libfdisk: (dos) fix log.partition delete

 - deallocate sector buffer and deincrement part_max when delete last
   logical partition
 - zap obsolete EBR on begin of the extended partition when no logical
   partition defined

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

diff --git a/libfdisk/src/dos.c b/libfdisk/src/dos.c
index 327a747cf7b25e94f9b379fc644b37c3d73cb5bf..5d01b3fbebb7a82b72c61ed73cd54476c8c1ed1d 100644 (file)
--- a/libfdisk/src/dos.c
+++ b/libfdisk/src/dos.c
@@ -142,7 +142,8 @@ static void partition_set_changed(
        if (!pe)
                return;
 
-       DBG(LABEL, dbgprint("DOS: setting %zu partition changed", i));
+       DBG(LABEL, dbgprint("DOS: setting %zu partition to %s", i,
+                               changed ? "changed" : "unchnaged"));
 
        pe->changed = changed ? 1 : 0;
        if (changed)
@@ -357,7 +358,8 @@ static int dos_delete_partition(struct fdisk_context *cxt, size_t partnum)
        if (!pe)
                return -EINVAL;
 
-       DBG(LABEL, dbgprint("DOS: delete partiton %zu", partnum));
+       DBG(LABEL, dbgprint("DOS: delete partiton %zu (max=%zu)", partnum,
+                               cxt->label->nparts_max));
 
        l = self_label(cxt);
        p = pe->pt_entry;
@@ -381,19 +383,20 @@ static int dos_delete_partition(struct fdisk_context *cxt, size_t partnum)
                clear_partition(l->ptes[partnum].ex_entry);
                partition_set_changed(cxt, partnum, 1);
        } else {
-               DBG(LABEL, dbgprint("--> delete logical [non-last, move down]"));
+               DBG(LABEL, dbgprint("--> delete logical [move down]"));
                if (partnum > 4) {
-                       /* delete this link in the chain */
+                       DBG(LABEL, dbgprint(" --> delete %zu logical link", partnum));
                        p = l->ptes[partnum - 1].ex_entry;
                        *p = *q;
                        dos_partition_set_start(p, dos_partition_get_start(q));
                        dos_partition_set_size(p, dos_partition_get_size(q));
                        partition_set_changed(cxt, partnum - 1, 1);
-               } else if (cxt->label->nparts_max > 5) {    /* 5 will be moved to 4 */
-                       /* the first logical in a longer chain */
-                       pe = &l->ptes[5];
 
-                       if (pe->pt_entry) /* prevent SEGFAULT */
+               } else if (cxt->label->nparts_max > 5) {
+                       DBG(LABEL, dbgprint(" --> delete first logical link"));
+                       pe = &l->ptes[5];       /* second logical */
+
+                       if (pe->pt_entry)       /* prevent SEGFAULT */
                                dos_partition_set_start(pe->pt_entry,
                                               get_abs_partition_start(pe) -
                                               l->ext_offset);
@@ -402,21 +405,35 @@ static int dos_delete_partition(struct fdisk_context *cxt, size_t partnum)
                }
 
                if (cxt->label->nparts_max > 5) {
+                       DBG(LABEL, dbgprint(" --> move ptes"));
                        cxt->label->nparts_max--;
                        if (l->ptes[partnum].private_sectorbuffer) {
-                               DBG(LABEL, dbgprint("--> freeing pte %zu sector buffer %p",
+                               DBG(LABEL, dbgprint("  --> freeing pte %zu sector buffer %p",
                                                        partnum, l->ptes[partnum].sectorbuffer));
                                free(l->ptes[partnum].sectorbuffer);
                        }
                        while (partnum < cxt->label->nparts_max) {
-                               DBG(LABEL, dbgprint("--> moving pte %zu <-- %zu", partnum, partnum + 1));
+                               DBG(LABEL, dbgprint("  --> moving pte %zu <-- %zu", partnum, partnum + 1));
                                l->ptes[partnum] = l->ptes[partnum + 1];
                                partnum++;
                        }
                        memset(&l->ptes[partnum], 0, sizeof(struct pte));
-               } else
-                       /* the only logical: clear only */
+               } else {
+                       DBG(LABEL, dbgprint(" --> the only logical: clear only"));
                        clear_partition(l->ptes[partnum].pt_entry);
+                       cxt->label->nparts_max--;
+
+                       if (partnum == 4) {
+                               DBG(LABEL, dbgprint("  --> clear last logical"));
+                               if (l->ptes[partnum].private_sectorbuffer) {
+                                       DBG(LABEL, dbgprint("  --> freeing pte %zu sector buffer %p",
+                                                       partnum, l->ptes[partnum].sectorbuffer));
+                                       free(l->ptes[partnum].sectorbuffer);
+                               }
+                               memset(&l->ptes[partnum], 0, sizeof(struct pte));
+                               partition_set_changed(cxt, l->ext_index, 1);
+                       }
+               }
        }
 
        fdisk_label_set_changed(cxt->label, 1);
@@ -440,7 +457,7 @@ static void read_extended(struct fdisk_context *cxt, size_t ext)
                return;
        }
 
-       DBG(LABEL, dbgprint("DOS: REading extended %zu", ext));
+       DBG(LABEL, dbgprint("DOS: Reading extended %zu", ext));
 
        while (IS_EXTENDED (p->sys_ind)) {
                struct pte *pe = self_pte(cxt, cxt->label->nparts_max);
@@ -705,15 +722,20 @@ static int dos_probe_label(struct fdisk_context *cxt)
 
        for (i = 3; i < cxt->label->nparts_max; i++) {
                struct pte *pe = self_pte(cxt, i);
+               struct fdisk_dos_label *l = self_label(cxt);
 
                if (!mbr_is_valid_magic(pe->sectorbuffer)) {
                        fdisk_info(cxt, _(
-                       "Invalid flag 0x%02x%02x of partition table %zu will "
-                       "be corrected by w(rite)"),
+                       "Invalid flag 0x%02x%02x of EBR (for partition %zu) will "
+                       "be corrected by w(rite)."),
                                pe->sectorbuffer[510],
                                pe->sectorbuffer[511],
                                i + 1);
-                       partition_set_changed(cxt, 1, 1);
+                       partition_set_changed(cxt, i, 1);
+
+                       /* mark also extended as changed to update the first EBR
+                        * in situation that there is no logical partitions at all */
+                       partition_set_changed(cxt, l->ext_index, 1);
                }
        }
 
@@ -1423,6 +1445,9 @@ static int write_sector(struct fdisk_context *cxt, sector_t secno,
                                (uintmax_t) secno);
                return rc;
        }
+
+       DBG(LABEL, dbgprint("DOS: writting to sector %ju", (uintmax_t) secno));
+
        if (write(cxt->dev_fd, buf, cxt->sector_size) != (ssize_t) cxt->sector_size)
                return -errno;
        return 0;
@@ -1455,6 +1480,19 @@ static int dos_write_disklabel(struct fdisk_context *cxt)
                        goto done;
        }
 
+       if (cxt->label->nparts_max <= 4 && l->ext_offset) {
+               /* we have empty extended partition, check if the partition has
+                * been modified and then cleanup possible remaining EBR  */
+               struct pte *pe = self_pte(cxt, l->ext_index);
+               unsigned char empty[512] = { 0 };
+               sector_t off = pe ? get_abs_partition_start(pe) : 0;
+
+               if (off && pe->changed) {
+                       mbr_set_magic(empty);
+                       write_sector(cxt, off, empty);
+               }
+       }
+
        /* EBR (logical partitions) */
        for (i = 4; i < cxt->label->nparts_max; i++) {
                struct pte *pe = self_pte(cxt, i);