fdisk: Correct handling of hybrid MBR

The traditional MBR has pretty well NO limitations on slices.  They can
be a single misaligned sector if desired.  While this is undesireable
for most real world uses, for the few places they're still used extra
limitations cause breakage not safety.

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

diff --git a/libfdisk/src/dos.c b/libfdisk/src/dos.c
index 28a9bafd46ae2de8f431fcd2d2626d9b8983c6b1..53713ec5ffd9d2ee98f77f42c5d6e5d3860f7c4d 100644 (file)
--- a/libfdisk/src/dos.c
+++ b/libfdisk/src/dos.c
@@ -1093,18 +1093,6 @@ static int get_disk_ranges(struct fdisk_context *cxt, int logical,
        return 0;
 }
 
-static int find_last_free_sector(struct fdisk_context *cxt, int logical, 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_last_free_sector_in_range(cxt, logical, first, last, result);
-}
-
 static int find_first_free_sector(struct fdisk_context *cxt,
                                int logical,
                                fdisk_sector_t start,
@@ -1126,10 +1114,9 @@ static int add_partition(struct fdisk_context *cxt, size_t n,
        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 pte *ext_pe = l->ext_offset ? self_pte(cxt, l->ext_index) : NULL;
        struct fdisk_ask *ask = NULL;
 
-       fdisk_sector_t start, stop = 0, limit, temp;
+       fdisk_sector_t start, stop, limit, temp;
 
        DBG(LABEL, ul_debug("DOS: adding partition %zu", n));
 
@@ -1143,32 +1130,28 @@ static int add_partition(struct fdisk_context *cxt, size_t n,
                return -EINVAL;
        }
 
-       rc = find_last_free_sector(cxt, is_logical, &limit);
-       if (rc == -ENOSPC)
-               fdisk_warnx(cxt, _("No free sectors available."));
+       rc = get_disk_ranges(cxt, is_logical, &start, &stop);
        if (rc)
                return rc;
 
-       if (!is_logical) {
-               if (cxt->parent && fdisk_is_label(cxt->parent, GPT))
-                       start = 1;              /* Bad boy modifies hybrid MBR */
-               else {
-                       if (cxt->script && pa && fdisk_partition_has_start(pa)
-                           && pa->start < cxt->first_lba
-                           && pa->start >= 1)
-                               fdisk_set_first_lba(cxt, 1);
+       if (!is_logical && cxt->parent && fdisk_is_label(cxt->parent, GPT))
+               start = 1;              /* Bad boy modifies hybrid MBR */
 
-                       start = cxt->first_lba;
-               }
-       } else {
-               assert(ext_pe);
+       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 (cxt->script && pa && fdisk_partition_has_start(pa)
-                   && pa->start >= l->ext_offset
-                   && pa->start < l->ext_offset + cxt->first_lba)
-                       fdisk_set_first_lba(cxt, 1);
+       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);
 
-               start = l->ext_offset + cxt->first_lba;
+               rc = get_disk_ranges(cxt, is_logical, &start, &stop);
+               if (rc) /* won't happen, but checking to be proper */
+                       return rc;
        }
 
        /*
@@ -1637,7 +1620,8 @@ static int dos_add_partition(struct fdisk_context *cxt,
                             struct fdisk_partition *pa,
                             size_t *partno)
 {
-       size_t i, free_primary = 0, free_sectors = 0;
+       size_t i;
+       uint8_t free_primary = 0, free_sectors = 0;
        fdisk_sector_t last = 0, grain;
        int rc = 0;
        struct fdisk_dos_label *l;
@@ -1729,6 +1713,12 @@ static int dos_add_partition(struct fdisk_context *cxt,
        grain = cxt->grain > cxt->sector_size ? cxt->grain / cxt->sector_size : 1;
        last = cxt->first_lba;
 
+       if (cxt->parent && fdisk_is_label(cxt->parent, GPT)) {
+               /* modifying a hybrid MBR, which throws out the rules */
+               grain = 1;
+               last = 1;
+       }
+
        for (i = 0; i < 4; i++) {
                struct dos_partition *p = self_partition(cxt, i);
 
@@ -1805,7 +1795,7 @@ static int dos_add_partition(struct fdisk_context *cxt,
                fdisk_ask_menu_set_default(ask, free_primary == 1
                                                && !l->ext_offset ? 'e' : 'p');
                snprintf(hint, sizeof(hint),
-                               _("%zu primary, %d extended, %zu free"),
+                               _("%u primary, %d extended, %u free"),
                                4 - (l->ext_offset ? 1 : 0) - free_primary,
                                l->ext_offset ? 1 : 0,
                                free_primary);