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Earlz
Asked: 2009-06-17 09:16:19 +0800 CST

Building a disk image without root privileges

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I am attempting to setup nightly builds of a Linux OS on my webserver. Well, the problem is I need to generate a floppy disk image without being root.

Really, I don't need to fully generate it. I just need to update the image. As I have a FFS image with boot manager and such, and just need to add my kernel file to the image. I have seen no useful image tools out there though with dealing with FFS.

Does anyone know of some tools to use for updating such a floppy image. I wouldn't mind programming a little glue program, but I really don't want to code up full FFS support by myself at the moment.

linux disk-image

3 Answers

  1. Best Answer

    I can offer two (non-ideal) options:

    • Create a 'placeholder' file inside your disk image and splice the kernel into the image (ick)
    • If you don't need to use FFS, you could try FAT. mtools is very handy for this sort of thing.

    Example:

    michael:~> mdir -i test.img ::
 Volume in drive : is Testing (abbr=TESTING    )
 Volume Serial Number is 0000-0000
Directory for ::/

No files
                          1 457 664 bytes free

michael:~> mcopy -i test.img kernel.com ::
michael:~> mdir -i test.img ::
 Volume in drive : is Testing (abbr=TESTING    )
 Volume Serial Number is 0000-0000
Directory for ::/

kernel   com     47632 2009-06-17  16:50 
        1 file               47 632 bytes
                          1 409 536 bytes free
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  2. Can you just mount it on loopback and access it as any other filesystem?

    I assume by FFS that you're meaning the BSD Fast File System? I don't know what kind of support Linux has for it offhand. If Linux can mount it, that's going to be your easiest bet. If not, then you either need to write your own FFS support, or use an OS that can manage it easier.

    Or switch to using a filesystem that is better supported.

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  3. I'm unsure which operations might require being root to create a disk image, so you should really post what are you doing exactly.

    If you need to mount a loop device or something like that, you might be able to give a regular user rights to do so. If not, there might be a Fuse module to do it.

    • -1