Package: libgdbm6
Version: 1.18.1-3
Severity: serious
Control: block 923238 with -1
GDBM databases created on stretch (gdbm 1.8.3-14) are not
compatible with libgdbm in sid/buster (1.18.1-3) on at least
the i386 (32-bit x86) architecture, probably also armhf.
This means that any local user databases will break on upgrade from
stretch to buster. It also breaks a few Debian packages that use GDBM
files (known affected are libmarc-charset-perl and command-not-found).
Bug #910911 discussed a similar problem that applied to all architectures.
It seems probable that the fix for that never worked on i386 but this
was just not detected earlier. The incompatibility was reported recently
in bug #923238 and was found because Ubuntu has a better architecture
coverage on their autopkgtest setup.
Below are steps to reproduce, testing with Python 2, Python 3, and Perl.
We make a trivial GDBM database with each, containing just one key "foo"
with the value "bar". After upgrading to buster on i386, none of these
databases can be read and "Malformed database file header" is reported.
On amd64, everything works fine after the upgrade.
# start from stretch
# apt install python-gdbm python3-gdbm perl
python - <<'EOF'
import gdbm
gdbm.open("py2-stretch.gdbm", "c")["foo"] = "bar"
EOF
python3 <<'EOF'
import dbm.gnu
dbm.gnu.open("py3-stretch.gdbm", "c")["foo"] = "bar"
EOF
perl <<'EOF'
use GDBM_File;
tie %h, q(GDBM_File), "perl-stretch.gdbm", &GDBM_WRCREAT, 0640
or die "opening GDBM file failed: $!";
$h{foo} = "bar"
EOF
# ls -l *.gdbm
-rw-r----- 1 root root 12294 Mar 2 19:04 perl-stretch.gdbm
-rw-r--r-- 1 root root 12294 Mar 2 19:04 py2-stretch.gdbm
-rw-r--r-- 1 root root 12294 Mar 2 19:04 py3-stretch.gdbm
# upgrade to buster
# sed -i s/stretch/buster/ /etc/apt/sources.list && apt update && apt
dist-upgrade && apt install gdbmtool
# test with gdbmtool
# gdbmtool py2-stretch.gdbm fetch foo
gdbmtool: stdin:1.1-10: cannot open database py2-stretch.gdbm: Malformed
database file header
# gdbmtool py3-stretch.gdbm fetch foo
gdbmtool: stdin:1.1-10: cannot open database py3-stretch.gdbm: Malformed
database file header
# gdbmtool perl-stretch.gdbm fetch foo
gdbmtool: stdin:1.1-10: cannot open database perl-stretch.gdbm: Malformed
database file header
# similar results with any of these:
perl <<'EOF'
use GDBM_File;
tie %h, q(GDBM_File), "perl-stretch.gdbm", &GDBM_READER, 0640
or die "opening GDBM file failed: $!";
print $h{foo}, "\n";
EOF
python <<'EOF'
import gdbm
print(gdbm.open("py2-stretch.gdbm", "r")["foo"])
EOF
python3 <<'EOF'
import dbm.gnu
print(dbm.gnu.open("py3-stretch.gdbm", "r")["foo"])
EOF
--
Niko Tyni nt...@debian.org
