libfdisk: fix logical partition reorder command

Reported-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 109 insertions, 50 deletions

diff --git a/libfdisk/src/dos.c b/libfdisk/src/dos.c
index 18ea8da95..1f5d8b33f 100644
--- a/libfdisk/src/dos.c
+++ b/libfdisk/src/dos.c
@@ -148,6 +148,17 @@ static sector_t get_abs_partition_start(struct pte *pe)
 	return pe->offset + dos_partition_get_start(pe->pt_entry);
 }
 
+static sector_t get_abs_partition_end(struct pte *pe)
+{
+	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);
+}
+
 /*
  * Linux kernel cares about partition size only. Things like
  * partition type or so are completely irrelevant -- kzak Nov-2013
@@ -1723,69 +1734,117 @@ static int dos_list_disklabel(struct fdisk_context *cxt)
 	return rc;
 }
 
+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);
+
+		printf("#%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)
+{
+	struct pte *ae = (struct pte *) a,
+		   *be = (struct pte *) b;
+
+	if (ae->offset == 0 && ae->offset == 0)
+		return 0;
+	if (ae->offset == 0)
+		return 1;
+	if (be->offset == 0)
+		return -1;
 
+	return ae->offset - be->offset;
+}
 /*
  * Fix the chain of logicals.
- * ext_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.
+ * 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);
-	size_t j, oj, ojj, sj, sjj;
-	struct dos_partition *pj,*pjj,tmp;
-
-	/* Stage 1: sort sectors but leave sector of part 4 */
-	/* (Its sector is the global ext_offset.) */
-stage1:
-	for (j = 5; j < cxt->label->nparts_max - 1; j++) {
-		oj = l->ptes[j].offset;
-		ojj = l->ptes[j + 1].offset;
-		if (oj > ojj) {
-			l->ptes[j].offset = ojj;
-			l->ptes[j + 1].offset = oj;
-			pj = l->ptes[j].pt_entry;
-			dos_partition_set_start(pj, dos_partition_get_start(pj)+oj-ojj);
-			pjj = l->ptes[j + 1].pt_entry;
-			dos_partition_set_start(pjj, dos_partition_get_start(pjj)+ojj-oj);
-			dos_partition_set_start(l->ptes[j - 1].ex_entry,
-				       ojj - l->ext_offset);
-			dos_partition_set_start(l->ptes[j].ex_entry,
-				       oj - l->ext_offset);
-			goto stage1;
+	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);
+
+		if (get_abs_partition_start(cur) >
+		    get_abs_partition_start(nxt)) {
+
+			struct dos_partition tmp = *cur->pt_entry;
+			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 tas to be still the same! */
+			dos_partition_set_start(cur->pt_entry, nxt_start - cur->offset);
+			dos_partition_set_start(nxt->pt_entry, cur_start - nxt->offset);
+
+			partition_set_changed(cxt, i, 1);
+			partition_set_changed(cxt, i + 1, 1);
+			goto again;
 		}
 	}
 
-	/* Stage 2: sort starting sectors */
-stage2:
-	for (j = 4; j < cxt->label->nparts_max - 1; j++) {
-		pj = l->ptes[j].pt_entry;
-		pjj = l->ptes[j + 1].pt_entry;
-		sj = dos_partition_get_start(pj);
-		sjj = dos_partition_get_start(pjj);
-		oj = l->ptes[j].offset;
-		ojj = l->ptes[j+1].offset;
-		if (oj+sj > ojj+sjj) {
-			tmp = *pj;
-			*pj = *pjj;
-			*pjj = tmp;
-			dos_partition_set_start(pj, ojj+sjj-oj);
-			dos_partition_set_start(pjj, oj+sj-ojj);
-			goto stage2;
+	/* 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);
+
+		sector_t noff = nxt->offset - l->ext_offset,
+			 ooff = dos_partition_get_start(cur->ex_entry);
+
+		if (noff == ooff)
+			continue;
+
+		DBG(LABEL, 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), MBR_DOS_EXTENDED_PARTITION);
+
+		if (i + 1 == cxt->label->nparts_max - 1) {
+			clear_partition(nxt->ex_entry);
+			partition_set_changed(cxt, i + 1, 1);
 		}
-	}
 
-	/* Probably something was changed */
-	for (j = 4; j < cxt->label->nparts_max; j++)
-		l->ptes[j].changed = 1;
+	}
+	DBG(LABEL, print_chain_of_logicals(cxt));
 }
 
 int fdisk_dos_fix_order(struct fdisk_context *cxt)