Currently virt-v2v has few custom C-based functions for libvirt
operations, which are limited in what they do, and there is a lot of
duplicated code.
Instead, switch to ocaml-libvirt for all the libvirt interaction
currently done by the Libvirt_utils module. This has few advantages:
- each input & output module now opens a libvirt connection only once,
only when needed
- no need to pass URIs and passwords around, if not needed
- a wider range of libvirt APIs can now be used, with no need to create
bindings manually
The hierarchy of input_libvirt* classes is changed to take a Lazy object
with the libvirt connection, accessing it through a "proctected" method:
this way, the connection is opened only at the first access.
Also, the Libvirt_utils module now is just helpers around the Libvirt
module, to centralize error handling, and few common operations.
In some places when generating XML output in C code we use some clever
macros:
start_element ("memory") {
attribute ("unit", "MiB");
string_format ("%d", g->memsize);
} end_element ();
This commit which is mostly refactoring moves the repeated definitions
of these macros into a common header file.
I also took this opportunity to change / clean up the macros:
- The macros are now documented properly.
- comment() and empty_element() macros are now available everywhere.
- Error handling has been made generic.
- Added do..while(0) around some of the macros to make them safe to
use in all contexts.
Remove:
common/utils/libxml2-utils.c
common/utils/libxml2-utils.h
These were accidentally added by
commit a63d02f8f1 because of a bad
interactive rebase.
Commit bd1c5c9f4d changed all the code
to use Jansson instead of yajl. However it didn't change the OCaml
module name (still Yajl).
This commit changes the module to a neutral name ("JSON_parser") and
moves it into common/mltools so it can be used by other tools.
This leaves us in a slightly awkward situation of having two JSON-ish
OCaml modules (JSON for creating trees and JSON_parser for parsing
them) with incompatible types. That is left for future work to
resolve. (It should be easier to do now that both modules live in the
same directory.)
This is just renaming and general refactoring. There should be no
change in functionality.
While YAJL mostly works fine, it did not see any active development in
the last 3 years. OTOH, Jansson is another JSON C implementation, with
a very liberal license, and a much nicer API.
Hence, switch all of libguestfs from YAJL to Jansson:
- configure checks, and buildsystem in general
- packages pulled in the appliance
- actual implementations
- contrib scripts
- documentation
This also makes use of the better APIs available (e.g. json_object_get,
json_array_foreach, and json_object_foreach). This does not change the
API of our OCaml Yajl module.
Do a configure check for the OPEN_UNSAFE flag in the OCaml binding of
Hivex, using it only when available. This makes it possible to use
hivex < 1.3.14 to build libguestfs (the daemon, actually).
Amend the building documentation accordingly, bringing the minimum
version of hivex back as it was before
commit 64f49df747.
common/mlutils: Unix_utils.StatVFS.statvfs: This commit implements a
full-featured binding for the statvfs(3) function.
We then use this to reimplement the daemon statvfs API in OCaml.
Note that the Gnulib fallback is dropped in this commit. It
previously referenced non-existent field names in the fs_usage struct
so it didn't work. Also it's not necessary as POSIX has supported
statvfs(3) since 2001, it's supported in *BSD, macOS > 10.4, and there
is already a Windows fallback.
This directory which previously contained random modules and functions
now has an official purpose: to be the place for any OCaml utility
needed by the OCaml virt tools.
This is just code movement, I didn't (yet) rename or move any of the
modules.
Add a --with-distro=ID argument for configure, so it is possible to
manually specify the distro to use for the packages (in case os-release
does not provide ID=.., or the ID is not recognized yet).
In the case when --with-distro is not set, keep doing the autodetection,
but using os-release only, i.e. dropping the checks for all the other
-release files -- since there is --with-distro, older distros with no
os-release can still be used.
RWMJ: Add documentation to guestfs-building(1).
Move the last remaining function ‘guestfs_int_download_to_tmp’ to
lib/inspect-icon.c (the main, but not only user of this function).
Then remove lib/inspect.c entirely.
This is not quite code motion because I updated the comment for the
function to reflect what it does in reality.
hivex has a function hivex_value_string. We were not calling it under
the mistaken belief that because hivex implements this using iconv,
the function wouldn't work inside the daemon. Instead we
reimplemented the functionality in the library.
This commit deprecates hivex_value_utf8 and removes the library side
code. It replaces it with a plain wrapper around hivex_value_string.
Thanks: Pino Toscano
This commit bundles the ocaml-augeas library (upstream here:
http://git.annexia.org/?p=ocaml-augeas.git;a=summary). It's identical
to the upstream version and should remain so.
We can work towards using system ocaml-augeas, when it's more widely
available.
The following functions were previously reimplemented in OCaml. This
commit replaces them with calls to the C functions:
- is_root_device
- prog_exists
- udev_settle
plus the internal get_verbose_flag function.
However note that we cannot do this for every utility function. In
particular the C function must not call any reply* functions.
This also reimplements the lv_canonical function in OCaml. We cannot
call the original C function because it calls reply_with_perror which
would break the OCaml bindings.
Move the list_filesystems API into the daemon, reimplementing it in
OCaml. Since this API makes many other API calls, it runs a lot
faster in the daemon.
The previously library-side ‘file_architecture’ API is reimplemented
in the daemon, in OCaml.
There are some significant differences compared to the C
implementation:
- The C code used libmagic. That is replaced by calling the ‘file’
command (because that is simpler than using the library).
- The C code had extra cases to deal with compressed files. This is
not necessary since the ‘file’ command supports the ‘-z’ option
which transparently looks inside compressed content (this is a
consequence of the change above).
This commit demonstrates a number of techniques which will be useful
for moving inspection code to the daemon:
- Moving an API from the C library to the OCaml daemon.
- Calling from one OCaml API inside the daemon to another (from
‘Filearch.file_architecture’ to ‘File.file’). This can be done and
is done with C daemon APIs but correct reply_with_error handling is
more difficult in C.
- Use of Str for regular expression matching within the appliance.
This change allows parts of the daemon to be written in the OCaml
programming language. I am using the ‘Main Program in C’ method along
with ‘-output-obj’ to create an object file from the OCaml code /
runtime, as described here:
https://caml.inria.fr/pub/docs/manual-ocaml/intfc.html
Furthermore, change the generator to allow individual APIs to be
implemented in OCaml. This is picked by setting:
impl = OCaml <ocaml_function>;
The generator creates ‘do_function’ (the same one you would have to
write by hand in C), with the function calling the named
‘ocaml_function’ and dealing with marshalling/unmarshalling the OCaml
parameters.
Previously the OCaml compiler was only required if building from git
but was at least theoretically optional if building from tarballs
(although this was never tested). Since we want to write parts of the
daemon in OCaml, this makes OCaml required for all builds.
Note that the ‘--disable-ocaml’ option remains, but it now only
disables OCaml bindings and OCaml virt tools. Using this option does
not disable the OCaml compiler requirement.
Also note that ‘HAVE_OCAML’ changes meaning slightly, so it now means
"build OCaml bindings and tools" (analogous to ‘HAVE_PERL’ and
others). The generator, daemon [in a future commit], and some utility
libraries needed by the generator or daemon do not test for this macro
because we can assume OCaml compiler availability.
