Index mounted .dmg?

Question

Level 2

424 points

Index mounted .dmg?

This follows up on a conversation in another thread; I thought it best to start a fresh one.

I've got some sensitive documents on a laptop that I maintain in an encrypted .dmg file. It's easy enough to get at them - just mount the .dmg. The problem is that I can't figure out a way to persuade Spotlight to index them from the .dmg. Name searches work okay but content searches return nothing. The same documents, residing in a regular folder, are indexed and fully searchable - so it's not a plug-in issue. I tried force-indexing the mounted .dmgs using both SpotlightIndexer and Highlight, and, while both apps report success, the .dmg file contents remain unsearchable.

Any suggestions?

Dual 2.5Ghz G5, Mac OS X (10.3.9), 3.5MB RAM

Posted on Jan 25, 2007 2:23 PM

Reply

Answer 1

Jan 25, 2007 5:14 PM in response to John Dorsey

Am I missing something here? If the documents are stored in an encrypted .dmg file, just what could Spotlight index other than the encryption codes, which would be useless. Is not the purpose of storing data on a drive and then encrypting the drive so that nobody can see the contents without un-encrypting the drive first?

Reply

Answer 2

John Dorsey Author

Level 2

424 points

Jan 25, 2007 6:40 PM in response to Daniel Marr

I agree. It would be stupid to index an encrypted .dmg file. I guess I wasn't clear enough. These are active files and from time to time I mount the .dmg to work with them. At that point they are no longer encrypted. I would like for Spotlight to index the mounted, unencrypted, disk image volume so that I can use Spotlight's various search capabilities on those files, while the disk image is mounted an unencrypted.

Is that possible?

Reply

Answer 3

Jan 25, 2007 10:07 PM in response to John Dorsey

A .dmg is like a CD. They both cannot be indexed, and thus you can't search for contents, because the index file has to be stored on the volume that is being indexed.

Reply

Answer 4

John Dorsey Author

Level 2

424 points

Jan 26, 2007 4:17 AM in response to Daniel Marr

This may be impossible but it isn't because a mounted .dmg is like a CD that cannot be indexed. It's more like an external hard drive, which SL automatically indexes upon mounting. I can write to the mounted .dmg just like an external drive. I can add, change or save documents stored on it, and all those changes to the volume are saved to the encrypted .dmg image when I eject the mounted volume. I have complete R/W access to the mounted .dmg, just like a hard drive, not like a CD. (There is incidentally plenty of room in the .dmg for an index - this is a 100MB image holding only 40MB of files).

Do we know this is impossible?

Reply

Answer 5

Jan 26, 2007 5:54 AM in response to John Dorsey

As I understand it, .dmg, .tar, .zip are image files. Like a jpeg, the contents aren't not indexable.

Reply

Answer 6

John Dorsey Author

Level 2

424 points

Jan 26, 2007 5:58 AM in response to Daniel Marr

I guess I'm not being clear. I don't want to index the .dmg as such. I want to index, even if only temporarily, the mounted volume into which the .dmg expands when I open it. The mounted volume is, to all appearances, the same as a mounted external hard drive, with folders and files and documents and the like.

It is beginning to sound like this is not possible, even though I can't think of any reason it shouldn't be.

Reply

Answer 7

Jan 26, 2007 7:02 AM in response to John Dorsey

You can find the files by name, however, Spotlight does not index the contents of files in an image file.

Reply

Answer 8

John Dorsey Author

Level 2

424 points

Jan 26, 2007 7:50 AM in response to Daniel Marr

Not only "doesn't", but now I am coming to understand, "won't". That doesn't make much sense to me, but it is what it is I guess. Perhaps in Leopard, when Apple enables SL to index networked volumes, they will include the ability to index mounted .dmg images.

Meantime, I've determined that Easyfind has no trouble searching the contents of the mounted volume, at least inside files of human-readable formats like .rtf and .txt. This is at best half a solution in that most of my files are .doc files, but it's better than nothing.

Reply

Answer 9

biovizier

Level 5

7,931 points

Jan 26, 2007 8:23 AM in response to John Dorsey

I don't use "Spotlight" very much - it has it's strengths, but the fact that it misses items is something that is not tolerable for what I would need it for. Anyway, that's just a disclaimer to say that I haven't tested this thoroughly, but have you tried using 'mdutil'? I.e. while logged in to an "admin" account, entering something like this using "/Applications" > "Utilities" > "Terminal.app":<pre>sudo mdutil -i on /Volumes/volumename</pre>I tried creating two disk images, and ran the command only on one. A test MSWord file was copied to each, but searching for a keyword in the content, only the copy on the enabled volume was found when searching from either the Spotlight menu or using a "Find" search for "Contents" (adding both volumes as targets in "Others…)".

Reply

Answer 10

John Dorsey Author

Level 2

424 points

Jan 26, 2007 9:06 AM in response to biovizier

Sonofagun! That did the trick! What's more, the command is sticky (at least within the same boot of OS X) - I ejected the volume, the index vanished with it, but when I remounted it Spotlight duly proceeded to re-index it.

On the assumption that this command doesn't persist across reboots, what I need now is to remember how to turn a terminal command into a double-clickable file!

Thanks!

Reply

Answer 11

John Dorsey Author

Level 2

424 points

Jan 26, 2007 10:36 AM in response to John Dorsey

This may be common knowledge, but the command persists across reboots. All I have to do is not change the mounted volume name, and I'm all set. Thanks again.

Reply

Answer 12

Jan 26, 2007 10:41 AM in response to John Dorsey

Just curious, but...

Where does the index reside?
Is it on the .dmg or on the HD volume?

Reply

Answer 13

John Dorsey Author

Level 2

424 points

Jan 26, 2007 11:56 AM in response to Mike-N-nahyunil

If that's indicated by the invisible folder (file?) .Spotlight-V100, then it appears to reside on the mounted volume. (Found it with EasyFind, hah.) I can also report that indexing upon re-mount is very quick, so I'm assuming that it's not rebuilding the thing from scratch.

This is handy. It means I can enjoy the benefits of both encrypted folders and Spotlight content searching, and it's painless once you take care of the initial setup.

Reply