[PATCH fstools] partname: Correct fstools_partname_fallback_scan comparison

[Christian Marangi]

On Tue, Jan 24, 2023 at 10:40:26PM -0800, Brian Norris wrote:
> On Tue, Jan 24, 2023 at 10:28:14PM -0800, Brian Norris wrote:
> > We want to return NULL if the param does *not* match 1 -- i.e., a
> > non-zero strcmp().
> > 
> > Fixes: 1ea5855e980c ("partname: Introduce fstools_partname_fallback_scan option")
> 
> Hmm, sorry for the quick self-reply, but after rereading, I noticed
> there's a second reason commit 1ea5855e980c may be incorrect:
> 
> This fallback *used* to (pre-1ea5855e980c) be used for any block device
> (eMMC, SATA, etc.) where we *didn't* specify root= in the boot args.
> This could perhaps happen with initramfs systems? (Sorry, I'm not
> extremely familiar with the openwrt ecosystem.)
> 
> So do we need to refactor this again, so that we allow the fallback in
> either (or both) of these cases:
> 
> (1) no root= arg
> (2) root=XXXX (where XXX is not a /device/path) +
>     fstools_partname_fallback_scan=1
> 
> ?
> 
> Anyway, it's probably at least safe to apply my bugfix, but we might
> need more.
>

Hi, you are right but in theory it should not be that hard to rework...
We surely need to handle the case with no root arg.

> > Signed-off-by: Brian Norris <computersforpeace at gmail.com>
> > ---
> > 
> >  libfstools/partname.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libfstools/partname.c b/libfstools/partname.c
> > index f42322a49d5b..82c723c02097 100644
> > --- a/libfstools/partname.c
> > +++ b/libfstools/partname.c
> > @@ -143,7 +143,7 @@ static struct volume *partname_volume_find(char *name)
> >  		if (!get_var_from_file("/proc/cmdline", "fstools_partname_fallback_scan", rootparam, sizeof(rootparam)))
> >  			return NULL;
> >  
> > -		if (!strcmp("1", rootparam))
> > +		if (strcmp("1", rootparam))
> >  			return NULL;
> >  
> >  		/* no useful 'root=' kernel cmdline parameter, find on any block device */
> > -- 
> > 2.39.0
> > 

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