path: root/fdisks/fdiskdoslabel.c

/*
 * Many, many hands.
 * Specific DOS label file  - Davidlohr Bueso <dave@gnu.org>
 */

#include <unistd.h>
#include <ctype.h>

#include "nls.h"
#include "xalloc.h"
#include "randutils.h"
#include "common.h"
#include "fdisk.h"
#include "fdiskdoslabel.h"

static struct fdisk_parttype dos_parttypes[] = {
	#include "dos_part_types.h"
};

#define set_hsc(h,s,c,sector) { \
		s = sector % cxt->geom.sectors + 1;			\
		sector /= cxt->geom.sectors;				\
		h = sector % cxt->geom.heads;				\
		sector /= cxt->geom.heads;				\
		c = sector & 0xff;					\
		s |= (sector >> 2) & 0xc0;				\
	}

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

struct pte ptes[MAXIMUM_PARTS];
sector_t extended_offset;
int ext_index;

unsigned int units_per_sector = 1, display_in_cyl_units = 0;

void update_units(struct fdisk_context *cxt)
{
	int cyl_units = cxt->geom.heads * cxt->geom.sectors;

	if (display_in_cyl_units && cyl_units)
		units_per_sector = cyl_units;
	else
		units_per_sector = 1;	/* in sectors */
}

void change_units(struct fdisk_context *cxt)
{
	display_in_cyl_units = !display_in_cyl_units;
	update_units(cxt);

	if (display_in_cyl_units)
		printf(_("Changing display/entry units to cylinders (DEPRECATED!)\n"));
	else
		printf(_("Changing display/entry units to sectors\n"));
}


static void warn_alignment(struct fdisk_context *cxt)
{
	if (nowarn)
		return;

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

	if (dos_compatible_flag)
		fprintf(stderr, _("\n"
"WARNING: DOS-compatible mode is deprecated. It's strongly recommended to\n"
"         switch off the mode (with command 'c')."));

	if (display_in_cyl_units)
		fprintf(stderr, _("\n"
"WARNING: cylinders as display units are deprecated. Use command 'u' to\n"
"         change units to sectors.\n"));

}

static int get_nonexisting_partition(struct fdisk_context *cxt, int warn, int max)
{
	int pno = -1;
	int i;
	int dflt = 0;

	for (i = 0; i < max; i++) {
		struct pte *pe = &ptes[i];
		struct partition *p = pe->part_table;

		if (p && is_cleared_partition(p)) {
			if (pno >= 0) {
				dflt = pno + 1;
				goto not_unique;
			}
			pno = i;
		}
	}
	if (pno >= 0) {
		printf(_("Selected partition %d\n"), pno+1);
		return pno;
	}
	printf(_("All primary partitions have been defined already!\n"));
	return -1;

 not_unique:
	return get_partition_dflt(cxt, warn, max, dflt);
}


/* Allocate a buffer and read a partition table sector */
static void read_pte(struct fdisk_context *cxt, int pno, sector_t offset)
{
	struct pte *pe = &ptes[pno];

	pe->offset = offset;
	pe->sectorbuffer = xcalloc(1, cxt->sector_size);

	if (read_sector(cxt, offset, pe->sectorbuffer) != 0)
		fprintf(stderr, _("Failed to read extended partition table (offset=%jd)\n"),
					(uintmax_t) offset);
	pe->changed = 0;
	pe->part_table = pe->ext_pointer = NULL;
}

static void mbr_set_id(unsigned char *b, unsigned int id)
{
	store4_little_endian(&b[440], id);
}

static void mbr_set_magic(unsigned char *b)
{
	b[510] = 0x55;
	b[511] = 0xaa;
}

int mbr_is_valid_magic(unsigned char *b)
{
	return (b[510] == 0x55 && b[511] == 0xaa);
}

static unsigned int mbr_get_id(const unsigned char *b)
{
	return read4_little_endian(&b[440]);
}

static void clear_partition(struct partition *p)
{
	if (!p)
		return;
	p->boot_ind = 0;
	p->head = 0;
	p->sector = 0;
	p->cyl = 0;
	p->sys_ind = 0;
	p->end_head = 0;
	p->end_sector = 0;
	p->end_cyl = 0;
	set_start_sect(p,0);
	set_nr_sects(p,0);
}

void dos_init(struct fdisk_context *cxt)
{
	int i;

	cxt->disklabel = FDISK_DISKLABEL_DOS;
	partitions = 4;
	ext_index = 0;
	extended_offset = 0;

	for (i = 0; i < 4; i++) {
		struct pte *pe = &ptes[i];

		pe->part_table = pt_offset(cxt->firstsector, i);
		pe->ext_pointer = NULL;
		pe->offset = 0;
		pe->sectorbuffer = cxt->firstsector;
		pe->changed = 0;
	}

	warn_geometry(cxt);
	warn_limits(cxt);
	warn_alignment(cxt);
}

static int dos_delete_partition(
		struct fdisk_context *cxt __attribute__ ((__unused__)),
		int partnum)
{
	struct pte *pe = &ptes[partnum];
	struct partition *p = pe->part_table;
	struct partition *q = pe->ext_pointer;

	/* Note that for the fifth partition (partnum == 4) we don't actually
	   decrement partitions. */

	if (partnum < 4) {
		if (IS_EXTENDED (p->sys_ind) && partnum == ext_index) {
			partitions = 4;
			ptes[ext_index].ext_pointer = NULL;
			extended_offset = 0;
		}
		clear_partition(p);
	} else if (!q->sys_ind && partnum > 4) {
		/* the last one in the chain - just delete */
		--partitions;
		--partnum;
		clear_partition(ptes[partnum].ext_pointer);
		ptes[partnum].changed = 1;
	} else {
		/* not the last one - further ones will be moved down */
		if (partnum > 4) {
			/* delete this link in the chain */
			p = ptes[partnum-1].ext_pointer;
			*p = *q;
			set_start_sect(p, get_start_sect(q));
			set_nr_sects(p, get_nr_sects(q));
			ptes[partnum-1].changed = 1;
		} else if (partitions > 5) {    /* 5 will be moved to 4 */
			/* the first logical in a longer chain */
			struct pte *pe = &ptes[5];

			if (pe->part_table) /* prevent SEGFAULT */
				set_start_sect(pe->part_table,
					       get_partition_start(pe) -
					       extended_offset);
			pe->offset = extended_offset;
			pe->changed = 1;
		}

		if (partitions > 5) {
			partitions--;
			while (partnum < partitions) {
				ptes[partnum] = ptes[partnum+1];
				partnum++;
			}
		} else
			/* the only logical: clear only */
			clear_partition(ptes[partnum].part_table);
	}

	return 0;
}

static void read_extended(struct fdisk_context *cxt, int ext)
{
	int i;
	struct pte *pex;
	struct partition *p, *q;

	ext_index = ext;
	pex = &ptes[ext];
	pex->ext_pointer = pex->part_table;

	p = pex->part_table;
	if (!get_start_sect(p)) {
		fprintf(stderr,
			_("Bad offset in primary extended partition\n"));
		return;
	}

	while (IS_EXTENDED (p->sys_ind)) {
		struct pte *pe = &ptes[partitions];

		if (partitions >= 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 = &ptes[partitions-1];

			fprintf(stderr,
				_("Warning: omitting partitions after #%d.\n"
				  "They will be deleted "
				  "if you save this partition table.\n"),
				partitions);
			clear_partition(pre->ext_pointer);
			pre->changed = 1;
			return;
		}

		read_pte(cxt, partitions, extended_offset + get_start_sect(p));

		if (!extended_offset)
			extended_offset = get_start_sect(p);

		q = p = pt_offset(pe->sectorbuffer, 0);
		for (i = 0; i < 4; i++, p++) if (get_nr_sects(p)) {
			if (IS_EXTENDED (p->sys_ind)) {
				if (pe->ext_pointer)
					fprintf(stderr,
						_("Warning: extra link "
						  "pointer in partition table"
						  " %d\n"), partitions + 1);
				else
					pe->ext_pointer = p;
			} else if (p->sys_ind) {
				if (pe->part_table)
					fprintf(stderr,
						_("Warning: ignoring extra "
						  "data in partition table"
						  " %d\n"), partitions + 1);
				else
					pe->part_table = p;
			}
		}

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

		p = pe->ext_pointer;
		partitions++;
	}

	/* remove empty links */
 remove:
	for (i = 4; i < partitions; i++) {
		struct pte *pe = &ptes[i];

		if (!get_nr_sects(pe->part_table) &&
		    (partitions > 5 || ptes[4].part_table->sys_ind)) {
			printf(_("omitting empty partition (%d)\n"), i+1);
			dos_delete_partition(cxt, i);
			goto remove; 	/* numbering changed */
		}
	}
}

void dos_print_mbr_id(struct fdisk_context *cxt)
{
	printf(_("Disk identifier: 0x%08x\n"), mbr_get_id(cxt->firstsector));
}

static int dos_create_disklabel(struct fdisk_context *cxt)
{
	unsigned int id;

	/* random disk signature */
	random_get_bytes(&id, sizeof(id));

	fprintf(stderr, _("Building a new DOS disklabel with disk identifier 0x%08x.\n"), id);

	dos_init(cxt);
	fdisk_zeroize_firstsector(cxt);
	set_all_unchanged();
	set_changed(0);

	/* Generate an MBR ID for this disk */
	mbr_set_id(cxt->firstsector, id);

	/* Put MBR signature */
	mbr_set_magic(cxt->firstsector);
	return 0;
}

void dos_set_mbr_id(struct fdisk_context *cxt)
{
	unsigned long new_id;
	char *ep;
	char ps[64];

	snprintf(ps, sizeof ps, _("New disk identifier (current 0x%08x): "),
		 mbr_get_id(cxt->firstsector));

	if (read_chars(ps) == '\n')
		return;

	new_id = strtoul(line_ptr, &ep, 0);
	if (*ep != '\n')
		return;

	mbr_set_id(cxt->firstsector, new_id);
	MBRbuffer_changed = 1;
	dos_print_mbr_id(cxt);
}

static void get_partition_table_geometry(struct fdisk_context *cxt,
			unsigned int *ph, unsigned int *ps)
{
	unsigned char *bufp = cxt->firstsector;
	struct partition *p;
	int i, h, s, hh, ss;
	int first = 1;
	int bad = 0;

	hh = ss = 0;
	for (i=0; i<4; i++) {
		p = pt_offset(bufp, i);
		if (p->sys_ind != 0) {
			h = p->end_head + 1;
			s = (p->end_sector & 077);
			if (first) {
				hh = h;
				ss = s;
				first = 0;
			} else if (hh != h || ss != s)
				bad = 1;
		}
	}

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

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

static int dos_reset_alignment(struct fdisk_context *cxt)
{
	/* overwrite necessary stuff by DOS deprecated stuff */
	if (dos_compatible_flag) {
		if (cxt->geom.sectors)
			cxt->first_lba = cxt->geom.sectors;	/* usually 63 */

		cxt->grain = cxt->sector_size;			/* usually 512 */
	}
	/* units_per_sector has impact to deprecated DOS stuff */
	update_units(cxt);

	return 0;
}

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

	for (i = 0; i < 4; i++) {
		struct pte *pe = &ptes[i];

		if (IS_EXTENDED (pe->part_table->sys_ind)) {
			if (partitions != 4)
				fprintf(stderr, _("Ignoring extra extended "
					"partition %d\n"), i + 1);
			else
				read_extended(cxt, i);
		}
	}

	for (i = 3; i < partitions; i++) {
		struct pte *pe = &ptes[i];

		if (!mbr_is_valid_magic(pe->sectorbuffer)) {
			fprintf(stderr,
				_("Warning: invalid flag 0x%04x of partition "
				"table %d will be corrected by w(rite)\n"),
				part_table_flag(pe->sectorbuffer), i + 1);
			pe->changed = 1;
		}
	}

	return 1;
}

/*
 * Avoid warning about DOS partitions when no DOS partition was changed.
 * Here a heuristic "is probably dos partition".
 * We might also do the opposite and warn in all cases except
 * for "is probably nondos partition".
 */
static int is_dos_partition(int t)
{
	return (t == 1 || t == 4 || t == 6 ||
		t == 0x0b || t == 0x0c || t == 0x0e ||
		t == 0x11 || t == 0x12 || t == 0x14 || t == 0x16 ||
		t == 0x1b || t == 0x1c || t == 0x1e || t == 0x24 ||
		t == 0xc1 || t == 0xc4 || t == 0xc6);
}

static void set_partition(struct fdisk_context *cxt,
			  int i, int doext, sector_t start,
			  sector_t stop, int sysid)
{
	struct partition *p;
	sector_t offset;

	if (doext) {
		p = ptes[i].ext_pointer;
		offset = extended_offset;
	} else {
		p = ptes[i].part_table;
		offset = ptes[i].offset;
	}
	p->boot_ind = 0;
	p->sys_ind = sysid;
	set_start_sect(p, start - offset);
	set_nr_sects(p, stop - start + 1);

	if (!doext)
		print_partition_size(cxt, i + 1, start, stop, sysid);

	if (dos_compatible_flag && (start/(cxt->geom.sectors*cxt->geom.heads) > 1023))
		start = cxt->geom.heads*cxt->geom.sectors*1024 - 1;
	set_hsc(p->head, p->sector, p->cyl, start);
	if (dos_compatible_flag && (stop/(cxt->geom.sectors*cxt->geom.heads) > 1023))
		stop = cxt->geom.heads*cxt->geom.sectors*1024 - 1;
	set_hsc(p->end_head, p->end_sector, p->end_cyl, stop);
	ptes[i].changed = 1;
}

static sector_t get_unused_start(struct fdisk_context *cxt,
				 int part_n, sector_t start,
				 sector_t first[], sector_t last[])
{
	int i;

	for (i = 0; i < partitions; i++) {
		sector_t lastplusoff;

		if (start == ptes[i].offset)
			start += cxt->first_lba;
		lastplusoff = last[i] + ((part_n < 4) ? 0 : cxt->first_lba);
		if (start >= first[i] && start <= lastplusoff)
			start = lastplusoff + 1;
	}

	return start;
}

static int add_partition(struct fdisk_context *cxt, int n, struct fdisk_parttype *t)
{
	char mesg[256];		/* 48 does not suffice in Japanese */
	int i, sys, read = 0;
	struct partition *p = ptes[n].part_table;
	struct partition *q = ptes[ext_index].part_table;
	sector_t start, stop = 0, limit, temp,
		first[partitions], last[partitions];

	sys = t ? t->type : LINUX_NATIVE;

	if (p && p->sys_ind) {
		printf(_("Partition %d is already defined.  Delete "
			 "it before re-adding it.\n"), n + 1);
		return -EINVAL;
	}
	fill_bounds(first, last);
	if (n < 4) {
		start = cxt->first_lba;
		if (display_in_cyl_units || !cxt->total_sectors)
			limit = cxt->geom.heads * cxt->geom.sectors * cxt->geom.cylinders - 1;
		else
			limit = cxt->total_sectors - 1;

		if (limit > UINT_MAX)
			limit = UINT_MAX;

		if (extended_offset) {
			first[ext_index] = extended_offset;
			last[ext_index] = get_start_sect(q) +
				get_nr_sects(q) - 1;
		}
	} else {
		start = extended_offset + cxt->first_lba;
		limit = get_start_sect(q) + get_nr_sects(q) - 1;
	}
	if (display_in_cyl_units)
		for (i = 0; i < partitions; i++)
			first[i] = (cround(first[i]) - 1) * units_per_sector;

	snprintf(mesg, sizeof(mesg), _("First %s"), str_units(SINGULAR));
	do {
		sector_t dflt, aligned;

		temp = start;
		dflt = start = get_unused_start(cxt, n, start, first, last);

		/* the default sector should be aligned and unused */
		do {
			aligned = align_lba_in_range(cxt, dflt, dflt, limit);
			dflt = get_unused_start(cxt, n, aligned, first, last);
		} while (dflt != aligned && dflt > aligned && dflt < limit);

		if (dflt >= limit)
			dflt = start;
		if (start > limit)
			break;
		if (start >= temp+units_per_sector && read) {
			printf(_("Sector %llu is already allocated\n"), temp);
			temp = start;
			read = 0;
		}
		if (!read && start == temp) {
			sector_t i = start;

			start = read_int(cxt, cround(i), cround(dflt), cround(limit),
					 0, mesg);
			if (display_in_cyl_units) {
				start = (start - 1) * units_per_sector;
				if (start < i) start = i;
			}
			read = 1;
		}
	} while (start != temp || !read);
	if (n > 4) {			/* NOT for fifth partition */
		struct pte *pe = &ptes[n];

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

	for (i = 0; i < partitions; i++) {
		struct pte *pe = &ptes[i];

		if (start < pe->offset && limit >= pe->offset)
			limit = pe->offset - 1;
		if (start < first[i] && limit >= first[i])
			limit = first[i] - 1;
	}
	if (start > limit) {
		printf(_("No free sectors available\n"));
		if (n > 4)
			partitions--;
		return -ENOSPC;
	}
	if (cround(start) == cround(limit)) {
		stop = limit;
	} else {
		int is_suffix_used = 0;

		snprintf(mesg, sizeof(mesg),
			_("Last %1$s, +%2$s or +size{K,M,G}"),
			 str_units(SINGULAR), str_units(PLURAL));

		stop = read_int_with_suffix(cxt,
					    cround(start), cround(limit), cround(limit),
					    cround(start), mesg, &is_suffix_used);
		if (display_in_cyl_units) {
			stop = stop * units_per_sector - 1;
			if (stop >limit)
				stop = limit;
		}

		if (is_suffix_used && 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 = align_lba_in_range(cxt, stop, start, limit) - 1;
			if (stop > limit)
				stop = limit;
		}
	}

	set_partition(cxt, n, 0, start, stop, sys);
	if (n > 4)
		set_partition(cxt, n - 1, 1, ptes[n].offset, stop, EXTENDED);

	if (IS_EXTENDED (sys)) {
		struct pte *pe4 = &ptes[4];
		struct pte *pen = &ptes[n];

		ext_index = n;
		pen->ext_pointer = p;
		pe4->offset = extended_offset = start;
		pe4->sectorbuffer = xcalloc(1, cxt->sector_size);
		pe4->part_table = pt_offset(pe4->sectorbuffer, 0);
		pe4->ext_pointer = pe4->part_table + 1;
		pe4->changed = 1;
		partitions = 5;
	}

	return 0;
}

static int add_logical(struct fdisk_context *cxt)
{
	if (partitions > 5 || ptes[4].part_table->sys_ind) {
		struct pte *pe = &ptes[partitions];

		pe->sectorbuffer = xcalloc(1, cxt->sector_size);
		pe->part_table = pt_offset(pe->sectorbuffer, 0);
		pe->ext_pointer = pe->part_table + 1;
		pe->offset = 0;
		pe->changed = 1;
		partitions++;
	}
	printf(_("Adding logical partition %d\n"), partitions);
	return add_partition(cxt, partitions - 1, NULL);
}

static int dos_verify_disklabel(struct fdisk_context *cxt)
{
	int i, j;
	sector_t total = 1, n_sectors = cxt->total_sectors;
	unsigned long long first[partitions], last[partitions];
	struct partition *p;

	fill_bounds(first, last);
	for (i = 0; i < partitions; i++) {
		struct pte *pe = &ptes[i];

		p = pe->part_table;
		if (p->sys_ind && !IS_EXTENDED (p->sys_ind)) {
			check_consistency(cxt, p, i);
			check_alignment(cxt, get_partition_start(pe), i);
			if (get_partition_start(pe) < first[i])
				printf(_("Warning: bad start-of-data in "
					 "partition %d\n"), i + 1);
			check(cxt, i + 1, p->end_head, p->end_sector, p->end_cyl,
			      last[i]);
			total += last[i] + 1 - first[i];
			for (j = 0; j < i; j++)
				if ((first[i] >= first[j] && first[i] <= last[j])
				    || ((last[i] <= last[j] && last[i] >= first[j]))) {
					printf(_("Warning: partition %d overlaps "
						 "partition %d.\n"), j + 1, i + 1);
					total += first[i] >= first[j] ?
						first[i] : first[j];
					total -= last[i] <= last[j] ?
						last[i] : last[j];
				}
		}
	}

	if (extended_offset) {
		struct pte *pex = &ptes[ext_index];
		sector_t e_last = get_start_sect(pex->part_table) +
			get_nr_sects(pex->part_table) - 1;

		for (i = 4; i < partitions; i++) {
			total++;
			p = ptes[i].part_table;
			if (!p->sys_ind) {
				if (i != 4 || i + 1 < partitions)
					printf(_("Warning: partition %d "
						 "is empty\n"), i + 1);
			}
			else if (first[i] < extended_offset ||
					last[i] > e_last)
				printf(_("Logical partition %d not entirely in "
					"partition %d\n"), i + 1, ext_index + 1);
		}
	}

	if (total > n_sectors)
		printf(_("Total allocated sectors %llu greater than the maximum"
			 " %llu\n"), total, n_sectors);
	else if (total < n_sectors)
		printf(_("Remaining %lld unallocated %ld-byte sectors\n"),
		       n_sectors - total, cxt->sector_size);

	return 0;
}

/*
 * 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,
			int partnum __attribute__ ((__unused__)),
			struct fdisk_parttype *t)
{
	int i, free_primary = 0, rc = 0;

	for (i = 0; i < 4; i++)
		free_primary += !ptes[i].part_table->sys_ind;

	if (!free_primary && partitions >= MAXIMUM_PARTS) {
		printf(_("The maximum number of partitions has been created\n"));
		return -EINVAL;
	}

	if (!free_primary) {
		if (extended_offset) {
			printf(_("All primary partitions are in use\n"));
			rc = add_logical(cxt);
		} else
			printf(_("If you want to create more than four partitions, you must replace a\n"
				 "primary partition with an extended partition first.\n"));
	} else if (partitions >= MAXIMUM_PARTS) {
		printf(_("All logical partitions are in use\n"));
		printf(_("Adding a primary partition\n"));
		rc = add_partition(cxt, get_partition(cxt, 0, 4), t);
	} else {
		char c, dflt, line[LINE_LENGTH];

		dflt = (free_primary == 1 && !extended_offset) ? 'e' : 'p';
		snprintf(line, sizeof(line),
			 _("Partition type:\n"
			   "   p   primary (%d primary, %d extended, %d free)\n"
			   "%s\n"
			   "Select (default %c): "),
			 4 - (extended_offset ? 1 : 0) - free_primary, extended_offset ? 1 : 0, free_primary,
			 extended_offset ? _("   l   logical (numbered from 5)") : _("   e   extended"),
			 dflt);

		c = tolower(read_chars(line));
		if (c == '\n') {
			c = dflt;
			printf(_("Using default response %c\n"), c);
		}
		if (c == 'p') {
			int i = get_nonexisting_partition(cxt, 0, 4);
			if (i >= 0)
				rc = add_partition(cxt, i, t);
			goto done;
		} else if (c == 'l' && extended_offset) {
			rc = add_logical(cxt);
			goto done;
		} else if (c == 'e' && !extended_offset) {
			int i = get_nonexisting_partition(cxt, 0, 4);
			if (i >= 0) {
				t = fdisk_get_parttype_from_code(cxt, EXTENDED);
				rc = add_partition(cxt, i, t);
			}
			goto done;
		} else
			printf(_("Invalid partition type `%c'\n"), c);
	}
done:
	return rc;
}

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

	rc = seek_sector(cxt, secno);
	if (rc != 0) {
		fprintf(stderr, _("write sector %jd failed: seek failed"),
				(uintmax_t) secno);
		return rc;
	}
	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)
{
	int i, rc = 0;

	/* MBR (primary partitions) */
	if (!MBRbuffer_changed) {
		for (i = 0; i < 4; i++)
			if (ptes[i].changed)
				MBRbuffer_changed = 1;
	}
	if (MBRbuffer_changed) {
		mbr_set_magic(cxt->firstsector);
		rc = write_sector(cxt, 0, cxt->firstsector);
		if (rc)
			goto done;
	}
	/* EBR (logical partitions) */
	for (i = 4; i < partitions; i++) {
		struct pte *pe = &ptes[i];

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

done:
	return rc;
}

static struct fdisk_parttype *dos_get_parttype(struct fdisk_context *cxt, int partnum)
{
	struct fdisk_parttype *t;
	struct partition *p;

	if (partnum >= partitions)
		return NULL;

	p = ptes[partnum].part_table;
	t = fdisk_get_parttype_from_code(cxt, p->sys_ind);
	if (!t)
		t = fdisk_new_unknown_parttype(p->sys_ind, NULL);
	return t;
}

static int dos_set_parttype(struct fdisk_context *cxt, int partnum,
			    struct fdisk_parttype *t)
{
	struct partition *p;

	if (partnum >= partitions || !t || t->type > UINT8_MAX)
		return -EINVAL;

	p = ptes[partnum].part_table;
	if (t->type == p->sys_ind)
		return 0;

	if (IS_EXTENDED(p->sys_ind) || IS_EXTENDED(t->type)) {
		printf(_("\nYou cannot change a partition into an extended one "
			 "or vice versa.\nDelete it first.\n\n"));
		return -EINVAL;
	}

	if (is_dos_partition(t->type) || is_dos_partition(p->sys_ind))
	    printf(
		_("\nWARNING: If you have created or modified any DOS 6.x"
		"partitions, please see the fdisk manual page for additional"
		"information.\n\n"));

	p->sys_ind = t->type;
	return 0;
}

const struct fdisk_label dos_label =
{
	.name = "dos",
	.parttypes = dos_parttypes,
	.nparttypes = ARRAY_SIZE(dos_parttypes),

	.probe = dos_probe_label,
	.write = dos_write_disklabel,
	.verify = dos_verify_disklabel,
	.create = dos_create_disklabel,
	.part_add = dos_add_partition,
	.part_delete = dos_delete_partition,
	.part_get_type = dos_get_parttype,
	.part_set_type = dos_set_parttype,
	.reset_alignment = dos_reset_alignment,
};