Libguestfs - Jun 2022 - [PATCH virt-v2v 2/3] test-data/phony-guests: Allow virt-v2v to work against phony Fedora

We didn't use the phony Fedora guest before with virt-v2v (only the
phony Windows image).  This commit makes miscellaneous changes so that
it can be used for testing:

 - Add dummy rpm and dracut commands.

 - Add dummy kernel, initramfs and modules directory.

 - Add dummy grub configuration pointing to the kernel.
---
 .gitignore                                |  1 +
 test-data/phony-guests/Makefile.am        | 19 +++++--
 test-data/phony-guests/fedora.c           | 67 +++++++++++++++++++++++
 test-data/phony-guests/make-fedora-img.pl | 26 ++++++++-
 4 files changed, 108 insertions(+), 5 deletions(-)

diff --git a/.gitignore b/.gitignore
index ac7d6a3ce0..04ab847dcd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -117,6 +117,7 @@ Makefile.in
 /test-data/phony-guests/fedora-luks.img
 /test-data/phony-guests/fedora-md1.img
 /test-data/phony-guests/fedora-md2.img
+/test-data/phony-guests/fedora-static-bin
 /test-data/phony-guests/fedora.db
 /test-data/phony-guests/guests.xml
 /test-data/phony-guests/guests-all-good.xml
diff --git a/test-data/phony-guests/Makefile.am
b/test-data/phony-guests/Makefile.am
index 60313548af..c45ddc1123 100644
--- a/test-data/phony-guests/Makefile.am
+++ b/test-data/phony-guests/Makefile.am
@@ -76,7 +76,8 @@ blank-%.img:
 # Make a (dummy) Fedora image.
 fedora.img: make-fedora-img.pl \
 		fedora-journal.tar.xz \
-		fedora.db
+		fedora.db \
+		fedora-static-bin
 	SRCDIR=$(srcdir) LAYOUT=partitions $(top_builddir)/run --test ./$<
 
 # Make a (dummy) Fedora image using md devices
@@ -84,7 +85,8 @@ fedora-md1.img fedora-md2.img: stamp-fedora-md.img
 
 stamp-fedora-md.img: make-fedora-img.pl \
 		fedora-journal.tar.xz \
-		fedora.db
+		fedora.db \
+		fedora-static-bin
 	rm -f $@
 	SRCDIR=$(srcdir) LAYOUT=partitions-md $(top_builddir)/run --test ./$<
 	touch $@
@@ -93,13 +95,15 @@ stamp-fedora-md.img: make-fedora-img.pl \
 # for root and home.
 fedora-btrfs.img: make-fedora-img.pl \
 		fedora-journal.tar.xz \
-		fedora.db
+		fedora.db \
+		fedora-static-bin
 	SRCDIR=$(srcdir) LAYOUT=btrfs $(top_builddir)/run --test ./$<
 
 # Make a (dummy) Fedora image with LVM encrypted with LUKS.
 fedora-luks.img: make-fedora-img.pl \
 		fedora-journal.tar.xz \
-		fedora.db
+		fedora.db \
+		fedora-static-bin
 	SRCDIR=$(srcdir) LAYOUT=lvm-luks $(top_builddir)/run --test ./$<
 
 # Make a (dummy) Debian image.
@@ -137,6 +141,13 @@ fedora.db: fedora-db.sql.xz
 	xzcat $< | $(SQLITE3) $@-t
 	mv $@-t $@
 
+# This is included in the phony Fedora image to act as a phony "rpm"
+# and "dracut" command.  For the use of -all-static here, see
+# libguestfs/tests/Makefile.am
+check_PROGRAMS = fedora-static-bin
+fedora_static_bin_SOURCES = fedora.c
+fedora_static_bin_LDFLAGS = -all-static
+
 windows-software: windows-software.reg
 	rm -f $@ $@-t
 	cp $(srcdir)/minimal-hive $@-t
diff --git a/test-data/phony-guests/fedora.c b/test-data/phony-guests/fedora.c
new file mode 100644
index 0000000000..36eaa233fc
--- /dev/null
+++ b/test-data/phony-guests/fedora.c
@@ -0,0 +1,67 @@
+/* libguestfs test images
+ * Copyright (C) 2009-2020 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
USA.
+ */
+
+/* This is "just enough" of a binary to look like RPM and dracut, as
+ * far as virt-v2v is concerned.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+/* NB: This is also defined in make-fedora-img.pl */
+#define KVER "5.19.0-0.rc1.14.fc37.x86_64"
+
+static const char *
+basename (const char *str)
+{
+  const char *ret = strrchr (str, '/');
+  return ret == NULL ? str : ret + 1;
+}
+
+int
+main (int argc, char *argv[])
+{
+  if (argc == 3 &&
+      strcmp (basename (argv[0]), "rpm") == 0 &&
+      strcmp (argv[1], "-ql") == 0 &&
+      strncmp (argv[2], "kernel-", 7) == 0) {
+    /* XXX These files and directories actually exist.  It would be
+     * better to list files in /boot and /lib/modules matching a
+     * pattern rather than hard-coding the list here, which duplicates
+     * information in make-fedora-img.pl.
+     */
+    printf ("/boot/vmlinuz-" KVER "\n");
+    printf ("/lib/modules/" KVER "\n");
+    printf ("/lib/modules/" KVER "/kernel\n");
+    printf ("/lib/modules/" KVER "/kernel/drivers\n");
+    printf ("/lib/modules/" KVER
"/kernel/drivers/block\n");
+    printf ("/lib/modules/" KVER
"/kernel/drivers/block/virtio_blk.ko\n");
+  }
+  else if (argc >= 1 &&
+           strcmp (basename (argv[0]), "dracut") == 0) {
+    // do nothing, pretend to rebuild the initramfs
+  }
+  else {
+    fprintf (stderr, "phony Fedora: unknown command\n");
+    exit (1);
+  }
+
+  exit (0);
+}
diff --git a/test-data/phony-guests/make-fedora-img.pl
b/test-data/phony-guests/make-fedora-img.pl
index f340f4d744..ad30960fa3 100755
--- a/test-data/phony-guests/make-fedora-img.pl
+++ b/test-data/phony-guests/make-fedora-img.pl
@@ -240,6 +240,7 @@ $g->mount ($bootdev, '/boot');
 $g->mkdir ('/bin');
 $g->mkdir ('/etc');
 $g->mkdir ('/etc/sysconfig');
+$g->mkdir ('/sbin');
 $g->mkdir ('/usr');
 $g->mkdir ('/usr/share');
 $g->mkdir ('/usr/share/zoneinfo');
@@ -276,8 +277,17 @@ $g->upload
($ENV{SRCDIR}.'/../binaries/bin-x86_64-dynamic', '/bin/ls');
 
 $g->tar_in ($ENV{SRCDIR}.'/fedora-journal.tar.xz',
'/var/log/journal', compress => "xz");
 
+# NB: This is also defined in fedora.c
+my $kver = "5.19.0-0.rc1.14.fc37.x86_64";
 $g->mkdir ('/boot/grub');
-$g->touch ('/boot/grub/grub.conf');
+$g->write ('/boot/grub/grub.conf', <<EOF);
+title Fedora
+    root (hd0,0)
+    kernel /vmlinuz-$kver
+    initrd /initramfs-$kver.img
+EOF
+
+$g->touch ('/etc/modprobe.conf');
 
 # Test files.
 $g->write ('/etc/test1', 'abcdefg');
@@ -300,6 +310,20 @@ $g->ln_s ('/bin/test1', '/bin/test5');
 $g->mkfifo (0777, '/bin/test6');
 $g->mknod (0777, 10, 10, '/bin/test7');
 
+# Virt-v2v needs an RPM command, or at least something which acts
+# similarly, and also a dracut command.
+$g->upload ('fedora-static-bin', '/bin/rpm');
+$g->chmod (0777, '/bin/rpm');
+$g->upload ('fedora-static-bin', '/sbin/dracut');
+$g->chmod (0777, '/sbin/dracut');
+
+# Virt-v2v also needs a kernel, initrd and modules path.
+$g->touch ("/boot/vmlinuz-$kver");
+$g->touch ("/boot/initramfs-$kver.img");
+$g->mkdir_p ("/lib/modules/$kver/kernel/drivers/block");
+$g->upload ($ENV{SRCDIR}.'/../binaries/bin-x86_64-dynamic',
+            "/lib/modules/$kver/kernel/drivers/block/virtio_blk.ko");
+
 # Cleanup
 $g->shutdown ();
 $g->close ();
-- 
2.35.1

On Wed, Jun 08, 2022 at 05:49:01PM +0100, Richard W.M. Jones
wrote:
> +# Virt-v2v also needs a kernel, initrd and modules path.
> +$g->touch ("/boot/vmlinuz-$kver");
> +$g->touch ("/boot/initramfs-$kver.img");
> +$g->mkdir_p ("/lib/modules/$kver/kernel/drivers/block");
> +$g->upload ($ENV{SRCDIR}.'/../binaries/bin-x86_64-dynamic',
> +           
"/lib/modules/$kver/kernel/drivers/block/virtio_blk.ko");
Surprisingly this works even on !x86-64.  I just tested it on aarch64.

Here:

https://github.com/libguestfs/virt-v2v/blob/0d1b2ec1b733db1ca0bebf2e4a9e8d5fd7db7f93/convert/linux_kernels.ml#L192

we use guestfs_file_architecture on a kernel module to determine the
architecture of the kernel.  Because we uploaded an x86-64 binary this
means we detect the kernel as being x86_64:

installed kernel packages in this guest:
* kernel 5.19.0-0.rc1.14.fc37.x86_64 (x86_64) <------- ki_arch
        /boot/vmlinuz-5.19.0-0.rc1.14.fc37.x86_64
        /boot/initramfs-5.19.0-0.rc1.14.fc37.x86_64.img
        no config
        /lib/modules/5.19.0-0.rc1.14.fc37.x86_64
        1 modules found
        virtio: blk=true net=false rng=false balloon=false
        pvpanic=false vsock=false xen=false debug=false

Then we run dracut, which would fail on a real guest if the host is
aarch64, but succeeds here because the phony dracut binary is aarch64:

libguestfs: trace: v2v: command "/sbin/dracut --verbose --add-drivers
virtio_blk /boot/initramfs-5.19.0-0.rc1.14.fc37.x86_64.img
5.19.0-0.rc1.14.fc37.x86_64"

Later:

gcaps_block_bus = virtio-blk
gcaps_net_bus = e1000
gcaps_virtio_rng = false
gcaps_virtio_balloon = false
gcaps_isa_pvpanic = false
gcaps_virtio_socket = false
gcaps_machine = i440fx
gcaps_arch = x86_64  <---------
gcaps_acpi = true
gcaps_virtio_1_0 = false
gcaps_default_cpu = true

Anyway this is kind of a bug in virt-v2v (because it should reject
conversion of a !hostarch guest), and also in this test, but this is a
fairly obscure corner case so I guess I'll leave it for now.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org

On 06/08/22 18:49, Richard W.M. Jones wrote:
> We didn't use the phony Fedora guest before with virt-v2v (only the
> phony Windows image).  This commit makes miscellaneous changes so that
> it can be used for testing:
> 
>  - Add dummy rpm and dracut commands.
> 
>  - Add dummy kernel, initramfs and modules directory.
> 
>  - Add dummy grub configuration pointing to the kernel.
> ---
>  .gitignore                                |  1 +
>  test-data/phony-guests/Makefile.am        | 19 +++++--
>  test-data/phony-guests/fedora.c           | 67 +++++++++++++++++++++++
>  test-data/phony-guests/make-fedora-img.pl | 26 ++++++++-
>  4 files changed, 108 insertions(+), 5 deletions(-)
> 
> diff --git a/.gitignore b/.gitignore
> index ac7d6a3ce0..04ab847dcd 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -117,6 +117,7 @@ Makefile.in
>  /test-data/phony-guests/fedora-luks.img
>  /test-data/phony-guests/fedora-md1.img
>  /test-data/phony-guests/fedora-md2.img
> +/test-data/phony-guests/fedora-static-bin
>  /test-data/phony-guests/fedora.db
>  /test-data/phony-guests/guests.xml
>  /test-data/phony-guests/guests-all-good.xml
> diff --git a/test-data/phony-guests/Makefile.am
b/test-data/phony-guests/Makefile.am
> index 60313548af..c45ddc1123 100644
> --- a/test-data/phony-guests/Makefile.am
> +++ b/test-data/phony-guests/Makefile.am
> @@ -76,7 +76,8 @@ blank-%.img:
>  # Make a (dummy) Fedora image.
>  fedora.img: make-fedora-img.pl \
>  		fedora-journal.tar.xz \
> -		fedora.db
> +		fedora.db \
> +		fedora-static-bin
>  	SRCDIR=$(srcdir) LAYOUT=partitions $(top_builddir)/run --test ./$<
>  
>  # Make a (dummy) Fedora image using md devices
> @@ -84,7 +85,8 @@ fedora-md1.img fedora-md2.img: stamp-fedora-md.img
>  
>  stamp-fedora-md.img: make-fedora-img.pl \
>  		fedora-journal.tar.xz \
> -		fedora.db
> +		fedora.db \
> +		fedora-static-bin
>  	rm -f $@
>  	SRCDIR=$(srcdir) LAYOUT=partitions-md $(top_builddir)/run --test ./$<
>  	touch $@
> @@ -93,13 +95,15 @@ stamp-fedora-md.img: make-fedora-img.pl \
>  # for root and home.
>  fedora-btrfs.img: make-fedora-img.pl \
>  		fedora-journal.tar.xz \
> -		fedora.db
> +		fedora.db \
> +		fedora-static-bin
>  	SRCDIR=$(srcdir) LAYOUT=btrfs $(top_builddir)/run --test ./$<
>  
>  # Make a (dummy) Fedora image with LVM encrypted with LUKS.
>  fedora-luks.img: make-fedora-img.pl \
>  		fedora-journal.tar.xz \
> -		fedora.db
> +		fedora.db \
> +		fedora-static-bin
>  	SRCDIR=$(srcdir) LAYOUT=lvm-luks $(top_builddir)/run --test ./$<
>  
>  # Make a (dummy) Debian image.
> @@ -137,6 +141,13 @@ fedora.db: fedora-db.sql.xz
>  	xzcat $< | $(SQLITE3) $@-t
>  	mv $@-t $@
>  
> +# This is included in the phony Fedora image to act as a phony
"rpm"
> +# and "dracut" command.  For the use of -all-static here, see
> +# libguestfs/tests/Makefile.am
> +check_PROGRAMS = fedora-static-bin
> +fedora_static_bin_SOURCES = fedora.c
> +fedora_static_bin_LDFLAGS = -all-static
> +
>  windows-software: windows-software.reg
>  	rm -f $@ $@-t
>  	cp $(srcdir)/minimal-hive $@-t
> diff --git a/test-data/phony-guests/fedora.c
b/test-data/phony-guests/fedora.c
> new file mode 100644
> index 0000000000..36eaa233fc
> --- /dev/null
> +++ b/test-data/phony-guests/fedora.c
> @@ -0,0 +1,67 @@
> +/* libguestfs test images
> + * Copyright (C) 2009-2020 Red Hat Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.
> + */
> +
> +/* This is "just enough" of a binary to look like RPM and
dracut, as
> + * far as virt-v2v is concerned.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <assert.h>
> +
> +/* NB: This is also defined in make-fedora-img.pl */
> +#define KVER "5.19.0-0.rc1.14.fc37.x86_64"
> +
> +static const char *
> +basename (const char *str)
> +{
> +  const char *ret = strrchr (str, '/');
> +  return ret == NULL ? str : ret + 1;
> +}
> +
> +int
> +main (int argc, char *argv[])
> +{
> +  if (argc == 3 &&
> +      strcmp (basename (argv[0]), "rpm") == 0 &&
> +      strcmp (argv[1], "-ql") == 0 &&
> +      strncmp (argv[2], "kernel-", 7) == 0) {
> +    /* XXX These files and directories actually exist.  It would be
> +     * better to list files in /boot and /lib/modules matching a
> +     * pattern rather than hard-coding the list here, which duplicates
> +     * information in make-fedora-img.pl.
> +     */
> +    printf ("/boot/vmlinuz-" KVER "\n");
> +    printf ("/lib/modules/" KVER "\n");
> +    printf ("/lib/modules/" KVER "/kernel\n");
> +    printf ("/lib/modules/" KVER "/kernel/drivers\n");
> +    printf ("/lib/modules/" KVER
"/kernel/drivers/block\n");
> +    printf ("/lib/modules/" KVER
"/kernel/drivers/block/virtio_blk.ko\n");
> +  }
> +  else if (argc >= 1 &&
> +           strcmp (basename (argv[0]), "dracut") == 0) {
> +    // do nothing, pretend to rebuild the initramfs
> +  }
> +  else {
> +    fprintf (stderr, "phony Fedora: unknown command\n");
> +    exit (1);
> +  }
> +
> +  exit (0);
> +}
> diff --git a/test-data/phony-guests/make-fedora-img.pl
b/test-data/phony-guests/make-fedora-img.pl
> index f340f4d744..ad30960fa3 100755
> --- a/test-data/phony-guests/make-fedora-img.pl
> +++ b/test-data/phony-guests/make-fedora-img.pl
> @@ -240,6 +240,7 @@ $g->mount ($bootdev, '/boot');
>  $g->mkdir ('/bin');
>  $g->mkdir ('/etc');
>  $g->mkdir ('/etc/sysconfig');
> +$g->mkdir ('/sbin');
>  $g->mkdir ('/usr');
>  $g->mkdir ('/usr/share');
>  $g->mkdir ('/usr/share/zoneinfo');
> @@ -276,8 +277,17 @@ $g->upload
($ENV{SRCDIR}.'/../binaries/bin-x86_64-dynamic', '/bin/ls');
>  
>  $g->tar_in ($ENV{SRCDIR}.'/fedora-journal.tar.xz',
'/var/log/journal', compress => "xz");
>  
> +# NB: This is also defined in fedora.c
> +my $kver = "5.19.0-0.rc1.14.fc37.x86_64";
>  $g->mkdir ('/boot/grub');
> -$g->touch ('/boot/grub/grub.conf');
> +$g->write ('/boot/grub/grub.conf', <<EOF);
> +title Fedora
> +    root (hd0,0)
> +    kernel /vmlinuz-$kver
> +    initrd /initramfs-$kver.img
> +EOF
> +
> +$g->touch ('/etc/modprobe.conf');
>  
>  # Test files.
>  $g->write ('/etc/test1', 'abcdefg');
> @@ -300,6 +310,20 @@ $g->ln_s ('/bin/test1',
'/bin/test5');
>  $g->mkfifo (0777, '/bin/test6');
>  $g->mknod (0777, 10, 10, '/bin/test7');
>  
> +# Virt-v2v needs an RPM command, or at least something which acts
> +# similarly, and also a dracut command.
> +$g->upload ('fedora-static-bin', '/bin/rpm');
> +$g->chmod (0777, '/bin/rpm');
> +$g->upload ('fedora-static-bin', '/sbin/dracut');
> +$g->chmod (0777, '/sbin/dracut');
> +
> +# Virt-v2v also needs a kernel, initrd and modules path.
> +$g->touch ("/boot/vmlinuz-$kver");
> +$g->touch ("/boot/initramfs-$kver.img");
> +$g->mkdir_p ("/lib/modules/$kver/kernel/drivers/block");
> +$g->upload ($ENV{SRCDIR}.'/../binaries/bin-x86_64-dynamic',
> +           
"/lib/modules/$kver/kernel/drivers/block/virtio_blk.ko");
> +
>  # Cleanup
>  $g->shutdown ();
>  $g->close ();
> 
Looks OK to me, I just suggest using a different function name rather
than "basename". While the C code is certainly OK, conceptually we
already have two standard basename() functions, a POSIX compatible one
from <libgen.h>, and a glibc (_GNU_SOURCE) override.

(While looking for sources on this, I stumbled upon
<https://nanxiao.me/en/beware-of-using-gnu-ibc-basename-function/>, so
apparently the glibc override does exactly what your version does. So I
think we should either rename the internal basename() to something else,
or just use (= statically link) the _GNU_SOURCE variant from glibc).

With that:

Acked-by: Laszlo Ersek <lersek at redhat.com>


Thanks
Laszlo