libfdisk: make default geom usage more robust

.. to avoid SIGFPE

References: https://bugzilla.redhat.com/show_bug.cgi?id=1005566
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libfdisk/src/alignment.c b/libfdisk/src/alignment.c
index 21dfa679f72c6bf279e483531b091998c55b76f8..9c29767f859ea0a003fb9b51b8eade7fe1636565 100644 (file)
--- a/libfdisk/src/alignment.c
+++ b/libfdisk/src/alignment.c
@@ -120,6 +120,11 @@ static unsigned long get_sector_size(int fd)
 
 static void recount_geometry(struct fdisk_context *cxt)
 {
+       if (!cxt->geom.heads)
+               cxt->geom.heads = 255;
+       if (!cxt->geom.sectors)
+               cxt->geom.sectors = 63;
+
        cxt->geom.cylinders = cxt->total_sectors /
                (cxt->geom.heads * cxt->geom.sectors);
 }
@@ -222,6 +227,7 @@ int fdisk_apply_user_device_properties(struct fdisk_context *cxt)
                cxt->geom.heads = cxt->user_geom.heads;
        if (cxt->user_geom.sectors)
                cxt->geom.sectors = cxt->user_geom.sectors;
+
        if (cxt->user_geom.cylinders)
                cxt->geom.cylinders = cxt->user_geom.cylinders;
        else if (cxt->user_geom.heads || cxt->user_geom.sectors)
@@ -284,7 +290,6 @@ int fdisk_reset_device_properties(struct fdisk_context *cxt)
 int fdisk_discover_geometry(struct fdisk_context *cxt)
 {
        sector_t nsects;
-       unsigned int h = 0, s = 0;
 
        assert(cxt);
        assert(cxt->geom.heads == 0);
@@ -296,16 +301,9 @@ int fdisk_discover_geometry(struct fdisk_context *cxt)
                cxt->total_sectors = (nsects / (cxt->sector_size >> 9));
 
        /* what the kernel/bios thinks the geometry is */
-       blkdev_get_geometry(cxt->dev_fd, &h, &s);
-       if (!h && !s) {
-               /* unable to discover geometry, use default values */
-               s = 63;
-               h = 255;
-       }
+       blkdev_get_geometry(cxt->dev_fd, &cxt->geom.heads, &cxt->geom.sectors);
 
        /* obtained heads and sectors */
-       cxt->geom.heads = h;
-       cxt->geom.sectors = s;
        recount_geometry(cxt);
 
        DBG(GEOMETRY, dbgprint("result: C/H/S: %u/%u/%u",
@@ -479,7 +477,7 @@ int fdisk_reset_alignment(struct fdisk_context *cxt)
        if (cxt->label && cxt->label->op->reset_alignment)
                rc = cxt->label->op->reset_alignment(cxt);
 
-       DBG(LABEL, dbgprint("%s alignment reseted to: "
+       DBG(TOPOLOGY, dbgprint("%s alignment reseted to: "
                            "first LBA=%ju, grain=%lu [rc=%d]",
                            cxt->label ? cxt->label->name : NULL,
                            (uintmax_t) cxt->first_lba,