mkdeb

#!/bin/bash
# Copyright 2015 The Project Buendia Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License.  You may obtain a copy
# of the License at: http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software distrib-
# uted under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
# OR CONDITIONS OF ANY KIND, either express or implied.  See the License for
# specific language governing permissions and limitations under the License.

set -e
output="$1"; shift
control="$1"; shift

if [ "$1" = "" ]; then
    cat <<EOF
Usage: $0 <output.deb> <control-dir> <data-dir> [<data-dir> ...]

Builds a Debian package at the specified output path, given the files to
install arranged under the given <data-dir> and the control files in
<control-dir>.  If more than one <data-dir> is specified, all files under
them are included; you must ensure that their contents do not collide.

If <control-dir> contains any files named *.template, they are rendered
(e.g. foo.template renders to produce foo) by performing bash-style parameter
expansion, command substitution, and arithmetic expansion.  These are
all the shell expansions triggered by the "\$" character: \$VAR and \${VAR}
expand to environment variables, \$(command) expands to the output of a
shell command, and \$((expression)) evaluates an arithmetic expression.

EOF
    exit 1
fi

tmp=/tmp/make_package.$$
trap 'rm -rf $tmp' EXIT

rm -rf $tmp
mkdir -p $tmp
TAR=$(which gtar || which tar)  # we prefer GNU tar for the --owner flag

# If --owner and --group are supported, use them.
touch $tmp/dummy.txt
if $TAR cf $tmp/dummy.tar --owner=0 --group=0 $tmp/dummy.txt 2>/dev/null; then
    function append_to_tar_with_uid_0() {
        dest="$1"
        input_root="$2"
        $TAR rvf "$dest" --owner=0 --group=0 -C "$input_root" .
    }
else
    # If --format=mtree is supported, use that to set owners and groups.
    if $TAR cf - --format=mtree $tmp | grep -q '/dummy.txt.*type=file'; then
        function append_to_tar_with_uid_0() {
            dest="$1"
            input_root="$2"
            $TAR cf - --format=mtree -C "$input_root" . | \
                sed -e 's/ .* \(type=[a-z]*\).*/ uid=0 gid=0 \1/' | \
                $TAR rvf "$dest" -C "$input_root" @-
        }
    else
        echo "$TAR doesn't support setting file owners or groups."
        echo "Please install GNU tar."
        exit 1
    fi
fi

# Copy the control files into a temporary directory.
mkdir -p $tmp/control
cp -pr $control/* $tmp/control

# Apply bash expansion to any *.template files.
for i in $tmp/control/*.template; do
    if [ -f $i ]; then
        result=${i%.template}
        cp $i $result  # copy permissions
        cat <(echo 'cat <<EOF') $i <(echo 'EOF') | bash > $result
        # Copy the timestamps from the original file, so that the resulting
        # data.tar remains exactly identical if none of the input files have
        # changed.  This lets us use diffdeb to detect meaningful changes.
        touch -r $i $result
        rm $i
    fi
done

# Set each directory's timestamp to the timestamp of the newest file within,
# giving deterministic timetsamps so that the resulting data.tar remains
# exactly identical if none of the input files have changed.
(
    unset CLICOLOR
    unset CLICOLOR_FORCE
    unset LSCOLORS
    unset LS_COLORS
    for dir in $(find $tmp -type d | sort -r); do
        cd $dir
        touch -r "$(command ls -1t | head -1)" .
    done
)

# Pack up the Debian package.
append_to_tar_with_uid_0 $tmp/control.tar $tmp/control
while [ -n "$1" ]; do
    append_to_tar_with_uid_0 $tmp/data.tar "$1"
    shift
done
gzip $tmp/control.tar $tmp/data.tar
echo 2.0 > $tmp/debian-binary
mkdir -p $(dirname "$output")
ar -r $output $tmp/debian-binary $tmp/control.tar.gz $tmp/data.tar.gz
echo "$output OK ($(echo $(wc -c < "$output")) bytes)"