On Mon, Apr 24, 2017 at 05:19:48PM -0400, John Snow wrote: > > > On 04/23/2017 05:03 AM, Ashijeet Acharya wrote: > > Hi, > > > > Great news! > > I have almost completed this task and the results are looking > > promising. I have not yet attended to the DMG files having bz2 > > compressed chunks but that should be easy and pretty similar to my > > approach for zlib compressed files. So, no worries there. > > > > For testing I am first converting the images to raw format and then > > comparing the resulting image with the one converted using v2.9.0 DMG > > driver and after battling for 2 days with my code, it finally prints > > "Images are identical." According to John, that should be pretty > > conclusive and I completely agree. > > > > Yes, comparing a sample.dmg against a raw file generated from the 2.9.0 > qemu-img tool should be reasonably good evidence that you have not > altered the behavior of the tool. > > > Now, the real thing I wanted to ask was, if someone is aware of a DMG > > file which has a chunk size above 64 MiB so that I can test those too. > > If yes, please share the download link with me. > > Currently I am testing the ones posted by Peter Wu while submitting > > his DMG work in 2014. > > Here -> > > https://lists.nongnu.org/archive/html/qemu-devel/2014-12/msg03606.html > > > > Are any of those over 64MB? I assume you're implying that they aren't. > > Maybe Peter knows?...
I don't know DMG with bzip2-compressed chunks over 64M. Looking through more recent files, there is this log for "Install macOS Sierra 10.12(16A323)-B.dmg" which contains only zlib-compressed or raw data where the uncompressed size (in the MISH block) is always at most 1MiB: https://github.com/Lekensteyn/dmg2img/issues/1#issuecomment-273662984 In an Xcode_7.2.dmg file, the situation was similar, only zlib or raw and also with a max uncompressed size of 1MiB (actually, an exact size of 1MiB in both cases based on "sectorCount"). Perhaps bzip2-compressed chunks are not so common for larger disk images since zlib is faster. -- Kind regards, Peter Wu https://lekensteyn.nl
