1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019
|
=head1 NAME
guestfs-hacking - extending and contributing to libguestfs
=head1 DESCRIPTION
This manual page is for hackers who want to extend libguestfs itself.
=head1 OVERVIEW OF THE SOURCE CODE
Libguestfs source is located in the github repository
L<https://github.com/libguestfs/libguestfs>
Large amounts of boilerplate code in libguestfs (RPC, bindings,
documentation) are generated. This means that many source files will
appear to be missing from a straightforward git checkout. You have to
run the generator (C<./autogen.sh && make -C generator>) in order to
create those files.
Libguestfs uses an autotools-based build system, with the main files
being F<configure.ac> and F<Makefile.am>. See L</THE BUILD SYSTEM>.
The F<generator> subdirectory contains the generator, plus files
describing the API. The F<src> subdirectory contains source for the
library. The F<appliance> and F<daemon> subdirectories contain the
source for the code that builds the appliance, and the code that runs
in the appliance respectively. Other directories are covered in the
section L<SOURCE CODE SUBDIRECTORIES> below.
Apart from the fact that all API entry points go via some generated
code, the library is straightforward. (In fact, even the generated
code is designed to be readable, and should be read as ordinary code).
Some actions run entirely in the library, and are written as C
functions in files under F<src>. Others are forwarded to the daemon
where (after some generated RPC marshalling) they appear as C
functions in files under F<daemon>.
To build from source, first read the L<guestfs-building(1)>.
=head1 SOURCE CODE SUBDIRECTORIES
There are a lot of subdirectories in the source tree! Which ones
should you concentrate on first? F<src> and F<daemon> which contain
the source code of the core library. F<generator> is the code
generator described above, so that is important. The F<Makefile.am>
in the root directory will tell you in which order the subdirectories
get built. And then if you are looking at a particular tool
(eg. F<v2v>) or language binding (eg. F<python>), go straight to that
subdirectory, but remember that if you didn't run the generator yet,
then you may find files which appear to be missing.
=over 4
=item F<align>
L<virt-alignment-scan(1)> command and documentation.
=item F<appliance>
The libguestfs appliance, build scripts and so on.
=item F<bash>
Bash tab-completion scripts.
=item F<build-aux>
Various build scripts used by autotools.
=item F<builder>
L<virt-builder(1)> command and documentation.
=item F<cat>
The L<virt-cat(1)>, L<virt-filesystems(1)>, L<virt-log(1)>
and L<virt-ls(1)> commands and documentation.
=item F<contrib>
Outside contributions, experimental parts.
=item F<customize>
L<virt-customize(1)> command and documentation.
=item F<daemon>
The daemon that runs inside the libguestfs appliance and carries out
actions.
=item F<df>
L<virt-df(1)> command and documentation.
=item F<dib>
L<virt-dib(1)> command and documentation.
=item F<diff>
L<virt-diff(1)> command and documentation.
=item F<docs>
Miscellaneous manual pages.
=item F<edit>
L<virt-edit(1)> command and documentation.
=item F<examples>
C API example code.
=item F<fish>
L<guestfish(1)>, the command-line shell, and various shell scripts
built on top such as L<virt-copy-in(1)>, L<virt-copy-out(1)>,
L<virt-tar-in(1)>, L<virt-tar-out(1)>.
=item F<format>
L<virt-format(1)> command and documentation.
=item F<fuse>
L<guestmount(1)>, FUSE (userspace filesystem) built on top of libguestfs.
=item F<generator>
The crucially important generator, used to automatically generate
large amounts of boilerplate C code for things like RPC and bindings.
=item F<get-kernel>
L<virt-get-kernel(1)> command and documentation.
=item F<gnulib>
Gnulib is used as a portability library. A copy of gnulib is included
under here.
=item F<inspector>
L<virt-inspector(1)>, the virtual machine image inspector.
=item F<logo>
Logo used on the website. The fish is called Arthur by the way.
=item F<m4>
M4 macros used by autoconf. See L</THE BUILD SYSTEM>.
=item F<make-fs>
L<virt-make-fs(1)> command and documentation.
=item F<mllib>
Various libraries and common code used by L<virt-resize(1)> and
the other tools which are written in OCaml.
=item F<p2v>
L<virt-p2v(1)> command, documentation and scripts for building the
virt-p2v ISO or disk image.
=item F<po>
Translations of simple gettext strings.
=item F<po-docs>
The build infrastructure and PO files for translations of manpages and
POD files. Eventually this will be combined with the F<po> directory,
but that is rather complicated.
=item F<rescue>
L<virt-rescue(1)> command and documentation.
=item F<resize>
L<virt-resize(1)> command and documentation.
=item F<sparsify>
L<virt-sparsify(1)> command and documentation.
=item F<src>
Source code to the C library.
=item F<sysprep>
L<virt-sysprep(1)> command and documentation.
=item F<tests>
Tests.
=item F<test-data>
Files and other test data used by the tests.
=item F<test-tool>
Test tool for end users to test if their qemu/kernel combination
will work with libguestfs.
=item F<tmp>
Used for temporary files when running the tests (instead of F</tmp>
etc). The reason is so that you can run multiple parallel tests of
libguestfs without having one set of tests overwriting the appliance
created by another.
=item F<tools>
Command line tools written in Perl (L<virt-win-reg(1)> and many others).
=item F<utils>
Miscellaneous utilities, such as C<boot-benchmark>.
=item F<v2v>
L<virt-v2v(1)> command and documentation.
=item F<website>
The L<http://libguestfs.org> website files.
=item F<csharp>
=item F<erlang>
=item F<gobject>
=item F<golang>
=item F<haskell>
=item F<java>
=item F<lua>
=item F<ocaml>
=item F<php>
=item F<perl>
=item F<python>
=item F<ruby>
Language bindings.
=back
=head1 THE BUILD SYSTEM
Libguestfs uses the GNU autotools build system (autoconf, automake,
libtool).
The F<./configure> script is generated from F<configure.ac> and
F<m4/guestfs_*.m4>. Most of the configure script is split over many
m4 macro files by topic, for example F<m4/guestfs_daemon.m4> deals
with the dependencies of the daemon.
The job of the top level F<Makefile.am> is mainly to list the
subdirectories (C<SUBDIRS>) in the order they should be compiled.
F<common-rules.mk> is included in every F<Makefile.am> (top level and
subdirectories). F<subdir-rules.mk> is included only in subdirectory
F<Makefile.am> files.
There are many make targets. Use this command to list them all:
make help
=head1 ADDING A NEW API
Because large amounts of boilerplate code in libguestfs are generated,
this makes it easy to extend the libguestfs API.
To add a new API action there are two changes:
=over 4
=item 1.
You need to add a description of the call (name, parameters, return
type, tests, documentation) to F<generator/actions.ml>.
There are two sorts of API action, depending on whether the call goes
through to the daemon in the appliance, or is serviced entirely by the
library (see L<guestfs-internals(1)/ARCHITECTURE>). L<guestfs(3)/guestfs_sync> is an example
of the former, since the sync is done in the appliance.
L<guestfs(3)/guestfs_set_trace> is an example of the latter, since a trace flag
is maintained in the handle and all tracing is done on the library
side.
Most new actions are of the first type, and get added to the
C<daemon_functions> list. Each function has a unique procedure number
used in the RPC protocol which is assigned to that action when we
publish libguestfs and cannot be reused. Take the latest procedure
number and increment it.
For library-only actions of the second type, add to the
C<non_daemon_functions> list. Since these functions are serviced by
the library and do not travel over the RPC mechanism to the daemon,
these functions do not need a procedure number, and so the procedure
number is set to C<-1>.
=item 2.
Implement the action (in C):
For daemon actions, implement the function C<do_E<lt>nameE<gt>> in the
C<daemon/> directory.
For library actions, implement the function C<guestfs_impl_E<lt>nameE<gt>>
in the C<src/> directory.
In either case, use another function as an example of what to do.
=back
After making these changes, use C<make> to compile.
Note that you don't need to implement the RPC, language bindings,
manual pages or anything else. It's all automatically generated from
the OCaml description.
=head2 Adding tests for an API
You can supply zero or as many tests as you want per API call. The
tests can either be added as part of the API description
(F<generator/actions.ml>), or in some rarer cases you may want to drop
a script into C<tests/*/>. Note that adding a script to C<tests/*/>
is slower, so if possible use the first method.
The following describes the test environment used when you add an API
test in F<actions.ml>.
The test environment has 4 block devices:
=over 4
=item F</dev/sda> 2 GB
General block device for testing.
=item F</dev/sdb> 2 GB
F</dev/sdb1> is an ext2 filesystem used for testing
filesystem write operations.
=item F</dev/sdc> 10 MB
Used in a few tests where two block devices are needed.
=item F</dev/sdd>
ISO with fixed content (see F<images/test.iso>).
=back
To be able to run the tests in a reasonable amount of time, the
libguestfs appliance and block devices are reused between tests. So
don't try testing L<guestfs(3)/guestfs_kill_subprocess> :-x
Each test starts with an initial scenario, selected using one of the
C<Init*> expressions, described in F<generator/types.ml>. These
initialize the disks mentioned above in a particular way as documented
in F<types.ml>. You should not assume anything about the previous
contents of other disks that are not initialized.
You can add a prerequisite clause to any individual test. This is a
run-time check, which, if it fails, causes the test to be skipped.
Useful if testing a command which might not work on all variations of
libguestfs builds. A test that has prerequisite of C<Always> means to
run unconditionally.
In addition, packagers can skip individual tests by setting
environment variables before running C<make check>.
SKIP_TEST_<CMD>_<NUM>=1
eg: C<SKIP_TEST_COMMAND_3=1> skips test #3 of L<guestfs(3)/guestfs_command>.
or:
SKIP_TEST_<CMD>=1
eg: C<SKIP_TEST_ZEROFREE=1> skips all L<guestfs(3)/guestfs_zerofree> tests.
Packagers can run only certain tests by setting for example:
TEST_ONLY="vfs_type zerofree"
See F<tests/c-api/tests.c> for more details of how these environment
variables work.
=head2 Debugging new APIs
Test new actions work before submitting them.
You can use guestfish to try out new commands.
Debugging the daemon is a problem because it runs inside a minimal
environment. However you can fprintf messages in the daemon to
stderr, and they will show up if you use C<guestfish -v>.
=head1 ADDING A NEW LANGUAGE BINDING
All language bindings must be generated by the generator
(see the F<generator> subdirectory).
There is no documentation for this yet. We suggest you look
at an existing binding, eg. F<generator/ocaml.ml> or
F<generator/perl.ml>.
=head2 Adding tests for language bindings
Language bindings should come with tests. Previously testing of
language bindings was rather ad-hoc, but we have been trying to
formalize the set of tests that every language binding should use.
Currently only the OCaml and Perl bindings actually implement the full
set of tests, and the OCaml bindings are canonical, so you should
emulate what the OCaml tests do.
This is the numbering scheme used by the tests:
- 000+ basic tests:
010 load the library
020 create
030 create-flags
040 create multiple handles
050 test setting and getting config properties
060 explicit close
065 implicit close (in GC'd languages)
070 optargs
080 version
090 retvalues
- 100 launch, create partitions and LVs and filesystems
- 400+ events:
410 close event
420 log messages
430 progress messages
- 800+ regression tests (specific to the language)
- 900+ any other custom tests for the language
To save time when running the tests, only 100, 430, 800+, 900+ should
launch the handle.
=head1 FORMATTING CODE
Our C source code generally adheres to some basic code-formatting
conventions. The existing code base is not totally consistent on this
front, but we do prefer that contributed code be formatted similarly.
In short, use spaces-not-TABs for indentation, use 2 spaces for each
indentation level, and other than that, follow the K&R style.
If you use Emacs, add the following to one of one of your start-up files
(e.g., ~/.emacs), to help ensure that you get indentation right:
;;; In libguestfs, indent with spaces everywhere (not TABs).
;;; Exceptions: Makefile and ChangeLog modes.
(add-hook 'find-file-hook
'(lambda () (if (and buffer-file-name
(string-match "/libguestfs\\>"
(buffer-file-name))
(not (string-equal mode-name "Change Log"))
(not (string-equal mode-name "Makefile")))
(setq indent-tabs-mode nil))))
;;; When editing C sources in libguestfs, use this style.
(defun libguestfs-c-mode ()
"C mode with adjusted defaults for use with libguestfs."
(interactive)
(c-set-style "K&R")
(setq c-indent-level 2)
(setq c-basic-offset 2))
(add-hook 'c-mode-hook
'(lambda () (if (string-match "/libguestfs\\>"
(buffer-file-name))
(libguestfs-c-mode))))
=head1 TESTING YOUR CHANGES
Turn warnings into errors when developing to make warnings hard to
ignore:
./configure --enable-werror
Useful targets are:
=over 4
=item C<make check>
Runs the regular test suite.
This is implemented using the regular automake C<TESTS> target. See
the automake documentation for details.
=item C<make check-valgrind>
Runs a subset of the test suite under valgrind.
See L</VALGRIND> below.
=item C<make check-valgrind-local-guests>
Runs a subset of the test suite under valgrind
using locally installed libvirt guests (read-only).
=item C<make check-direct>
Runs all tests using default appliance back-end. This only
has any effect if a non-default backend was selected
using C<./configure --with-default-backend=...>
=item C<make check-valgrind-direct>
Run a subset of the test suite under valgrind using the
default appliance back-end.
=item C<make check-uml>
Runs all tests using the User-Mode Linux backend.
As there is no standard location for the User-Mode Linux kernel, you
I<have> to set C<LIBGUESTFS_HV> to point to the kernel image, eg:
make check-uml LIBGUESTFS_HV=~/d/linux-um/vmlinux
=item C<make check-valgrind-uml>
Runs all tests using the User-Mode Linux backend, under valgrind.
As above, you have to set C<LIBGUESTFS_HV> to point to the kernel.
=item C<make check-with-upstream-qemu>
Runs all tests using a local qemu binary. It looks for the qemu
binary in QEMUDIR (defaults to F<$HOME/d/qemu>), but you can set this
to another directory on the command line, eg:
make check-with-upstream-qemu QEMUDIR=/usr/src/qemu
=item C<make check-with-upstream-libvirt>
Runs all tests using a local libvirt. This only has any effect if the
libvirt backend was selected using
C<./configure --with-default-backend=libvirt>
It looks for libvirt in LIBVIRTDIR (defaults to F<$HOME/d/libvirt>),
but you can set this to another directory on the command line, eg:
make check-with-upstream-libvirt LIBVIRTDIR=/usr/src/libvirt
=item C<make check-slow>
Runs some slow/long-running tests which are not run by default.
To mark a test as slow/long-running:
=over 4
=item *
Add it to the list of C<TESTS> in the F<Makefile.am>, just like a
normal test.
=item *
Modify the test so it checks if the C<SLOW=1> environment variable is
set, and if I<not> set it skips (ie. returns with exit code 77).
=item *
Add a variable C<SLOW_TESTS> to the F<Makefile.am> listing the slow
tests.
=item *
Add a rule to the F<Makefile.am>:
check-slow:
$(MAKE) check TESTS="$(SLOW_TESTS)" SLOW=1
=back
=item C<make check-all>
Equivalent to running all C<make check*> rules.
=item C<make check-release>
Runs a subset of C<make check*> rules that are required to pass
before a tarball can be released. Currently this is:
=over 4
=item *
check
=item *
check-valgrind
=item *
check-direct
=item *
check-valgrind-direct
=item *
check-slow
=back
=item C<make installcheck>
Run C<make check> on the installed copy of libguestfs.
The version of installed libguestfs being tested, and the version of
the libguestfs source tree must be the same.
Do:
./autogen.sh
make clean ||:
make
make installcheck
=back
=head2 VALGRIND
When you do C<make check-valgrind>, it searches for any F<Makefile.am>
in the tree that has a C<check-valgrind:> target and runs it.
Writing the F<Makefile.am> and tests correctly to use valgrind and
working with automake parallel tests is subtle.
If your tests are run via a shell script wrapper, then in the wrapper
use:
$VG virt-foo
and in the F<Makefile.am> use:
check-valgrind:
make VG="@VG@" check
However, if your binaries run directly from the C<TESTS> rule, you
have to modify the F<Makefile.am> like this:
LOG_COMPILER = $(VG)
check-valgrind:
make VG="@VG@" check
In either case, check that the right program is being tested by
examining the F<tmp/valgrind*> log files carefully.
=head1 SUBMITTING PATCHES
Submit patches to the mailing list:
L<http://www.redhat.com/mailman/listinfo/libguestfs>
and CC to L<rjones@redhat.com>.
You do not need to subscribe to the mailing list if you don't want to.
There may be a short delay while your message is moderated.
=head1 DAEMON CUSTOM PRINTF FORMATTERS
In the daemon code we have created custom printf formatters C<%Q> and
C<%R>, which are used to do shell quoting.
=over 4
=item %Q
Simple shell quoted string. Any spaces or other shell characters are
escaped for you.
=item %R
Same as C<%Q> except the string is treated as a path which is prefixed
by the sysroot.
=back
For example:
asprintf (&cmd, "cat %R", path);
would produce C<cat /sysroot/some\ path\ with\ spaces>
I<Note:> Do I<not> use these when you are passing parameters to the
C<command{,r,v,rv}()> functions. These parameters do NOT need to be
quoted because they are not passed via the shell (instead, straight to
exec). You probably want to use the C<sysroot_path()> function
however.
=head1 INTERNATIONALIZATION (I18N) SUPPORT
We support i18n (gettext anyhow) in the library.
However many messages come from the daemon, and we don't translate
those at the moment. One reason is that the appliance generally has
all locale files removed from it, because they take up a lot of space.
So we'd have to readd some of those, as well as copying our PO files
into the appliance.
Debugging messages are never translated, since they are intended for
the programmers.
=head1 HOW OCAML PROGRAMS ARE COMPILED AND LINKED
Mostly this section is "how we make automake & ocamlopt work together"
since OCaml programs themselves are easy to compile.
Automake has no native support for OCaml programs, ocamlc nor
ocamlopt. What we do instead is to treat OCaml programs as C programs
which happen to contain these "other objects" (C<"DEPENDENCIES"> in
automake-speak) that happen to be the OCaml objects. This works
because OCaml programs usually have C files for native bindings etc.
So a typical program is described as just its C sources:
virt_v2v_SOURCES = ... utils-c.c xml-c.c
For programs that have no explicit C sources, we create an empty
F<dummy.c> file, and list that instead:
virt_resize_SOURCES = dummy.c
The OCaml objects which contain most of the code are listed as
automake dependencies (other dependencies may also be listed):
virt_v2v_DEPENDENCIES = ... cmdline.cmx v2v.cmx
The only other special thing we need to do is to provide a custom link
command. This is needed because automake won't assemble the ocamlopt
command, the list of objects and the C<-cclib> libraries in the
correct order otherwise.
virt_v2v_LINK = \
$(top_srcdir)/ocaml-link.sh -cclib '-lutils -lgnu' -- ...
The actual rules, which you can examine in F<v2v/Makefile.am>, are a
little bit more complicated than this because they have to handle:
=over 4
=item *
Compiling for byte code or native code.
=item *
The pattern rules needed to compile the OCaml sources to objects.
These are now kept in F<subdir-rules.mk> at the top level, which is
included in every subdirectory F<Makefile.am>.
=item *
Adding OCaml sources files to C<EXTRA_DIST>.
Automake isn't aware of the complete list of sources for a binary, so
it will not add them all automatically.
=back
=head1 VIRT-V2V
First a little history. Virt-v2v has been through at least two
complete rewrites, so this is probably about the third version (but we
don't intend to rewrite it again). The previous version was written
in Perl and can be found here:
L<https://git.fedorahosted.org/git/virt-v2v.git>
The current version started out as almost a line-for-line rewrite of
the Perl code in OCaml + C, and it still has a fairly similar
structure. Therefore if there are details of this code that you don't
understand (especially in the details of guest conversion), checking
the Perl code may help.
The files to start with when reading this code are:
=over 4
=item *
F<types.mli>
=item *
F<v2v.ml>
=back
F<types.mli> defines all the structures used and passed around when
communicating between different bits of the program. F<v2v.ml>
controls how the program runs in stages.
After studying those files, you may want to branch out into the input
modules (F<input_*>), the output modules (F<output_*>) or the
conversion modules (F<convert_*>). The input and output modules
define I<-i> and I<-o> options (see the manual). The conversion
modules define what guest types we can handle and the detailed steps
involved in converting them.
Every other file in this directory is a support module / library of
some sort. Some code is written in C, especially where we want to use
an external C library such as libxml2.
=head1 VIRT-P2V
Virt-p2v is a front end on virt-v2v. ie. All it does is act as a GUI
front end, and it calls out to virt-v2v to perform the actual
conversion. Therefore most of the C code in the F<p2v/> subdirectory
is Gtk (GUI) code, or supporting code for talking to the remote
conversion server. There is no special support for physical machines
in virt-v2v. They are converted in the same way as foreign VMs.
=head2 Running virt-p2v
You can run the F<p2v/virt-p2v> binary directly, but it will try to
convert your machine's real F</dev/sda> which is unlikely to work
well. However virt-p2v also has a test mode in which you can supply a
test disk:
make -C p2v run-virt-p2v-directly
This is a wrapper around the L<virt-p2v(1)> I<--test-disk> option.
You can control the "physical machine" disk by setting
C<PHYSICAL_MACHINE> to point to a disk image.
A more realistic test is to run virt-p2v inside a VM on the local
machine. To do that, do:
make -C p2v run-virt-p2v-in-a-vm
This also runs qemu with the "physical machine" disk (which you can
set by setting C<PHYSICAL_MACHINE>), a virtual CD, and a variety of
network cards for testing.
A third way to run virt-p2v simulates fairly accurately the program
being downloaded over PXE and then doing an automatic conversion of
the source physical machine (the non-GUI path -- see next section
below):
make -C p2v run-virt-p2v-non-gui-conversion
=head2 Understanding the virt-p2v code
I<See also:> L<virt-p2v(1)/HOW VIRT-P2V WORKS>
There are two paths through the code, GUI or non-GUI (parsing the
kernel command line):
main.c ──────┬─────▶ gui.c ──────┬─────▶ conversion.c
│ │
│ │
└────▶ kernel.c ────┘
but both paths call back to the F<conversion.c> function
C<start_conversion> to run the remote virt-v2v.
The main task of F<gui.c>/F<kernel.c> is to populate the virt-v2v
configuration (F<config.c>).
During conversion, we need to establish ssh connections, and that is
done using two libraries:
conversion.c ──────▶ ssh.c ──────▶ miniexpect.c
where F<ssh.c> is responsible for managing ssh connections overall,
and F<miniexpect.c> implements "expect-like" functionality for talking
interactively to the remote virt-v2v conversion server.
(Note that miniexpect is a separate library with its own upstream, so
if you patch miniexpect.c, then please make sure the changes get
reflected in miniexpect's upstream too:
F<http://git.annexia.org/?p=miniexpect.git;a=summary>)
=head1 MAKING A STABLE RELEASE
When we make a stable release, there are several steps documented
here. See L<guestfs(3)/LIBGUESTFS VERSION NUMBERS> for general information
about the stable branch policy.
=over 4
=item *
Check C<make && make check> works on at least Fedora, Debian and
Ubuntu.
=item *
Check C<./configure --without-libvirt> works.
=item *
Finalize F<guestfs-release-notes.pod>
=item *
Push and pull from Zanata.
Run:
zanata push
to push the latest POT files to Zanata. Then run:
./zanata-pull.sh
which is a wrapper to pull the latest translated F<*.po> files.
=item *
Consider updating gnulib to latest upstream version.
=item *
Create new stable and development directories under
L<http://libguestfs.org/download>.
=item *
Edit F<website/index.html.in>.
=item *
Set the version (in F<configure.ac>) to the new I<stable> version,
ie. 1.XX.0, and commit it:
./localconfigure
make distclean -k
./localconfigure
make && make dist
make maintainer-commit
make maintainer-tag
=item *
Create the stable branch in git:
git branch stable-1.XX
git push origin stable-1.XX
=item *
Do a full release of the stable branch.
=item *
Set the version to the next development version and commit that.
Optionally do a full release of the development branch.
=back
=head1 INTERNAL DOCUMENTATION
This section documents internal functions inside libguestfs and
various utilities. It is intended for libguestfs developers only.
This section is autogenerated from C</**> comments in source files,
which are marked up in POD format.
B<These functions are not publicly exported, and may change or be
removed at any time.>
__INTERNAL_DOCUMENTATION__
=head1 SEE ALSO
L<guestfs(3)>,
L<guestfs-building(1)>,
L<guestfs-examples(3)>,
L<guestfs-internals(1)>,
L<guestfs-performance(1)>,
L<guestfs-release-notes(1)>,
L<guestfs-testing(1)>,
L<libguestfs-test-tool(1)>,
L<libguestfs-make-fixed-appliance(1)>,
L<http://libguestfs.org/>.
=head1 AUTHORS
Richard W.M. Jones (C<rjones at redhat dot com>)
=head1 COPYRIGHT
Copyright (C) 2009-2016 Red Hat Inc.
|