[Libguestfs] [PATCH 0/5] Import directly from OVA tar archive if possible

This is still a draft, not ready for commit yet. But feedback is welcomed. This series is related to the problem of inefficient import of OVA files. The needed enhancements of QEMU was merged into the codebase and should be available in QEMU 2.8. From there we can use 'size' and 'offset' options in raw driver to tell QEMU to use only subset of a file as an image. The first three patches are just preparation. The main work is in patch four. There are still some issues that need to be addressed: 1) The obviously missing check whether QEMU installed in the system supports the feature we need. Do we already have such (or similar) checks in libguestfs? Should it be compile-time check or runtime check? 2) Lots of 'tar' invocations that may not be easily understandable. 3) We need a check for sparse files in tar archive. There is a GNU extension to tar format that allows space-efficient archiving of sparse files. While the OVF standard does not allow the use of GNU extensions we probably should not rely on that. To address points 2) and 3) I see two possible options. We can either use some OCaml module that understands tar. There is however a risk that such module won't provide the necessary info to detect 3). The second option is to use e.g. libarchive and write small set of C functions that would implement the necessary magic and use those in OCaml code. Richard, do you have any preferences or suggestions in this matter? Tomáš Golembiovský (5): mllib: compute checksum of file inside tar v2v: ova: don't detect compressed disks, read the OVF instead v2v: ova: move the untar function v2v: ova: don't extract files from OVA if it's not needed v2v: update tests to match changes in OVA import mllib/checksums.ml | 10 ++- mllib/checksums.mli | 2 +- v2v/Makefile.am | 1 + v2v/input_ova.ml | 144 ++++++++++++++++++++++++++------- v2v/test-v2v-i-ova-formats.sh | 5 +- v2v/test-v2v-i-ova-gz.ovf | 2 +- v2v/test-v2v-i-ova-subfolders.expected | 2 +- v2v/test-v2v-i-ova-tar.expected | 18 +++++ v2v/test-v2v-i-ova-tar.ovf | 138 +++++++++++++++++++++++++++++++ v2v/test-v2v-i-ova-tar.sh | 64 +++++++++++++++ v2v/test-v2v-i-ova-two-disks.expected | 4 +- v2v/test-v2v-i-ova-two-disks.sh | 5 +- 12 files changed, 354 insertions(+), 41 deletions(-) create mode 100644 v2v/test-v2v-i-ova-tar.expected create mode 100644 v2v/test-v2v-i-ova-tar.ovf create mode 100755 v2v/test-v2v-i-ova-tar.sh -- 2.10.1