libfdisk: (dos) improve logical partition reorder command

 - use qsort to sort by EBR offsets
 - sort by EBR data partition start sectors

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

diff --git a/libfdisk/src/dos.c b/libfdisk/src/dos.c
index d3bd01cd906c744018c101e90a815c300389a6f5..e365e722d0cb0b4e0871d90bcffdd2c5dcae91ca 100644 (file)
--- a/libfdisk/src/dos.c
+++ b/libfdisk/src/dos.c
@@ -1725,6 +1725,21 @@ static void print_chain_of_logicals(struct fdisk_context *cxt)
        }
 }
 
+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.
  *
@@ -1738,50 +1753,41 @@ static void fix_chain_of_logicals(struct fdisk_context *cxt)
        struct fdisk_dos_label *l = self_label(cxt);
        size_t i;
 
-
        DBG(LABEL, print_chain_of_logicals(cxt));
 
-       /* fix within memory EBR chain */
+       /* 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);
-               unsigned char *buf;
-               sector_t off;
-               struct dos_partition *p;
-
-               if (cur->offset < nxt->offset)
-                       continue;
 
-               DBG(LABEL, ul_debug("DOS: sort EBR [%10ju] %zu -> %zu",
-                                       (uintmax_t) cur->offset, i, i + 1));
+               if (get_abs_partition_start(cur) >
+                   get_abs_partition_start(nxt)) {
 
-               /* Move pointer to EBR sector */
-               buf = cur->sectorbuffer;
-               cur->sectorbuffer = nxt->sectorbuffer;
-               nxt->sectorbuffer = buf;
+                       struct dos_partition tmp = *cur->pt_entry;
+                       sector_t cur_start = get_abs_partition_start(cur),
+                                nxt_start = get_abs_partition_start(nxt);
 
-               /* Move EBR offset */
-               off = cur->offset;
-               cur->offset = nxt->offset;
-               nxt->offset = off;
+                       /* swap data partitions */
+                       *cur->pt_entry = *nxt->pt_entry;
+                       *nxt->pt_entry = tmp;
 
-               /* Move pointers to EBR data partition */
-               p = cur->pt_entry;
-               cur->pt_entry = nxt->pt_entry;
-               nxt->pt_entry = p;
+                       /* 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);
 
-               /* Move pointers to EBR extended partition */
-               p = cur->ex_entry;
-               cur->ex_entry = nxt->ex_entry;
-               nxt->ex_entry = p;
-
-               partition_set_changed(cxt, i, 1);
-               partition_set_changed(cxt, i + 1, 1);
-               goto again;
+                       partition_set_changed(cxt, i, 1);
+                       partition_set_changed(cxt, i + 1, 1);
+                       goto again;
+               }
        }
 
-       /* update EBR links */
+       /* 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);
@@ -1789,7 +1795,6 @@ again:
                sector_t noff = nxt->offset - l->ext_offset,
                         ooff = dos_partition_get_start(cur->ex_entry);
 
-
                if (noff == ooff)
                        continue;