Why file content sniffing sucks

[Fabio Gomes <bugtraq gs2 com br>]

It finally happened. Today I was creating a project. I was using
Nautilus to create the folders. I created a 'doc' folder where I started
to write some text files explaining the project. It is a simple backup
script. One of the text files I wrote was an example of a backup job
descriptor. The file name was example.txt. The first line of the file
had a <heade> rtag. After I closed vim, Nautilus ASSUMED that it was an
HTML file, so it PREVENTED me from opening the f %(#$*%ing file from the
"incredibly high-quality GNOME UI". The only options were Mozilla and
OpenOffice. This prevented me from working for several minutes while I
tried to figure out how to open that damn file without going to the
console.

No way. I finally quit. I decided to open a xterm. Not to edit my file
and make it look less like HTML, but to GET RID of the most stupid
feature ever implemented in a file manager. I moved
/etc/gnome-vfs-mime-magic to somewhere else and restarted Nautilus.

Now the damn file manager sees that the .txt file is really a text file
(what a great guess! :-)) and allows me to open vim to edit it. Great.

The only drawback I noticed is that Nautilus does not know how to handle
.desktop files anymore, even though it recognizes the file type as I can
see in the properties dialog. Weird.

Well. This happened to me, an experienced GNOME user. But now stop and
imagine this kind of thing happening in a company with 100+ machines
runinng GNOME while dozens of people work with Nautilus to create some
project... 

I am thinking seriously about stopping some personal projects in favor
of creating a patch for nautilus+gnome-vfs to completely disable the
unrequested opening of files and distribute it among GNOME users. This
seems to be the only way to convince Nautilus and gnome-vfs maintainers
to (at least give an option to) disable this thing and make nautilus
finally work properly and with decent performance.

File type determination by content is crap. It's a misfeature. It is 
completely unnecessary. Its benefits do not compensate its drawbacks:

- The information generated by it is proven to not be accurate enough to
  be used by a program do determine its actions (the above example and
  the dozens of related bugs in bugzilla are sufficient). This data
  should be used merely for informational purposes to the user in the
  Properties dialog, for example.

- It reduces performance of Nautilus to a dead turtle:

  - In addition of simply opendir/readdir/closedir ONCE, 
    nautilus+vfs does open/read/close on EVERY
    file in a directory.

  - A directory with 250 files (1MB each) is sufficient to
    make nautilus spend 20 seconds on a Duron 950MHz with
    a 40GB ATA133 hard disk and 256 MB of memory.

  - The same directory takes less than 50 miliseconds to
    be loaded in Windows Explorer and xfe[1] (also same
    machine)

  - Nautilus spends 40x more time to load the directory
    than Windows Explorer and xfe[1]

  - This is obviously the main performance bottleneck of
    Nautilus.

- The item above implies on unnecessary evil disk activity
  (seeking, etc) that reduces the life time of the hardware.

- The bugs generated by this feature are endless. If you search
  bugzilla.gnome.org for gnome-vfs bugs related to mime-type mapping,
  you will see historic examples of:
  - .mp3 seen as .zip
  - .1st, .sys, .swf, .ogg, and .ico seen as MP3
  - .java and .css seen as C/C++
  - .php and .xml seen as HTML
  - There are DOZENS of bugs like these.
  - There will never be a definitive fix for this kind of bug.
	
GNOME needs to cut its own body to get rid of these stupid useless
unneeded features that only mess with people's work instead of helping
them.

The maintainers argue that it is a useful/needed/killer/great feature,
but Nautilus was never released without it to allow people (even
themselves) decide if the feature is useful/needed or not.

If type determination by content was good, we would see it in lots of
file managers in the world, since it is so trivial to implement. But no.
The only file manager that implement such a feature is
Nautilus+GnomeVFS.

The type determination by content should be available in a context
menu/menu item such as "Discover file type" that, when the user clicks
on it, it discovers the type of the file and asks the user if he/she
wants to fix the file extension/suffix to match the discovered file
type.

And you? Do you USER have an opinion about this subject?

And you, developer? Any toughts?

Maintainers? Convinced?

[1] xfe = X File Explorer, http://sourceforge.net/projects/xfe/

-- 
Fabio Gomes de Souza <fabio gs2 com br> (+55 81 9127-0597)

.- GS2 TECNOLOGIA DA INFORMACAO LTDA :: www.gs2.com.br
|- IT Infrastructure :: Security :: Embedded systems :: Linux
`- Olinda, Brazil - +55 81 3492-7777 - negocios gs2 com br