Workaround for #1630

get-signal.sh

#!/bin/sh
#
# (c)2018 Christian Kujau <lists@nerdbynature.de>
#
# A (far too complicated) script to get the Ubuntu package of
# Signal on a non-Debian based Desktop.
#
# Packages for rpm-based linux distributions like Fedora #1630 
# https://github.com/signalapp/Signal-Desktop/issues/1630
#
BASEURL=https://updates.signal.org/desktop/apt
   DIST=dists/xenial

# Kill it with fire
_die() {
	echo "$@"
	exit 1
}

case $1 in
	download)
	TEMP=$(mktemp -d)
	;;

	install)
	[ -d "$2" ] && TEMP="$2" || TEMP=$(mktemp -d)
	INSTALL=1
	;;

	*)
	_die "Usage: $(basename $0) [download|install] || [install] (DIR)"
	;;
esac

cd "$TEMP" || _die "Could not change to directory $TEMP"

# Download & verify the InRelease file
if [ ! -f InRelease ]; then
	curl -sLO "$BASEURL"/"$DIST"/InRelease	|| _die "Failed to download InRelease"
fi
gpg --verify InRelease				|| _die "Signature verification failed"
SHA256=$(grep -A5 ^SHA256 InRelease | awk '/main\/binary-amd64\/Packages.bz2/ {print $1}')

# Download & verify the Packages.bz2 file
if [ ! -f Packages.bz2 ]; then
	curl -sLO "$BASEURL"/"$DIST"/main/binary-amd64/Packages.bz2 \
						|| _die "Failed to download Packages.bz2"
fi
sha256sum Packages.bz2 | grep -q $SHA256	|| _die "Checksum verification of Packages.bz2 failed"

echo "### Available versions:"
bzip2 -dc Packages.bz2  | grep ^Version | sort -n && echo

# Try to find out the newest version
VER=$(bzip2 -dc Packages.bz2  | awk '/^Version:/ {print $NF}' | sort -n | head -1)

# There must be a better way to do this...
bzip2 -dc Packages.bz2 | grep -m1 -A20 'Package: signal-desktop-beta' | \
	awk '/^Filename/ || /^Version/ || /SHA256/ {print $2}' | xargs echo | while read v f s; do
	#	echo "### DEBUG: v: $v f: $f s: $s"
		[ $v = $VER ]					|| continue
		echo "### Downloading ${f}..."
		if [ ! -f "$(basename "$f")" ]; then
			curl -LO "$BASEURL"/"$f"		|| _die "Failed to download package"
		fi
		sha256sum signal-desktop*amd64.deb | grep -q $s || _die "Checksum verification of package failed"
done

# Extract the data part of the Debian package 
ar x signal-desktop*amd64.deb data.tar.xz || _die "Package extraction failed"

# Install
if [ "$INSTALL" = 1 ]; then
	echo "### Installing in /opt/Signal Beta..."
	sudo rm -r "/opt/Signal Beta.old"
	sudo mv -v "/opt/Signal Beta" "/opt/Signal Beta.old"
	sudo tar -C /                                   -xJf data.tar.xz ./opt
	     tar -C / --transform="s|usr|$HOME/.local|" -xJf data.tar.xz ./usr/share/icons/
	sudo chown -R root:root "/opt/Signal Beta"
	sudo ln -svf "/opt/Signal Beta/signal-desktop-beta" /usr/local/bin/signal-desktop-beta
	rm -r InRelease Packages.bz2 signal-desktop*amd64.deb data.tar.xz "$TEMP"
else
	echo "Files can be found in "$TEMP""
	exit 0
fi