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From: Ed Bartosh <ed.bartosh@linux.intel.com>
To: Jonathan Liu <net147@gmail.com>
Cc: openembedded-core@lists.openembedded.org
Subject: Re: [PATCH v3] wic: ensure generated disk system identifier is non-zero
Date: Sun, 30 Jul 2017 13:02:36 +0300	[thread overview]
Message-ID: <20170730100236.GA28203@linux.intel.com> (raw)
In-Reply-To: <20170728144527.24322-1-net147@gmail.com>

On Sat, Jul 29, 2017 at 12:45:27AM +1000, Jonathan Liu wrote:
> Zero may be interpreted as no MBR signature present and another
> partitioning program might install a new MBR signature.
> 
> Signed-off-by: Jonathan Liu <net147@gmail.com>
> ---
>  scripts/lib/wic/plugins/imager/direct.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/lib/wic/plugins/imager/direct.py b/scripts/lib/wic/plugins/imager/direct.py
> index f20d8433f1..fe9b688ab0 100644
> --- a/scripts/lib/wic/plugins/imager/direct.py
> +++ b/scripts/lib/wic/plugins/imager/direct.py
> @@ -297,7 +297,7 @@ class PartitionedImage():
>                            # all partitions (in bytes)
>          self.ptable_format = ptable_format  # Partition table format
>          # Disk system identifier
> -        self.identifier = int.from_bytes(os.urandom(4), 'little')
> +        self.identifier = int.from_bytes(os.urandom(4), 'little') or 0xffffffff
>  

Can we generate random identifier by calling os.urandom again if
self.identifier is zero? Something like this, may be?

while True:
    self.identifier = int.from_bytes(os.urandom(4), 'little')
    if self.identifier:
        break

Assigning constant 0xffffffff can potentially create nonunique identifiers.

>          self.partitions = partitions
>          self.partimages = []
> -- 
> 2.13.2
> 
> -- 
> _______________________________________________
> Openembedded-core mailing list
> Openembedded-core@lists.openembedded.org
> http://lists.openembedded.org/mailman/listinfo/openembedded-core

-- 
--
Regards,
Ed


  reply	other threads:[~2017-07-30 10:25 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-28 14:45 [PATCH v3] wic: ensure generated disk system identifier is non-zero Jonathan Liu
2017-07-30 10:02 ` Ed Bartosh [this message]
2017-07-30 10:37   ` Jonathan Liu
2017-07-31  7:28     ` Ed Bartosh
2017-07-31  7:58       ` Jonathan Liu
2017-07-31  8:04         ` Jonathan Liu
2017-07-31  7:59           ` Ed Bartosh

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