July 2010 - Libguestfs - libguestfs List Archives

[PATCH 0/3] Inspection code in C
by Richard W.M. Jones 02 Aug '10

02 Aug '10

These three patches (two were previously posted) can do simple operating system inspection in C. Example of use: ><fs> add-ro rhel55.img ><fs> run ><fs> inspect-os /dev/VolGroup00/LogVol00 ><fs> inspect-get-type /dev/VolGroup00/LogVol00 linux ><fs> inspect-get-distro /dev/VolGroup00/LogVol00 rhel ><fs> inspect-get-arch /dev/VolGroup00/LogVol00 x86_64 ><fs> inspect-get-major-version /dev/VolGroup00/LogVol00 5 ><fs> inspect-get-minor-version /dev/VolGroup00/LogVol00 5 ><fs> inspect-get-product-name /dev/VolGroup00/LogVol00 Red Hat Enterprise Linux Server release 5.5 (Tikanga) ><fs> inspect-get-filesystems /dev/VolGroup00/LogVol00 /dev/VolGroup00/LogVol00 /dev/vda1 /dev/VolGroup00/LogVol01 ><fs> inspect-get-mountpoints /dev/VolGroup00/LogVol00 /dev/VolGroup00/LogVol00: / /dev/vda1: /boot I've tested this with all of my available guests. The only ones it *doesn't* work on were a Fedora guest with an encrypted disk, and some FreeBSD/PCBSD guests. For the encrypted guest, you have to open the device first. We could probably get the *BSD guests working with some effort. Anyway I'm quite happy with this and I intend to push it if no one objects. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones New in Fedora 11: Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 70 libraries supprt'd http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw

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[PATCH] Enable coredumps to be captured from the appliance (RHBZ#619334).
by Richard W.M. Jones 02 Aug '10

02 Aug '10

https://bugzilla.redhat.com/show_bug.cgi?id=619334 This is a slightly unsatisfactory patch which allows coredumps to be captured when they occur inside the appliance. You can capture coredumps by doing: export LIBGUESTFS_COREDUMP=/sysroot/core.%t.%p.%e or equivalently: g.set_coredump ("/sysroot/core.%t.%p.%e") or variations thereof, see the manual page. When a coredump occurs, a core file will be dropped into the root directory of the currently mounted guest disk. If it is guestfsd which crashes, then the appliance will exit, but I have checked that the coredump is written and synched first. You can then copy this out of the guest disk using guestfish and debug using gdb: $ guestfish --ro -a guest_disk -m /dev/vg/lv_root ><fs> ll / ><fs> download /core.xxx.yyy.zzz core $ gdb daemon/guestfsd core http://fedoraproject.org/wiki/StackTraces#Obtaining_a_stack_trace_from_a_co… Clearly you need to have a writable guest disk mounted for this to work, and you have to not care too much about having large core files written to it. Ideally we would have liked to use a special capture disk, but it turns out that the kernel contains code which disallows using a /dev device (or any non-regular file) for coredumps: http://lxr.linux.no/linux+v2.6.34.1/fs/exec.c#L1930 We could do it using a coredump-to-pipe, but I think it would be better to just remove this limitation in the kernel. Another shortcoming is that a coredump isn't a stack trace, and to get a stack trace you really need a copy of the daemon around with debugging enabled. It is possible we could change the RPM packaging to ship this. Luckily the suspected bug in Augeas which we are chasing (RHBZ#613967) happens in aug_init or aug_save when the conditions above are satisfied and we should be able to get a useful coredump. However since I am unable to reproduce this bug at all, I cannot help with this, so it's over to Marek and Matt. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into Xen guests. http://et.redhat.com/~rjones/virt-p2v

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[PATCH] New API: is-lv: check if a block device is a logical volume (RHBZ#619793)
by Richard W.M. Jones 30 Jul '10

30 Jul '10

Fix for: https://bugzilla.redhat.com/show_bug.cgi?id=619793 Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones New in Fedora 11: Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 70 libraries supprt'd http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw

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Create new Sys::VirtV2V::Util
by Matthew Booth 29 Jul '10

29 Jul '10

These 2 patches are mostly code motion. They were prompted by an apparent augeas error in BZ 613967 which didn't display useful error message. The error seems to happen in Converter::Linux. GuestOS::RedHat had a handy function which displayed verbose augeas error messages. This function moves into the new module where it can be used by both modules. The second patch is an consequential tidy up. UserMessage moves into the new module. * [PATCH 1/2] Move augeas error reporting into new Sys::VirtV2V::Util * [PATCH 2/2] Move user_message into Sys::VirtV2V::Util

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RHEL 6 guest support
by Matthew Booth 29 Jul '10

29 Jul '10

The following patches add RHEL 6 guest support to virt-v2v. This was actually quite a lot easier than I expected. * [PATCH 1/4] Update virt-v2v.conf for RHEL 6 virtio support * [PATCH 2/4] Check kudzu exists before attempting to disable it * [PATCH 3/4] Use dracut rather than mkinitrd if it's available * [PATCH 4/4] Properly convert RHEL 6 guest console

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[PATCH] New APIs: findfs-label and findfs-uuid
by Richard W.M. Jones 28 Jul '10

28 Jul '10

These APIs are needed for ease of inspection of /etc/fstab from C. (Actually the way we are doing it currently in Perl is incredibly convoluted .. we should have just used findfs). Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones New in Fedora 11: Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 70 libraries supprt'd http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw

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[PATCH] New API: file-architecture
by Richard W.M. Jones 28 Jul '10

28 Jul '10

I've nearly converted the Perl code for inspection into C, but while I'm fixing the bugs, it strikes me that the 'file_architecture' part of this is simple and self-contained. This is just a translation of the Perl call into C. The Perl call continues to exist, but is marked as deprecated. Probably we should simply replace it with a call to the new API. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://et.redhat.com/~rjones/libguestfs/ See what it can do: http://et.redhat.com/~rjones/libguestfs/recipes.html

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Inspection code in C
by Richard W.M. Jones 27 Jul '10

27 Jul '10

Currently virt-inspector is a Perl script[1], which uses a Perl library called Sys::Guestfs::Lib[2]. This library contains (amongst other things) heuristics for determining what operating system is in a disk image. The library is the basis for both virt-inspector and virt-v2v. [1] http://git.annexia.org/?p=libguestfs.git;a=blob;f=inspector/virt-inspector;… [2] http://git.annexia.org/?p=libguestfs.git;a=blob;f=perl/lib/Sys/Guestfs/Lib.… Writing these in Perl was useful at the time because they involved a lot of string matching, and rules which we thought would change frequently. However these have proved to be simpler and more stable than we originally thought. If we rewrite these rules in C and make them available as part of the core libguestfs API, then we gain some benefits: (a) The generator will create bindings for us in all languages. (b) We don't need to run an external virt-inspector binary to implement the "guestfish -i" option, which means that option will work much faster and with fewer limitations. (c) We can get rid of the inspector-generator code which only works for OCaml, is a big hack, and is not used by anyone. (d) People can write tools like virt-edit, virt-cat, virt-inspector, virt-v2v in languages other than Perl. The downside is that this will become a core API which we cannot break (because of the C ABI guarantee). The main issues (hardest first) are: (i) How to map the current tree structure returned by Sys::Guestfs::- Lib into the flat list-of-structures that the generator supports (or modifying the generator to support trees, but that is much more complex and I don't think necessary). (ii) Decide on the final API. (iii) Decide how much of the current API to move to C. The current "inspect_in_detail" call lists applications, kernels, drivers etc installed in the guest. Furthermore the current API exposes a lot of information about individual filesystems, such as their UUID, which is nowadays unnecessary since we added calls such as guestfs_vfs_uuid to the main libguestfs API. I don't think it's necessary to move all of this into C. We can move it later if we want to, or leave it to the higher level tools. But it's not necessary to gain the benefits (a) through (d) above. As a result, the proposed API below is considerably simpler than the current Perl API, which (I think) exposing all the important information that anyone cares about and cannot be derived in any other way. (iv) Modify virt-v2v and virt-inspector to use the new API. (v) Introduces a direct dependency on hivex. Please read the proposed API below, and let me know what you think. Rich. ---------------------------------------------------------------------- /* Inspect and return list of operating systems found. * Returned list empty => no operating systems found. * 1 element => single operating system found. * > 1 element => multi-boot image. */ char ** /* list of root devices */ guestfs_inspect_os (guestfs_h *g); /* Pass in a root device of one of the operating systems. These * functions return ancillary information such as the name of the * OS, version numbers, etc. If it could not be determined, these * return an error. */ char * guestfs_inspect_get_name (guestfs_h *g, const char *root); char * guestfs_inspect_get_arch (guestfs_h *g, const char *root); char * guestfs_inspect_get_distro (guestfs_h *g, const char *root); char * guestfs_inspect_get_product_name (guestfs_h *g, const char *root); int guestfs_inspect_get_major_version (guestfs_h *g, const char *root); int guestfs_inspect_get_minor_version (guestfs_h *g, const char *root); char * guestfs_inspect_get_package_format (guestfs_h *g, const char *root); char * guestfs_inspect_get_package_management (guestfs_h *g, const char *root); char ** /* hash of mount point -> device */ guestfs_inspect_get_mountpoints (guestfs_h *g, const char *root); char ** /* list of filesystems */ guestfs_inspect_get_filesystems (guestfs_h *g, const char *root); -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://et.redhat.com/~rjones/libguestfs/ See what it can do: http://et.redhat.com/~rjones/libguestfs/recipes.html

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[PATCH] Revert "add_drive_ro adds readonly=on option if available." (RHBZ#617200).
by Richard W.M. Jones 22 Jul '10

22 Jul '10

-- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into Xen guests. http://et.redhat.com/~rjones/virt-p2v

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Fwd: [PATCH hivex] non-ASCII characters in node names
by Richard W.M. Jones 22 Jul '10

22 Jul '10

Hilko, forwarding this to the mailing list. Please post patches over there. Rich. ----- Forwarded message ----- Date: Wed, 21 Jul 2010 17:09:53 +0200 From: Hilko Bengen Subject: patch: non-ASCII characters in node names Hi Richard, I was a little bit surprised when a colleague claimed that key and value names in the registry could contain non-ASCII characters. I created keys and values with the following names: * "asdf" * "äöü" (common in German, can be represented in Windows-1252, Latin1, Latin9) * the Euro sign (can be represented in Windows-1252, Latin9) * the international currency symbol (can be represented in Windows-1252, Latin1) >From looking at the nodes/values, I have come to the conclusion that Windows first looks if all characters in a string can be represented in the Latin1 encoding. If that fails, UTF-16 is used. A bit in the "flags" field is used to indicate the character encoding. I have implemented and briefly tested read support for those names in the patch below. If that patch is acceptable, I'll do write support tomorrow. -Hilko ----- End forwarded message ----- -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://et.redhat.com/~rjones/virt-top

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