From 81745b42a2722f11006c05de87ff90de08cf8cee Mon Sep 17 00:00:00 2001

From: Karel Zak <kzak@redhat.com>

Date: Tue, 28 Jun 2016 11:30:21 +0200

Subject: [PATCH] fdisk: backport DOS logical partitions chain reorder

... from the current upstream.

Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=1304246

Signed-off-by: Karel Zak <kzak@redhat.com>

---

 fdisks/fdiskdoslabel.c | 170 +++++++++++++++++++++++++++++++++----------------

 include/c.h            |   8 +++

 2 files changed, 124 insertions(+), 54 deletions(-)

diff --git a/fdisks/fdiskdoslabel.c b/fdisks/fdiskdoslabel.c

index fe04ac7..b7eb35a 100644

--- a/fdisks/fdiskdoslabel.c

+++ b/fdisks/fdiskdoslabel.c

@@ -55,6 +55,22 @@ static int MBRbuffer_changed;

 #define cround(c, n)	(fdisk_context_use_cylinders(c) ? \

 				((n) / fdisk_context_get_units_per_sector(c)) + 1 : (n))

+

+static unsigned long long

+get_abs_partition_start(struct pte *pe)

+{

+	return pe->offset + get_start_sect(pe->part_table);

+}

+

+static unsigned long long

+get_abs_partition_end(struct pte *pe)

+{

+	unsigned long long size;

+

+	size = get_nr_sects(pe->part_table);

+	return get_abs_partition_start(pe) + size - (size ? 1 : 0);

+}

+

 static void warn_alignment(struct fdisk_context *cxt)

 {

 	if (nowarn)

@@ -1254,67 +1270,113 @@ void dos_list_table_expert(struct fdisk_context *cxt, int extend)

 	}

 }

-/*

- * Fix the chain of logicals.

- * extended_offset is unchanged, the set of sectors used is unchanged

- * The chain is sorted so that sectors increase, and so that

- * starting sectors increase.

- *

- * After this it may still be that cfdisk doesn't like the table.

- * (This is because cfdisk considers expanded parts, from link to

- * end of partition, and these may still overlap.)

- * Now

- *   sfdisk /dev/hda > ohda; sfdisk /dev/hda < ohda

- * may help.

- */

+

+static void print_chain_of_logicals(struct fdisk_context *cxt)

+{

+	size_t i;

+

+	fputc('\n', stdout);

+

+	for (i = 4; i < cxt->label->nparts_max; i++) {

+		struct pte *pe = &ptes[i];

+

+		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) get_start_sect(pe->part_table),

+			(uintmax_t) get_abs_partition_start(pe),

+			(uintmax_t) get_nr_sects(pe->part_table),

+			/* link */

+			(uintmax_t) get_start_sect(pe->ext_pointer),

+			(uintmax_t) (extended_offset + get_start_sect(pe->ext_pointer)),

+			(uintmax_t) get_nr_sects(pe->ext_pointer));

+	}

+}

+

+static int cmp_ebr_offsets(const void *a, const void *b)

+{

+	struct pte *ae = (struct pte *) a,

+		   *be = (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);

+}

+

 static void fix_chain_of_logicals(struct fdisk_context *cxt)

 {

-	size_t j, oj, ojj, sj, sjj;

-	struct partition *pj,*pjj,tmp;

-

-	/* Stage 1: sort sectors but leave sector of part 4 */

-	/* (Its sector is the global extended_offset.) */

- stage1:

-	for (j = 5; j < cxt->label->nparts_max - 1; j++) {

-		oj = ptes[j].offset;

-		ojj = ptes[j+1].offset;

-		if (oj > ojj) {

-			ptes[j].offset = ojj;

-			ptes[j+1].offset = oj;

-			pj = ptes[j].part_table;

-			set_start_sect(pj, get_start_sect(pj)+oj-ojj);

-			pjj = ptes[j+1].part_table;

-			set_start_sect(pjj, get_start_sect(pjj)+ojj-oj);

-			set_start_sect(ptes[j-1].ext_pointer,

-				       ojj-extended_offset);

-			set_start_sect(ptes[j].ext_pointer,

-				       oj-extended_offset);

-			goto stage1;

+	struct pte *last;

+	size_t i;

+

+	DBG(CONTEXT, print_chain_of_logicals(cxt));

+

+	/* Sort chain by EBR offsets */

+	qsort(&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 = &ptes[i],

+			   *nxt = &ptes[i + 1];

+

+		if (get_abs_partition_start(cur) >

+		    get_abs_partition_start(nxt)) {

+

+			struct partition tmp = *cur->part_table;

+			sector_t cur_start = get_abs_partition_start(cur),

+				 nxt_start = get_abs_partition_start(nxt);

+

+			/* swap data partitions */

+			*cur->part_table = *nxt->part_table;

+			*nxt->part_table = tmp;

+

+			/* Recount starts according to EBR offsets, the absolute

+			 * address still has to be the same! */

+			set_start_sect(cur->part_table, nxt_start - cur->offset);

+			set_start_sect(nxt->part_table, cur_start - nxt->offset);

+

+			cur->changed = 1;

+			nxt->changed = 1;

+			goto again;

 		}

 	}

-	/* Stage 2: sort starting sectors */

- stage2:

-	for (j = 4; j < cxt->label->nparts_max - 1; j++) {

-		pj = ptes[j].part_table;

-		pjj = ptes[j+1].part_table;

-		sj = get_start_sect(pj);

-		sjj = get_start_sect(pjj);

-		oj = ptes[j].offset;

-		ojj = ptes[j+1].offset;

-		if (oj+sj > ojj+sjj) {

-			tmp = *pj;

-			*pj = *pjj;

-			*pjj = tmp;

-			set_start_sect(pj, ojj+sjj-oj);

-			set_start_sect(pjj, oj+sj-ojj);

-			goto stage2;

-		}

+	/* Update EBR links */

+	for (i = 4; i < cxt->label->nparts_max - 1; i++) {

+		struct pte *cur = &ptes[i],

+			   *nxt = &ptes[i + 1];

+

+		sector_t noff = nxt->offset - extended_offset,

+		         ooff = get_start_sect(cur->ext_pointer);

+

+		if (noff == ooff)

+			continue;

+

+		DBG(CONTEXT, dbgprint("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),

+				EXTENDED);

+	}

+

+	/* always terminate the chain ! */

+	last = &ptes[cxt->label->nparts_max - 1];

+	if (last) {

+		clear_partition(last->ext_pointer);

+		last->changed = 1;

 	}

-	/* Probably something was changed */

-	for (j = 4; j < cxt->label->nparts_max; j++)

-		ptes[j].changed = 1;

+	DBG(CONTEXT, print_chain_of_logicals(cxt));

 }

 void dos_fix_partition_table_order(struct fdisk_context *cxt)

diff --git a/include/c.h b/include/c.h

index a50e8a5..ef2ea69 100644

--- a/include/c.h

+++ b/include/c.h

@@ -110,6 +110,14 @@

 	_max1 > _max2 ? _max1 : _max2; })

 #endif

+#ifndef cmp_numbers

+# define cmp_numbers(x, y) __extension__ ({	\

+	__typeof__(x) _a = (x);			\

+	__typeof__(y) _b = (y);			\

+	(void) (&_a == &_b);			\

+	_a == _b ? 0 : _a > _b ? 1 : -1; })

+#endif

+

 #ifndef offsetof

 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

 #endif

-- 

2.7.4