[PATCH] sfdisk: warn if partition starts above 2 TiB limit

[PATCH] sfdisk: warn if partition starts above 2 TiB limit

[Petr Uzel]

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Signed-off-by: Petr Uzel <petr.uzel@suse.cz>
---
 fdisk/sfdisk.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/fdisk/sfdisk.c b/fdisk/sfdisk.c
index 4ed5d37..d498371 100644
--- a/fdisk/sfdisk.c
+++ b/fdisk/sfdisk.c
@@ -1304,6 +1304,17 @@ partitions_ok(struct disk_desc *z) {
 	    }
     }
 
+    /* Do the partitions start below the DOS 2TiB limit? */
+    {
+	for (p = partitions; p < partitions + partno; p++)
+	    if (p->size && p->start > (unsigned long) UINT32_MAX) {
+	        my_warn(_("Warning: partition %s has starting sector %lu, "
+		          "which is above the DOS 2 TiB limit\n"),
+			PNO(p), p->start);
+		return 0;
+	    }
+    }
+
     /* At most one chain of DOS extended partitions ? */
     /* It seems that the OS/2 fdisk has the additional requirement
        that the extended partition must be the fourth one */
-- 
1.7.3.4


Petr

--
Petr Uzel
IRC: ptr_uzl @ freenode

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Re: [PATCH] sfdisk: warn if partition starts above 2 TiB limit

[Karel Zak]

On Fri, Jul 01, 2011 at 01:11:56PM +0200, Petr Uzel wrote:
> 
> Signed-off-by: Petr Uzel <petr.uzel@suse.cz>
> ---
>  fdisk/sfdisk.c |   11 +++++++++++
>  1 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/fdisk/sfdisk.c b/fdisk/sfdisk.c
> index 4ed5d37..d498371 100644
> --- a/fdisk/sfdisk.c
> +++ b/fdisk/sfdisk.c
> @@ -1304,6 +1304,17 @@ partitions_ok(struct disk_desc *z) {
>  	    }
>      }
>  
> +    /* Do the partitions start below the DOS 2TiB limit? */
> +    {
> +	for (p = partitions; p < partitions + partno; p++)
> +	    if (p->size && p->start > (unsigned long) UINT32_MAX) {

 ULONG_MAX is not greater than UINT32_MAX on 32-bit archs ;-)

 IMHO you have to use 64-bit number for the p->size or you have 
 move the check to the place where (before) p->start is incremented.

> +	        my_warn(_("Warning: partition %s has starting sector %lu, "
> +		          "which is above the DOS 2 TiB limit\n"),

 The warning is incorrect. The limit is not 2 TiB, but UINT32_MAX
 *sectors*. It's 2TiB for 512-byte sectors, but for 4K sectors is it
 more...

 See fdisk.fdisk.c: warn_limits().

    Karel


-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: [PATCH] sfdisk: warn if partition starts above 2 TiB limit

[Petr Uzel]

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On Fri, Jul 01, 2011 at 03:11:40PM +0200, Karel Zak wrote:
> On Fri, Jul 01, 2011 at 01:11:56PM +0200, Petr Uzel wrote:
> > 
> > Signed-off-by: Petr Uzel <petr.uzel@suse.cz>
> > ---
> >  fdisk/sfdisk.c |   11 +++++++++++
> >  1 files changed, 11 insertions(+), 0 deletions(-)
> > 
> > diff --git a/fdisk/sfdisk.c b/fdisk/sfdisk.c
> > index 4ed5d37..d498371 100644
> > --- a/fdisk/sfdisk.c
> > +++ b/fdisk/sfdisk.c
> > @@ -1304,6 +1304,17 @@ partitions_ok(struct disk_desc *z) {
> >  	    }
> >      }
> >  
> > +    /* Do the partitions start below the DOS 2TiB limit? */
> > +    {
> > +	for (p = partitions; p < partitions + partno; p++)
> > +	    if (p->size && p->start > (unsigned long) UINT32_MAX) {
> 
>  ULONG_MAX is not greater than UINT32_MAX on 32-bit archs ;-)
> 
>  IMHO you have to use 64-bit number for the p->size or you have 
>  move the check to the place where (before) p->start is incremented.
> 
> > +	        my_warn(_("Warning: partition %s has starting sector %lu, "
> > +		          "which is above the DOS 2 TiB limit\n"),
> 
>  The warning is incorrect. The limit is not 2 TiB, but UINT32_MAX
>  *sectors*. It's 2TiB for 512-byte sectors, but for 4K sectors is it
>  more...
> 
>  See fdisk.fdisk.c: warn_limits().
> 
>     Karel

Thanks for the review! I'll rework the patch and resubmit.

Petr

--
Petr Uzel
IRC: ptr_uzl @ freenode

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