Trash Spec Idea
backup95 at netcabo.pt
Thu Aug 14 07:42:58 PDT 2008
Andrea Francia wrote:
> 2008/8/13 João Valverde <backup95 at netcabo.pt <mailto:backup95 at netcabo.pt>>
> I was looking into doing a bash command line trash implementation as a
> beginner's exercise but I quickly realized it would be much
> hairier than
> I thought at first. Besides some inherent complexity from the file
> system hierarchy and permissions I think the spec has some
> and from browsing the archive I see that they have been discussed
> I created a similar program. A command line interface written in
> python for the trash can.
> The website is http://code.google.com/p/trash-cli/
> May be we can collaborate.
Interesting, thanks. I'll be sure to take a look and contact you if I
can be of use. Unfortunately my knowledge of Python is limited to
skimming some books and code but I've been meaning to dive in sometime.
> Is this feasible? Better than going through mtab right? How else
> could I
> find mount points for trash folders? How much can be done
> when mounting or unmounting volumes? Are there any plans to
> involve HAL
> on this? My ignorance starts to show here...
> The component that knows the informations about the mount points is
> the kernel.
> There's no need to duplicate these informations in $XDG_DATA_HOME with
> the risk that those are inaccurate or non synchronized.
> The kernel communicates the status of the current mount points with
> /etc/mtab and (in some systems) with /proc/mounts.
> To parse the /etc/mtab (or the /proc/mounts) file you should use
> getmnt(2) system function that recognizes all the special cases (like
> spaces in mount points) that and a reinvented parser may not consider.
Your points are all valid. The problem with mtab is that there is a lot
of cruft in there. It's not straightforward to interpret its contents.
Anyway doing this from the shell would require writing a parser using
getmntent(2) as you mentioned. How do we distinguish which filesystems
are "interesting" from the mntent structure without reading every single
one and checking whether a .Trash* folder exists? Do we go by filesystem
type? There are a lot of filesystems out there and it seems futile to
keep track of every single one. One possibility is writing a parser in C
that compares the filesystems in /proc/filesystems (I assume "nodev"
means it's a virtual filesystem?) against /etc/mtab and returns the
mount points that have the correct type. On my system I get
$ cat /proc/filesystems
So in this case the C parser would return the mnt_dir from struct
mnt_ent for every entry in mtab of type "cramfs", "fuseblk", "ext3" and
"vfat". From there the script would check those mount points for Trash
contents. What am I missing?
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