array_t* array,int index, int count)
{
  assert(index >=0);
  assert(count > 0);
  assert(index + count <= (int)array->next);
  if (array_roll(array,array->next-1,index,count))
    return -1;
  array->next -= count;
  return 0;
}

static int array_remove(array_t* array,int index)
{
  return array_remove_slice(array, index, 1);
}

// return the index for a given member
static int array_index(array_t* array, void* pointer)
{
  size_t offset = (char*)pointer - array->pointer;
  assert((offset % array->item_size) == 0);
  assert(offset/array->item_size < array->next);
  return offset/array->item_size;
}
#endif

#if defined(_MSC_VER)
#pragma pack(push, 1)
#elif defined(__MWERKS__) && defined(macintosh)
#pragma options align=packed
#endif

typedef
#if defined(_MSC_VER) && (_MSC_VER>=1300)
  __declspec(align(1))
#endif
  struct bootsector_t {
    Bit8u  jump[3];
    Bit8u  name[8];
    Bit16u sector_size;
    Bit8u  sectors_per_cluster;
    Bit16u reserved_sectors;
    Bit8u  number_of_fats;
    Bit16u root_entries;
    Bit16u total_sectors16;
    Bit8u  media_type;
    Bit16u sectors_per_fat;
    Bit16u sectors_per_track;
    Bit16u number_of_heads;
    Bit32u hidden_sectors;
    Bit32u total_sectors;
    union {
#if defined(_MSC_VER) && (_MSC_VER>=1300)
      __declspec(align(1))
#endif
      struct {
        Bit8u  drive_number;
        Bit8u  reserved;
        Bit8u  signature;
        Bit32u id;
        Bit8u  volume_label[11];
        Bit8u fat_type[8];
        Bit8u ignored[0x1c0];
      }
#if !defined(_MSC_VER)
      GCC_ATTRIBUTE((packed))
#endif
      fat16;
#if defined(_MSC_VER) && (_MSC_VER>=1300)
    __declspec(align(1))
#endif
    struct {
        Bit32u sectors_per_fat;
        Bit16u flags;
        Bit8u  major, minor;
        Bit32u first_cluster_of_root_dir;
        Bit16u info_sector;
        Bit16u backup_boot_sector;
        Bit8u  reserved1[12];
        Bit8u  drive_number;
        Bit8u  reserved2;
        Bit8u  signature;
        Bit32u id;
        Bit8u  volume_label[11];
        Bit8u  fat_type[8];
        Bit8u  ignored[0x1a4];
    }
#if !defined(_MSC_VER)
    GCC_ATTRIBUTE((packed))
#endif
    fat32;
    } u;
    Bit8u magic[2];
}
#if !defined(_MSC_VER)
    GCC_ATTRIBUTE((packed))
#endif
bootsector_t;

typedef
#if defined(_MSC_VER) && (_MSC_VER>=1300)
  __declspec(align(1))
#endif
  struct partition_t {
    Bit8u     attributes; /* 0x80 = bootable */
    mbr_chs_t start_CHS;
    Bit8u     fs_type; /* 0x1 = FAT12, 0x6 = FAT16, 0xe = FAT16_LBA, 0xb = FAT32, 0xc = FAT32_LBA */
    mbr_chs_t end_CHS;
    Bit32u    start_sector_long;
    Bit32u    length_sector_long;
}
#if !defined(_MSC_VER)
    GCC_ATTRIBUTE((packed))
#endif
partition_t;

typedef
#if defined(_MSC_VER) && (_MSC_VER>=1300)
  __declspec(align(1))
#endif
  struct mbr_t {
    Bit8u       ignored[0x1b8];
    Bit32u      nt_id;
    Bit8u       ignored2[2];
    partition_t partition[4];
    Bit8u       magic[2];
}
#if !defined(_MSC_VER)
    GCC_ATTRIBUTE((packed))
#endif
mbr_t;

typedef
#if defined(_MSC_VER) && (_MSC_VER>=1300)
  __declspec(align(1))
#endif
  struct infosector_t {
    Bit32u signature1;
    Bit8u  ignored[0x1e0];
    Bit32u signature2;
    Bit32u free_clusters;
    Bit32u mra_cluster; // most recently allocated cluster
    Bit8u  reserved[14];
    Bit8u  magic[2];
}
#if !defined(_MSC_VER)
    GCC_ATTRIBUTE((packed))
#endif
infosector_t;

#if defined(_MSC_VER)
#pragma pack(pop)
#elif defined(__MWERKS__) && defined(macintosh)
#pragma options align=reset
#endif

vvfat_image_t::vvfat_image_t(Bit64u size, const char* _redolog_name)
{
  first_sectors = new Bit8u[0xc000];
  memset(&first_sectors[0], 0, 0xc000);

  hd_size = size;
  redolog = new redolog_t();
  redolog_temp = NULL;
  redolog_name = NULL;
  if (_redolog_name != NULL) {
    if (strcmp(_redolog_name,"") != 0) {
      redolog_name = strdup(_redolog_name);
    }
  }
}

vvfat_image_t::~vvfat_image_t()
{
  delete [] first_sectors;
  delete redolog;
}

bx_bool vvfat_image_t::sector2CHS(Bit32u spos, mbr_chs_t *chs)
{
  Bit32u head, sector;

  sector = spos % sectors;
  spos   /= sectors;
  head   = spos % heads;
  spos   /= heads;
  if (spos > 1023) {
    /* Overflow,
    it happens if 32bit sector positions are used, while CHS is only 24bit.
    Windows/Dos is said to take 1023/255/63 as nonrepresentable CHS */
    chs->head     = 0xff;
    chs->sector   = 0xff;
    chs->cylinder = 0xff;
    return 1;
  }
  chs->head     = (Bit8u)head;
  chs->sector   = (Bit8u)((sector+1) | ((spos >> 8) << 6));
  chs->cylinder = (Bit8u)spos;
  return 0;
}

void vvfat_image_t::init_mbr(void)
{
  mbr_t* real_mbr = (mbr_t*)first_sectors;
  partition_t* partition = &(real_mbr->partition[0]);
  bx_bool lba;

  // Win NT Disk Signature
  real_mbr->nt_id = htod32(0xbe1afdfa);

  partition->attributes = 0x80; // bootable

  // LBA is used when partition is outside the CHS geometry
  lba = sector2CHS(offset_to_bootsector, &partition->start_CHS);
  lba |= sector2CHS(sector_count - 1, &partition->end_CHS);

  // LBA partitions are identified only by start/length_sector_long not by CHS
  partition->start_sector_long = htod32(offset_to_bootsector);
  partition->length_sector_long = htod32(sector_count - offset_to_bootsector);

  /* FAT12/FAT16/FAT32 */
  /* DOS uses different types when partition is LBA,
     probably to prevent older versions from using CHS on them */
  partition->fs_type = fat_type==12 ? 0x1:
                       fat_type==16 ? (lba?0xe:0x06):
                       /*fat_tyoe==32*/ (lba?0xc:0x0b);

  real_mbr->magic[0] = 0x55;
  real_mbr->magic[1] = 0xaa;
}

// dest is assumed to hold 258 bytes, and pads with 0xffff up to next multiple of 26
static inline int short2long_name(char* dest,const char* src)
{
  int i;
  int len;

  for (i = 0; (i < 129) && src[i]; i++) {
    dest[2*i] = src[i];
    dest[2*i+1] = 0;
  }
  len = 2 * i;
  dest[2*i] = dest[2*i+1] = 0;
  for (i = 2 * i + 2; (i % 26); i++)
    dest[i] = (char)0xff;
  return len;
}

direntry_t* vvfat_image_t::create_long_filename(const char* filename)
{
  char buffer[258];
  int length = short2long_name(buffer, filename),
      number_of_entries = (length+25) / 26, i;
  direntry_t* entry;

  for (i = 0; i < number_of_entries; i++) {
    entry = (direntry_t*)array_get_next(&directory);
    entry->attributes = 0xf;
    entry->reserved[0] = 0;
    entry->begin = 0;
    entry->name[0] = (number_of_entries - i) | (i==0 ? 0x40:0);
  }
  for (i = 0; i < 26 * number_of_entries; i++) {
    int offset = (i % 26);
    if (offset < 10) offset = 1 + offset;
    else if (offset < 22) offset = 14 + offset - 10;
    else offset = 28 + offset - 22;
    entry = (direntry_t*)array_get(&directory, directory.next - 1 - (i / 26));
    entry->name[offset] = buffer[i];
  }
  return (direntry_t*)array_get(&directory, directory.next-number_of_entries);
}

static char is_long_name(const direntry_t* direntry)
{
    return direntry->attributes == 0xf;
}

static void set_begin_of_direntry(direntry_t* direntry, Bit32u begin)
{
  direntry->begin = htod16(begin & 0xffff);
  direntry->begin_hi = htod16((begin >> 16) & 0xffff);
}

static inline Bit8u fat_chksum(const direntry_t* entry)
{
  Bit8u chksum = 0;
  int i;

  for (i = 0; i < 11; i++) {
    unsigned char c;

    c = (i < 8) ? entry->name[i] : entry->extension[i-8];
    chksum = (((chksum & 0xfe) >> 1) | ((chksum & 0x01) ? 0x80:0)) + c;
  }

  return chksum;
}

// if return_time==0, this returns the fat_date, else the fat_time
#ifndef WIN32
static Bit16u fat_datetime(time_t time, int return_time)
{
  struct tm* t;
  struct tm t1;

  t = &t1;
  localtime_r(&time, t);
  if (return_time)
    return htod16((t->tm_sec/2) | (t->tm_min<<5) | (t->tm_hour<<11));
  return htod16((t->tm_mday) | ((t->tm_mon+1)<<5) | ((t->tm_year-80)<<9));
}
#else
static Bit16u fat_datetime(FILETIME time, int return_time)
{
  FILETIME localtime;
  SYSTEMTIME systime;

  FileTimeToLocalFileTime(&time, &localtime);
  FileTimeToSystemTime(&localtime, &systime);
  if (return_time)
    return htod16((systime.wSecond/2) | (systime.wMinute<<5) | (systime.wHour<<11));
  return htod16((systime.wDay) | (systime.wMonth<<5) | ((systime.wYear-1980)<<9));
}
#endif

void vvfat_image_t::fat_set(unsigned int cluster, Bit32u value)
{
  if (fat_type == 32) {
    Bit32u* entry = (Bit32u*)array_get(&fat, cluster);
    *entry = htod32(value);
  } else if (fat_type == 16) {
    Bit16u* entry = (Bit16u*)array_get(&fat, cluster);
    *entry = htod16(value & 0xffff);
  } else {
    int offset = (cluster * 3 / 2);
    Bit8u* p = (Bit8u*)array_get(&fat, offset);
    switch (cluster & 1) {
      case 0:
        p[0] = value & 0xff;
        p[1] = (p[1] & 0xf0) | ((value>>8) & 0xf);
        break;
      case 1:
        p[0] = (p[0]&0xf) | ((value&0xf)<<4);
        p[1] = (value>>4);
        break;
    }
  }
}

void vvfat_image_t::init_fat(void)
{
  if (fat_type == 12) {
    array_init(&fat, 1);
    array_ensure_allocated(&fat, sectors_per_fat * 0x200 * 3 / 2 - 1);
  } else {
    array_init(&fat, (fat_type==32) ? 4:2);
    array_ensure_allocated(&fat, sectors_per_fat * 0x200 / fat.item_size - 1);
  }
  memset(fat.pointer, 0, fat.size);

  switch (fat_type) {
    case 12: max_fat_value = 0xfff; break;
    case 16: max_fat_value = 0xffff; break;
    case 32: max_fat_value = 0x0fffffff; break;
    default: max_fat_value = 0; /* error... */
  }
}

direntry_t* vvfat_image_t::create_short_and_long_name(
  unsigned int directory_start, const char* filename, int is_dot)
{
  int i, j, long_index = directory.next;
  direntry_t* entry = NULL;
  direntry_t* entry_long = NULL;

  if (is_dot) {
    entry = (direntry_t*)array_get_next(&directory);
    memset(entry->name,0x20,11);
    memcpy(entry->name,filename,strlen(filename));
    return entry;
  }

  entry_long = create_long_filename(filename);

  i = strlen(filename);
  for (j = i - 1; j>0  && filename[j]!='.';j--);
  if (j > 0)
    i = (j > 8 ? 8 : j);
  else if (i > 8)
    i = 8;

  entry = (direntry_t*)array_get_next(&directory);
  memset(entry->name, 0x20, 11);
  memcpy(entry->name, filename, i);

  if (j > 0)
    for (i = 0; i < 3 && filename[j+1+i]; i++)
      entry->extension[i] = filename[j+1+i];

  // upcase & remove unwanted characters
  for (i=10;i>=0;i--) {
    if (i==10 || i==7) for (;i>0 && entry->name[i]==' ';i--);
    if (entry->name[i]<=' ' || entry->name[i]>0x7f
      || strchr(".*?<>|\":/\\[];,+='",entry->name[i]))
      entry->name[i]='_';
    else if (entry->name[i]>='a' && entry->name[i]<='z')
      entry->name[i]+='A'-'a';
  }
  if (entry->name[0] == 0xe5) entry->name[0] = 0x05;

  // mangle duplicates
  while (1) {
    direntry_t* entry1 = (direntry_t*)array_get(&directory, directory_start);
    int j;

    for (;entry1<entry;entry1++)
      if (!is_long_name(entry1) && !memcmp(entry1->name,entry->name,11))
        break; // found dupe
    if (entry1==entry) // no dupe found
      break;

    // use all 8 characters of name
    if (entry->name[7]==' ') {
      int j;
      for(j=6;j>0 && entry->name[j]==' ';j--)
        entry->name[j]='~';
    }

    // increment number
    for (j=7;j>0 && entry->name[j]=='9';j--)
      entry->name[j]='0';
    if (j > 0) {
      if (entry->name[j]<'0' || entry->name[j]>'9')
        entry->name[j]='0';
      else
        entry->name[j]++;
    }
  }

  // calculate checksum; propagate to long name
  if (entry_long) {
    Bit8u chksum = fat_chksum(entry);

    // calculate anew, because realloc could have taken place
    entry_long = (direntry_t*)array_get(&directory, long_index);
    while (entry_long<entry && is_long_name(entry_long)) {
      entry_long->reserved[1]=chksum;
      entry_long++;
    }
  }

  return entry;
}

/*
 * Read a directory. (the index of the corresponding mapping must be passed).
 */
int vvfat_image_t::read_directory(int mapping_index)
{
  mapping_t* mapping = (mapping_t*)array_get(&this->mapping, mapping_index);
  direntry_t* direntry;
  const char* dirname = mapping->path;
  Bit32u first_cluster = mapping->begin;
  int parent_index = mapping->info.dir.parent_mapping_index;
  mapping_t* parent_mapping = (mapping_t*)
      (parent_index >= 0 ? array_get(&this->mapping, parent_index) : NULL);
  int first_cluster_of_parent = parent_mapping ? (int)parent_mapping->begin : -1;
  int count = 0;

#ifndef WIN32
  DIR* dir = opendir(dirname);
  struct dirent* entry;
  int i;

  assert(mapping->mode & MODE_DIRECTORY);

  if (!dir) {
    mapping->end = mapping->begin;
    return -1;
  }

  i = mapping->info.dir.first_dir_index =
    first_cluster == first_cluster_of_root_dir ? 0 : directory.next;

  if (first_cluster != first_cluster_of_root_dir) {
    // create the top entries of a subdirectory
    direntry = create_short_and_long_name(i, ".", 1);
    direntry = create_short_and_long_name(i, "..", 1);
  }

  // actually read the directory, and allocate the mappings
  while ((entry=readdir(dir))) {
    if ((first_cluster == 0) && (directory.next >= (Bit16u)(root_entries - 1))) {
      BX_ERROR(("Too many entries in root directory, using only %d", count));
      closedir(dir);
      return -2;
    }
    unsigned int length = strlen(dirname) + 2 + strlen(entry->d_name);
    char* buffer;
    direntry_t* direntry;
    struct stat st;
    bx_bool is_dot = !strcmp(entry->d_name, ".");
    bx_bool is_dotdot = !strcmp(entry->d_name, "..");
    if ((first_cluster == first_cluster_of_root_dir) && (is_dotdot || is_dot))
      continue;

    buffer = (char*)malloc(length);
    snprintf(buffer,length,"%s/%s",dirname,entry->d_name);

    if (stat(buffer, &st) < 0) {
      free(buffer);
      continue;
    }

    bx_bool is_mbr_file = !strcmp(entry->d_name, VVFAT_MBR);
    bx_bool is_boot_file = !strcmp(entry->d_name, VVFAT_BOOT);
    bx_bool is_attr_file = !strcmp(entry->d_name, VVFAT_ATTR);
    if (first_cluster == first_cluster_of_root_dir) {
      if (is_attr_file || ((is_mbr_file || is_boot_file) && (st.st_size == 512))) {
        free(buffer);
        continue;
      }
    }

    count++;
    // create directory entry for this file
    if (!is_dot && !is_dotdot) {
      direntry = create_short_and_long_name(i, entry->d_name, 0);
    } else {
      direntry = (direntry_t*)array_get(&directory, is_dot ? i : i + 1);
    }
    direntry->attributes = (S_ISDIR(st.st_mode) ? 0x10 : 0x20);
    direntry->reserved[0] = direntry->reserved[1]=0;
    direntry->ctime = fat_datetime(st.st_ctime, 1);
    direntry->cdate = fat_datetime(st.st_ctime, 0);
    direntry->adate = fat_datetime(st.st_atime, 0);
    direntry->begin_hi = 0;
    direntry->mtime = fat_datetime(st.st_mtime, 1);
    direntry->mdate = fat_datetime(st.st_mtime, 0);
    if (is_dotdot)
      set_begin_of_direntry(direntry, first_cluster_of_parent);
    else if (is_dot)
      set_begin_of_direntry(direntry, first_cluster);
    else
      direntry->begin = 0; // do that later
    if (st.st_size > 0x7fffffff) {
      BX_ERROR(("File '%s' is larger than 2GB", buffer));
      free(buffer);
      closedir(dir);
      return -3;
    }
    direntry->size = htod32(S_ISDIR(st.st_mode) ? 0:st.st_size);

    // create mapping for this file
    if (!is_dot && !is_dotdot && (S_ISDIR(st.st_mode) || st.st_size)) {
      current_mapping = (mapping_t*)array_get_next(&this->mapping);
      current_mapping->begin = 0;
      current_mapping->end = st.st_size;
      /*
       * we get the direntry of the most recent direntry, which
       * contains the short name and all the relevant information.
       */
      current_mapping->dir_index = directory.next-1;
      current_mapping->first_mapping_index = -1;
      if (S_ISDIR(st.st_mode)) {
        current_mapping->mode = MODE_DIRECTORY;
        current_mapping->info.dir.parent_mapping_index =
          mapping_index;
      } else {
        current_mapping->mode = MODE_UNDEFINED;
        current_mapping->info.file.offset = 0;
      }
      current_mapping->path = buffer;
      current_mapping->read_only =
        (st.st_mode & (S_IWUSR | S_IWGRP | S_IWOTH)) == 0;
    }
  }
  closedir(dir);
#else
  WIN32_FIND_DATA finddata;
  char filter[MAX_PATH];
  wsprintf(filter, "%s\\*.*", dirname);
  HANDLE hFind = FindFirstFile(filter, &finddata);
  int i;

  assert(mapping->mode & MODE_DIRECTORY);

  if (hFind == INVALID_HANDLE_VALUE) {
    mapping->end = mapping->begin;
    return -1;
  }

  i = mapping->info.dir.first_dir_index =
    first_cluster == first_cluster_of_root_dir ? 0 : directory.next;

  if (first_cluster != first_cluster_of_root_dir) {
    // create the top entries of a subdirectory
    direntry = create_short_and_long_name(i, ".", 1);
    direntry = create_short_and_long_name(i, "..", 1);
  }

  // actually read the directory, and allocate the mappings
  do {
    if ((first_cluster == 0) && (directory.next >= (Bit16u)(root_entries - 1))) {
      BX_ERROR(("Too many entries in root directory, using only %d", count));
      FindClose(hFind);
      return -2;
    }
    unsigned int length = lstrlen(dirname) + 2 + lstrlen(finddata.cFileName);
    char* buffer;
    direntry_t* direntry;
    bx_bool is_dot = !lstrcmp(finddata.cFileName, ".");
    bx_bool is_dotdot = !lstrcmp(finddata.cFileName, "..");
    if ((first_cluster == first_cluster_of_root_dir) && (is_dotdot || is_dot))
      continue;
    bx_bool is_mbr_file = !lstrcmp(finddata.cFileName, VVFAT_MBR);
    bx_bool is_boot_file = !lstrcmp(finddata.cFileName, VVFAT_BOOT);
    bx_bool is_attr_file = !lstrcmp(finddata.cFileName, VVFAT_ATTR);
    if (first_cluster == first_cluster_of_root_dir) {
      if (is_attr_file || ((is_mbr_file || is_boot_file) && (finddata.nFileSizeLow == 512)))
        continue;
    }

    buffer = (char*)malloc(length);
    snprintf(buffer, length, "%s/%s", dirname, finddata.cFileName);

    count++;
    // create directory entry for this file
    if (!is_dot && !is_dotdot) {
      direntry = create_short_and_long_name(i, finddata.cFileName, 0);
    } else {
      direntry = (direntry_t*)array_get(&directory, is_dot ? i : i + 1);
    }
    direntry->attributes = ((finddata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) ? 0x10 : 0x20);
    direntry->reserved[0] = direntry->reserved[1]=0;
    direntry->ctime = fat_datetime(finddata.ftCreationTime, 1);
    direntry->cdate = fat_datetime(finddata.ftCreationTime, 0);
    direntry->adate = fat_datetime(finddata.ftLastAccessTime, 0);
    direntry->begin_hi = 0;
    direntry->mtime = fat_datetime(finddata.ftLastWriteTime, 1);
    direntry->mdate = fat_datetime(finddata.ftLastWriteTime, 0);
    if (is_dotdot)
      set_begin_of_direntry(direntry, first_cluster_of_parent);
    else if (is_dot)
      set_begin_of_direntry(direntry, first_cluster);
    else
      direntry->begin = 0; // do that later
    if (finddata.nFileSizeLow > 0x7fffffff) {
      BX_ERROR(("File '%s' is larger than 2GB", buffer));
      free(buffer);
      FindClose(hFind);
      return -3;
    }
    direntry->size = htod32((finddata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) ? 0:finddata.nFileSizeLow);

    // create mapping for this file
    if (!is_dot && !is_dotdot && ((finddata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) || finddata.nFileSizeLow)) {
      current_mapping = (mapping_t*)array_get_next(&this->mapping);
      current_mapping->begin = 0;
      current_mapping->end = finddata.nFileSizeLow;
      /*
       * we get the direntry of the most recent direntry, which
       * contains the short name and all the relevant information.
       */
      current_mapping->dir_index = directory.next-1;
      current_mapping->first_mapping_index = -1;
      if (finddata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
        current_mapping->mode = MODE_DIRECTORY;
        current_mapping->info.dir.parent_mapping_index =
          mapping_index;
      } else {
        current_mapping->mode = MODE_UNDEFINED;
        current_mapping->info.file.offset = 0;
      }
      current_mapping->path=buffer;
      current_mapping->read_only = (finddata.dwFileAttributes & FILE_ATTRIBUTE_READONLY);
    }
  } while (FindNextFile(hFind, &finddata));
  FindClose(hFind);
#endif

  // fill with zeroes up to the end of the cluster
  while (directory.next % (0x10 * sectors_per_cluster)) {
    direntry_t* direntry = (direntry_t*)array_get_next(&directory);
    memset(direntry, 0, sizeof(direntry_t));
  }

  if (fat_type != 32) {
    if ((mapping_index == 0) && (directory.next < root_entries)) {
      // root directory
      int cur = directory.next;
      array_ensure_allocated(&directory, root_entries - 1);
      memset(array_get(&directory, cur), 0,
             (root_entries - cur) * sizeof(direntry_t));
    }
  }

  // reget the mapping, since this->mapping was possibly realloc()ed
  mapping = (mapping_t*)array_get(&this->mapping, mapping_index);
  if (first_cluster == 0) {
    first_cluster = 2;
  } else {
    first_cluster += (directory.next - mapping->info.dir.first_dir_index)
                     * 0x20 / cluster_size;
  }
  mapping->end = first_cluster;

  direntry = (direntry_t*)array_get(&directory, mapping->dir_index);
  set_begin_of_direntry(direntry, mapping->begin);

  return 0;
}

Bit32u vvfat_image_t::sector2cluster(off_t sector_num)
{
    return (Bit32u)((sector_num - offset_to_data) / sectors_per_cluster) + 2;
}

off_t vvfat_image_t::cluster2sector(Bit32u cluster_num)
{
    return (off_t)(offset_to_data + (cluster_num - 2) * sectors_per_cluster);
}

int vvfat_image_t::init_directories(const char* dirname)
{
  bootsector_t* bootsector;
  infosector_t* infosector;
  mapping_t* mapping;
  unsigned int i;
  unsigned int cluster;
  char size_txt[8];
  Bit32u volume_sector_count = 0, tmpsc;

  cluster_size   = sectors_per_cluster * 0x200;
  cluster_buffer = new Bit8u[cluster_size];

  bootsector = (bootsector_t*)(first_sectors + offset_to_bootsector * 0x200);

  if (!use_boot_file) {
    volume_sector_count = sector_count - offset_to_bootsector;
    tmpsc = volume_sector_count - reserved_sectors - root_entries / 16;
    cluster_count = (tmpsc * 0x200) / ((sectors_per_cluster * 0x200) + fat_type / 4);
    sectors_per_fat = ((cluster_count + 2) * fat_type / 8) / 0x200;
    sectors_per_fat += (((cluster_count + 2) * fat_type / 8) % 0x200) > 0;
  } else {
    if (fat_type != 32) {
      sectors_per_fat = bootsector->sectors_per_fat;
    } else {
      sectors_per_fat = bootsector->u.fat32.sectors_per_fat;
    }
  }

  offset_to_fat = offset_to_bootsector + reserved_sectors;
  offset_to_root_dir = offset_to_fat + sectors_per_fat * 2;
  offset_to_data = offset_to_root_dir + root_entries / 16;
  if (use_boot_file) {
    cluster_count = (sector_count - offset_to_data) / sectors_per_cluster;
  }

  array_init(&this->mapping, sizeof(mapping_t));
  array_init(&directory, sizeof(direntry_t));

  /* add volume label */
  {
    direntry_t *entry = (direntry_t*)array_get_next(&directory);
    entry->attributes = 0x28; // archive | volume label
    entry->mdate = 0x3d81; // 01.12.2010
    entry->mtime = 0x6000; // 12:00:00
    memcpy(entry->name, "BOCHS VV", 8);
    memcpy(entry->extension, "FAT", 3);
  }

  // Now build FAT, and write back information into directory
  init_fat();

  mapping = (mapping_t*)array_get_next(&this->mapping);
  mapping->begin = 0;
  mapping->dir_index = 0;
  mapping->info.dir.parent_mapping_index = -1;
  mapping->first_mapping_index = -1;
  mapping->path = strdup(dirname);
  i = strlen(mapping->path);
  if (i > 0 && mapping->path[i - 1] == '/')
    mapping->path[i - 1] = '\0';
  mapping->mode = MODE_DIRECTORY;
  mapping->read_only = 0;
  vvfat_path = mapping->path;

  for (i = 0, cluster = first_cluster_of_root_dir; i < this->mapping.next; i++) {
    // fix fat entry if not root directory of FAT12/FAT16
    int fix_fat = (cluster != 0);
    mapping = (mapping_t*)array_get(&this->mapping, i);

    if (mapping->mode & MODE_DIRECTORY) {
      mapping->begin = cluster;
      if (read_directory(i)) {
        BX_PANIC(("Could not read directory '%s'", mapping->path));
        return -1;
      }
      mapping = (mapping_t*)array_get(&this->mapping, i);
    } else {
      assert(mapping->mode == MODE_UNDEFINED);
      mapping->mode = MODE_NORMAL;
      mapping->begin = cluster;
      if (mapping->end > 0) {
        direntry_t* direntry = (direntry_t*)array_get(&directory, mapping->dir_index);

        mapping->end = cluster + 1 + (mapping->end-1) / cluster_size;
        set_begin_of_direntry(direntry, mapping->begin);
      } else {
        mapping->end = cluster + 1;
        fix_fat = 0;
      }
    }

    assert(mapping->begin < mapping->end);

    /* next free cluster */
    cluster = mapping->end;

    if (cluster >= (cluster_count + 2)) {
      sprintf(size_txt, "%d", (sector_count >> 11));
      BX_PANIC(("Directory does not fit in FAT%d (capacity %s MB)",
                fat_type,
                (fat_type == 12) ? (sector_count == 2880) ? "1.44":"2.88"
                : size_txt));
      return -EINVAL;
    }

    // fix fat for entry
    if (fix_fat) {
      int j;
      for (j = mapping->begin; j < (int)(mapping->end - 1); j++)
        fat_set(j, j + 1);
      fat_set(mapping->end - 1, max_fat_value);
    }
  }

  mapping = (mapping_t*)array_get(&this->mapping, 0);
  assert((fat_type == 32) || (mapping->end == 2));

  // the FAT signature
  fat_set(0, max_fat_value);
  fat_set(1, max_fat_value);

  current_mapping = NULL;

  if (!use_boot_file) {
    bootsector->jump[0] = 0xeb;
    if (fat_type != 32) {
      bootsector->jump[1] = 0x3e;
    } else {
      bootsector->jump[1] = 0x58;
    }
    bootsector->jump[2] = 0x90;
    memcpy(bootsector->name,"MSWIN4.1", 8); // Win95/98 need this to detect FAT32
    bootsector->sector_size = htod16(0x200);
    bootsector->sectors_per_cluster = sectors_per_cluster;
    bootsector->reserved_sectors = htod16(reserved_sectors);
    bootsector->number_of_fats = 0x2;
    if (fat_type != 32) {
      bootsector->root_entries = htod16(root_entries);
    }
    bootsector->total_sectors16 = (volume_sector_count > 0xffff) ? 0:htod16(volume_sector_count);
    bootsector->media_type = ((fat_type != 12) ? 0xf8:0xf0);
    if (fat_type != 32) {
      bootsector->sectors_per_fat = htod16(sectors_per_fat);
    }
    bootsector->sectors_per_track = htod16(sectors);
    bootsector->number_of_heads = htod16(heads);
    bootsector->hidden_sectors = htod32(offset_to_bootsector);
    bootsector->total_sectors = htod32((volume_sector_count > 0xffff) ? volume_sector_count:0);
    if (fat_type != 32) {
      bootsector->u.fat16.drive_number = (fat_type == 12) ? 0:0x80; // assume this is hda (TODO)
      bootsector->u.fat16.signature = 0x29;
      bootsector->u.fat16.id = htod32(0xfabe1afd);
      memcpy(bootsector->u.fat16.volume_label, "BOCHS VVFAT", 11);
      memcpy(bootsector->u.fat16.fat_type, (fat_type==12) ? "FAT12   ":"FAT16   ", 8);
    } else {
      bootsector->u.fat32.sectors_per_fat = htod32(sectors_per_fat);
      bootsector->u.fat32.first_cluster_of_root_dir = first_cluster_of_root_dir;
      bootsector->u.fat32.info_sector = htod16(1);
      bootsector->u.fat32.backup_boot_sector = htod16(6);
      bootsector->u.fat32.drive_number = 0x80; // assume this is hda (TODO)
      bootsector->u.fat32.signature = 0x29;
      bootsector->u.fat32.id = htod32(0xfabe1afd);
      memcpy(bootsector->u.fat32.volume_label, "BOCHS VVFAT", 11);
      memcpy(bootsector->u.fat32.fat_type, "FAT32   ", 8);
    }
    bootsector->magic[0] = 0x55;
    bootsector->magic[1] = 0xaa;
  }
  fat.pointer[0] = bootsector->media_type;

  if (fat_type == 32) {
    // backup boot sector
    memcpy(&first_sectors[(offset_to_bootsector + 6) * 0x200], &first_sectors[offset_to_bootsector * 0x200], 0x200);
    // FS info sector
    infosector = (infosector_t*)(first_sectors + (offset_to_bootsector + 1) * 0x200);
    infosector->signature1 = htod32(0x41615252);
    infosector->signature2 = htod32(0x61417272);
    infosector->free_clusters = htod32(cluster_count - cluster + 2);
    infosector->mra_cluster = htod32(2);
    infosector->magic[0] = 0x55;
    infosector->magic[1] = 0xaa;
  }

  return 0;
}

bx_bool vvfat_image_t::read_sector_from_file(const char *path, Bit8u *buffer, Bit32u sector)
{
  int fd = ::open(path, O_RDONLY
#ifdef O_BINARY
                  | O_BINARY
#endif
#ifdef O_LARGEFILE
                  | O_LARGEFILE
#endif
                  );
  if (fd < 0)
    return 0;
  int offset = sector * 0x200;
  if (::lseek(fd, offset, SEEK_SET) != offset) {
    return 0;
    ::close(fd);
  }
  int result = ::read(fd, buffer, 0x200);
  ::close(fd);
  bx_bool bootsig = ((buffer[0x1fe] == 0x55) && (buffer[0x1ff] == 0xaa));

  return (result == 0x200) && bootsig;
}

void vvfat_image_t::set_file_attributes(void)
{
  char path[BX_PATHNAME_LEN];
  char fpath[BX_PATHNAME_LEN];
  char line[512];
  char *ret, *ptr;
  FILE *fd;
  Bit8u attributes;
  int i;

  sprintf(path, "%s/%s", vvfat_path, VVFAT_ATTR);
  fd = fopen(path, "r");
  if (fd != NULL) {
    do {
      ret = fgets(line, sizeof(line) - 1, fd);
      if (ret != NULL) {
        line[sizeof(line) - 1] = '\0';
        size_t len = strlen(line);
        if ((len > 0) && (line[len - 1] < ' ')) line[len - 1] = '\0';
        ptr = strtok(line, ":");
        if (ptr[0] == 34) {
          strcpy(fpath, ptr + 1);
        } else {
          strcpy(fpath, ptr);
        }
        if (fpath[strlen(fpath) - 1] == 34) {
          fpath[strlen(fpath) - 1] = '\0';
        }
        mapping_t* mapping = find_mapping_for_path(fpath);
        direntry_t* entry = (direntry_t*)array_get(&directory, mapping->dir_index);
        attributes = entry->attributes;
        ptr = strtok(NULL, "");
        for (i = 0; i < (int)strlen(ptr); i++) {
          switch (ptr[i]) {
            case 'a':
              attributes &= ~0x20;
              break;
            case 'S':
              attributes |= 0x04;
              break;
            case 'H':
              attributes |= 0x02;
              break;
            case 'R':
              attributes |= 0x01;
              break;
          }
        }
        entry->attributes = attributes;
      }
    } while (!feof(fd));
    fclose(fd);
  }
}

int vvfat_image_t::open(const char* dirname)
{
  Bit32u size_in_mb;
  char path[BX_PATHNAME_LEN];
  Bit8u sector_buffer[0x200];
  int filedes;
  const char *logname = NULL;
  char ftype[10];
  bx_bool ftype_ok;

  use_mbr_file = 0;
  use_boot_file = 0;
  fat_type = 0;
  sectors_per_cluster = 0;

  snprintf(path, BX_PATHNAME_LEN, "%s/%s", dirname, VVFAT_MBR);
  if (read_sector_from_file(path, sector_buffer, 0)) {
    mbr_t* real_mbr = (mbr_t*)sector_buffer;
    partition_t* partition = &(real_mbr->partition[0]);
    if ((partition->fs_type != 0) && (partition->length_sector_long > 0)) {
      if ((partition->fs_type == 0x06) || (partition->fs_type == 0x0e)) {
        fat_type = 16;
      } else if ((partition->fs_type == 0x0b) || (partition->fs_type == 0x0c)) {
        fat_type = 32;
      } else {
        BX_ERROR(("MBR file: unsupported FS type = 0x%02x", partition->fs_type));
      }
      if (fat_type != 0) {
        sector_count = partition->start_sector_long + partition->length_sector_long;
        sectors = partition->start_sector_long;
        if (partition->end_CHS.head > 15) {
          heads = 16;
        } else {
          heads = partition->end_CHS.head + 1;
        }
        cylinders = sector_count / (heads * sectors);
        offset_to_bootsector = sectors;
        memcpy(&first_sectors[0], sector_buffer, 0x200);
        use_mbr_file = 1;
        BX_INFO(("VVFAT: using MBR from file"));
      }
    }
  }

  snprintf(path, BX_PATHNAME_LEN, "%s/%s", dirname, VVFAT_BOOT);
  if (read_sector_from_file(path, sector_buffer, 0)) {
    bootsector_t* bs = (bootsector_t*)sector_buffer;
    if (use_mbr_file) {
      sprintf(ftype, "FAT%d   ", fat_type);
      if (fat_type == 32) {
        ftype_ok = memcmp(bs->u.fat32.fat_type, ftype, 8) == 0;
      } else {
        ftype_ok = memcmp(bs->u.fat16.fat_type, ftype, 8) == 0;
      }
      Bit32u sc = bs->total_sectors16 + bs->total_sectors + bs->hidden_sectors;
      if (ftype_ok && (sc == sector_count) && (bs->number_of_fats == 2)) {
        use_boot_file = 1;
      }
    } else {
      if (memcmp(bs->u.fat16.fat_type, "FAT12   ", 8) == 0) {
        fat_type = 12;
      } else if (memcmp(bs->u.fat16.fat_type, "FAT16   ", 8) == 0) {
        fat_type = 16;
      } else if (memcmp(bs->u.fat32.fat_type, "FAT32   ", 8) == 0) {
        fat_type = 32;
      } else {
        memcpy(ftype, bs->u.fat16.fat_type, 8);
        ftype[8] = 0;
        BX_PANIC(("boot sector file: unsupported FS type = '%s'", ftype));
        return -1;
      }
      if ((fat_type != 0) && (bs->number_of_fats == 2)) {
        sector_count = bs->total_sectors16 + bs->total_sectors + bs->hidden_sectors;
        sectors = bs->sectors_per_track;
        if (bs->number_of_heads > 15) {
          heads = 16;
        } else {
          heads = bs->number_of_heads;
        }
        cylinders = sector_count / (heads * sectors);
        offset_to_bootsector = bs->hidden_sectors;
        use_boot_file = 1;
      }
    }
    if (use_boot_file) {
      sectors_per_cluster = bs->sectors_per_cluster;
      reserved_sectors = bs->reserved_sectors;
      root_entries = bs->root_entries;
      first_cluster_of_root_dir = (fat_type != 32) ? 0 : bs->u.fat32.first_cluster_of_root_dir;
      memcpy(&first_sectors[offset_to_bootsector * 0x200], sector_buffer, 0x200);
      BX_INFO(("VVFAT: using boot sector from file"));
    }
  }

  if (!use_mbr_file && !use_boot_file) {
    if (hd_size == 1474560) {
      // floppy support
      cylinders = 80;
      heads = 2;
      sectors = 18;
      offset_to_bootsector = 0;
      fat_type = 12;
      sectors_per_cluster = 1;
      first_cluster_of_root_dir = 0;
      root_entries = 224;
      reserved_sectors = 1;
    } else {
      if (cylinders == 0) {
        cylinders = 1024;
        heads = 16;
        sectors = 63;
      }
      offset_to_bootsector = sectors;
    }
    sector_count = cylinders * heads * sectors;
  }

  hd_size = sector_count * 512;
  if (sectors_per_cluster == 0) {
    size_in_mb = (Bit32u)(hd_size >> 20);
    if ((size_in_mb >= 2047) || (fat_type == 32)) {
      fat_type = 32;
      if (size_in_mb >= 32767) {
        sectors_per_cluster = 64;
      } else if (size_in_mb >= 16383) {
        sectors_per_cluster = 32;
      } else if (size_in_mb >= 8191) {
        sectors_per_cluster = 16;
      } else {
        sectors_per_cluster = 8;
      }
      first_cluster_of_root_dir = 2;
      root_entries = 0;
      reserved_sectors = 32;
    } else {
      fat_type = 16;
      if (size_in_mb >= 1023) {
        sectors_per_cluster = 64;
      } else if (size_in_mb >= 511) {
        sectors_per_cluster = 32;
      } else if (size_in_mb >= 255) {
        sectors_per_cluster = 16;
      } else if (size_in_mb >= 127) {
        sectors_per_cluster = 8;
      } else {
        sectors_per_cluster = 4;
      }
      first_cluster_of_root_dir = 0;
      root_entries = 512;
      reserved_sectors = 1;
    }
  }

  current_cluster = 0xffff;
  current_fd = 0;

  if ((!use_mbr_file) && (offset_to_bootsector > 0))
    init_mbr();

  init_directories(dirname);
  set_file_attributes();

  // VOLATILE WRITE SUPPORT
  snprintf(path, BX_PATHNAME_LEN, "%s/vvfat.dir", dirname);
  // if redolog name was set
  if (redolog_name != NULL) {
    if (strcmp(redolog_name, "") != 0) {
      logname = redolog_name;
    }
  }

  // otherwise use path as template
  if (logname == NULL) {
    logname = path;
  }

  redolog_temp = (char*)malloc(strlen(logname) + VOLATILE_REDOLOG_EXTENSION_LENGTH + 1);
  sprintf(redolog_temp, "%s%s", logname, VOLATILE_REDOLOG_EXTENSION);

  filedes = mkstemp(redolog_temp);

  if (filedes < 0) {
    BX_PANIC(("Can't create volatile redolog '%s'", redolog_temp));
    return -1;
  }
  if (redolog->create(filedes, REDOLOG_SUBTYPE_VOLATILE, hd_size) < 0) {
    BX_PANIC(("Can't create volatile redolog '%s'", redolog_temp));
    return -1;
  }

#if (!defined(WIN32)) && !BX_WITH_MACOS
  // on unix it is legal to delete an open file
  unlink(redolog_temp);
#endif

  vvfat_modified = 0;

  BX_INFO(("'vvfat' disk opened: directory is '%s', redolog is '%s'", dirname, redolog_temp));

  return 0;
}

direntry_t* vvfat_image_t::read_direntry(Bit8u *buffer, char *filename)
{
  const Bit8u lfn_map[13] = {1, 3, 5, 7, 9, 14, 16, 18, 20, 22, 24, 28, 30};
  direntry_t *entry;
  bx_bool entry_ok = 0, has_lfn = 0;
  char lfn_tmp[BX_PATHNAME_LEN];
  int i;

  memset(filename, 0, BX_PATHNAME_LEN);
  lfn_tmp[0] = 0;
  do {
    entry = (direntry_t*)buffer;
    if (entry->name[0] == 0) {
      entry = NULL;
      break;
    } else if ((entry->name[0] != '.') && (entry->name[0] != 0xe5) &&
               ((entry->attributes & 0x0f) != 0x08)) {
      if (is_long_name(entry)) {
        for (i = 0; i < 13; i++) {
          lfn_tmp[i] = buffer[lfn_map[i]];
        }
        lfn_tmp[i] = 0;
        strcat(lfn_tmp, filename);
        strcpy(filename, lfn_tmp);
        has_lfn = 1;
        buffer += 32;
      } else {
        if (!has_lfn) {
          if (entry->name[0] == 0x05) entry->name[0] = 0xe5;
          memcpy(filename, entry->name, 8);
          i = 7;
          while ((i > 0) && (filename[i] == ' ')) filename[i--] = 0;
          if (entry->extension[0] != ' ') strcat(filename, ".");
          memcpy(filename+i+2, entry->extension, 3);
          i = strlen(filename) - 1;
          while (filename[i] == ' ') filename[i--] = 0;
          for (i = 0; i < (int)strlen(filename); i++) {
            if ((filename[i] > 0x40) && (filename[i] < 0x5b)) {
              filename[i] |= 0x20;
            }
          }
        }
        entry_ok = 1;
      }
    } else {
      buffer += 32;
    }
  } while (!entry_ok);
  return entry;
}

Bit32u vvfat_image_t::fat_get_next(Bit32u current)
{
  if (fat_type == 32) {
    return dtoh32(((Bit32u*)fat2)[current]);
  } else if (fat_type == 16) {
    return dtoh16(((Bit16u*)fat2)[current]);
  } else {
    int offset = (current * 3 / 2);
    Bit8u* p = (((Bit8u*)fat2) + offset);
    Bit32u value = 0;
    switch (current & 1) {
      case 0:
        value = p[0] | ((p[1] & 0x0f) << 8);
        break;
      case 1:
        value = (p[0] >> 4) | (p[1] << 4);
        break;
    }
    return value;
  }
}

bx_bool vvfat_image_t::write_file(const char *path, direntry_t *entry, bx_bool create)
{
  int fd;
  Bit32u csize, fsize, fstart, cur, next, rsvd_clusters, bad_cluster;
  Bit64u offset;
  Bit8u *buffer;
#ifndef WIN32
  struct tm tv;
  struct utimbuf ut;
#else
  HANDLE hFile;
  FILETIME at, mt, tmp;
  SYSTEMTIME st;
#endif

  csize = sectors_per_cluster * 0x200;
  rsvd_clusters = max_fat_value - 15;
  bad_cluster = max_fat_value - 8;
  fsize = dtoh32(entry->size);
  fstart = dtoh16(entry->begin) | (dtoh16(entry->begin_hi) << 16);
  if (create) {
    fd = ::open(path, O_CREAT | O_RDWR | O_TRUNC
#ifdef O_BINARY
                | O_BINARY
#endif
#ifdef O_LARGEFILE
                | O_LARGEFILE
#endif
                , 0644);
  } else {
    fd = ::open(path, O_RDWR | O_TRUNC
#ifdef O_BINARY
                | O_BINARY
#endif
#ifdef O_LARGEFILE
                | O_LARGEFILE
#endif
                );
  }
  if (fd < 0)
    return 0;
  buffer = (Bit8u*)malloc(csize);
  next = fstart;
  do {
    cur = next;
    offset = cluster2sector(cur);
    lseek(offset * 0x200, SEEK_SET);
    read(buffer, csize);
    if (fsize > csize) {
      ::write(fd, buffer, csize);
      fsize -= csize;
    } else {
      ::write(fd, buffer, fsize);
    }
    next = fat_get_next(cur);
    if ((next >= rsvd_clusters) && (next < bad_cluster)) {
      BX_ERROR(("reserved clusters not supported"));
    }
  } while (next < rsvd_clusters);
  ::close(fd);

#ifndef WIN32
  tv.tm_year = (entry->mdate >> 9) + 80;
  tv.tm_mon = ((entry->mdate >> 5) & 0x0f) - 1;
  tv.tm_mday = entry->mdate & 0x1f;
  tv.tm_hour = (entry->mtime >> 11);
  tv.tm_min = (entry->mtime >> 5) & 0x3f;
  tv.tm_sec = (entry->mtime & 0x1f) << 1;
  tv.tm_isdst = -1;
  ut.modtime = mktime(&tv);
  if (entry->adate != 0) {
    tv.tm_year = (entry->adate >> 9) + 80;
    tv.tm_mon = ((entry->adate >> 5) & 0x0f) - 1;
    tv.tm_mday = entry->adate & 0x1f;
    tv.tm_hour = 0;
    tv.tm_min = 0;
    tv.tm_sec = 0;
    ut.actime = mktime(&tv);
  } else {
    ut.actime = ut.modtime;
  }
  utime(path, &ut);
#else
  hFile = CreateFile(path, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
  if (hFile != INVALID_HANDLE_VALUE) {
    memset(&st, 0, sizeof(st));
    st.wYear = (entry->mdate >> 9) + 1980;
    st.wMonth = ((entry->mdate >> 5) & 0x0f);
    st.wDay = entry->mdate & 0x1f;
    st.wHour = (entry->mtime >> 11);
    st.wMinute = (entry->mtime >> 5) & 0x3f;
    st.wSecond = (entry->mtime & 0x1f) << 1;
    SystemTimeToFileTime(&st, &tmp);
    LocalFileTimeToFileTime(&tmp, &mt);
    if (entry->adate != 0) {
      st.wYear = (entry->adate >> 9) + 1980;
      st.wMonth = ((entry->adate >> 5) & 0x0f);
      st.wDay = entry->adate & 0x1f;
      st.wHour = 0;
      st.wMinute = 0;
      st.wSecond = 0;
      SystemTimeToFileTime(&st, &tmp);
      LocalFileTimeToFileTime(&tmp, &at);
    } else {
      at = mt;
    }
    SetFileTime(hFile, NULL, &at, &mt);
    CloseHandle(hFile);
  }
#endif

  return 1;
}

void vvfat_image_t::parse_directory(const char *path, Bit32u start_cluster)
{
  Bit32u csize, fstart, cur, next, size;
  Bit64u offset;
  Bit8u *buffer, *ptr;
  direntry_t *entry, *newentry;
  char filename[BX_PATHNAME_LEN];
  char full_path[BX_PATHNAME_LEN];
  char attr_txt[4];
  mapping_t *mapping;

  csize = sectors_per_cluster * 0x200;
  if (start_cluster == 0) {
    size = root_entries * 32;
    offset = offset_to_root_dir;
    buffer = (Bit8u*)malloc(size);
    lseek(offset * 0x200, SEEK_SET);
    read(buffer, size);
  } else {
    size = csize;
    buffer = (Bit8u*)malloc(size);
    next = start_cluster;
    do {
      cur = next;
      offset = cluster2sector(cur);
      lseek(offset * 0x200, SEEK_SET);
      read(buffer+(size-csize), csize);
      next = fat_get_next(cur);
      if (next != max_fat_value) {
        size += csize;
        buffer = (Bit8u*)realloc(buffer, size);
      }
    } while (next != max_fat_value);
  }
  ptr = buffer;
  do {
    newentry = read_direntry(ptr, filename);
    if (newentry != NULL) {
      sprintf(full_path, "%s/%s", path, filename);
      if ((newentry->attributes != 0x10) && (newentry->attributes != 0x20)) {
        if (vvfat_attr_fd != NULL) {
          attr_txt[0] = 0;
          if ((newentry->attributes & 0x30) == 0) strcpy(attr_txt, "a");
          if (newentry->attributes & 0x04) strcpy(attr_txt, "S");
          if (newentry->attributes & 0x02) strcat(attr_txt, "H");
          if (newentry->attributes & 0x01) strcat(attr_txt, "R");
          fprintf(vvfat_attr_fd, "\"%s\":%s\n", full_path, attr_txt);
        }
      }
      fstart = dtoh16(newentry->begin) | (dtoh16(newentry->begin_hi) << 16);
      mapping = find_mapping_for_cluster(fstart);
      if (mapping == NULL) {
        if (newentry->attributes == 0x10) {
          bx_mkdir(full_path);
          parse_directory(full_path, fstart);
        } else {
          if (access(full_path, F_OK) == 0) {
            mapping = find_mapping_for_path(full_path);
            if (mapping != NULL) {
              mapping->mode &= ~MODE_DELETED;
            }
            write_file(full_path, newentry, 0);
          } else {
            write_file(full_path, newentry, 1);
          }
        }
      } else {
        entry = (direntry_t*)array_get(&directory, mapping->dir_index);
        if (!strcmp(full_path, mapping->path)) {
          if (newentry->attributes == 0x10) {
            parse_directory(full_path, fstart);
            mapping->mode &= ~MODE_DELETED;
          } else {
            if ((newentry->mdate != entry->mdate) || (newentry->mtime != entry->mtime) ||
                (newentry->size != entry->size)) {
              write_file(full_path, newentry, 0);
            }
            mapping->mode &= ~MODE_DELETED;
          }
        } else {
          if ((newentry->cdate == entry->cdate) && (newentry->ctime == entry->ctime)) {
            rename(mapping->path, full_path);
            if (newentry->attributes == 0x10) {
              parse_directory(full_path, fstart);
              mapping->mode &= ~MODE_DELETED;
            } else {
              if ((newentry->mdate != entry->mdate) || (newentry->mtime != entry->mtime) ||
                  (newentry->size != entry->size)) {
                write_file(full_path, newentry, 0);
              }
              mapping->mode &= ~MODE_DELETED;
            }
          } else {
            if (newentry->attributes == 0x10) {
              bx_mkdir(full_path);
              parse_directory(full_path, fstart);
            } else {
              if (access(full_path, F_OK) == 0) {
                mapping = find_mapping_for_path(full_path);
                if (mapping != NULL) {
                  mapping->mode &= ~MODE_DELETED;
                }
                write_file(full_path, newentry, 0);
              } else {
                write_file(full_path, newentry, 1);
              }
            }
          }
        }
      }
      ptr = (Bit8u*)newentry+32;
    }
  } while ((newentry != NULL) && ((Bit32u)(ptr - buffer) < size));
  free(buffer);
}

void vvfat_image_t::commit_changes(void)
{
  char path[BX_PATHNAME_LEN];
  mapping_t *mapping;
  int i;

  // read modified FAT
  fat2 = malloc(sectors_per_fat * 0x200);
  lseek(offset_to_fat * 0x200, SEEK_SET);
  read(fat2, sectors_per_fat * 0x200);
  // mark all mapped directories / files for delete
  for (i = 1; i < (int)this->mapping.next; i++) {
    mapping = (mapping_t*)array_get(&this->mapping, i);
    if (mapping->first_mapping_index < 0) {
      mapping->mode |= MODE_DELETED;
    }
  }
  sprintf(path, "%s/%s", vvfat_path, VVFAT_ATTR);
  vvfat_attr_fd = fopen(path, "w");
  // parse new directory tree and create / modify directories and files
  parse_directory(vvfat_path, (fat_type == 32) ? first_cluster_of_root_dir : 0);
  if (vvfat_attr_fd != NULL) 
    fclose(vvfat_attr_fd);
  // remove all directories and files still marked for delete
  for (i = this->mapping.next - 1; i > 0; i--) {
    mapping = (mapping_t*)array_get(&this->mapping, i);
    if (mapping->mode & MODE_DELETED) {
      direntry_t* entry = (direntry_t*)array_get(&directory, mapping->dir_index);
      if (entry->attributes == 0x10) {
        bx_rmdir(mapping->path);
      } else {
        unlink(mapping->path);
      }
    }
  }
  free(fat2);
}

void vvfat_image_t::close(void)
{
  char msg[BX_PATHNAME_LEN + 80];

  if (vvfat_modified) {
    sprintf(msg, "Write back changes to directory '%s'?\n\nWARNING: This feature is still experimental!", vvfat_path);
    if (SIM->ask_yes_no("Bochs VVFAT modified", msg, 0)) {
      commit_changes();
    }
  }
  array_free(&fat);
  array_free(&directory);
  array_free(&mapping);
  if (cluster_buffer != NULL)
    delete [] cluster_buffer;

  redolog->close();

#if defined(WIN32) || BX_WITH_MACOS
  // on non-unix we have to wait till the file is closed to delete it
  unlink(redolog_temp);
#endif
  if (redolog_temp!=NULL)
    free(redolog_temp);

  if (redolog_name!=NULL)
    free(redolog_name);
}

Bit64s vvfat_image_t::lseek(Bit64s offset, int whence)
{
  redolog->lseek(offset, whence);
  if (whence == SEEK_SET) {
    sector_num = (Bit32u)(offset / 512);
  } else if (whence == SEEK_CUR) {
    sector_num += (Bit32u)(offset / 512);
  } else {
    BX_ERROR(("lseek: mode not supported yet"));
    return -1;
  }
  if (sector_num >= sector_count)
    return -1;
  return 0;
}

void vvfat_image_t::close_current_file(void)
{
  if(current_mapping) {
    current_mapping = NULL;
    if (current_fd) {
      ::close(current_fd);
      current_fd = 0;
    }
  }
  current_cluster = 0xffff;
}

// mappings between index1 and index2-1 are supposed to be ordered
// return value is the index of the last mapping for which end>cluster_num
int vvfat_image_t::find_mapping_for_cluster_aux(int cluster_num, int index1, int index2)
{
  while(1) {
    int index3;
    mapping_t* mapping;
    index3 = (index1+index2) / 2;
    mapping = (mapping_t*)array_get(&this->mapping, index3);
    assert(mapping->begin < mapping->end);
    if (mapping->begin >= (unsigned int)cluster_num) {
      assert(index2 != index3 || index2 == 0);
      if (index2 == index3)
        return index1;
      index2 = index3;
    } else {
      if (index1 == index3)
        return (mapping->end <= (unsigned int)cluster_num) ? index2 : index1;
      index1 = index3;
    }
    assert(index1 <= index2);
  }
}

mapping_t* vvfat_image_t::find_mapping_for_cluster(int cluster_num)
{
  int index = find_mapping_for_cluster_aux(cluster_num, 0, mapping.next);
  mapping_t* mapping;
  if (index >= (int)this->mapping.next)
    return NULL;
  mapping = (mapping_t*)array_get(&this->mapping, index);
  if ((int)mapping->begin > cluster_num)
    return NULL;
  assert(((int)mapping->begin <= cluster_num) && ((int)mapping->end > cluster_num));
  return mapping;
}

// This function simply compares path == mapping->path. Since the mappings
// are sorted by cluster, this is expensive: O(n).
mapping_t* vvfat_image_t::find_mapping_for_path(const char* path)
{
    int i;

    for (i = 0; i < (int)this->mapping.next; i++) {
      mapping_t* mapping = (mapping_t*)array_get(&this->mapping, i);
      if ((mapping->first_mapping_index < 0) && !strcmp(path, mapping->path))
        return mapping;
    }
    return NULL;
}

int vvfat_image_t::open_file(mapping_t* mapping)
{
  if (!mapping)
    return -1;
  if (!current_mapping ||
    strcmp(current_mapping->path, mapping->path)) {
    /* open file */
    int fd = ::open(mapping->path, O_RDONLY
#ifdef O_BINARY
                    | O_BINARY
#endif
#ifdef O_LARGEFILE
                    | O_LARGEFILE
#endif
                    );
    if (fd < 0)
      return -1;
    close_current_file();
    current_fd = fd;
    current_mapping = mapping;
  }
  return 0;
}

int vvfat_image_t::read_cluster(int cluster_num)
{
  mapping_t* mapping;

  if (current_cluster != cluster_num) {
    int result=0;
    off_t offset;
    assert(!current_mapping || current_fd || (current_mapping->mode & MODE_DIRECTORY));
    if (!current_mapping
        || ((int)current_mapping->begin > cluster_num)
        || ((int)current_mapping->end <= cluster_num)) {
      // binary search of mappings for file
      mapping = find_mapping_for_cluster(cluster_num);

      assert(!mapping || ((cluster_num >= (int)mapping->begin) && (cluster_num < (int)mapping->end)));

      if (mapping && mapping->mode & MODE_DIRECTORY) {
        close_current_file();
        current_mapping = mapping;
read_cluster_directory:
        offset = cluster_size * (cluster_num - current_mapping->begin);
        cluster = (unsigned char*)directory.pointer+offset
                     + 0x20 * current_mapping->info.dir.first_dir_index;
        assert(((cluster -(unsigned char*)directory.pointer) % cluster_size) == 0);
        assert((char*)cluster + cluster_size <= directory.pointer + directory.next * directory.item_size);
        current_cluster = cluster_num;
        return 0;
      }

      if (open_file(mapping))
        return -2;
    } else if (current_mapping->mode & MODE_DIRECTORY)
      goto read_cluster_directory;

    assert(current_fd);

    offset = cluster_size * (cluster_num - current_mapping->begin) + current_mapping->info.file.offset;
    if (::lseek(current_fd, offset, SEEK_SET) != offset)
      return -3;
    cluster = cluster_buffer;
    result = ::read(current_fd, cluster, cluster_size);
    if (result < 0) {
      current_cluster = 0xffff;
      return -1;
    }
    current_cluster = cluster_num;
  }
  return 0;
}

ssize_t vvfat_image_t::read(void* buf, size_t count)
{
  char *cbuf = (char*)buf;
  Bit32u scount = (Bit32u)(count / 0x200);

  while (scount-- > 0) {
    if ((size_t)redolog->read(cbuf, 0x200) != 0x200) {
      if (sector_num < offset_to_data) {
        if (sector_num < (offset_to_bootsector + reserved_sectors))
          memcpy(cbuf, &first_sectors[sector_num * 0x200], 0x200);
        else if ((sector_num - offset_to_fat) < sectors_per_fat)
          memcpy(cbuf, &fat.pointer[(sector_num - offset_to_fat) * 0x200], 0x200);
        else if ((sector_num - offset_to_fat - sectors_per_fat) < sectors_per_fat)
          memcpy(cbuf, &fat.pointer[(sector_num - offset_to_fat - sectors_per_fat) * 0x200], 0x200);
        else
          memcpy(cbuf, &directory.pointer[(sector_num - offset_to_root_dir) * 0x200], 0x200);
      } else {
        Bit32u sector = sector_num - offset_to_data,
        sector_offset_in_cluster = (sector % sectors_per_cluster),
        cluster_num = sector / sectors_per_cluster + 2;
        if (read_cluster(cluster_num) != 0) {
          memset(cbuf, 0, 0x200);
        } else {
          memcpy(cbuf, cluster + sector_offset_in_cluster * 0x200, 0x200);
        }
      }
    }
    sector_num++;
    cbuf += 0x200;
  }
  return count;
}

ssize_t vvfat_image_t::write(const void* buf, size_t count)
{
  ssize_t ret = 0;
  char *cbuf = (char*)buf;
  Bit32u scount = (Bit32u)(count / 512);

  while (scount-- > 0) {
    if (sector_num == 0) {
      // allow writing to MBR (except partition table)
      memcpy(&first_sectors[0], cbuf, 0x1b8);
    } else if ((fat_type == 32) && (sector_num == (offset_to_bootsector + 1))) {
      // allow writing to FS info sector
      memcpy(&first_sectors[sector_num * 0x200], cbuf, 0x200);
    } else if (sector_num < (offset_to_bootsector + reserved_sectors)) {
      BX_ERROR(("VVFAT write ignored: sector=%d, count=%d", sector_num, scount));
      ret = -1;
    } else {
      vvfat_modified = 1;
      ret = redolog->write(cbuf, 0x200);
    }
    if (ret < 0) break;
    sector_num++;
    cbuf += 0x200;
  }
  return (ret < 0) ? ret : count;
}

Bit32u vvfat_image_t::get_capabilities(void)
{
  return HDIMAGE_HAS_GEOMETRY;
}