add ldconfig.fakechroot and translate symlinks for bit-by-bit identical buildd variant

This commit is contained in:
Johannes Schauer Marin Rodrigues 2021-09-16 16:23:46 +02:00
parent b3e08897c3
commit 6d59d51a4a
Signed by untrusted user: josch
GPG key ID: F2CBA5C78FBD83E1
3 changed files with 127 additions and 20 deletions

View file

@ -96,6 +96,13 @@ if [ ! -e shared/proxysolver ] || [ proxysolver -nt shared/proxysolver ]; then
cp -a /usr/lib/apt/solvers/mmdebstrap-dump-solution shared/proxysolver
fi
fi
if [ ! -e shared/ldconfig.fakechroot ] || [ ldconfig.fakechroot -nt shared/ldconfig.fakechroot ]; then
if [ -e ./ldconfig.fakechroot ]; then
cp -a ldconfig.fakechroot shared
else
cp -a /usr/libexec/mmdebstrap/ldconfig.fakechroot shared/ldconfig.fakechroot
fi
fi
mkdir -p shared/hooks
if [ ! -e shared/hooks/setup00-merged-usr.sh ] || [ hooks/setup00-merged-usr.sh -nt shared/hooks/setup00-merged-usr.sh ]; then
if [ -e hooks/setup00-merged-usr.sh ]; then
@ -754,8 +761,10 @@ fi
runuser -u user -- $CMD --mode=unshare --variant=$variant $DEFAULT_DIST /tmp/debian-chroot-unshare.$format $mirror
cmp /tmp/debian-chroot-root.$format /tmp/debian-chroot-unshare.$format
rm /tmp/debian-chroot-unshare.$format
case $variant in essential|apt|minbase)
# /etc/ld.so.cache differs with some variants
case $variant in essential|apt|minbase|buildd)
# variants important and standard differ because permissions drwxr-sr-x
# and extended attributes of ./var/log/journal/ cannot be preserved
# in fakechroot mode
runuser -u user -- $CMD --mode=fakechroot --variant=$variant $DEFAULT_DIST /tmp/debian-chroot-fakechroot.$format $mirror
cmp /tmp/debian-chroot-root.$format /tmp/debian-chroot-fakechroot.$format
rm /tmp/debian-chroot-fakechroot.$format

111
ldconfig.fakechroot Executable file
View file

@ -0,0 +1,111 @@
#!/usr/bin/env python3
#
# This script is in the public domain
#
# Author: Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>
#
# This is command substitution for ldconfig under fakechroot:
#
# export FAKECHROOT_CMD_SUBST=/sbin/ldconfig=/path/to/ldconfig.fakechroot
#
# Statically linked binaries cannot work with fakechroot and thus have to be
# replaced by either /bin/true or a more clever solution like this one. The
# ldconfig command supports the -r option which allows passing a chroot
# directory for ldconfig to work in. This can be used to run ldconfig without
# fakechroot but still let it create /etc/ld.so.cache inside the chroot.
#
# Since absolute symlinks are broken without fakechroot to translate them,
# we read /etc/ld.so.conf and turn all absolute symlink shared libraries into
# relative ones. At program exit, the original state is restored.
import os
import sys
import subprocess
import atexit
import glob
from pathlib import Path
symlinks = []
def restore_symlinks():
for (link, target, atime, mtime) in symlinks:
link.unlink()
link.symlink_to(target)
os.utime(link, times=None, ns=(atime, mtime), follow_symlinks=False)
atexit.register(restore_symlinks)
def get_libdirs(chroot, configs):
res = []
for conf in configs:
for line in (Path(conf)).read_text().splitlines():
line = line.strip()
if not line:
continue
if line.startswith("#"):
continue
if line.startswith("include "):
assert line.startswith("include /")
res.extend(
get_libdirs(chroot, chroot.glob(line.removeprefix("include /")))
)
continue
assert line.startswith("/"), line
line = line.lstrip("/")
if not (chroot / Path(line)).is_dir():
continue
for f in (chroot / Path(line)).iterdir():
if not f.is_symlink():
continue
linktarget = f.readlink()
# make sure that the linktarget is an absolute path inside the
# chroot
if not str(linktarget).startswith("/"):
continue
if chroot not in linktarget.parents:
continue
# store original link so that we can restore it later
symlinks.append(
(f, linktarget, f.lstat().st_atime_ns, f.lstat().st_mtime_ns)
)
# replace absolute symlink by relative link
relative = os.path.relpath(linktarget, f.parent)
f.unlink()
f.symlink_to(relative)
return res
def main():
if "FAKECHROOT_BASE_ORIG" not in os.environ:
print("FAKECHROOT_BASE_ORIG is not set", file=sys.stderr)
print(
"must be executed under fakechroot using FAKECHROOT_CMD_SUBST",
file=sys.stderr,
)
sys.exit(1)
chroot = Path(os.environ["FAKECHROOT_BASE_ORIG"])
if not (chroot / "sbin" / "ldconfig").exists():
sys.exit(0)
(chroot / "var" / "cache" / "ldconfig").mkdir(
mode=0o700, parents=True, exist_ok=True
)
for d in get_libdirs(chroot, [chroot / "etc" / "ld.so.conf"]):
make_relative(d)
# we add any additional arguments before "-r" such that any other "-r"
# option will be overwritten by the one we set
subprocess.check_call(
[chroot / "sbin" / "ldconfig"] + sys.argv[1:] + ["-r", chroot]
)
if __name__ == "__main__":
main()

View file

@ -2660,28 +2660,15 @@ sub run_prepare {
# /etc/fakechroot/debootstrap.env and
# /etc/fakechroot/chroot.env
{
# we add "$@" before "-r" such that any other "-r" options will be
# overwritten by the one we set
my $escapedroot = shellescape $options->{root};
my ($fh, $filename) = tempfile(
"mmdebstrap.ldconfig.XXXXXXXXXXXX",
UNLINK => 1,
TMPDIR => 1
);
print $fh <<EOF;
#!/bin/sh
set -e
if [ ! -e $escapedroot/sbin/ldconfig ]; then exit 0; fi
mkdir --mode=700 --parents $escapedroot/var/cache/ldconfig
$escapedroot/sbin/ldconfig "\$@" -r $escapedroot
EOF
close $fh;
chmod 0755, $filename or error "cannot chmod $filename";
my $ldconfig = getcwd() . '/ldconfig.fakechroot';
if (!-x $ldconfig) {
$ldconfig = '/usr/libexec/mmdebstrap/ldconfig.fakechroot';
}
my @fakechrootsubst = ();
foreach my $d ('/usr/sbin', '/usr/bin', '/sbin', '/bin') {
push @fakechrootsubst, "$d/chroot=/usr/sbin/chroot.fakechroot";
push @fakechrootsubst, "$d/mkfifo=/bin/true";
push @fakechrootsubst, "$d/ldconfig=$filename";
push @fakechrootsubst, "$d/ldconfig=$ldconfig";
push @fakechrootsubst, "$d/ldd=/usr/bin/ldd.fakechroot";
push @fakechrootsubst, "$d/ischroot=/bin/true";
}