prepare-testmachine-chroot

#!/bin/sh -x

. "$(dirname "$0")"/functions
. detect-environment
. compile-options

#
# This script sets up chroot environment for testing.
# It creates the directory structure and populates it with a minimal set of system files.
#
# The script can be run as follows:
# $ ./buildscripts/build-scripts/prepare-testmachine-chroot
#

# Path to file that will contain file-filtering rules for rsync.
TRANSFER_SCRIPT=$BASEDIR/prepare-testmachine-chroot-transfer-script.rsync

# Create the directory where the chroot environment is to be created.
# Don't lose the trailing slash!
CHROOT_ROOT=$HOME/testmachine-chroot/
sudo mkdir -p "$CHROOT_ROOT"

# Clean up previous chroot state by killing any processes that are using the CHROOT_ROOT directory.
sudo "$FUSER" -k "$CHROOT_ROOT" >/dev/null 2>&1 || true
# Unmount the /proc filesystem if it was previously mounted inside the chroot.
sudo umount "${CHROOT_ROOT}proc" >/dev/null 2>&1 || true

# Tell rsync not to touch the BASEDIR and PREFIX directories
echo "P $BASEDIR" >"$TRANSFER_SCRIPT"
echo "P $PREFIX" >>"$TRANSFER_SCRIPT"
# Generate the file-filter for rsync (see functions script)
generate_chroot_transfer_script >>"$TRANSFER_SCRIPT"

# Run a process in the background to print "Keep alive" every 60 seconds until the .keepalive-echo file exists.
# This is to prevent the session from timing out on a remote machine.
touch .keepalive-echo
(while test -e .keepalive-echo; do
    sleep 60
    echo Keep alive
done) &

RETURN_CODE=0
# Core file transfer command.
# -D is for copying device files as well.
# --delete to remove files in destination that are not present in source
# --delete-excluded to remove excluded files in destination
sudo rsync --filter=". $TRANSFER_SCRIPT" -Da --delete --delete-excluded / "$CHROOT_ROOT" || RETURN_CODE=$?

# Now we can stop the keep alive process
rm .keepalive-echo

# Return code 24 means "some files vanished before they could be transferred",
# which we don't care about, since a running system might experience this
# without it being an error.
if [ $RETURN_CODE -ne 0 ] && [ $RETURN_CODE -ne 24 ]; then
    exit $RETURN_CODE
fi

# Create and set permissions for essential directories inside chroot
for d in tmp var/tmp run root; do
    sudo mkdir -p "${CHROOT_ROOT}${d}"
done
sudo chmod 1777 "${CHROOT_ROOT}tmp"
sudo chmod 1777 "${CHROOT_ROOT}var/tmp"

# Safeguard to terminate operation if we have somehow ended up outside the
# chroot, so we don't start running unsafe tests there.
sudo touch "${CHROOT_ROOT}inside-chroot.txt"

# Trick in order to get a login command that starts out in the home dir instead of the root.
# See the login command for chroot in test-on-testmachine
sudo bash -c "cat > ${CHROOT_ROOT}run-in-home-dir.sh" <<EOF
#!/bin/sh -x
if [ ! -f /inside-chroot.txt ]; then
    echo Something is wrong. We should be inside the chroot now. Bailing...
    exit 2
fi
cd $HOME
EOF

# Include entire environment in chroot, and make sure everything is exported,
# and added to the existing environment.
# Split on newlines, not on spaces.
IFS='
'
for entry in $(export); do
    name=$(echo "$entry" | sed -e 's/^[^=]* //; s/^\([^=]*\)=.*/\1/')
    if [ "$name" = "PATH" ]; then
        # Skip the PATH variable as it's handled below
        continue
    fi
    value="$(echo "$entry" | sed -e 's/^[^=]*=//')"
    printf "%s=%s\nexport %s\n" "$name" "$value" "$name"
done | sudo sh -c "cat >> ${CHROOT_ROOT}run-in-home-dir.sh"
# Restore normal splitting semantics.
unset IFS

# Treat PATH specifically, and add to existing path.
# shellcheck disable=SC2016
printf 'PATH="%s:$PATH"\nexport PATH\n' "$PATH" | sudo sh -c "cat >> ${CHROOT_ROOT}run-in-home-dir.sh"

# Note different quote style on Here document.
sudo bash -c "cat >> ${CHROOT_ROOT}run-in-home-dir.sh" <<'EOF'
exec "$@"
EOF

# Make the run-in-home-dir.sh script executable
sudo chmod ugo+x "${CHROOT_ROOT}run-in-home-dir.sh"

# Creates the /proc mount point inside the chroot.
# This is done after the rsync because /proc is explicitly excluded in the filter rules.
# The /proc filesystem is typically mounted, not copied.
sudo mkdir -p "${CHROOT_ROOT}proc"

# Create a dummy /dev/random & /dev/urandom.
# For a fully functional chroot, these devices should be mounted.
if [ ! -e "${CHROOT_ROOT}dev" ]; then
    sudo mkdir -p "${CHROOT_ROOT}dev"
    sudo dd if=/dev/urandom of="${CHROOT_ROOT}dev/urandom" bs=1048576 count=10
    sudo dd if=/dev/urandom of="${CHROOT_ROOT}dev/random" bs=1048576 count=10

    if [ "$OS_FAMILY" = aix ]; then
        # This device is needed for the lscfg command to work on AIX.
        # We use that command to get number of cores in the detect-environment script.
        sudo mkdir -p "$CHROOT_ROOT"dev
        sudo cp -R /dev/nvram "$CHROOT_ROOT"dev/nvram
    fi
fi