"Eject" and "Unmount"

[Jannis Pohlmann]

Am Wed, 11 Feb 2009 23:21:42 -0800
schrieb "Brian J. Tarricone" <bjt23 at cornell.edu>:

> On Thu, 12 Feb 2009 07:47:40 +0100 Yves-Alexis Perez wrote:
> 
> > On jeu, 2009-02-12 at 14:03 +0800, Shou-Lien Chen wrote:
> > > hello all:
> > > According to
> > > http://www.xfce.org/documentation/api/thunar-vfs/ThunarVfsVolume.html#thunar-vfs-volume-is-ejectable
> > > The thunar_vfs_volume_is_ejectable () should return TRUE only if a
> > > medium is present and the volume is removable Is this mean it
> > > reference the hal key: storage.removable = true  ? I found my usb
> > > disk and sd card is treat as "reject" if I want remove them, but
> > > there is a storage.requires_eject = false key  found if I monitor
> > > my usb disk by lshal command
> > > 
> > > Thus, which hal key is referenced by the thunar-vfs lib to judge
> > > if a volume need to be eject or unmount?
> > 
> > http://bugzilla.xfce.org/show_bug.cgi?id=3978
> 
> Jannis, can you explain this change a bit better? Unless I'm
> misunderstanding, that fix is incorrect.

Well, what we had before was:

  /* check if HAL drive requires eject */
  if (THUNAR_VFS_VOLUME_HAL (volume)->requires_eject)
    return TRUE;

  /* otherwise we can only eject removable media, that are present
     (surprise, surprise) */
  return (thunar_vfs_volume_is_present (volume) 
          && thunar_vfs_volume_is_removable (volume));

which basically displayed the eject button for all mounted devices such
as USB sticks, CD drives etc. However, you can't eject USB sticks, at
least not with thunar_vfs_volume_hal_eject() which calls exo-eject ...
which fails. So basically this broke disconnecting all kinds of devices
except for those which actually support ejecting (which were only the
devices with requires_eject=true for me). 

Too bad that almost no API docs for HAL exist. I think this change
works fine but I agree with you: "requires" and "supports" are two
different things.

> thunar_vfs_volume_is_ejectable() should NOT correspond to
> storage.requires_eject.  Just because a volume doesn't *require*
> eject, it doesn't mean that it's not ejectable.

I know that logically these two things mean something different.
However, requires_eject seems to be true exactly for the devices that
*can* be ejected. At least I haven't seen a device where that was not
the case.
 
> As previously discussed, we should *not* have "Unmount" in Thunar's
> (or xfdesktop's) UI anywhere.  Any place where we do would be
> considered a usability bug.
> 
> Ejecting normal USB media is entirely safe and probably a good idea
> (after unmounting), even if storage.requires_eject is false.

Ejecting normal USB media with exo-eject will fail. Right now what we
do is:

  1. Unmount (all devices)
  2. Eject (only devices with requires_eject=true)

What we could do is:

  1. Unmount (all devices)
  2. Eject and any ignore errors from exo-eject (all devices)

I doubt this is a good idea though because for some devices you
actually want errors of exo-eject to be displayed. So, option three is:

  1. Unmount (all devices)
  2. Eject (all devices) and ignore errors from exo-eject (only devices
     with requires_eject=false)

But since the current way of doing it seems to be fine (except for the
mount/unmount labels, which we could change without adding new strings
by the way) and GIO/GVfs will completely change how this works anyway,
I'm not really interested in putting too much effort into it right now.

  - Jannis
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