release 1.5.0

CHANGELOG.md

@@ -1,3 +1,8 @@
+1.5.0 (2024-05-14)
+------------------
+
+ - add --format=ext4
+
 1.4.3 (2024-02-01)
 ------------------
 

coverage.py

@@ -34,7 +34,7 @@ all_variants = [
     "standard",
 ]
 default_format = "auto"
-all_formats = ["auto", "directory", "tar", "squashfs", "ext2", "null"]
+all_formats = ["auto", "directory", "tar", "squashfs", "ext2", "ext4", "null"]
 
 mirror = os.getenv("mirror", "http://127.0.0.1/debian")
 hostarch = subprocess.check_output(["dpkg", "--print-architecture"]).decode().strip()

coverage.txt

@@ -59,7 +59,7 @@ Needs-QEMU: true
 Test: mmdebstrap
 Needs-Root: true
 Modes: root
-Formats: tar squashfs ext2
+Formats: tar squashfs ext2 ext4
 Variants: essential apt minbase buildd - standard
 Skip-If:
  variant == "standard" and dist == "oldstable" # #864082, #1004557, #1004558
@@ -68,7 +68,7 @@ Skip-If:
 
 Test: check-for-bit-by-bit-identical-format-output
 Modes: unshare fakechroot
-Formats: tar squashfs ext2
+Formats: tar squashfs ext2 ext4
 Variants: essential apt minbase buildd - standard
 Skip-If:
  variant == "standard" and dist == "oldstable" # #864082, #1004557, #1004558

make_mirror.sh

@@ -33,7 +33,7 @@ deletecache() {
 		done
 		# deleting artifacts from test "mmdebstrap"
 		for variant in essential apt minbase buildd - standard; do
-			for format in tar ext2 squashfs; do
+			for format in tar ext2 ext4 squashfs; do
 				if [ -e "$dir/mmdebstrap-$dist-$variant.$format" ]; then
 					# attempt to delete for all dists because DEFAULT_DIST might've been different the last time
 					rm "$dir/mmdebstrap-$dist-$variant.$format"
@@ -453,7 +453,7 @@ if [ "$HAVE_QEMU" = "yes" ]; then
 	tmpdir="$(mktemp -d)"
 	trap 'kill "$PROXYPID" || :;cleanuptmpdir; cleanup_newcachedir' EXIT INT TERM
 
-	pkgs=perl-doc,systemd-sysv,perl,arch-test,fakechroot,fakeroot,mount,uidmap,qemu-user-static,qemu-user,dpkg-dev,mini-httpd,libdevel-cover-perl,libtemplate-perl,debootstrap,procps,apt-cudf,aspcud,python3,libcap2-bin,gpg,debootstrap,distro-info-data,iproute2,ubuntu-keyring,apt-utils,squashfs-tools-ng,genext2fs,linux-image-generic,passwd
+	pkgs=perl-doc,systemd-sysv,perl,arch-test,fakechroot,fakeroot,mount,uidmap,qemu-user-static,qemu-user,dpkg-dev,mini-httpd,libdevel-cover-perl,libtemplate-perl,debootstrap,procps,apt-cudf,aspcud,python3,libcap2-bin,gpg,debootstrap,distro-info-data,iproute2,ubuntu-keyring,apt-utils,squashfs-tools-ng,genext2fs,linux-image-generic,passwd,e2fsprogs,uuid-runtime
 	if [ ! -e ./mmdebstrap ]; then
 		pkgs="$pkgs,mmdebstrap"
 	fi

mmdebstrap

@@ -23,7 +23,7 @@
 use strict;
 use warnings;
 
-our $VERSION = '1.4.3';
+our $VERSION = '1.5.0';
 
 use English;
 use Getopt::Long;
@@ -46,6 +46,7 @@ use Socket;
 use Time::HiRes;
 use Math::BigInt;
 use Text::ParseWords;
+use Digest::SHA;
 use version;
 
 ## no critic (InputOutput::RequireBriefOpen)
@@ -66,13 +67,16 @@ use version;
 *MS_BIND    = \0x1000;
 *MS_REC     = \0x4000;
 *MNT_DETACH = \2;
+# uuid_t NameSpace_DNS in rfc4122
+*UUID_NS_DNS = \'6ba7b810-9dad-11d1-80b4-00c04fd430c8';
 our (
     $CLONE_NEWNS,                 $CLONE_NEWUTS,
     $CLONE_NEWIPC,                $CLONE_NEWUSER,
     $CLONE_NEWPID,                $CLONE_NEWNET,
     $_LINUX_CAPABILITY_VERSION_3, $CAP_SYS_ADMIN,
     $PR_CAPBSET_READ,             $MS_BIND,
-    $MS_REC,                      $MNT_DETACH
+    $MS_REC,                      $MNT_DETACH,
+    $UUID_NS_DNS
 );
 
 #<<<
@@ -216,10 +220,11 @@ sub minor {
 
 sub can_execute {
     my $tool    = shift;
+    my $verbose = shift // '--version';
     my $pid     = open my $fh, '-|' // return 0;
     if ($pid == 0) {
         open(STDERR, '>&', STDOUT) or die;
-        exec {$tool} $tool, '--version' or die;
+        exec {$tool} $tool, $verbose or die;
     }
     chomp(
         my $content = do { local $/; <$fh> }
@@ -303,6 +308,28 @@ sub shellescape {
     return "'$string'";
 }
 
+sub create_v5_uuid {
+    use bytes;
+    my $ns_uuid = shift;
+    my $name    = shift;
+    my $version = 0x50;
+    # convert the namespace uuid to binary
+    $ns_uuid =~ tr/-//d;
+    $ns_uuid = pack 'H*', $ns_uuid;
+    # concatenate namespace and name and take sha1
+    my $digest = Digest::SHA->new(1);
+    $digest->add($ns_uuid);
+    $digest->add($name);
+    # only the first 16 bytes matter
+    my $uuid = substr($digest->digest(), 0, 16);
+    # set the version
+    substr $uuid, 6, 1, chr(ord(substr($uuid, 6, 1)) & 0x0f | $version);
+    substr $uuid, 8, 1, chr(ord(substr $uuid, 8, 1) & 0x3f | 0x80);
+    # convert binary back to uuid formatting
+    return join '-', map { unpack 'H*', $_ }
+      map { substr $uuid, 0, $_, '' } (4, 2, 2, 2, 6);
+}
+
 sub test_unshare_userns {
     my $verbose = shift;
 
@@ -4381,14 +4408,15 @@ sub guess_sources_format {
 
 sub approx_disk_usage {
     my $directory  = shift;
+    my $block_size = shift;
     info "approximating disk usage...";
     # the "du" utility reports different results depending on the underlying
     # filesystem, see https://bugs.debian.org/650077 for a discussion
     #
     # we use code similar to the one used by dpkg-gencontrol instead
     #
-    # Regular files are measured in number of 1024 byte blocks. All other
+    # Regular files are measured in number of $block_size byte blocks. All
-    # entries are assumed to take one block of space.
+    # other entries are assumed to take one block of space.
     #
     # We ignore /dev because depending on the mode, the directory might be
     # populated or not and we want consistent disk usage results independent
@@ -4412,8 +4440,8 @@ sub approx_disk_usage {
             return if exists $hardlink{"$dev:$ino"};
             # Track hardlinks to avoid repeated additions.
             $hardlink{"$dev:$ino"} = 1 if $nlink > 1;
-            # add file size in 1024 byte blocks, rounded up
+            # add file size in $block_size byte blocks, rounded up
-            $installed_size += int(((-s _) + 1024) / 1024);
+            $installed_size += int(((-s _) + $block_size) / $block_size);
         } else {
             # all other entries are assumed to only take up one block
             $installed_size += 1;
@@ -4805,7 +4833,7 @@ sub main() {
         $options->{format} = 'directory';
     }
     my @valid_formats
-      = ('auto', 'directory', 'tar', 'squashfs', 'ext2', 'null');
+      = ('auto', 'directory', 'tar', 'squashfs', 'ext2', 'ext4', 'null');
     if (none { $_ eq $options->{format} } @valid_formats) {
         error "invalid format. Choose from " . (join ', ', @valid_formats);
     }
@@ -5670,6 +5698,30 @@ sub main() {
             if ($exitstatus != 0) {
                 error "genext2fs failed with exit status: $exitstatus";
             }
+        } elsif ($options->{target} =~ /\.ext4$/) {
+            $options->{format} = 'ext4';
+            # check if the installed version of e2fsprogs supports tarballs on
+            # stdin
+            (undef, my $filename) = tempfile(
+                "mmdebstrap.ext4.XXXXXXXXXXXX",
+                OPEN   => 0,
+                TMPDIR => 1
+            );
+            # creating file to suppress message "Creating regular file ..."
+            { open my $fh, '>', $filename; }
+            open my $fh, '|-', 'mke2fs', '-q', '-F', '-o', 'Linux', '-T',
+              'ext4', '-b', '4096', '-d', '-', $filename,
+              '16384' // error "failed to fork(): $!";
+            # write 10240 null-bytes to mke2fs -- this represents an empty
+            # tar archive
+            print $fh ("\0" x 10240)
+              or error "cannot write to mke2fs process";
+            close $fh;
+            my $exitstatus = $?;
+            unlink $filename // die "cannot unlink $filename";
+            if ($exitstatus != 0) {
+                error "mke2fs failed with exit status: $exitstatus";
+            }
         } else {
             $options->{format} = 'directory';
         }
@@ -5687,21 +5739,30 @@ sub main() {
         info "ignoring target $options->{target} with null format";
     }
 
+    my $blocksize = -1;
     if ($options->{format} eq 'ext2') {
         if (!can_execute 'genext2fs') {
             error "need genext2fs for ext2 format";
         }
+        $blocksize = 1024;
+    } elsif ($options->{format} eq 'ext4') {
+        if (!can_execute 'mke2fs', '-V') {
+            error "need mke2fs for ext4 format";
+        }
+        $blocksize = 4096;
     } elsif ($options->{format} eq 'squashfs') {
         if (!can_execute 'tar2sqfs') {
             error "need tar2sqfs binary from the squashfs-tools-ng package";
         }
+        $blocksize = 1048576;
     }
 
-    if (any { $_ eq $options->{format} } ('tar', 'squashfs', 'ext2', 'null')) {
+    if (any { $_ eq $options->{format} }
+        ('tar', 'squashfs', 'ext2', 'ext4', 'null')) {
         if ($options->{format} ne 'null') {
             if (any { $_ eq $options->{variant} } ('extract', 'custom')
                   and $options->{mode} eq 'fakechroot') {
-                info "creating a tarball or squashfs image or ext2 image in"
+                info "creating a tarball, squashfs, ext2 or ext4 image in"
                   . " fakechroot mode might fail in extract and"
                   . " custom variants because there might be no tar inside the"
                   . " chroot";
@@ -5885,7 +5946,7 @@ sub main() {
     # If both the above assertion change, we can stop creating /dev entries as
     # well.
     my $devtar = '';
-    if (any { $_ eq $options->{format} } ('tar', 'squashfs', 'ext2')) {
+    if (any { $_ eq $options->{format} } ('tar', 'squashfs', 'ext2', 'ext4')) {
         foreach my $file (@devfiles) {
             my ($fname, $mode, $type, $linkname, $devmajor, $devminor)
               = @{$file};
@@ -5954,6 +6015,9 @@ sub main() {
         push @taropts, '--xattrs', '--xattrs-exclude=system.*';
     } elsif ($options->{format} eq "ext2") {
         warning "genext2fs does not support extended attributes";
+        warning "ext2 does not support sub-second precision timestamps";
+        warning "ext2 does not support timestamps beyond 2038 January 18";
+        warning "ext2 inode size of 128 prevents removing these limitations";
     } else {
         push @taropts, '--xattrs';
     }
@@ -6001,8 +6065,9 @@ sub main() {
         close $childsock;
 
         close $nblkreader;
-        if (!$options->{dryrun} && $options->{format} eq 'ext2') {
+        if (!$options->{dryrun} && any { $_ eq $options->{format} }
-            my $numblocks = approx_disk_usage($options->{root});
+            ('ext2', 'ext4')) {
+            my $numblocks = approx_disk_usage($options->{root}, $blocksize);
             print $nblkwriter "$numblocks\n";
             $nblkwriter->flush();
         }
@@ -6010,8 +6075,8 @@ sub main() {
 
         if ($options->{dryrun}) {
             info "simulate creating tarball...";
-        } elsif (any { $_ eq $options->{format} } ('tar', 'squashfs', 'ext2'))
+        } elsif (any { $_ eq $options->{format} }
-        {
+            ('tar', 'squashfs', 'ext2', 'ext4')) {
             info "creating tarball...";
 
             # redirect tar output to the writing end of the pipe so
@@ -6132,7 +6197,8 @@ sub main() {
 
     my $numblocks = 0;
     close $nblkwriter;
-    if (!$options->{dryrun} && $options->{format} eq 'ext2') {
+    if (!$options->{dryrun} && any { $_ eq $options->{format} }
+        ('ext2', 'ext4')) {
         $numblocks = <$nblkreader>;
         if (defined $numblocks) {
             chomp $numblocks;
@@ -6151,9 +6217,11 @@ sub main() {
         # nothing to do
     } elsif (any { $_ eq $options->{format} } ('directory', 'null')) {
         # nothing to do
-    } elsif ($options->{format} eq 'ext2' && $numblocks <= 0) {
+    } elsif ((any { $_ eq $options->{format} } ('ext2', 'ext4'))
+        && $numblocks <= 0) {
         # nothing to do because of invalid $numblocks
-    } elsif (any { $_ eq $options->{format} } ('tar', 'squashfs', 'ext2')) {
+    } elsif (any { $_ eq $options->{format} }
+        ('tar', 'squashfs', 'ext2', 'ext4')) {
         # we use eval() so that error() doesn't take this process down and
         # thus leaves the setup() process without a parent
         eval {
@@ -6162,8 +6230,8 @@ sub main() {
                     error "cannot copy to standard output: $!";
                 }
             } else {
-                if (   $options->{format} eq 'squashfs'
+                if (any { $_ eq $options->{format} }
-                    or $options->{format} eq 'ext2'
+                    ('squashfs', 'ext2', 'ext4')
                       or defined $tar_compressor) {
                     my @argv = ();
                     if ($options->{format} eq 'squashfs') {
@@ -6171,7 +6239,7 @@ sub main() {
                           '--quiet', '--no-skip', '--force',
                           '--exportable',
                           '--compressor', 'xz',
-                          '--block-size', '1048576',
+                          '--block-size', $blocksize,
                           $options->{target};
                     } elsif ($options->{format} eq 'ext2') {
                         if ($numblocks <= 0) {
@@ -6179,6 +6247,26 @@ sub main() {
                         }
                         push @argv, 'genext2fs', '-B', 1024, '-b', $numblocks,
                           '-i', '16384', '-a', '-', $options->{target};
+                    } elsif ($options->{format} eq 'ext4') {
+                        if ($numblocks <= 0) {
+                            error "invalid number of blocks: $numblocks";
+                        }
+                        push @argv, 'mke2fs', '-q', '-F', '-o', 'Linux', '-T',
+                          'ext4';
+                        if (exists $ENV{SOURCE_DATE_EPOCH}) {
+                            # if SOURCE_DATE_EPOCH was set, make the image
+                            # reproducible by setting a fixed uuid and
+                            # hash_seed
+                            my $uuid = create_v5_uuid(
+                                create_v5_uuid(
+                                    $UUID_NS_DNS, "mister-muffin.de"
+                                ),
+                                $mtime
+                            );
+                            push @argv, '-U', $uuid, '-E', "hash_seed=$uuid";
+                        }
+                        push @argv, '-b', $blocksize, '-d', '-',
+                          $options->{target}, $numblocks;
                     } elsif ($options->{format} eq 'tar') {
                         push @argv, @{$tar_compressor};
                     } else {
@@ -6200,8 +6288,8 @@ sub main() {
                           or error "Can't unblock signals: $!";
 
                         # redirect stdout to file or /dev/null
-                        if (   $options->{format} eq 'squashfs'
+                        if (any { $_ eq $options->{format} }
-                            or $options->{format} eq 'ext2') {
+                            ('squashfs', 'ext2', 'ext4')) {
                             open(STDOUT, '>', '/dev/null')
                               or error "cannot open /dev/null for writing: $!";
                         } elsif ($options->{format} eq 'tar') {
@@ -6282,7 +6370,7 @@ sub main() {
     if (any { $_ eq $options->{format} } ('directory')) {
         # nothing to do
     } elsif (any { $_ eq $options->{format} }
-        ('tar', 'squashfs', 'ext2', 'null')) {
+        ('tar', 'squashfs', 'ext2', 'ext4', 'null')) {
         if (!-e $options->{root}) {
             error "$options->{root} does not exist";
         }
@@ -6381,12 +6469,12 @@ can be disabled by choosing the empty string for I<SUITE>. See the section
 B<VARIANTS> for more information.
 
 The I<TARGET> option may either be the path to a directory, the path to a
-tarball filename, the path to a squashfs image, the path to an ext2 image, a
+tarball filename, the path to a squashfs image, the path to an ext2 or ext4
-FIFO, a character special device, or C<->.  The I<TARGET> option is optional if
+image, a FIFO, a character special device, or C<->.  The I<TARGET> option is
-no I<MIRROR> option is provided. If I<TARGET> is missing or if I<TARGET> is
+optional if no I<MIRROR> option is provided. If I<TARGET> is missing or if
-C<->, an uncompressed tarball will be sent to standard output. Without the
+I<TARGET> is C<->, an uncompressed tarball will be sent to standard output.
-B<--format> option, I<TARGET> will be used to choose the format. See the
+Without the B<--format> option, I<TARGET> will be used to choose the format.
-section B<FORMATS> for more information.
+See the section B<FORMATS> for more information.
 
 The I<MIRROR> option may either be provided as a URI, in apt one-line format,
 as a path to a file in apt's one-line or deb822-format, or C<->.  If no
@@ -6463,8 +6551,8 @@ information.
 =item B<--format>=I<name>
 
 Choose the output format. Valid format I<name>s are B<auto>, B<directory>,
-B<tar>, B<squashfs>, B<ext2> and B<null>. The default format is B<auto>. See
+B<tar>, B<squashfs>, B<ext2>, B<ext4> and B<null>. The default format is
-the section B<FORMATS> for more information.
+B<auto>. See the section B<FORMATS> for more information.
 
 =item B<--aptopt>=I<option>|I<file>
 
@@ -7043,6 +7131,7 @@ I<TARGET> equals C<->, or if I<TARGET> is a named pipe (fifo) or if I<TARGET>
 is a character special file, then the B<tar> format will be chosen. If
 I<TARGET> ends with C<.squashfs> or C<.sqfs>, then the B<squashfs> format will
 be chosen. If I<TARGET> ends with C<.ext2> then the B<ext2> format will be
+chosen. If I<TARGET> ends with C<.ext4> then the B<ext4> format will be
 chosen. If none of these conditions apply, the B<directory> format will be
 chosen.
 
@@ -7092,8 +7181,24 @@ with this format because C<genext2fs> can only write to a regular file. If you
 need your ext2 image be named C<->, then just explicitly pass the relative path
 to it like F<./->. To convert the result to an ext3 image, use C<tune2fs -O
 has_journal TARGET> and to convert it to ext4, use C<tune2fs -O
-extents,uninit_bg,dir_index,has_journal TARGET>. Since C<genext2fs> does not
+extents,uninit_bg,dir_index,has_journal TARGET>.
-support extended attributes, the resulting image will not contain them.
+
+B<CAUTION>: the ext2 format does not support timestamps beyond 2038 January 19,
+does not support sub-second precision timestamps and does not support extended
+attributes. Its inode size of 128 prevents adding these features with tune2fs
+later on.
+
+=item B<ext4>
+
+A temporary chroot directory will be created in C<$TMPDIR> or F</tmp> if
+C<$TMPDIR> is not set. A tarball of that directory will be piped to the
+C<mke2fs> utility, which will create an ext4 image that will be approximately
+90% full in I<TARGET>. The special I<TARGET> C<-> does not work with this
+format because C<mke2fs> can only write to a regular file. If you need your
+ext4 image be named C<->, then just explicitly pass the relative path to it
+like F<./->.  If C<SOURCE_DATE_EPOCH> is set, the filesystem UUID and hash_seed
+will be set to a UUID derived from SOURCE_DATE_EPOCH to create reproducible
+images.
 
 =item B<null>
 
@@ -7190,7 +7295,12 @@ B<--skip=tar-in/mknod>.
 =item B<tar-out> I<pathinside> I<outside.tar>
 
 Packs the path I<pathinside> from inside the chroot into a tarball, placing it
-into a certain location I<outside.tar> outside the chroot.
+into a certain location I<outside.tar> outside the chroot. To emulate behaviour
+of C<cp> and to provide control over the path which gets put into the tarball,
+a C<chdir()> is performed to the C<dirname()> of I<pathinside> and then the
+C<basename()> of I<pathinside> is packaged as a tarball. For example, if
+I<pathinside> is C</boot/.> then first a C<chdir()> into C</boot> will be
+performed before packing up the contents of C<.> inside C</boot>.
 
 =item B<download> I<fileinside> I<fileoutside>
 
@@ -7402,8 +7512,8 @@ Performs cleanup tasks, unless B<--skip=cleanup> is used:
 =item B<output>
 
 For formats other than B<directory>, pack up the temporary chroot directory
-into a tarball, ext2 image or squashfs image and delete the temporary chroot
+into a tarball, ext2 image, ext4 image or squashfs image and delete the
-directory.
+temporary chroot directory.
 
 If B<--skip=output/dev> is added, the resulting chroot will not contain the
 device nodes, directories and symlinks that B<debootstrap> creates but just
@@ -7738,7 +7848,7 @@ Limitations in comparison to debootstrap:
 =item * Some debootstrap options don't exist, namely:
 
 I<--second-stage>, I<--exclude>, I<--resolve-deps>, I<--force-check-gpg>,
-I<--merged-usr> and I<--no-merged-usr>
+I<--merged-usr>, I<--no-merged-usr> and I<--cache-dir>.
 
 =back
 

mmdebstrap-autopkgtest-build-qemu

@@ -361,6 +361,9 @@ fi
 
 EXT4_OFFSET_BYTES=$(( (FAT_OFFSET_SECTORS + FAT_SIZE_SECTORS) * 512))
 EXT4_OPTIONS="offset=$EXT4_OFFSET_BYTES,assume_storage_prezeroed=1"
+
+# the --no-mtab option to mount is a workaround for https://github.com/util-linux/util-linux/issues/2981
+# revert 8c0ddc32660ca4e98c988966251f9c05d6bcccef once it is no longer needed
 set -- "$@" \
 	"--customize-hook=download vmlinuz '$WORKDIR/kernel'" \
 	"--customize-hook=download initrd.img '$WORKDIR/initrd'" \

tests/missing-dev-sys-proc-inside-the-chroot

@@ -17,4 +17,8 @@ if [ "$(id -u)" -eq 0 ] && [ "{{ MODE }}" != "root" ] && [ "{{ MODE }}" != "auto
 	prefix="runuser -u ${SUDO_USER:-user} --"
 fi
 
-$prefix {{ CMD }} --mode={{ MODE }} --variant={{ VARIANT }} --include=dpkg,dash,diffutils,coreutils,libc-bin,sed {{ DIST }} /dev/null {{ MIRROR }}
+# creating /sbin manually because of #1071078
+$prefix {{ CMD }} --mode={{ MODE }} --variant={{ VARIANT }} \
+	--setup-hook='mkdir "$1/sbin"' \
+	--include=dpkg,dash,diffutils,coreutils,libc-bin,sed \
+	{{ DIST }} /dev/null {{ MIRROR }}

tests/mmdebstrap

@@ -5,15 +5,26 @@ export SOURCE_DATE_EPOCH={{ SOURCE_DATE_EPOCH }}
 
 [ "$(id -u)" -eq 0 ]
 [ {{ MODE }} = "root" ]
-case {{ FORMAT }} in tar|squashfs|ext2) : ;; *) exit 1;; esac
+case {{ FORMAT }} in tar|squashfs|ext2|ext4) : ;; *) exit 1;; esac
 
-{{ CMD }} --mode={{ MODE }} --variant={{ VARIANT }} {{ DIST }} ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.{{ FORMAT }} {{ MIRROR }}
+{{ CMD }} --mode={{ MODE }} --variant={{ VARIANT }} {{ DIST }} /tmp/mmdebstrap-{{ DIST }}-{{ VARIANT }}.{{ FORMAT }} {{ MIRROR }}
+# creating an ext4 image on a 9p filesystem produces different results compared
+# to creating it on a tmpfs or ext4 fs because 9p does not support discards and
+# even when running with -E nodiscard, the number of written bytes will differ
+# https://lore.kernel.org/linux-ext4/171484520952.2626447.2160419274451668597@localhost/T/#t
+mv /tmp/mmdebstrap-{{ DIST }}-{{ VARIANT }}.{{ FORMAT }} ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.{{ FORMAT }}
 if [ "{{ FORMAT }}" = tar ]; then
 	printf 'ustar ' | cmp --bytes=6 --ignore-initial=257:0 ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.tar -
 elif [ "{{ FORMAT }}" = squashfs ]; then
 	printf 'hsqs' | cmp --bytes=4 ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.squashfs -
 elif [ "{{ FORMAT }}" = ext2 ]; then
 	printf '\123\357' | cmp --bytes=2 --ignore-initial=1080:0 ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.ext2 -
+	printf '\000\000\000\000\000\000\000\000\000\000\000\000' | cmp --bytes=12 --ignore-initial=1116:0 ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.ext2 -
+elif [ "{{ FORMAT }}" = ext4 ]; then
+	printf '\123\357' | cmp --bytes=2 --ignore-initial=1080:0 ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.ext4 -
+	printf '\074\020\000\000\302\042\000\000\153\004\000\000' | cmp --bytes=12 --ignore-initial=1116:0 ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.ext4 -
+
+	[ "$(/sbin/blkid --match-tag UUID --output value ./cache/mmdebstrap-{{ DIST }}-{{ VARIANT }}.ext4)" = "$(uuidgen --sha1 --namespace="$(uuidgen --sha1 --namespace='@dns' --name mister-muffin.de)" --name $SOURCE_DATE_EPOCH)" ]
 else
 	echo "unknown format: {{ FORMAT }}" >&2
 	exit 1