linux-kernel - Re: [PATCH v3 1/1] partitions/msdos: FreeBSD UFS2 file systems are not recognized

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Date:   Fri, 26 May 2017 16:42:04 -0700
From:   Joe Perches <joe@...ches.com>
To:     Richard Narron <comet.berkeley@...il.com>
Cc:     linux-kernel@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Jens Axboe <axboe@...nel.dk>, Andries Brouwer <aeb@....nl>
Subject: Re: [PATCH v3 1/1] partitions/msdos: FreeBSD UFS2 file systems are
 not recognized

On Fri, 2017-05-26 at 16:30 -0700, Richard Narron wrote:
> On Fri, 26 May 2017, Joe Perches wrote:
> 
> > On Fri, 2017-05-26 at 03:48 -0700, Richard Narron wrote:
> > > The code in block/partitions/msdos.c recognizes FreeBSD, OpenBSD
> > > and NetBSD partitions and does a reasonable job picking out OpenBSD
> > > and NetBSD UFS subpartitions.
> > > 
> > > But for FreeBSD the subpartitions are always "bad".
> > > 
> > >      Kernel: <bsd:bad subpartition - ignored
> > 
> > []
> > >   block/partitions/msdos.c | 2 ++
> > 
> > []
> > > @@ -300,6 +300,8 @@ static void parse_bsd(struct parsed_part
> > >   			continue;
> > >   		bsd_start = le32_to_cpu(p->p_offset);
> > >   		bsd_size = le32_to_cpu(p->p_size);
> > > +		if (memcmp(flavour, "bsd\0", 4) == 0)
> > 
> > Weird code.  Why not:
> > 
> > 		if (strcmp(flavor, "bsd") == 0)
> > 
> 
> I instinctively trust the memcmp function as it seems more like 
> assembly language to me and more straight forward and more reliable than 
> strcmp.

That really doesn't matter.

Your code stores "bsd\0\0" and not just "bsd\0"