[Qemu-devel] [Bug 907063] Re: Error reading VMDK4 with footer instead of header

[Thomas Huth]

Looks like something similar has been commited here:
http://git.qemu.org/?p=qemu.git;a=commitdiff;h=65bd155c7356d448ffee7
So is this problem fixed nowadays?

** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/907063

Title:
  Error reading VMDK4 with footer instead of header

Status in QEMU:
  Incomplete

Bug description:
  VMDK4 files can have a footer in the last block, which is the same 
datastructure as the header but must be used instead if present. In this case, 
the gd_offset in the usual header at the beginning of the file is the special 
flag -1 (VMDK 1.1 spec, page 17, "GD_AT_END
  "). qemu-img doesn't know about this flag so it goes on to try to read 
extents with a bogus l1_table from the wrong location in the file.

  I have regression-tested this with various OVAs exported from
  VSphere/ESXi 3 and 4. Current master and all previous QEMU versions
  were unable to import any compressed VMDKs with a footer. It now works
  on all the ones I have.

  bb45ded93115ad4303471c9a492579dc36716547 changed the order of
  gd_offset and rgd_offset in the VMDK4Header struct. Page 8 of the VMDK
  1.1 spec from VMWare shows the structure as rgd_ then gd_, while QEMU
  now has gd_ *before* rgd_offset. I was only able to get VMDK
  conversion to work by switching the order back to that specified by
  VMWare and previously used by QEMU. I don't know what VMDK this commit
  is referring to, so I can't test to see if I've broken it. :(

  I will submit this patch to the mailing list if I get a chance, but
  I'm also uploading it here so I don't lose it.

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