[PATCH] guess_fstype applet

[Tanguy Pruvot]

here is our (cm) latest version (squashed and applied to 1.23 branch) :
https://github.com/tpruvot/android_external_busybox/commit/783122b34e3647583c746908371b4121a7d249a6

2015-02-12 9:21 GMT+01:00 walter harms <wharms at bfs.de>:

> hi all,
> i was following the discussions a bit and now i have a minor question.
> so the idea guess_fstype is to be a subroutine of mount ?!
> why not make it a proper command ?
> Output could be something like  a mount cmdline.
>
> I got this idea because in the past i had the problem of cloning a
> drive setup (keywords: size, raid, lvm). In the end I wrote a small script
> with the right setup but i guess it would be a boom for backup programms
> and guessing the filesystem parameters would be a nice first step.
>
> just my two cents,
>  wh
>
>
> Am 12.02.2015 01:20, schrieb Tanguy Pruvot:
> > Thanks, i think it will be another divergence, the main purpose of this
> > patch is for the android recovery which should be able to mount badly set
> > fstype (exemple: for a backup)
> >
> > Even if in CM the recovery can be installed on each nightly, we have the
> > ability to keep a custom one (to handle different backup formats etc...)
> > and the fstab can be different of the recovery one.
> >
> > Now we have another problem about that, its the ability to use encrypted
> > file systems...
> >
> > 2015-02-11 20:37 GMT+01:00 Tanguy Pruvot <tanguy.pruvot at gmail.com>:
> >
> >> Thanks for the review... was merged too fast
> >>
> >> 2015-02-11 20:32 GMT+01:00 Isaac Dunham <ibid.ag at gmail.com>:
> >>
> >>> On Wed, Feb 11, 2015 at 07:50:49PM +0100, Tanguy Pruvot wrote:
> >>>> 2015-02-11 19:48 GMT+01:00 Denys Vlasenko <vda.linux at googlemail.com>:
> >>>>
> >>>>> On Fri, Feb 6, 2015 at 5:35 PM, Tanguy Pruvot <
> >>> tanguy.pruvot at gmail.com>
> >>>>> wrote:
> >>>>>> From CyanogenMod :
> >>>>>>
> >>>>>> http://review.cyanogenmod.org/#/c/87995/
> >>>>>>
> >>>>>> 2013-08-23 6:20 GMT+02:00 James B <jamesbond3142 at gmail.com>:
> >>>>>>>
> >>>>>>> If the interface can be simplifed to detect filesystem only
> >>> (instead
> >>>>>>> of also looking for labels and UUID) I think I think it would get
> >>> an
> >>>>>>> order of magnitude speed-up (taking the cues from Puppy Linux's
> >>>>>>> original guess_fstype which basically does just that). I'm not so
> >>> sure
> >>>>>>> about code-size reduction, though.
> >>>>>>>
> >>>>>>> It is called guess_fstype for historical reason (because that's
> >>> how it
> >>>>>>> was used and called in Puppy Linux), I'm happy to change it to
> >>>>>>> "fstype" if that helps everybody else :)
> >>>>>
> >>>>> I'm confused.
> >>>>> Is here something proposed for inclusion into busybox,
> >>>>> or you are now talking about hacks for a particular project only?
> >>>>
> >>>> its a feature to enhance the auto mount with blkid code... we are
> about
> >>> to
> >>>> merge this commit soon in CM12
> >>>
> >>> Comments:
> >>> - do NOT let code override a user specification.
> >>> If I specify -t (ntfs|ntfs-3g) or (msdos|vfat) manually, it should
> force
> >>> mount to try mounting using that specific driver and then *fail* if
> >>> it's impossible.
> >>> If fstype overrides user specifications, you may end up breaking future
> >>> filesystems.
> >>> I would think that this would be better:
> >>>         // Treat fstype "auto" as unspecified
> >>>         if (mp->mnt_type && strcmp(mp->mnt_type, "auto") == 0)
> >>>                 mp->mnt_type = NULL;
> >>> +#if ENABLE_FEATURE_BLKID_TYPE
> >>> +       // try to to autodetect type
> >>> +       if (!mp->mnt_type)
> >>> +               mp->mnt_type = get_fstype_from_devname(mp->mnt_fsname);
> >>> #endif
> >>>
> >>> OTOH, if I specify -t auto and userspace code selects the wrong fs type
> >>> (as it surely will, because bugs and unexpected inputs happen...),
> >>> it would be proper for mount to keep retrying, as would be done if
> >>> mp->mnt_type is unset after the new code.
> >>>
> >>> - I'm guessing that the use of != to compare two strings is a mistake?
> >>> +       || (detected_fstype != NULL && detected_fstype !=
> mp->mnt_type))
> >>>
> >>> - guess_fstype, fstype, blkid commands:
> >>>  guess_fstype is the name that Puppy Linux has used for a command that
> >>>  outputs filesystem type without label/uuid.
> >>>  fstype is the name that it goes by in Toybox, which is now in Android.
> >>>  However, upstream Android turns it off and just uses blkid.
> >>>
> >>> HTH,
> >>> Isaac Dunham
> >>>
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> busybox at busybox.net
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