This page describes various formats for disk images used in Darwin, Mac OS X, and Linux. This is a work in progress. Please add to the table. Note that this page might mention tools that are only available in Mac OS X, but not in PureDarwin. Hard disk images.dmg (disk image).dmg files can contain either an image of one volume (partition) or of an entire disk (device; including the MBR).
These files are used on the Mac. They can be created by Disk Utility, for example.
file reports "VAX COFF executable - version 8122" for compressed images. To mount these on a PureDarwin system, they need to be uncompressed first using the dmg2img utility. Here is an example: URL="http://macfuse.googlecode.com/files/MacFUSE-2.0.3%2C2.dmg" DMG="MacFUSE-2.0.3,2.dmg" MOUNTPOINT=/Volumes/test/ VN=/dev/vn0 set +v # be verbose set +e # exit on errors wget -c "${URL}" # download compressed DMG IMG=$(echo "${DMG}" | sed -e "s|.dmg$|.img|g" ) # get name of IMG dmg2img "${DMG}" -o "/tmp/${IMG}" -v # uncompress to IMG, http://trac.macports.org/ticket/23489 vndevice attach /dev/vn0 "/tmp/${IMG}" # attach IMG to device mkdir "${MOUNTPOINT}" # create mount point mount -t hfs "${VN}" "${MOUNTPOINT}" # mount find "${MOUNTPOINT}" -iname Archive.pax.gz # do something # install (to be written)... umount "${MOUNTPOINT}" && rm -r "${MOUNTPOINT}" # unmount vndevice detach "${VN}" # detach device rm "/tmp/${IMG}" # delete IMG The dmg2img utility can be compiled on a PureDarwin system using MacPorts (see #23489). .dd/.cdr (raw image)These files are raw dumps, as the dd program uses them.
You can convert .dmg files to these on the Mac, using the following command:
hdiutil convert some.dmg -format UDTO -o some.ddhdiutil uses the suffix ".cdr" for these files, but in fact the result is a raw dump that can be used with standard, cross-platform tools such as dd. This is why we prefer the ".dd" suffix. To write a raw dump to a physical disk:
CAUTION: the following commands are dangerous. You might accidentially wipe your hard disk. Do not use this if you do not know what you are doing.
dd if=some.dd of=/dev/sdaX bs=2048 CD/DVD images
.iso (ISO 9660 CD-ROM filesystem data) First, you need to populate a temporary directory that contains the boot-132 files and that has cdboot as its El Torito boot image (this allows BIOS-based machines to boot). ELTORITOISO=/tmp/eltorito.iso cp cdboot ... /tmp/i386/ cd /tmp/i386 From the temporary directory, run mkisofs: mkisofs -quiet -V "PureDarwin" -no-emul-boot -boot-load-size 4 -c boot.cat -b cdboot -o "$ELTORITOISO" In order to retreive the sector count: sectors=$(du "$ELTORITOISO" | tail -1 | awk '{print $1}') size_mb=$(du -h "$ELTORITOISO" | tail -1 | awk '{print $1}') Then create, initialize and mount a HFS+ disk image (dmg) hdiutil create -fs HFS+J -o "$CDDMG" -size 256M -layout NONE -type UDIF -nospotlight Partitioning with pdisk + newfs_hfs. (please add text) The tricky way is to "injects" parts of the temporary El Torito ISO into the dmg using dd if="$ELTORITOISO" of=$rdev skip=64 seek=64 bs=512 (please add text) Dump a CD/DVD to an iso imagehdiutil create -srcdevice /dev/disk1s0 -format UDTO some.isomv some.iso.cdr some.iso Hybrid mediaUp to four file systems supported: HFS+, ISO-9660, Joliet and/or UDF.-hfs Generate an HFS+ filesystem -iso Generate an ISO9660 filesystem -joliet Generate Joliet extensions to ISO9660 -udf Generate a UDF filesystem (Please write some text) hdiutil makehybrid -o ... ... Bootable CDsFor bootable CDs, see here. Mounting DMGs on PureDarwinIt looks like compressed DMGs (UDIF) cannot readily be mounted on PureDarwin since Darwin lacks the neccessary frameworks (e.g., DiskImages.framework) and/or kernel extensions (e.g., IOHDIXController.kext and its plug-ins) that Mac OS X uses for this purpose. IOHDIXController.kext used to be distributed with Darwin under the Apple Binary License. Perhaps that's what we need to do for PureDarwin as well. vndeviceUsing the raw BSD vndevice would mean that we cannot seemingly use compressed DMGs (UDIF). Since we want to use a compressed filesystem, it appears that the raw vndevice approach is not an option for PureDarwin. hdikMac OS X comes with a little tool called hdik. Its description reads like it could exactly do what we need in PureDarwin: hdik is a lightweight tool that can be used to attach disk images in-ker- nel (i.e. not using a user-land process to providing the backing store). Only a subset of disk images can be mounted in this manner including read/write disk images, UDIF disk images that use zlib compression, shad- owed disk images, and sparse disk images. hdik is intended for use in situations where linking against the DiskIm- ages framework is problematic or an extremely lightweight mechanism for attaching a disk image is needed. And it looks like it has no "impure" dependencies. However, it apparently calls /usr/libexec/load_hdi which, according to its man page, "is used to load the disk image driver. load_hdi is invoked by the DiskImages framework when it needs to attach images and the user client in IOHDIXController.kext is not available". Besides, it looks like the source for hdik is not available. Apparently, hdik is part of the closed-source project DiskImages-195. So it appears that it is not an option for PureDarwin either. Source code as starting point for own developmentsFor compressed DMGs (UDIF) see here (sample code in Java) and here (C)
Also have a look at this: https://svn.greensocs.com/public/packages/qemu_systemc/qemu-0.9.1/block-dmg.c |
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 The goal of this project is to make Darwin more usable by providing an installation ISO, documentation, and add-on software. You are welcome to join #puredarwin on irc.freenode.net if you would like to join PureDarwin development and to add to this site. |
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Disk images |