/src/util-linux/libfdisk/src/dos.c

Source
/*
 *
 * Copyright (C) 2007-2013 Karel Zak <kzak@redhat.com>
 *                    2012 Davidlohr Bueso <dave@gnu.org>
 *                    2021 Pali Rohár <pali.rohar@gmail.com>
 *
 * This is re-written version for libfdisk, the original was fdiskdoslabel.c
 * from util-linux fdisk.
 */
#include "c.h"
#include "randutils.h"
#include "pt-mbr.h"
#include "strutils.h"
#include "sysfs.h"

#include "fdiskP.h"

#include <ctype.h>

#define MAXIMUM_PARTS 60
#define ACTIVE_FLAG     0x80

/**
 * SECTION: dos
 * @title: DOS
 * @short_description: disk label specific functions
 *
 */


#define IS_EXTENDED(i) \
  ((i) == MBR_DOS_EXTENDED_PARTITION \
   || (i) == MBR_W95_EXTENDED_PARTITION \
   || (i) == MBR_LINUX_EXTENDED_PARTITION)

/*
 * per partition table entry data
 *
 * The four primary partitions have the same sectorbuffer
 * and have NULL ex_entry.
 *
 * Each logical partition table entry has two pointers, one for the
 * partition and one link to the next one.
 */
struct pte {
  struct dos_partition *pt_entry; /* on-disk MBR entry */
  struct dos_partition *ex_entry; /* on-disk EBR entry */
  fdisk_sector_t offset;          /* disk sector number */
  unsigned char *sectorbuffer;  /* disk sector contents */

  unsigned int changed : 1,
         private_sectorbuffer : 1;
};

/*
 * in-memory fdisk GPT stuff
 */
struct fdisk_dos_label {
  struct fdisk_label  head;   /* generic part */

  struct pte  ptes[MAXIMUM_PARTS];  /* partition */
  fdisk_sector_t  ext_offset;   /* start of the ext.partition */
  size_t    ext_index;    /* ext.partition index (if ext_offset is set) */
  unsigned int  compatible : 1,   /* is DOS compatible? */
      non_pt_changed : 1; /* MBR, but no PT changed */
};

/*
 * Partition types
 */
static const struct fdisk_parttype dos_parttypes[] = {
  #include "pt-mbr-partnames.h"
};

static const struct fdisk_shortcut dos_parttype_cuts[] =
{
  { .shortcut = "L", .alias = "linux",    .data = "83" },
  { .shortcut = "S", .alias = "swap",     .data = "82" },
  { .shortcut = "E", .alias = "extended", .data = "05", .deprecated = 1 }, /* collision with 0x0e type */
  { .shortcut = "Ex",.alias = "extended", .data = "05" }, /* MBR extended */
  { .shortcut = "U", .alias = "uefi",     .data = "EF" }, /* UEFI system */
  { .shortcut = "R", .alias = "raid",     .data = "FD" }, /* Linux RAID */
  { .shortcut = "V", .alias = "lvm",      .data = "8E" }, /* LVM */
  { .shortcut = "X", .alias = "linuxex",  .data = "85" }  /* Linux extended */
};


#define sector(s) ((s) & 0x3f)
#define cylinder(s, c)  ((c) | (((s) & 0xc0) << 2))

#define alignment_required(_x)  ((_x)->grain != (_x)->sector_size)

#define is_dos_compatible(_x) \
       (fdisk_is_label(_x, DOS) && \
                    fdisk_dos_is_compatible(fdisk_get_label(_x, NULL)))

#define cround(c, n)  fdisk_cround(c, n)


static inline struct fdisk_dos_label *self_label(struct fdisk_context *cxt)
{
  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  return (struct fdisk_dos_label *) cxt->label;
}

static inline struct pte *self_pte(struct fdisk_context *cxt, size_t i)
{
  struct fdisk_dos_label *l = self_label(cxt);

  if (i >= ARRAY_SIZE(l->ptes))
    return NULL;

  return &l->ptes[i];
}

static inline struct dos_partition *self_partition(
        struct fdisk_context *cxt,
        size_t i)
{
  struct pte *pe = self_pte(cxt, i);
  return pe ? pe->pt_entry : NULL;
}

struct dos_partition *fdisk_dos_get_partition(
        struct fdisk_context *cxt,
        size_t i)
{
  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  return self_partition(cxt, i);
}

static struct fdisk_parttype *dos_partition_parttype(
    struct fdisk_context *cxt,
    struct dos_partition *p)
{
  struct fdisk_parttype *t
    = fdisk_label_get_parttype_from_code(cxt->label, p->sys_ind);
  return t ? : fdisk_new_unknown_parttype(p->sys_ind, NULL);
}

/*
 * Linux kernel cares about partition size only. Things like
 * partition type or so are completely irrelevant -- kzak Nov-2013
 */
static int is_used_partition(struct dos_partition *p)
{
  return p && dos_partition_get_size(p) != 0;
}

static void partition_set_changed(
        struct fdisk_context *cxt,
        size_t i,
        int changed)
{
  struct pte *pe = self_pte(cxt, i);

  if (!pe)
    return;

  DBG(LABEL, ul_debug("DOS: setting %zu partition to %s", i,
        changed ? "changed" : "unchanged"));

  pe->changed = changed ? 1 : 0;
  if (changed)
    fdisk_label_set_changed(cxt->label, 1);
}

static fdisk_sector_t get_abs_partition_start(struct pte *pe)
{
  assert(pe);
  assert(pe->pt_entry);

  return pe->offset + dos_partition_get_start(pe->pt_entry);
}

static fdisk_sector_t get_abs_partition_end(struct pte *pe)
{
  fdisk_sector_t size;

  assert(pe);
  assert(pe->pt_entry);

  size = dos_partition_get_size(pe->pt_entry);
  return get_abs_partition_start(pe) + size - (size ? 1 : 0);
}

static int is_cleared_partition(struct dos_partition *p)
{
  return !(!p || p->boot_ind || p->bh || p->bs || p->bc ||
     p->sys_ind || p->eh || p->es || p->ec ||
     dos_partition_get_start(p) || dos_partition_get_size(p));
}

static int get_partition_unused_primary(struct fdisk_context *cxt,
          struct fdisk_partition *pa,
          size_t *partno)
{
  size_t org, n;
  int rc;

  assert(cxt);
  assert(cxt->label);
  assert(partno);

  org = cxt->label->nparts_max;

  cxt->label->nparts_max = 4;
  rc = fdisk_partition_next_partno(pa, cxt, &n);
  cxt->label->nparts_max = org;

  if (rc == 1) {
    fdisk_info(cxt, _("All primary partitions have been defined already."));
    rc = -1;
  } else if (rc == -ERANGE) {
    fdisk_warnx(cxt, _("Primary partition not available."));
  } else if (rc == 0)
    *partno = n;

  return rc;
}

static int seek_sector(struct fdisk_context *cxt, fdisk_sector_t secno)
{
  off_t offset = (off_t) secno * cxt->sector_size;

  return lseek(cxt->dev_fd, offset, SEEK_SET) == (off_t) -1 ? -errno : 0;
}

static int read_sector(struct fdisk_context *cxt, fdisk_sector_t secno,
      unsigned char *buf)
{
  int rc = seek_sector(cxt, secno);
  ssize_t r;

  if (rc < 0)
    return rc;

  r = read(cxt->dev_fd, buf, cxt->sector_size);
  if (r == (ssize_t) cxt->sector_size)
    return 0;
  if (r < 0)
    return -errno;
  return -1;
}

/* Allocate a buffer and read a partition table sector */
static int read_pte(struct fdisk_context *cxt, size_t pno, fdisk_sector_t offset)
{
  int rc;
  unsigned char *buf;
  struct pte *pe = self_pte(cxt, pno);

  if (!pe)
    return -EINVAL;

  buf = calloc(1, cxt->sector_size);
  if (!buf)
    return -ENOMEM;

  DBG(LABEL, ul_debug("DOS: reading EBR %zu: offset=%ju, buffer=%p",
        pno, (uintmax_t) offset, buf));

  pe->offset = offset;
  pe->sectorbuffer = buf;
  pe->private_sectorbuffer = 1;

  rc = read_sector(cxt, offset, pe->sectorbuffer);
  if (rc) {
    fdisk_warn(cxt, _("Failed to read extended partition table "
        "(offset=%ju)"), (uintmax_t) offset);
    return rc;
  }

  pe->changed = 0;
  pe->pt_entry = pe->ex_entry = NULL;
  return 0;
}


static void clear_partition(struct dos_partition *p)
{
  if (!p)
    return;
  p->boot_ind = 0;
  p->bh = 0;
  p->bs = 0;
  p->bc = 0;
  p->sys_ind = 0;
  p->eh = 0;
  p->es = 0;
  p->ec = 0;
  dos_partition_set_start(p,0);
  dos_partition_set_size(p,0);
}

static void dos_init(struct fdisk_context *cxt)
{
  struct fdisk_dos_label *l = self_label(cxt);
  size_t i;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  DBG(LABEL, ul_debug("DOS: initialize, first sector buffer %p", cxt->firstsector));

  cxt->label->nparts_max = 4; /* default, unlimited number of logical */

  l->ext_index = 0;
  l->ext_offset = 0;
  l->non_pt_changed = 0;

  memset(l->ptes, 0, sizeof(l->ptes));

  for (i = 0; i < 4; i++) {
    struct pte *pe = self_pte(cxt, i);

    assert(pe);
    pe->pt_entry = mbr_get_partition(cxt->firstsector, i);
    pe->ex_entry = NULL;
    pe->offset = 0;
    pe->sectorbuffer = cxt->firstsector;
    pe->private_sectorbuffer = 0;
    pe->changed = 0;

    DBG(LABEL, ul_debug("DOS: initialize: #%zu start=%u size=%u sysid=%02x",
          i,
          dos_partition_get_start(pe->pt_entry),
          dos_partition_get_size(pe->pt_entry),
          pe->pt_entry->sys_ind));
  }

  if (fdisk_is_listonly(cxt))
    return;
  /*
   * Various warnings...
   */
  if (fdisk_missing_geometry(cxt))
    fdisk_warnx(cxt, _("You can set geometry from the extra functions menu."));

  if (is_dos_compatible(cxt)) {
    fdisk_warnx(cxt, _("DOS-compatible mode is deprecated."));

    if (cxt->sector_size != cxt->phy_sector_size)
      fdisk_info(cxt, _(
    "The device presents a logical sector size that is smaller than "
    "the physical sector size. Aligning to a physical sector (or optimal "
    "I/O) size boundary is recommended, or performance may be impacted."));
  }

  if (fdisk_use_cylinders(cxt))
    fdisk_warnx(cxt, _("Cylinders as display units are deprecated."));

  if (cxt->total_sectors > UINT_MAX) {
    uint64_t bytes = cxt->total_sectors * cxt->sector_size;
    char *szstr = size_to_human_string(SIZE_SUFFIX_SPACE
             | SIZE_SUFFIX_3LETTER, bytes);
    fdisk_warnx(cxt,
    _("The size of this disk is %s (%ju bytes). DOS "
      "partition table format cannot be used on drives for "
      "volumes larger than %lu bytes for %lu-byte "
      "sectors. Use GUID partition table format (GPT)."),
      szstr, bytes,
      UINT_MAX * cxt->sector_size,
      cxt->sector_size);
    free(szstr);
  }
}

/* callback called by libfdisk */
static void dos_deinit(struct fdisk_label *lb)
{
  size_t i;
  struct fdisk_dos_label *l = (struct fdisk_dos_label *) lb;

  for (i = 0; i < ARRAY_SIZE(l->ptes); i++) {
    struct pte *pe = &l->ptes[i];

    if (pe->private_sectorbuffer && pe->sectorbuffer) {
      DBG(LABEL, ul_debug("DOS: freeing pte %zu sector buffer %p",
            i, pe->sectorbuffer));
      free(pe->sectorbuffer);
    }
    pe->sectorbuffer = NULL;
    pe->private_sectorbuffer = 0;
  }

  memset(l->ptes, 0, sizeof(l->ptes));
}

static void reset_pte(struct pte *pe)
{
  assert(pe);

  if (pe->private_sectorbuffer) {
    DBG(LABEL, ul_debug("   --> freeing pte sector buffer %p",
          pe->sectorbuffer));
    free(pe->sectorbuffer);
  }
  memset(pe, 0, sizeof(struct pte));
}

static int delete_partition(struct fdisk_context *cxt, size_t partnum)
{
  struct fdisk_dos_label *l;
  struct pte *pe;
  struct dos_partition *p;
  struct dos_partition *q;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  pe = self_pte(cxt, partnum);
  if (!pe)
    return -EINVAL;

  DBG(LABEL, ul_debug("DOS: delete partition %zu (max=%zu)", partnum,
        cxt->label->nparts_max));

  l = self_label(cxt);
  p = pe->pt_entry;
  q = pe->ex_entry;

  /* Note that for the fifth partition (partnum == 4) we don't actually
     decrement partitions. */
  if (partnum < 4) {
    DBG(LABEL, ul_debug("--> delete primary"));
    if (IS_EXTENDED(p->sys_ind) && partnum == l->ext_index) {
      size_t i;
      DBG(LABEL, ul_debug(" --> delete extended"));
      for (i = 4; i < cxt->label->nparts_max; i++) {
        DBG(LABEL, ul_debug("  --> delete logical #%zu", i));
        reset_pte(&l->ptes[i]);

      }
      cxt->label->nparts_max = 4;
      l->ptes[l->ext_index].ex_entry = NULL;
      l->ext_offset = 0;
      l->ext_index = 0;
    }
    partition_set_changed(cxt, partnum, 1);
    clear_partition(p);
  } else if (!q->sys_ind && partnum > 4) {
    DBG(LABEL, ul_debug("--> delete logical [last in the chain]"));
    reset_pte(&l->ptes[partnum]);
    --cxt->label->nparts_max;
    --partnum;
    /* clear link to deleted partition */
    clear_partition(l->ptes[partnum].ex_entry);
    partition_set_changed(cxt, partnum, 1);
  } else {
    DBG(LABEL, ul_debug("--> delete logical [move down]"));
    if (partnum > 4) {
      DBG(LABEL, ul_debug(" --> delete %zu logical link", partnum));
      p = l->ptes[partnum - 1].ex_entry;
      *p = *q;
      dos_partition_set_start(p, dos_partition_get_start(q));
      dos_partition_set_size(p, dos_partition_get_size(q));
      dos_partition_sync_chs(p, pe->offset, cxt->geom.sectors, cxt->geom.heads);
      partition_set_changed(cxt, partnum - 1, 1);

    } else if (cxt->label->nparts_max > 5) {
      DBG(LABEL, ul_debug(" --> delete first logical link"));
      pe = &l->ptes[5]; /* second logical */

      if (pe->pt_entry) /* prevent SEGFAULT */
        dos_partition_set_start(pe->pt_entry,
                 get_abs_partition_start(pe) -
                 l->ext_offset);
      pe->offset = l->ext_offset;
      dos_partition_sync_chs(p, pe->offset, cxt->geom.sectors, cxt->geom.heads);
      partition_set_changed(cxt, 5, 1);
    }

    if (cxt->label->nparts_max > 5) {
      DBG(LABEL, ul_debug(" --> move ptes"));
      cxt->label->nparts_max--;
      reset_pte(&l->ptes[partnum]);
      while (partnum < cxt->label->nparts_max) {
        DBG(LABEL, ul_debug("  --> moving pte %zu <-- %zu", partnum, partnum + 1));
        l->ptes[partnum] = l->ptes[partnum + 1];
        partnum++;
      }
      memset(&l->ptes[partnum], 0, sizeof(struct pte));
    } else {
      DBG(LABEL, ul_debug(" --> the only logical: clear only"));
      clear_partition(l->ptes[partnum].pt_entry);
      cxt->label->nparts_max--;

      if (partnum == 4) {
        DBG(LABEL, ul_debug("  --> clear last logical"));
        reset_pte(&l->ptes[partnum]);
        partition_set_changed(cxt, l->ext_index, 1);
      }
    }
  }

  fdisk_label_set_changed(cxt->label, 1);
  return 0;
}

static int dos_delete_partition(struct fdisk_context *cxt, size_t partnum)
{
  struct pte *pe;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  pe = self_pte(cxt, partnum);
  if (!pe || !is_used_partition(pe->pt_entry))
    return -EINVAL;

  return delete_partition(cxt, partnum);
}

static void read_extended(struct fdisk_context *cxt, size_t ext)
{
  size_t i;
  struct pte *pex, *pe;
  struct dos_partition *p, *q;
  struct fdisk_dos_label *l = self_label(cxt);

  if (fdisk_is_listonly(cxt) &&
      !sysfs_devno_is_wholedisk(fdisk_get_devno(cxt))) {
    DBG(LABEL, ul_debug("DOS: unable to gather logical partition chain "
          "when running on a non-whole disk device."));
    return;
  }

  l->ext_index = ext;
  pex = self_pte(cxt, ext);
  if (!pex) {
    DBG(LABEL, ul_debug("DOS: uninitialized pointer to %zu pex", ext));
    return;
  }
  pex->ex_entry = pex->pt_entry;

  p = pex->pt_entry;
  if (!dos_partition_get_start(p)) {
    fdisk_warnx(cxt, _("Bad offset in primary extended partition."));
    return;
  }

  DBG(LABEL, ul_debug("DOS: Reading extended %zu", ext));

  while (IS_EXTENDED (p->sys_ind)) {
    if (cxt->label->nparts_max >= MAXIMUM_PARTS) {
      /* This is not a Linux restriction, but
         this program uses arrays of size MAXIMUM_PARTS.
         Do not try to `improve' this test. */
      struct pte *pre = self_pte(cxt,
            cxt->label->nparts_max - 1);
      fdisk_warnx(cxt,
      _("Omitting partitions after #%zu. They will be deleted "
        "if you save this partition table."),
        cxt->label->nparts_max);

      if (pre) {
        clear_partition(pre->ex_entry);
        partition_set_changed(cxt,
            cxt->label->nparts_max - 1, 1);
      }
      return;
    }

    pe = self_pte(cxt, cxt->label->nparts_max);
    if (!pe)
      return;

    if (read_pte(cxt, cxt->label->nparts_max, l->ext_offset +
            dos_partition_get_start(p)))
      return;

    if (!l->ext_offset)
      l->ext_offset = dos_partition_get_start(p);

    assert(pe->sectorbuffer);
    q = p = mbr_get_partition(pe->sectorbuffer, 0);

    for (i = 0; i < 4; i++, p++) {
      if (!dos_partition_get_size(p))
        continue;

      if (IS_EXTENDED (p->sys_ind)) {
        if (pe->ex_entry)
          fdisk_warnx(cxt, _(
          "Extra link pointer in partition "
          "table %zu."),
            cxt->label->nparts_max + 1);
        else
          pe->ex_entry = p;
      } else if (p->sys_ind) {
        if (pe->pt_entry)
          fdisk_warnx(cxt, _(
          "Ignoring extra data in partition "
          "table %zu."),
            cxt->label->nparts_max + 1);
        else
          pe->pt_entry = p;
      }
    }

    /* very strange code here... */
    if (!pe->pt_entry) {
      if (q != pe->ex_entry)
        pe->pt_entry = q;
      else
        pe->pt_entry = q + 1;
    }
    if (!pe->ex_entry) {
      if (q != pe->pt_entry)
        pe->ex_entry = q;
      else
        pe->ex_entry = q + 1;
    }

    p = pe->ex_entry;
    cxt->label->nparts_cur = ++cxt->label->nparts_max;

    DBG(LABEL, ul_debug("DOS: EBR[offset=%ju]: link: type=%x,  start=%u, size=%u; "
                                 " data: type=%x, start=%u, size=%u",
            (uintmax_t) pe->offset,
            pe->ex_entry->sys_ind,
            dos_partition_get_start(pe->ex_entry),
            dos_partition_get_size(pe->ex_entry),
            pe->pt_entry->sys_ind,
            dos_partition_get_start(pe->pt_entry),
            dos_partition_get_size(pe->pt_entry)));

  }

  /* remove last empty EBR */
  pe = self_pte(cxt, cxt->label->nparts_max - 1);
  if (pe &&
      is_cleared_partition(pe->ex_entry) &&
      is_cleared_partition(pe->pt_entry)) {
    DBG(LABEL, ul_debug("DOS: EBR[offset=%ju]: empty, remove", (uintmax_t) pe->offset));
    reset_pte(pe);
    cxt->label->nparts_max--;
    cxt->label->nparts_cur--;
  }

  /* remove empty links */
 remove:
  q = self_partition(cxt, 4);
  for (i = 4; i < cxt->label->nparts_max; i++) {
    p = self_partition(cxt, i);

    if (p && !dos_partition_get_size(p) &&
        (cxt->label->nparts_max > 5 || (q && q->sys_ind))) {
      fdisk_info(cxt, _("omitting empty partition (%zu)"), i+1);
      delete_partition(cxt, i);
      goto remove;  /* numbering changed */
    }
  }

  DBG(LABEL, ul_debug("DOS: nparts_max: %zu", cxt->label->nparts_max));
}

static int dos_create_disklabel(struct fdisk_context *cxt)
{
  unsigned int id = 0;
  int rc, has_id = 0;
  struct fdisk_dos_label *l;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  DBG(LABEL, ul_debug("DOS: creating new disklabel"));

  if (cxt->script) {
    char *end = NULL;
    const char *s = fdisk_script_get_header(cxt->script, "label-id");

    if (s) {
      errno = 0;
      id = strtoul(s, &end, 16);
      if (!errno && end && s < end) {
        has_id = 1;
        DBG(LABEL, ul_debug("DOS: re-use ID from script (0x%08x)", id));
      } else
        DBG(LABEL, ul_debug("DOS: failed to parse label=id '%s'", s));
    }
  }

  /* random disk signature */
  if (!has_id) {
    DBG(LABEL, ul_debug("DOS: generate new ID"));
    ul_random_get_bytes(&id, sizeof(id));
  }

  if (fdisk_has_protected_bootbits(cxt))
    rc = fdisk_init_firstsector_buffer(cxt, 0, MBR_PT_BOOTBITS_SIZE);
  else
    rc = fdisk_init_firstsector_buffer(cxt, 0, 0);
  if (rc)
    return rc;
  dos_init(cxt);

  l = self_label(cxt);

  /* Generate an MBR ID for this disk */
  mbr_set_id(cxt->firstsector, id);
  l->non_pt_changed = 1;
  fdisk_label_set_changed(cxt->label, 1);

  /* Put MBR signature */
  mbr_set_magic(cxt->firstsector);

  fdisk_info(cxt, _("Created a new DOS (MBR) disklabel with disk "
       "identifier 0x%08x."), id);
  return 0;
}

static int dos_set_disklabel_id(struct fdisk_context *cxt, const char *str)
{
  char *buf = NULL;
  unsigned int id, old;
  struct fdisk_dos_label *l;
  int rc = 0;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  DBG(LABEL, ul_debug("DOS: setting Id"));

  l = self_label(cxt);
  old = mbr_get_id(cxt->firstsector);

  if (!str) {
    rc = fdisk_ask_string(cxt,
      _("Enter the new disk identifier"), &buf);
    str = buf;
  }
  if (!rc) {
    char *end = NULL;

    errno = 0;
    id = strtoul(str, &end, 0);
    if (errno || str == end || (end && *end)) {
      fdisk_warnx(cxt, _("Incorrect value."));
      rc = -EINVAL;
    }
  }

  free(buf);
  if (rc)
    return -EINVAL;

  mbr_set_id(cxt->firstsector, id);
  l->non_pt_changed = 1;
  fdisk_label_set_changed(cxt->label, 1);

  fdisk_info(cxt, _("Disk identifier changed from 0x%08x to 0x%08x."),
      old, id);
  return 0;
}

static unsigned int chs_div_minus(unsigned int a1, unsigned int a2, unsigned int b1, unsigned int b2)
{
  if (a1 > a2 && b1 > b2) {
    a1 = a1 - a2;
    b1 = b1 - b2;
  } else if (a2 > a1 && b2 > b1) {
    a1 = a2 - a1;
    b1 = b2 - b1;
  } else {
    return 0;
  }
  if (a1 % b1)
    return 0;
  return a1 / b1;
}

static inline int chs_overflowed(unsigned int c, unsigned int h, unsigned int s)
{
  /* 1023/254/63 or 1023/255/63 indicates overflowed/invalid C/H/S values */
  return (c == 1023 && (h == 254 || h == 255) && s == 63);
}

static inline int lba_overflowed(fdisk_sector_t start, fdisk_sector_t sects)
{
  /* Check if the last LBA sector can be represented by unsigned 32bit int */
  return (start + (sects-1) > UINT32_MAX);
}

static void get_partition_table_geometry(struct fdisk_context *cxt,
      unsigned int *ph, unsigned int *ps)
{
  unsigned char *bufp = cxt->firstsector;
  struct { unsigned int c, h, o, v; } t[8] = { 0 };
  unsigned int n1, n2, n3, n4, n5, n6;
  const struct dos_partition *p;
  unsigned int c, h, s, l;
  unsigned int hh, ss;
  unsigned int sects;
  int i, j, dif;

#define chs_set_t(c, h, s, l, t, i) do { \
  t[i].c = c; \
  t[i].h = h; \
  t[i].o = l - (s-1); \
  t[i].v = (!chs_overflowed(c, h, s) && s && s-1 <= l); \
} while (0)

  /*
   * Conversion from C/H/S to LBA is defined by formula:
   *   LBA = (c * N_heads + h) * N_sectors + (s - 1)
   * Let o to be:
   *   o = LBA - (s - 1)
   * Then formula can be expressed as:
   *   o = (c * N_heads + h) * N_sectors
   * In general from two tuples (LBA1, c1, h1, s1), (LBA2, c2, h2, s2)
   * we can derive formulas for N_heads and N_sectors:
   *   N_heads = (o1 * h2 - o2 * h1) / (o2 * c1 - o1 * c2)
   *   N_sectors = (o2 * c1 - o1 * c2) / (c1 * h2 - c2 * h1)
   * MBR table contains for very partition start and end tuple.
   * So we have up to 8 tuples which leads to up to 28 equations
   * for calculating N_heads and N_sectors. Try to calculate
   * N_heads and N_sectors from the first possible partition and
   * if it fails then try also mixed tuples (beginning from first
   * partition and end from second). Calculation may fail if both
   * first and last sectors are on cylinder or head boundary
   * (dividend or divisor is zero). It is possible that different
   * partitions would have different C/H/S geometry. In this case
   * we want geometry from the first partition as in most cases
   * this partition is or was used by BIOS for booting.
   */

  hh = ss = 0;
  for (i = 0; i < 4; i++) {
    p = mbr_get_partition(bufp, i);
    if (!p->sys_ind)
      continue;

    c = cylinder(p->bs, p->bc);
    h = p->bh;
    s = sector(p->bs);
    l = dos_partition_get_start(p);
    chs_set_t(c, h, s, l, t, 2*i);

    sects = dos_partition_get_size(p);
    if (!sects || lba_overflowed(l, sects))
      continue;

    c = cylinder(p->es, p->ec);
    h = p->eh;
    s = sector(p->es);
    l += sects-1;
    chs_set_t(c, h, s, l, t, 2*i+1);
  }

  for (dif = 1; dif < 8; dif++) {
    for (i = 0; i + dif < 8; i++) {
      j = i + dif;
      if (!t[i].v || !t[j].v)
        continue;
      n1 = t[i].o * t[j].h;
      n2 = t[j].o * t[i].h;
      n3 = t[j].o * t[i].c;
      n4 = t[i].o * t[j].c;
      n5 = t[i].c * t[j].h;
      n6 = t[j].c * t[i].h;
      if (!hh && n1 != n2 && n3 != n4) {
        h = chs_div_minus(n1, n2, n3, n4);
        if (h > 0 && h <= 256)
          hh = h;
      }
      if (!ss && n3 != n4 && n5 != n6) {
        s = chs_div_minus(n3, n4, n5, n6);
        if (s > 0 && s <= 63)
          ss = s;
      }
      if (hh && ss)
        break;
    }
    if (hh && ss)
      break;
  }

  if (hh && ss) {
    *ph = hh;
    *ps = ss;
  }

  DBG(LABEL, ul_debug("DOS PT geometry: heads=%u, sectors=%u", *ph, *ps));
}

static int dos_reset_alignment(struct fdisk_context *cxt)
{
  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  /* overwrite necessary stuff by DOS deprecated stuff */
  if (is_dos_compatible(cxt)) {
    DBG(LABEL, ul_debug("DOS: resetting alignment for DOS-compatible PT"));
    if (cxt->geom.sectors)
      cxt->first_lba = cxt->geom.sectors; /* usually 63 */

    cxt->grain = cxt->sector_size;      /* usually 512 */
  }

  return 0;
}

/* TODO: move to include/pt-dos.h and share with libblkid */
#define AIX_MAGIC_STRING  "\xC9\xC2\xD4\xC1"
#define AIX_MAGIC_STRLEN  (sizeof(AIX_MAGIC_STRING) - 1)

static int dos_probe_label(struct fdisk_context *cxt)
{
  size_t i;
  unsigned int h = 0, s = 0;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  /* ignore disks with AIX magic number */
  if (memcmp(cxt->firstsector, AIX_MAGIC_STRING, AIX_MAGIC_STRLEN) == 0)
    return 0;

  if (!mbr_is_valid_magic(cxt->firstsector))
    return 0;

  dos_init(cxt);

  get_partition_table_geometry(cxt, &h, &s);
  if (h && s) {
    cxt->geom.heads = h;
          cxt->geom.sectors = s;
    cxt->geom.cylinders = cxt->total_sectors /
          (cxt->geom.heads * cxt->geom.sectors);

    if (fdisk_has_user_device_geometry(cxt))
      fdisk_apply_user_device_properties(cxt);
  }

  for (i = 0; i < 4; i++) {
    struct pte *pe = self_pte(cxt, i);

    assert(pe);
    if (is_used_partition(pe->pt_entry))
      cxt->label->nparts_cur++;

    if (IS_EXTENDED (pe->pt_entry->sys_ind)) {
      if (cxt->label->nparts_max != 4)
        fdisk_warnx(cxt, _(
        "Ignoring extra extended partition %zu"),
          i + 1);
      else
        read_extended(cxt, i);
    }
  }

  for (i = 3; i < cxt->label->nparts_max; i++) {
    struct pte *pe = self_pte(cxt, i);
    struct fdisk_dos_label *l = self_label(cxt);

    assert(pe);
    if (!mbr_is_valid_magic(pe->sectorbuffer)) {
      fdisk_info(cxt, _(
      "Invalid flag 0x%02x%02x of EBR (for partition %zu) will "
      "be corrected by w(rite)."),
        pe->sectorbuffer[510],
        pe->sectorbuffer[511],
        i + 1);
      partition_set_changed(cxt, i, 1);

      /* mark also extended as changed to update the first EBR
       * in situation that there is no logical partitions at all */
      partition_set_changed(cxt, l->ext_index, 1);
    }
  }

  return 1;
}

static void set_partition(struct fdisk_context *cxt,
        int i, int doext, fdisk_sector_t start,
        fdisk_sector_t stop, int sysid, int boot)
{
  struct pte *pe = self_pte(cxt, i);
  struct dos_partition *p;
  fdisk_sector_t offset;

  assert(!FDISK_IS_UNDEF(start));
  assert(!FDISK_IS_UNDEF(stop));
  assert(pe);

  if (doext) {
    struct fdisk_dos_label *l = self_label(cxt);
    p = pe->ex_entry;
    offset = l->ext_offset;
  } else {
    p = pe->pt_entry;
    offset = pe->offset;
  }

  DBG(LABEL, ul_debug("DOS: setting partition %d%s, offset=%zu, start=%zu, size=%zu, sysid=%02x",
        i, doext ? " [extended]" : "",
        (size_t) offset,
        (size_t) (start -  offset),
        (size_t) (stop - start + 1),
        sysid));

  p->boot_ind = boot ? ACTIVE_FLAG : 0;
  p->sys_ind = sysid;
  dos_partition_set_start(p, start - offset);
  dos_partition_set_size(p, stop - start + 1);
  dos_partition_sync_chs(p, offset, cxt->geom.sectors, cxt->geom.heads);
  partition_set_changed(cxt, i, 1);
}


static int get_start_from_user( struct fdisk_context *cxt,
        fdisk_sector_t *start,
        fdisk_sector_t low,
        fdisk_sector_t dflt,
        fdisk_sector_t limit,
        struct fdisk_partition *pa)
{
  assert(start);

  /* try to use template from 'pa' */
  if (pa && pa->start_follow_default)
    *start = dflt;

  else if (pa && fdisk_partition_has_start(pa)) {
    DBG(LABEL, ul_debug("DOS: start: wanted=%ju, low=%ju, limit=%ju",
        (uintmax_t) pa->start, (uintmax_t) low, (uintmax_t) limit));
    *start = pa->start;
    if (*start < low || *start > limit) {
      fdisk_warnx(cxt, _("Start sector %ju out of range."),
          (uintmax_t) *start);
      return -ERANGE;
    }
  } else {
    /* ask user by dialog */
    struct fdisk_ask *ask = fdisk_new_ask();
    int rc;

    if (!ask)
      return -ENOMEM;
    fdisk_ask_set_query(ask,
      fdisk_use_cylinders(cxt) ?
        _("First cylinder") : _("First sector"));
    fdisk_ask_set_type(ask, FDISK_ASKTYPE_NUMBER);
    fdisk_ask_number_set_low(ask, fdisk_cround(cxt, low));
    fdisk_ask_number_set_default(ask, fdisk_cround(cxt, dflt));
    fdisk_ask_number_set_high(ask, fdisk_cround(cxt, limit));

    rc = fdisk_do_ask(cxt, ask);
    *start = fdisk_ask_number_get_result(ask);
    fdisk_unref_ask(ask);
    if (rc)
      return rc;
    if (fdisk_use_cylinders(cxt)) {
            *start = (*start - 1)
        * fdisk_get_units_per_sector(cxt);
      if (*start < low)
        *start = low;
    }
  }

  DBG(LABEL, ul_debug("DOS: start is %ju", (uintmax_t) *start));
  return 0;
}

/* Returns last available sector in the free space pointed to by start. */
static int find_last_free(
      struct fdisk_context *cxt,
      int logical,
      fdisk_sector_t begin,
      fdisk_sector_t stop,
      fdisk_sector_t *result)
{
  fdisk_sector_t last = stop;

  size_t i = logical ? 4 : 0;

  for ( ; i < cxt->label->nparts_max; i++) {
    struct pte *pe = self_pte(cxt, i);

    assert(pe);
    fdisk_sector_t p_start = get_abs_partition_start(pe);
    fdisk_sector_t p_end = get_abs_partition_end(pe);

    if (is_cleared_partition(pe->pt_entry))
      continue;
    /* count EBR and begin of the logical partition as used area */
    if (pe->offset)
      p_start -= cxt->first_lba;

    if ((p_start >= begin && p_start <= last) ||
        (p_end >= begin && p_end <= last)) {
      last = p_start - 1;
    }
    if (last < begin) {
      DBG(LABEL, ul_debug("no free space <%ju,%ju>",
          (uintmax_t) begin, (uintmax_t) stop));
      return -ENOSPC;
    }
  }

  if (last == begin)
    last = stop;

  DBG(LABEL, ul_debug("DOS: last free sector  <%ju,%ju>: %ju",
      (uintmax_t) begin, (uintmax_t) stop, (uintmax_t) last));

  *result = last;
  return 0;
}

static int find_last_free_sector_in_range(
      struct fdisk_context *cxt,
      int logical,
      fdisk_sector_t begin,
      fdisk_sector_t end,
      fdisk_sector_t *result)
{
  int last_moved;
  fdisk_sector_t last = end;

  do {
    size_t i = logical ? 4 : 0;

    last_moved = 0;
    for ( ; i < cxt->label->nparts_max; i++) {
      struct pte *pe = self_pte(cxt, i);

      assert(pe);
      fdisk_sector_t p_start = get_abs_partition_start(pe);
      fdisk_sector_t p_end = get_abs_partition_end(pe);

      if (is_cleared_partition(pe->pt_entry))
        continue;

      /* count EBR and begin of the logical partition as used area */
      if (pe->offset)
        p_start -= cxt->first_lba;

      if (last >= p_start && last <= p_end) {
        last = p_start - 1;
        last_moved = 1;

        if (last < begin) {
          DBG(LABEL, ul_debug("DOS: last free out of range <%ju,%ju>: %ju",
            (uintmax_t) begin, (uintmax_t) end, (uintmax_t) last));

          return -ENOSPC;
        }
      }
    }
  } while (last_moved == 1);

  DBG(LABEL, ul_debug("DOS: last unused sector in range <%ju,%ju>: %ju",
      (uintmax_t) begin, (uintmax_t) end, (uintmax_t) last));

  *result = last;
  return 0;
}

static int find_first_free_sector_in_range(
      struct fdisk_context *cxt,
      int logical,
      fdisk_sector_t begin,
      fdisk_sector_t end,
      fdisk_sector_t *result)
{
  int first_moved = 0;
  fdisk_sector_t first = begin;

  do {
    size_t i = logical ? 4 : 0;

    first_moved = 0;
    for (; i < cxt->label->nparts_max; i++) {
      struct pte *pe = self_pte(cxt, i);

      assert(pe);
      fdisk_sector_t p_start = get_abs_partition_start(pe);
      fdisk_sector_t p_end = get_abs_partition_end(pe);

      if (is_cleared_partition(pe->pt_entry))
        continue;
      /* count EBR and begin of the logical partition as used area */
      if (pe->offset)
        p_start -= cxt->first_lba;
      if (first < p_start)
        continue;
      if (first <= p_end) {
        first = p_end + 1 + (logical ? cxt->first_lba : 0);
        first_moved = 1;

        if (first > end) {
          DBG(LABEL, ul_debug("DOS: first free out of range <%ju,%ju>: %ju",
            (uintmax_t) begin, (uintmax_t) end, (uintmax_t) first));
          return -ENOSPC;
        }
      }
    }
  } while (first_moved == 1);

  DBG(LABEL, ul_debug("DOS: first unused sector in range <%ju,%ju>: %ju",
      (uintmax_t) begin, (uintmax_t) end, (uintmax_t) first));
  *result = first;
  return 0;
}

static int get_disk_ranges(struct fdisk_context *cxt, int logical,
         fdisk_sector_t *first, fdisk_sector_t *last)
{
  if (logical) {
    /* logical partitions */
    struct fdisk_dos_label *l = self_label(cxt);
    struct pte *ext_pe = l->ext_offset ? self_pte(cxt, l->ext_index) : NULL;

    if (!ext_pe)
      return -EINVAL;

    *first = l->ext_offset + cxt->first_lba;
    *last = get_abs_partition_end(ext_pe);

  } else {
    /* primary partitions */
    if (fdisk_use_cylinders(cxt) || !cxt->total_sectors)
      *last = cxt->geom.heads * cxt->geom.sectors * cxt->geom.cylinders - 1;
    else
      *last = cxt->total_sectors - 1;

    if (*last > UINT_MAX)
      *last = UINT_MAX;
    *first = cxt->first_lba;
  }

  return 0;
}

/* first free sector on disk */
static int find_first_free_sector(struct fdisk_context *cxt,
        int logical,
        fdisk_sector_t start,
        fdisk_sector_t *result)
{
  fdisk_sector_t first, last;
  int rc;

  rc = get_disk_ranges(cxt, logical, &first, &last);
  if (rc)
    return rc;

  return find_first_free_sector_in_range(cxt, logical, start, last, result);
}

static int add_partition(struct fdisk_context *cxt, size_t n,
       struct fdisk_partition *pa)
{
  int sys, read = 0, rc, isrel = 0, is_logical;
  struct fdisk_dos_label *l = self_label(cxt);
  struct dos_partition *p = self_partition(cxt, n);
  struct fdisk_ask *ask = NULL;

  fdisk_sector_t start, stop, limit, temp;

  DBG(LABEL, ul_debug("DOS: adding partition %zu", n));

  sys = pa && pa->type ? pa->type->code : MBR_LINUX_DATA_PARTITION;
  is_logical = n >= 4;

  if (p && is_used_partition(p)) {
    fdisk_warnx(cxt, _("Partition %zu is already defined.  "
                 "Delete it before re-adding it."),
        n + 1);
    return -EINVAL;
  }

  rc = get_disk_ranges(cxt, is_logical, &start, &stop);
  if (rc)
    return rc;

  if (!is_logical && cxt->parent && fdisk_is_label(cxt->parent, GPT))
    start = 1;   /* Bad boy modifies hybrid MBR */

  rc = find_last_free_sector_in_range(cxt, is_logical, start, stop, &limit);
  if (rc == -ENOSPC)
    fdisk_warnx(cxt, _("No free sectors available."));
  if (rc)
    return rc;

  if ((is_logical || !cxt->parent || !fdisk_is_label(cxt->parent, GPT))
      && cxt->script && pa && fdisk_partition_has_start(pa)
      && pa->start >= (is_logical ? l->ext_offset : 1)
      && pa->start < start) {
    fdisk_set_first_lba(cxt, 1);

    rc = get_disk_ranges(cxt, is_logical, &start, &stop);
    if (rc) /* won't happen, but checking to be proper */
      return rc;
  }

  /*
   * Ask for first sector
   */
  do {
    fdisk_sector_t dflt, aligned;

    temp = start;

    DBG(LABEL, ul_debug("DOS: >>> search for first free from %ju", start));
    rc = find_first_free_sector(cxt, is_logical, start, &dflt);
    if (rc == -ENOSPC)
      fdisk_warnx(cxt, _("No free sectors available."));
    if (rc)
      return rc;
    start = dflt;

    if (n >= 4 && pa && fdisk_partition_has_start(pa) && cxt->script
        && cxt->first_lba > 1
        && temp == start - cxt->first_lba) {
      fdisk_set_first_lba(cxt, 1);
      start = pa->start;
    }

    /* the default sector should be aligned and unused */
    do {
      aligned = fdisk_align_lba_in_range(cxt, dflt, dflt, limit);
      find_first_free_sector(cxt, is_logical, aligned, &dflt);
    } while (dflt != aligned && dflt > aligned && dflt < limit);

    if (dflt >= limit)
      dflt = start;
    if (start > limit)
      break;
    if (start >= temp + fdisk_get_units_per_sector(cxt)
        && read) {
      if (!pa || !pa->start_follow_default)
        fdisk_info(cxt, _("Sector %ju is already allocated."),
            (uintmax_t) temp);
      temp = start;
      read = 0;
      if (pa && fdisk_partition_has_start(pa))
        break;
    }

    if (!read && start == temp) {
      rc = get_start_from_user(cxt, &start, temp, dflt, limit, pa);
      if (rc)
        return rc;
      read = 1;
    }
    if (pa && fdisk_partition_has_size(pa)) {
      fdisk_sector_t last;

      rc = find_last_free(cxt, is_logical, start, limit, &last);
      if (rc == 0 && last - start + 1 < fdisk_partition_get_size(pa)) {
        DBG(LABEL, ul_debug("DOS: area <%ju,%ju> too small [wanted=%ju aval=%ju]",
              (uintmax_t) start, (uintmax_t) last,
              fdisk_partition_get_size(pa),
              last - start));

        if (fdisk_partition_has_start(pa)
            && fdisk_partition_get_start(pa) <= last)
          rc = -ENOSPC;
        else {
          start = last + 1;
          continue;
        }
      }
      if (rc == -ENOSPC) {
        fdisk_warnx(cxt, _("No free sectors available."));
        return rc;
      }
    }

  } while (start != temp || !read);

  if (n == 4) {
    /* The first EBR is stored at begin of the extended partition */
    struct pte *pe = self_pte(cxt, n);

    assert(pe);
    pe->offset = l->ext_offset;
  } else if (n > 4) {
    /* The second (and another) EBR */
    struct pte *pe = self_pte(cxt, n);

    assert(pe);
    assert(start >= cxt->first_lba);

    pe->offset = start - cxt->first_lba;
    DBG(LABEL, ul_debug("DOS: setting EBR offset to %ju [start=%ju]", pe->offset, start));

    if (pe->offset == l->ext_offset) { /* must be corrected */
      pe->offset++;
      if (cxt->first_lba == 1)
        start++;
    }
  }

  rc = find_last_free(cxt, is_logical, start, limit, &stop);
  if (rc == -ENOSPC)
    fdisk_warnx(cxt, _("No free sectors available."));
  if (rc)
    return rc;
  limit = stop;

  /*
   * Ask for last sector
   */
  if (fdisk_cround(cxt, start) == fdisk_cround(cxt, limit))
    stop = limit;
  else if (pa && pa->end_follow_default)
    stop = limit;
  else if (pa && fdisk_partition_has_size(pa)) {
    stop = start + pa->size;
    isrel = pa->size_explicit ? 0 : 1;
    if ((!isrel || !alignment_required(cxt)) && stop > start)
      stop -= 1;
  } else {
    /* ask user by dialog */
    for (;;) {
      if (!ask)
        ask = fdisk_new_ask();
      else
        fdisk_reset_ask(ask);
      if (!ask)
        return -ENOMEM;
      fdisk_ask_set_type(ask, FDISK_ASKTYPE_OFFSET);

      if (fdisk_use_cylinders(cxt)) {
        fdisk_ask_set_query(ask, _("Last cylinder, +/-cylinders or +/-size{K,M,G,T,P}"));
        fdisk_ask_number_set_unit(ask,
               cxt->sector_size *
               fdisk_get_units_per_sector(cxt));
      } else {
        fdisk_ask_set_query(ask, _("Last sector, +/-sectors or +/-size{K,M,G,T,P}"));
        fdisk_ask_number_set_unit(ask,cxt->sector_size);
      }

      fdisk_ask_number_set_low(ask, fdisk_cround(cxt, start));
      fdisk_ask_number_set_default(ask, fdisk_cround(cxt, limit));
      fdisk_ask_number_set_high(ask, fdisk_cround(cxt, limit));
      fdisk_ask_number_set_base(ask, fdisk_cround(cxt, start)); /* base for relative input */
      fdisk_ask_number_set_wrap_negative(ask, 1); /* wrap negative around high */

      rc = fdisk_do_ask(cxt, ask);
      if (rc)
        goto done;

      stop = fdisk_ask_number_get_result(ask);
      isrel = fdisk_ask_number_is_relative(ask);
      if (fdisk_use_cylinders(cxt)) {
        stop = stop * fdisk_get_units_per_sector(cxt) - 1;
        if (stop >limit)
          stop = limit;
      }

      if (stop >= start && stop <= limit)
        break;
      fdisk_warnx(cxt, _("Value out of range."));
    }
  }

  DBG(LABEL, ul_debug("DOS: raw stop: %ju [limit %ju]", (uintmax_t) stop, (uintmax_t) limit));

  if (stop > limit)
    stop = limit;

  if (isrel && stop - start < (cxt->grain / fdisk_get_sector_size(cxt))) {
    /* Don't try to be smart on very small partitions and don't align so small sizes */
    isrel = 0;
    DBG(LABEL, ul_debug("DOS: don't align end of tiny partition [start=%ju, stop=%ju, grain=%lu]",
          (uintmax_t)start,  (uintmax_t)stop, cxt->grain));
  }

  if (stop < limit && isrel && alignment_required(cxt)) {
    /* the last sector has not been exactly requested (but
     * defined by +size{K,M,G} convention), so be smart and
     * align the end of the partition. The next partition
     * will start at phy.block boundary.
     */
    stop = fdisk_align_lba_in_range(cxt, stop, start, limit);
    if (stop > start)
      stop -= 1; /* end one sector before aligned offset */
    if (stop > limit)
      stop = limit;
    DBG(LABEL, ul_debug("DOS: aligned stop: %ju", (uintmax_t) stop));
  }

  set_partition(cxt, n, 0, start, stop, sys, fdisk_partition_is_bootable(pa));
  if (n > 4) {
    struct pte *pe = self_pte(cxt, n);
    assert(pe);
    set_partition(cxt, n - 1, 1, pe->offset, stop,
          MBR_DOS_EXTENDED_PARTITION, 0);
  }

  /* report */
  {
    struct fdisk_parttype *t =
      fdisk_label_get_parttype_from_code(cxt->label, sys);
    fdisk_info_new_partition(cxt, n + 1, start, stop, t);
    fdisk_unref_parttype(t);
  }


  if (IS_EXTENDED(sys)) {
    struct pte *pen = self_pte(cxt, n);

    assert(pen);
    l->ext_index = n;
    l->ext_offset = start;
    pen->ex_entry = p;
  }

  fdisk_label_set_changed(cxt->label, 1);
  rc = 0;
done:
  fdisk_unref_ask(ask);
  return rc;
}

static int add_logical(struct fdisk_context *cxt,
           struct fdisk_partition *pa,
           size_t *partno)
{
  struct pte *pe;
  int rc;

  assert(cxt);
  assert(partno);
  assert(cxt->label);
  assert(self_label(cxt)->ext_offset);

  DBG(LABEL, ul_debug("DOS: nparts max: %zu", cxt->label->nparts_max));
  pe = self_pte(cxt, cxt->label->nparts_max);
  assert(pe);

  if (!pe->sectorbuffer) {
    pe->sectorbuffer = calloc(1, cxt->sector_size);
    if (!pe->sectorbuffer)
      return -ENOMEM;
    DBG(LABEL, ul_debug("DOS: logical: %zu: new EBR sector buffer %p",
          cxt->label->nparts_max, pe->sectorbuffer));
    pe->private_sectorbuffer = 1;
  }
  pe->pt_entry = mbr_get_partition(pe->sectorbuffer, 0);
  pe->ex_entry = pe->pt_entry + 1;
  pe->offset = 0;
  partition_set_changed(cxt, cxt->label->nparts_max, 1);

  cxt->label->nparts_max++;

  /* this message makes sense only when we use extended/primary/logical
   * dialog. The dialog is disable for scripts, see dos_add_partition() */
  if (!cxt->script)
    fdisk_info(cxt, _("Adding logical partition %zu"),
        cxt->label->nparts_max);
  *partno = cxt->label->nparts_max - 1;
  rc = add_partition(cxt, *partno, pa);

  if (rc) {
    /* reset on error */
    cxt->label->nparts_max--;
    pe->pt_entry = NULL;
    pe->ex_entry = NULL;
    pe->offset = 0;
    pe->changed = 0;
  }

  return rc;
}

static int check(struct fdisk_context *cxt, size_t n,
     unsigned int h, unsigned int s, unsigned int c,
     unsigned int lba_sector)
{
  unsigned int chs_sector, real_s, real_c;
  int nerrors = 0;

  if (!is_dos_compatible(cxt))
    return 0;

  real_s = sector(s) - 1;
  real_c = cylinder(s, c);
  chs_sector = (real_c * cxt->geom.heads + h) * cxt->geom.sectors + real_s;

  if (!chs_sector) {
    fdisk_warnx(cxt, _("Partition %zu: contains sector 0"), n);
    nerrors++;
  }
  if (h >= cxt->geom.heads) {
    fdisk_warnx(cxt, _("Partition %zu: head %d greater than "
           "maximum %d"), n, h + 1, cxt->geom.heads);
    nerrors++;
  }
  if (real_s >= cxt->geom.sectors) {
    fdisk_warnx(cxt, _("Partition %zu: sector %d greater than "
           "maximum %ju"), n, real_s + 1,
        (uintmax_t) cxt->geom.sectors);
    nerrors++;
  }
  if (real_c >= cxt->geom.cylinders) {
    fdisk_warnx(cxt, _("Partition %zu: cylinder %d greater than "
           "maximum %ju"),
        n, real_c + 1,
        (uintmax_t) cxt->geom.cylinders);
    nerrors++;
  }
  if (lba_sector / (cxt->geom.heads * cxt->geom.sectors) < 1024 && lba_sector != chs_sector) {
    fdisk_warnx(cxt, _("Partition %zu: LBA sector %u "
           "disagrees with C/H/S calculated sector %u"),
        n, lba_sector, chs_sector);
    nerrors++;
  }

  return nerrors;
}

/* check_consistency() and long2chs() added Sat Mar 6 12:28:16 1993,
 * faith@cs.unc.edu, based on code fragments from pfdisk by Gordon W. Ross,
 * Jan.  1990 (version 1.2.1 by Gordon W. Ross Aug. 1990; Modified by S.
 * Lubkin Oct.  1991). */

static void
long2chs(struct fdisk_context *cxt, unsigned long ls,
   unsigned int *c, unsigned int *h, unsigned int *s) {
  int spc = cxt->geom.heads * cxt->geom.sectors;

  *c = ls / spc;
  ls = ls % spc;
  *h = ls / cxt->geom.sectors;
  *s = ls % cxt->geom.sectors + 1;  /* sectors count from 1 */
}

static int check_consistency(struct fdisk_context *cxt, struct dos_partition *p,
            size_t partition)
{
  unsigned int pbc, pbh, pbs; /* physical beginning c, h, s */
  unsigned int pec, peh, pes; /* physical ending c, h, s */
  unsigned int lbc, lbh, lbs; /* logical beginning c, h, s */
  unsigned int lec, leh, les; /* logical ending c, h, s */
  int nerrors = 0;

  if (!is_dos_compatible(cxt))
    return 0;

  if (!cxt->geom.heads || !cxt->geom.sectors || (partition >= 4))
    return 0;   /* do not check extended partitions */

  /* physical beginning c, h, s */
  pbc = cylinder(p->bs, p->bc);
  pbh = p->bh;
  pbs = sector(p->bs);

  /* physical ending c, h, s */
  pec = cylinder(p->es, p->ec);
  peh = p->eh;
  pes = sector(p->es);

  /* compute logical beginning (c, h, s) */
  long2chs(cxt, dos_partition_get_start(p), &lbc, &lbh, &lbs);

  /* compute logical ending (c, h, s) */
  long2chs(cxt, dos_partition_get_start(p) + dos_partition_get_size(p) - 1, &lec, &leh, &les);

  /* Same physical / logical beginning? */
  if (lbc < 1024
      && (pbc != lbc || pbh != lbh || pbs != lbs)) {
    fdisk_warnx(cxt, _("Partition %zu: different physical/logical "
      "beginnings (non-Linux?): "
      "phys=(%d, %d, %d), logical=(%d, %d, %d)"),
      partition + 1,
      pbc, pbh, pbs,
      lbc, lbh, lbs);
    nerrors++;
  }

  /* Same physical / logical ending? */
  if (lec < 1024
      && (pec != lec || peh != leh || pes != les)) {
    fdisk_warnx(cxt, _("Partition %zu: different physical/logical "
      "endings: phys=(%d, %d, %d), logical=(%d, %d, %d)"),
      partition + 1,
      pec, peh, pes,
      lec, leh, les);
    nerrors++;
  }

  /* Ending on cylinder boundary? */
  if (peh != (cxt->geom.heads - 1) || pes != cxt->geom.sectors) {
    fdisk_warnx(cxt, _("Partition %zu: does not end on "
           "cylinder boundary."),
      partition + 1);
    nerrors++;
  }

  return nerrors;
}

static void fill_bounds(struct fdisk_context *cxt,
      fdisk_sector_t *first, fdisk_sector_t *last)
{
  size_t i;
  struct pte *pe = self_pte(cxt, 0);
  struct dos_partition *p;

  assert(pe);
  for (i = 0; i < cxt->label->nparts_max; pe++,i++) {
    p = pe->pt_entry;
    if (is_cleared_partition(p) || IS_EXTENDED (p->sys_ind)) {
      first[i] = SIZE_MAX;
      last[i] = 0;
    } else {
      first[i] = get_abs_partition_start(pe);
      last[i]  = get_abs_partition_end(pe);
    }
  }
}

static int dos_verify_disklabel(struct fdisk_context *cxt)
{
  size_t i, j;
  fdisk_sector_t total = 1, n_sectors = cxt->total_sectors;
  fdisk_sector_t *first, *last;
  struct dos_partition *p;
  struct fdisk_dos_label *l = self_label(cxt);
  int nerrors = 0;

  assert(fdisk_is_label(cxt, DOS));

  first = calloc(cxt->label->nparts_max, sizeof(*first));
  last = calloc(cxt->label->nparts_max, sizeof(*first));

  if (!first || !last) {
    free(first);
    free(last);
    return -ENOMEM;
  }

  fill_bounds(cxt, first, last);
  for (i = 0; i < cxt->label->nparts_max; i++) {
    struct pte *pe = self_pte(cxt, i);

    p = self_partition(cxt, i);
    if (p && is_used_partition(p) && !IS_EXTENDED(p->sys_ind)) {
      nerrors += check_consistency(cxt, p, i);
      assert(pe);
      if (get_abs_partition_start(pe) < first[i]) {
        fdisk_warnx(cxt, _(
          "Partition %zu: bad start-of-data."),
           i + 1);
        nerrors++;
      }

      nerrors += check(cxt, i + 1, p->bh, p->bs, p->bc, first[i]);
      nerrors += check(cxt, i + 1, p->eh, p->es, p->ec, last[i]);
      total += last[i] + 1 - first[i];

      if (i == 0)
        total += get_abs_partition_start(pe) - 1;

      for (j = 0; j < i; j++) {
        if ((first[i] >= first[j] && first[i] <= last[j])
            || ((last[i] <= last[j] && last[i] >= first[j]))) {

          fdisk_warnx(cxt, _("Partition %zu: "
            "overlaps partition %zu."),
            j + 1, i + 1);
          nerrors++;

          total += first[i] >= first[j] ?
            first[i] : first[j];
          total -= last[i] <= last[j] ?
            last[i] : last[j];
        }
      }
    }
  }

  if (l->ext_offset) {
    fdisk_sector_t e_last;
    struct pte *ext_pe = self_pte(cxt, l->ext_index);

    assert(ext_pe);
    e_last = get_abs_partition_end(ext_pe);

    for (i = 4; i < cxt->label->nparts_max; i++) {
      total++;
      p = self_partition(cxt, i);
      assert(p);

      if (!p->sys_ind) {
        if (i != 4 || i + 1 < cxt->label->nparts_max) {
          fdisk_warnx(cxt,
            _("Partition %zu: empty."),
            i + 1);
          nerrors++;
        }
      } else if (first[i] < l->ext_offset
           || last[i] > e_last) {

        fdisk_warnx(cxt, _("Logical partition %zu: "
          "not entirely in partition %zu."),
          i + 1, l->ext_index + 1);
        nerrors++;
      }
    }
  }

  if (!nerrors) {
    fdisk_info(cxt, _("No errors detected."));
    if (total > n_sectors)
      fdisk_info(cxt, _("Total allocated sectors %ju greater "
        "than the maximum %ju."), (uintmax_t) total, (uintmax_t) n_sectors);
    else if (total < n_sectors)
      fdisk_info(cxt, _("Remaining %ju unallocated %ld-byte "
        "sectors."), (uintmax_t) n_sectors - total, cxt->sector_size);
  } else
    fdisk_warnx(cxt,
      P_("%d error detected.", "%d errors detected.", nerrors),
      nerrors);

  free(first);
  free(last);
  return nerrors;
}

/*
 * Ask the user for new partition type information (logical, extended).
 * This function calls the actual partition adding logic - add_partition.
 *
 * API callback.
 */
static int dos_add_partition(struct fdisk_context *cxt,
           struct fdisk_partition *pa,
           size_t *partno)
{
  size_t i;
  uint8_t free_primary = 0, free_sectors = 0;
  fdisk_sector_t first = 0, grain;
  int rc = 0;
  struct fdisk_dos_label *l;
  struct pte *ext_pe;
  size_t res = 0;   /* partno */

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  DBG(LABEL, ul_debug("DOS: new partition wanted"));

  l = self_label(cxt);

  if (cxt->label->nparts_max >= MAXIMUM_PARTS) {
    fdisk_warnx(cxt, _("The maximum number of partitions has "
          "been created."));
    return -EINVAL;
  }

  ext_pe = l->ext_offset ? self_pte(cxt, l->ext_index) : NULL;

  /*
   * partition template (@pa) based partitioning
   */

  /* A) template specifies start within extended partition; add logical */
  if (pa && fdisk_partition_has_start(pa) && ext_pe
      && pa->start >= l->ext_offset
      && pa->start <= get_abs_partition_end(ext_pe)) {
    DBG(LABEL, ul_debug("DOS: pa template %p: add logical (by offset)", pa));

    if (fdisk_partition_has_partno(pa) && fdisk_partition_get_partno(pa) < 4) {
      DBG(LABEL, ul_debug("DOS: pa template specifies partno<4 for logical partition"));
      return -EINVAL;
    }
    rc = add_logical(cxt, pa, &res);
    goto done;

  /* B) template specifies start out of extended partition; add primary */
  } else if (pa && fdisk_partition_has_start(pa) && ext_pe) {
    DBG(LABEL, ul_debug("DOS: pa template %p: add primary (by offset)", pa));

    if (fdisk_partition_has_partno(pa) && fdisk_partition_get_partno(pa) >= 4) {
      DBG(LABEL, ul_debug("DOS: pa template specifies partno>=4 for primary partition"));
      return -EINVAL;
    }
    if (ext_pe && pa->type && IS_EXTENDED(pa->type->code)) {
      fdisk_warnx(cxt, _("Extended partition already exists."));
      return -EINVAL;
    }
    rc = get_partition_unused_primary(cxt, pa, &res);
    if (rc == 0)
      rc = add_partition(cxt, res, pa);
    goto done;

  /* C) template specifies start (or default), partno < 4; add primary */
  } else if (pa && (fdisk_partition_start_is_default(pa) || fdisk_partition_has_start(pa))
       && fdisk_partition_has_partno(pa)
       && pa->partno < 4) {
    DBG(LABEL, ul_debug("DOS: pa template %p: add primary (by partno)", pa));

    if (ext_pe && pa->type && IS_EXTENDED(pa->type->code)) {
      fdisk_warnx(cxt, _("Extended partition already exists."));
      return -EINVAL;
    }
    rc = get_partition_unused_primary(cxt, pa, &res);
    if (rc == 0)
      rc = add_partition(cxt, res, pa);
    goto done;

  /* D) template specifies start (or default), partno >= 4; add logical */
  } else if (pa && (fdisk_partition_start_is_default(pa) || fdisk_partition_has_start(pa))
       && fdisk_partition_has_partno(pa)
       && pa->partno >= 4) {
    DBG(LABEL, ul_debug("DOS: pa template %p: add logical (by partno)", pa));

    if (!ext_pe) {
      fdisk_warnx(cxt, _("Extended partition does not exists. Failed to add logical partition."));
      return -EINVAL;
    }

    if (fdisk_partition_has_start(pa)
         && pa->start < l->ext_offset
         && pa->start > get_abs_partition_end(ext_pe)) {
      DBG(LABEL, ul_debug("DOS: pa template specifies partno>=4, but start out of extended"));
      return -EINVAL;
    }

    rc = add_logical(cxt, pa, &res);
    goto done;
  }

  DBG(LABEL, ul_debug("DOS: dialog driven partitioning"));
  /* Note @pa may be still used for things like partition type, etc */

  /* check if there is space for primary partition */
  grain = cxt->grain > cxt->sector_size ? cxt->grain / cxt->sector_size : 1;
  first = cxt->first_lba;

  if (cxt->parent && fdisk_is_label(cxt->parent, GPT)) {
    /* modifying a hybrid MBR, which throws out the rules */
    grain = 1;
    first = 1;
  }

  /* set @first after the last used partition, set @free_sectors if there
   * is gap in front if the first partition or between used parrtitions. */
  for (i = 0; i < 4; i++) {
    struct dos_partition *p = self_partition(cxt, i);

    if (p && is_used_partition(p)) {
      fdisk_sector_t start = dos_partition_get_start(p);
      if (first + grain <= start)
        free_sectors = 1;
      first = start + dos_partition_get_size(p);
    } else
      free_primary++;
  }

  /* set @free_sectors if there is a space after the first usable sector */
  if (first + grain - 1 <= cxt->total_sectors - 1)
    free_sectors = 1;

  DBG(LABEL, ul_debug("DOS: primary: first free: %ju, last on disk: %ju, "
          "free_sectors=%d, free_primary=%d",
        (uintmax_t) first,
        (uintmax_t) cxt->total_sectors - 1,
        free_sectors, free_primary));

  if (!free_primary || !free_sectors) {
    DBG(LABEL, ul_debug("DOS: primary impossible"));
    if (l->ext_offset) {
      if (!pa || fdisk_partition_has_start(pa)) {
        /* See above case A); here we have start, but
         * out of extended partition */
        const char *msg;
        if (!free_primary)
          msg = _("All primary partitions are in use.");
        else
          msg =  _("All space for primary partitions is in use.");

        if (pa && fdisk_partition_has_start(pa)) {
          fdisk_warnx(cxt, "%s", msg);
          return -EINVAL;
        }
        fdisk_info(cxt, "%s", msg);
      }
      DBG(LABEL, ul_debug("DOS: trying logical"));
      rc = add_logical(cxt, pa, &res);
    } else {
      if (free_primary)
        fdisk_info(cxt, _("All space for primary partitions is in use."));
      else
      /* TRANSLATORS: Try to keep this within 80 characters. */
        fdisk_info(cxt, _("To create more partitions, first replace "
            "a primary with an extended partition."));
      return -EINVAL;
    }
  } else {
    char hint[BUFSIZ];
    struct fdisk_ask *ask;
    int c = 0;

    /* the default layout for scripts is to create primary partitions */
    if (cxt->script || !fdisk_has_dialogs(cxt)) {
      rc = get_partition_unused_primary(cxt, pa, &res);
      if (rc == 0)
        rc = add_partition(cxt, res, pa);
      goto done;
    }

    ask = fdisk_new_ask();
    if (!ask)
      return -ENOMEM;
    fdisk_ask_set_type(ask, FDISK_ASKTYPE_MENU);
    fdisk_ask_set_query(ask, _("Partition type"));
    fdisk_ask_menu_set_default(ask, free_primary == 1
            && !l->ext_offset ? 'e' : 'p');
    snprintf(hint, sizeof(hint),
        _("%u primary, %d extended, %u free"),
        4 - (l->ext_offset ? 1 : 0) - free_primary,
        l->ext_offset ? 1 : 0,
        free_primary);

    fdisk_ask_menu_add_item(ask, 'p', _("primary"), hint);
    if (!l->ext_offset)
      fdisk_ask_menu_add_item(ask, 'e', _("extended"), _("container for logical partitions"));
    else
      fdisk_ask_menu_add_item(ask, 'l', _("logical"), _("numbered from 5"));

    rc = fdisk_do_ask(cxt, ask);
    if (!rc)
      fdisk_ask_menu_get_result(ask, &c);
    fdisk_unref_ask(ask);
    if (rc)
      return rc;

    if (c == 'p') {
      rc = get_partition_unused_primary(cxt, pa, &res);
      if (rc == 0)
        rc = add_partition(cxt, res, pa);
      goto done;
    } else if (c == 'l' && l->ext_offset) {
      rc = add_logical(cxt, pa, &res);
      goto done;
    } else if (c == 'e' && !l->ext_offset) {
      rc = get_partition_unused_primary(cxt, pa, &res);
      if (rc == 0) {
        struct fdisk_partition *xpa = NULL;
        struct fdisk_parttype *t;

        t = fdisk_label_get_parttype_from_code(cxt->label,
            MBR_DOS_EXTENDED_PARTITION);
        if (!pa) {
          pa = xpa = fdisk_new_partition();
          if (!xpa)
            return -ENOMEM;
        }
        fdisk_partition_set_type(pa, t);
        rc = add_partition(cxt, res, pa);
        if (xpa) {
          fdisk_unref_partition(xpa);
          pa = NULL;
        }
      }
      goto done;
    } else
      fdisk_warnx(cxt, _("Invalid partition type `%c'."), c);
  }
done:
  if (rc == 0) {
    cxt->label->nparts_cur++;
    if (partno)
      *partno = res;
  }
  return rc;
}

static int write_sector(struct fdisk_context *cxt, fdisk_sector_t secno,
             unsigned char *buf)
{
  int rc;

  rc = seek_sector(cxt, secno);
  if (rc != 0) {
    fdisk_warn(cxt, _("Cannot write sector %jd: seek failed"),
        (uintmax_t) secno);
    return rc;
  }

  DBG(LABEL, ul_debug("DOS: writing to sector %ju", (uintmax_t) secno));

  if (write(cxt->dev_fd, buf, cxt->sector_size) != (ssize_t) cxt->sector_size)
    return -errno;
  return 0;
}

static int dos_write_disklabel(struct fdisk_context *cxt)
{
  struct fdisk_dos_label *l = self_label(cxt);
  size_t i;
  int rc = 0, mbr_changed = 0;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  DBG(LABEL, ul_debug("DOS: write PT requested [label-changed: %d, non-pt-changed: %d]",
        cxt->label->changed, l->non_pt_changed));

  mbr_changed = l->non_pt_changed;

  /* MBR (primary partitions) */
  if (!mbr_changed) {
    for (i = 0; i < 4; i++) {
      struct pte *pe = self_pte(cxt, i);

      assert(pe);
      if (pe->changed)
        mbr_changed = 1;
    }
  }
  if (mbr_changed) {
    DBG(LABEL, ul_debug("DOS: MBR changed, writing"));
    mbr_set_magic(cxt->firstsector);
    rc = write_sector(cxt, 0, cxt->firstsector);
    if (rc)
      goto done;
  }

  if (cxt->label->nparts_max <= 4 && l->ext_offset) {
    /* we have empty extended partition, check if the partition has
     * been modified and then cleanup possible remaining EBR  */
    struct pte *pe = self_pte(cxt, l->ext_index);
    unsigned char empty[512] = { 0 };
    fdisk_sector_t off = pe ? get_abs_partition_start(pe) : 0;

    if (off && pe->changed) {
      mbr_set_magic(empty);
      write_sector(cxt, off, empty);
    }
  }

  /* EBR (logical partitions) */
  for (i = 4; i < cxt->label->nparts_max; i++) {
    struct pte *pe = self_pte(cxt, i);

    assert(pe);
    if (!pe->changed || !pe->offset || !pe->sectorbuffer)
      continue;

    mbr_set_magic(pe->sectorbuffer);
    rc = write_sector(cxt, pe->offset, pe->sectorbuffer);
    if (rc)
      goto done;
  }

done:
  return rc;
}

static int dos_locate_disklabel(struct fdisk_context *cxt, int n,
    const char **name, uint64_t *offset, size_t *size)
{
  assert(cxt);

  *name = NULL;
  *offset = 0;
  *size = 0;

  switch (n) {
  case 0:
    *name = "MBR";
    *offset = 0;
    *size = 512;
    break;
  default:
    /* extended partitions */
    if ((size_t)n - 1 + 4 < cxt->label->nparts_max) {
      struct pte *pe = self_pte(cxt, n - 1 + 4);

      assert(pe);
      assert(pe->private_sectorbuffer);

      *name = "EBR";
      *offset = (uint64_t) pe->offset * cxt->sector_size;
      *size = 512;
    } else
      return 1;
    break;
  }

  return 0;
}

/*
 * Check whether partition entries are ordered by their starting positions.
 * Return 0 if OK. Return i if partition i should have been earlier.
 * Two separate checks: primary and logical partitions.
 */
static int wrong_p_order(struct fdisk_context *cxt, size_t *prev)
{
  size_t last_p_start_pos = 0, p_start_pos;
  size_t i, last_i = 0;

  for (i = 0 ; i < cxt->label->nparts_max; i++) {

    struct pte *pe = self_pte(cxt, i);
    struct dos_partition *p;

    assert(pe);
    p = pe->pt_entry;

    if (i == 4) {
      last_i = 4;
      last_p_start_pos = 0;
    }
    if (is_used_partition(p)) {
      p_start_pos = get_abs_partition_start(pe);

      if (last_p_start_pos > p_start_pos) {
        if (prev)
          *prev = last_i;
        return i;
      }

      last_p_start_pos = p_start_pos;
      last_i = i;
    }
  }
  return 0;
}

static int dos_get_disklabel_item(struct fdisk_context *cxt, struct fdisk_labelitem *item)
{
  int rc = 0;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  switch (item->id) {
  case FDISK_LABELITEM_ID:
  {
    unsigned int num = mbr_get_id(cxt->firstsector);
    item->name = _("Disk identifier");
    item->type = 's';
    if (asprintf(&item->data.str, "0x%08x", num) < 0)
      rc = -ENOMEM;
    break;
  }
  default:
    if (item->id < __FDISK_NLABELITEMS)
      rc = 1; /* unsupported generic item */
    else
      rc = 2; /* out of range */
    break;
  }

  return rc;

}

static int dos_get_partition(struct fdisk_context *cxt, size_t n,
           struct fdisk_partition *pa)
{
  struct dos_partition *p;
  struct pte *pe;
  struct fdisk_dos_label *lb;

  assert(cxt);
  assert(pa);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  lb = self_label(cxt);

  pe = self_pte(cxt, n);
  assert(pe);

  p = pe->pt_entry;
  pa->used = !is_cleared_partition(p);
  if (!pa->used)
    return 0;

  pa->type = dos_partition_parttype(cxt, p);
  pa->boot = p->boot_ind == ACTIVE_FLAG ? 1 : 0;
  pa->start = get_abs_partition_start(pe);
  pa->size = dos_partition_get_size(p);
  pa->container = lb->ext_offset && n == lb->ext_index;

  if (n >= 4)
    pa->parent_partno = lb->ext_index;

  if (p->boot_ind && asprintf(&pa->attrs, "%02x", p->boot_ind) < 0)
    return -ENOMEM;

  /* start C/H/S */
  if (asprintf(&pa->start_chs, "%d/%d/%d",
        cylinder(p->bs, p->bc),
        p->bh,
        sector(p->bs)) < 0)
    return -ENOMEM;

  /* end C/H/S */
  if (asprintf(&pa->end_chs, "%d/%d/%d",
        cylinder(p->es, p->ec),
        p->eh,
        sector(p->es)) < 0)
    return -ENOMEM;

  return 0;
}

static int has_logical(struct fdisk_context *cxt)
{
  size_t i;
  struct fdisk_dos_label *l = self_label(cxt);

  for (i = 4; i < cxt->label->nparts_max; i++) {
    if (l->ptes[i].pt_entry)
      return 1;
  }
  return 0;
}

static int dos_set_partition(struct fdisk_context *cxt, size_t n,
           struct fdisk_partition *pa)
{
  struct fdisk_dos_label *l;
  struct dos_partition *p;
  struct pte *pe;
  int orgtype;
  fdisk_sector_t start, size;

  assert(cxt);
  assert(pa);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  if (n >= cxt->label->nparts_max)
    return -EINVAL;

  l = self_label(cxt);
  p = self_partition(cxt, n);
  assert(p);

  pe = self_pte(cxt, n);
  if (!pe)
    return -EINVAL;

  orgtype = p->sys_ind;

  if (pa->type) {
    if (IS_EXTENDED(pa->type->code) && l->ext_offset && l->ext_index != n) {
      fdisk_warnx(cxt, _("Extended partition already exists."));
      return -EINVAL;
    }

    if (!pa->type->code)
      fdisk_warnx(cxt, _("Type 0 means free space to many systems. "
           "Having partitions of type 0 is probably unwise."));

    if (IS_EXTENDED(p->sys_ind) && !IS_EXTENDED(pa->type->code) && has_logical(cxt)) {
      fdisk_warnx(cxt, _(
        "Cannot change type of the extended partition which is "
        "already used by logical partitions. Delete logical "
        "partitions first."));
      return -EINVAL;
    }
  }

  FDISK_INIT_UNDEF(start);
  FDISK_INIT_UNDEF(size);

  if (fdisk_partition_has_start(pa))
    start = pa->start;
  if (fdisk_partition_has_size(pa))
    size = pa->size;

  if (!FDISK_IS_UNDEF(start) || !FDISK_IS_UNDEF(size)) {
    DBG(LABEL, ul_debug("DOS: resize partition"));

    if (FDISK_IS_UNDEF(start))
      start = get_abs_partition_start(pe);
    if (FDISK_IS_UNDEF(size))
      size = dos_partition_get_size(p);

    set_partition(cxt, n, 0, start, start + size - 1,
        pa->type  ? pa->type->code : p->sys_ind,
        FDISK_IS_UNDEF(pa->boot) ?
          p->boot_ind == ACTIVE_FLAG :
          fdisk_partition_is_bootable(pa));
  } else {
    DBG(LABEL, ul_debug("DOS: keep size, modify properties"));
    if (pa->type)
      p->sys_ind = pa->type->code;
    if (!FDISK_IS_UNDEF(pa->boot))
      p->boot_ind = fdisk_partition_is_bootable(pa) ? ACTIVE_FLAG : 0;
  }

  if (pa->type) {
    if (IS_EXTENDED(pa->type->code) && !IS_EXTENDED(orgtype)) {
      /* new extended partition - create a reference  */
      l->ext_index = n;
      l->ext_offset = dos_partition_get_start(p);
      pe->ex_entry = p;
     } else if (IS_EXTENDED(orgtype)) {
      /* remove extended partition */
      cxt->label->nparts_max = 4;
      l->ptes[l->ext_index].ex_entry = NULL;
      l->ext_offset = 0;
      l->ext_index = 0;
     }
  }

  partition_set_changed(cxt, n, 1);
  return 0;
}

static void print_chain_of_logicals(struct fdisk_context *cxt)
{
  size_t i;
  struct fdisk_dos_label *l = self_label(cxt);

  fputc('\n', stdout);

  for (i = 4; i < cxt->label->nparts_max; i++) {
    struct pte *pe = self_pte(cxt, i);

    assert(pe);
    fprintf(stderr, "#%02zu EBR [%10ju], "
      "data[start=%10ju (%10ju), size=%10ju], "
      "link[start=%10ju (%10ju), size=%10ju]\n",
      i, (uintmax_t) pe->offset,
      /* data */
      (uintmax_t) dos_partition_get_start(pe->pt_entry),
      (uintmax_t) get_abs_partition_start(pe),
      (uintmax_t) dos_partition_get_size(pe->pt_entry),
      /* link */
      (uintmax_t) dos_partition_get_start(pe->ex_entry),
      (uintmax_t) l->ext_offset + dos_partition_get_start(pe->ex_entry),
      (uintmax_t) dos_partition_get_size(pe->ex_entry));
  }
}

static int cmp_ebr_offsets(const void *a, const void *b)
{
  const struct pte *ae = (const struct pte *) a,
       *be = (const struct pte *) b;

  if (ae->offset == 0 && be->offset == 0)
    return 0;
  if (ae->offset == 0)
    return 1;
  if (be->offset == 0)
    return -1;

  return cmp_numbers(ae->offset, be->offset);
}

/*
 * Fix the chain of logicals.
 *
 * The function does not modify data partitions within EBR tables
 * (pte->pt_entry). It sorts the chain by EBR offsets and then update links
 * (pte->ex_entry) between EBR tables.
 *
 */
static void fix_chain_of_logicals(struct fdisk_context *cxt)
{
  struct fdisk_dos_label *l = self_label(cxt);
  struct pte *last;
  size_t i;

  DBG(LABEL, print_chain_of_logicals(cxt));

  /* Sort chain by EBR offsets */
  qsort(&l->ptes[4], cxt->label->nparts_max - 4, sizeof(struct pte),
      cmp_ebr_offsets);

again:
  /* Sort data partitions by start */
  for (i = 4; i < cxt->label->nparts_max - 1; i++) {
    struct pte *cur = self_pte(cxt, i),
         *nxt = self_pte(cxt, i + 1);

    assert(cur);
    assert(nxt);

    if (get_abs_partition_start(cur) >
        get_abs_partition_start(nxt)) {

      struct dos_partition tmp = *cur->pt_entry;
      fdisk_sector_t cur_start = get_abs_partition_start(cur),
         nxt_start = get_abs_partition_start(nxt);

      /* swap data partitions */
      *cur->pt_entry = *nxt->pt_entry;
      *nxt->pt_entry = tmp;

      /* Recount starts according to EBR offsets, the absolute
       * address still has to be the same! */
      dos_partition_set_start(cur->pt_entry, nxt_start - cur->offset);
      dos_partition_sync_chs(cur->pt_entry, cur->offset, cxt->geom.sectors, cxt->geom.heads);
      dos_partition_set_start(nxt->pt_entry, cur_start - nxt->offset);
      dos_partition_sync_chs(nxt->pt_entry, nxt->offset, cxt->geom.sectors, cxt->geom.heads);

      partition_set_changed(cxt, i, 1);
      partition_set_changed(cxt, i + 1, 1);
      goto again;
    }
  }

  /* Update EBR links */
  for (i = 4; i < cxt->label->nparts_max - 1; i++) {
    struct pte *cur = self_pte(cxt, i),
         *nxt = self_pte(cxt, i + 1);

    assert(cur);
    assert(nxt);

    fdisk_sector_t noff = nxt->offset - l->ext_offset,
     ooff = dos_partition_get_start(cur->ex_entry);

    if (noff == ooff)
      continue;

    DBG(LABEL, ul_debug("DOS: fix EBR [%10ju] link %ju -> %ju",
      (uintmax_t) cur->offset,
      (uintmax_t) ooff, (uintmax_t) noff));

    set_partition(cxt, i, 1, nxt->offset,
        get_abs_partition_end(nxt),
        MBR_DOS_EXTENDED_PARTITION, 0);
  }

  /* always terminate the chain ! */
  last = self_pte(cxt, cxt->label->nparts_max - 1);
  if (last) {
    clear_partition(last->ex_entry);
    partition_set_changed(cxt, cxt->label->nparts_max - 1, 1);
  }

  DBG(LABEL, print_chain_of_logicals(cxt));
}

static int dos_reorder(struct fdisk_context *cxt)
{
  struct pte *pei, *pek;
  size_t i,k;

  if (!wrong_p_order(cxt, NULL))
    return 1;

  while ((i = wrong_p_order(cxt, &k)) != 0 && i < 4) {
    /* partition i should have come earlier, move it */
    /* We have to move data in the MBR */
    struct dos_partition *pi, *pk, *pe, pbuf;
    pei = self_pte(cxt, i);
    pek = self_pte(cxt, k);

    assert(pei);
    assert(pek);

    pe = pei->ex_entry;
    pei->ex_entry = pek->ex_entry;
    pek->ex_entry = pe;

    pi = pei->pt_entry;
    pk = pek->pt_entry;

    memmove(&pbuf, pi, sizeof(struct dos_partition));
    memmove(pi, pk, sizeof(struct dos_partition));
    memmove(pk, &pbuf, sizeof(struct dos_partition));

    partition_set_changed(cxt, i, 1);
    partition_set_changed(cxt, k, 1);
  }

  if (i)
    fix_chain_of_logicals(cxt);

  return 0;
}

/**
 * fdisk_dos_fix_chs:
 * @cxt: fdisk context
 *
 * Fix beginning and ending C/H/S values for every partition
 * according to LBA relative offset, relative beginning and
 * size and fdisk idea of disk geometry (sectors per track
 * and number of heads).
 *
 * Returns: number of fixed (changed) partitions.
 */
int fdisk_dos_fix_chs(struct fdisk_context *cxt)
{
  unsigned int obc, obh, obs; /* old beginning c, h, s */
  unsigned int oec, oeh, oes; /* old ending c, h, s */
  unsigned int nbc, nbh, nbs; /* new beginning c, h, s */
  unsigned int nec, neh, nes; /* new ending c, h, s */
  fdisk_sector_t l, sects;  /* lba beginning and size */
  struct dos_partition *p;
  struct pte *pe;
  int changed = 0;
  size_t i;

  assert(fdisk_is_label(cxt, DOS));

  for (i = 0; i < cxt->label->nparts_max; i++) {
    p = self_partition(cxt, i);
    if (!p || !is_used_partition(p))
      continue;

    pe = self_pte(cxt, i);

    /* old beginning c, h, s */
    obc = cylinder(p->bs, p->bc);
    obh = p->bh;
    obs = sector(p->bs);

    /* old ending c, h, s */
    oec = cylinder(p->es, p->ec);
    oeh = p->eh;
    oes = sector(p->es);

    /* new beginning c, h, s */
    l = get_abs_partition_start(pe);
    long2chs(cxt, l, &nbc, &nbh, &nbs);
    if (l > UINT32_MAX || nbc >= 1024) {
      nbc = 1023;
      nbh = cxt->geom.heads-1;
      nbs = cxt->geom.sectors;
    }

    /* new ending c, h, s */
    sects = dos_partition_get_size(p);
    long2chs(cxt, l + sects - 1, &nec, &neh, &nes);
    if (lba_overflowed(l, sects) || nec >= 1024) {
      nec = 1023;
      neh = cxt->geom.heads-1;
      nes = cxt->geom.sectors;
    }

    if (obc != nbc || obh != nbh || obs != nbs ||
        oec != nec || oeh != neh || oes != nes) {
      DBG(LABEL, ul_debug("DOS: changing %zu partition CHS "
        "from (%d, %d, %d)-(%d, %d, %d) "
        "to (%d, %d, %d)-(%d, %d, %d)",
        i, obc, obh, obs, oec, oeh, oes,
        nbc, nbh, nbs, nec, neh, nes));
      p->bc = nbc & 0xff;
      p->bh = nbh;
      p->bs = nbs | ((nbc >> 2) & 0xc0);
      p->ec = nec & 0xff;
      p->eh = neh;
      p->es = nes | ((nec >> 2) & 0xc0);
      partition_set_changed(cxt, i, 1);
      changed++;
    }
  }

  return changed;
}

/* TODO: use fdisk_set_partition() API */
int fdisk_dos_move_begin(struct fdisk_context *cxt, size_t i)
{
  struct pte *pe;
  struct dos_partition *p;
  unsigned int new, free_start, curr_start, last;
  uintmax_t res = 0;
  size_t x;
  int rc;

  assert(cxt);
  assert(fdisk_is_label(cxt, DOS));

  pe = self_pte(cxt, i);
  if (!pe)
    return -EINVAL;

  p = pe->pt_entry;

  if (!is_used_partition(p) || IS_EXTENDED (p->sys_ind)) {
    fdisk_warnx(cxt, _("Partition %zu: no data area."), i + 1);
    return 0;
  }

  /* The safe start is at the second sector, but some use-cases require
   * to have MBR within the first partition , so default to the first
   * sector of the disk or at the second sector of the extended partition
   */
  free_start = pe->offset ? pe->offset + 1 : 0;

  curr_start = get_abs_partition_start(pe);

  /* look for a free space before the current start of the partition */
  for (x = 0; x < cxt->label->nparts_max; x++) {
    unsigned int end;
    struct pte *prev_pe = self_pte(cxt, x);
    struct dos_partition *prev_p;

    assert(prev_pe);

    prev_p = prev_pe->pt_entry;
    if (!prev_p)
      continue;
    end = get_abs_partition_start(prev_pe)
          + dos_partition_get_size(prev_p);

    if (is_used_partition(prev_p) &&
        end > free_start && end <= curr_start)
      free_start = end;
  }

  last = get_abs_partition_end(pe);

  rc = fdisk_ask_number(cxt, free_start, curr_start, last,
      _("New beginning of data"), &res);
  if (rc)
    return rc;

  new = res - pe->offset;

  if (new != dos_partition_get_size(p)) {
    unsigned int sects = dos_partition_get_size(p)
        + dos_partition_get_start(p) - new;

    dos_partition_set_size(p, sects);
    dos_partition_set_start(p, new);
    dos_partition_sync_chs(p, pe->offset, cxt->geom.sectors, cxt->geom.heads);

    partition_set_changed(cxt, i, 1);

    if (new == 0)
      fdisk_info(cxt, _("The new beginning of the partition overlaps the disk "
            "label area. Be very careful when using the partition. "
            "You can lose all your partitions on the disk."));
  }

  return rc;
}

static int dos_partition_is_used(
    struct fdisk_context *cxt,
    size_t i)
{
  struct dos_partition *p;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  if (i >= cxt->label->nparts_max)
    return 0;

  p = self_partition(cxt, i);

  return p && !is_cleared_partition(p);
}

static int dos_toggle_partition_flag(
    struct fdisk_context *cxt,
    size_t i,
    unsigned long flag)
{
  struct dos_partition *p;

  assert(cxt);
  assert(cxt->label);
  assert(fdisk_is_label(cxt, DOS));

  if (i >= cxt->label->nparts_max)
    return -EINVAL;

  p = self_partition(cxt, i);
  assert(p);

  switch (flag) {
  case DOS_FLAG_ACTIVE:
    if (IS_EXTENDED(p->sys_ind) && !p->boot_ind)
      fdisk_warnx(cxt, _("Partition %zu: is an extended "
          "partition."), i + 1);

    p->boot_ind = (p->boot_ind ? 0 : ACTIVE_FLAG);
    partition_set_changed(cxt, i, 1);
    fdisk_info(cxt, p->boot_ind ?
      _("The bootable flag on partition %zu is enabled now.") :
      _("The bootable flag on partition %zu is disabled now."),
      i + 1);
    break;
  default:
    return 1;
  }

  return 0;
}

static const struct fdisk_field dos_fields[] =
{
  /* basic */
  { FDISK_FIELD_DEVICE, N_("Device"),  10,  0 },
  { FDISK_FIELD_BOOT, N_("Boot"),   1,  0 },
  { FDISK_FIELD_START,  N_("Start"),    5,  FDISK_FIELDFL_NUMBER },
  { FDISK_FIELD_END,  N_("End"),    5,  FDISK_FIELDFL_NUMBER },
  { FDISK_FIELD_SECTORS,  N_("Sectors"),    5,  FDISK_FIELDFL_NUMBER },
  { FDISK_FIELD_CYLINDERS,N_("Cylinders"),  5,  FDISK_FIELDFL_NUMBER },
  { FDISK_FIELD_SIZE, N_("Size"),   5,  FDISK_FIELDFL_NUMBER | FDISK_FIELDFL_EYECANDY },
  { FDISK_FIELD_TYPEID, N_("Id"),   2,  FDISK_FIELDFL_NUMBER },
  { FDISK_FIELD_TYPE, N_("Type"), 0.1,  0 },

  /* expert mode */
  { FDISK_FIELD_SADDR,  N_("Start-C/H/S"), 1,   FDISK_FIELDFL_NUMBER | FDISK_FIELDFL_DETAIL },
  { FDISK_FIELD_EADDR,  N_("End-C/H/S"),   1,   FDISK_FIELDFL_NUMBER | FDISK_FIELDFL_DETAIL },
  { FDISK_FIELD_ATTR, N_("Attrs"),     2,   FDISK_FIELDFL_NUMBER | FDISK_FIELDFL_DETAIL }

};

static const struct fdisk_label_operations dos_operations =
{
  .probe    = dos_probe_label,
  .write    = dos_write_disklabel,
  .verify   = dos_verify_disklabel,
  .create   = dos_create_disklabel,
  .locate   = dos_locate_disklabel,
  .get_item = dos_get_disklabel_item,
  .set_id   = dos_set_disklabel_id,

  .get_part = dos_get_partition,
  .set_part = dos_set_partition,
  .add_part = dos_add_partition,
  .del_part = dos_delete_partition,
  .reorder  = dos_reorder,

  .part_toggle_flag = dos_toggle_partition_flag,
  .part_is_used = dos_partition_is_used,

  .reset_alignment = dos_reset_alignment,

  .deinit   = dos_deinit,
};

/*
 * allocates DOS in-memory stuff
 */
struct fdisk_label *fdisk_new_dos_label(struct fdisk_context *cxt __attribute__ ((__unused__)))
{
  struct fdisk_label *lb;
  struct fdisk_dos_label *dos;

  dos = calloc(1, sizeof(*dos));
  if (!dos)
    return NULL;

  /* initialize generic part of the driver */
  lb = (struct fdisk_label *) dos;
  lb->name = "dos";
  lb->id = FDISK_DISKLABEL_DOS;
  lb->op = &dos_operations;

  lb->parttypes = dos_parttypes;
  lb->nparttypes = ARRAY_SIZE(dos_parttypes) - 1;
  lb->parttype_cuts = dos_parttype_cuts;
  lb->nparttype_cuts = ARRAY_SIZE(dos_parttype_cuts);

  lb->fields = dos_fields;
  lb->nfields = ARRAY_SIZE(dos_fields);

  lb->geom_min.sectors = 1;
  lb->geom_min.heads = 1;
  lb->geom_min.cylinders = 1;

  lb->geom_max.sectors = 63;
  lb->geom_max.heads = 255;
  lb->geom_max.cylinders = 1048576;

  /* return calloc() result to keep static anaylizers happy */
  return (struct fdisk_label *) dos;
}

/**
 * fdisk_dos_enable_compatible:
 * @lb: DOS label (see fdisk_get_label())
 * @enable: 0 or 1
 *
 * Enables deprecated DOS compatible mode, in this mode library checks for
 * cylinders boundary, cases about CHS addressing and another obscure things.
 *
 * Returns: 0 on success, <0 on error.
 */
int fdisk_dos_enable_compatible(struct fdisk_label *lb, int enable)
{
  struct fdisk_dos_label *dos = (struct fdisk_dos_label *) lb;

  if (!lb)
    return -EINVAL;

  dos->compatible = enable;
  if (enable)
    lb->flags |= FDISK_LABEL_FL_REQUIRE_GEOMETRY;
  return 0;
}

/**
 * fdisk_dos_is_compatible:
 * @lb: DOS label
 *
 * Returns: 0 if DOS compatibility disabled, 1 if enabled
 */
int fdisk_dos_is_compatible(struct fdisk_label *lb)
{
  return ((struct fdisk_dos_label *) lb)->compatible;
}

Coverage Report

Created: 2025-10-13 06:53