#!/bin/bash
#
# updpkgsums - update source checksums in-place in PKGBUILDs
#
# Copyright (C) 2012-2013 Dave Reisner <dreisner@archlinux.org>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

shopt -s extglob

declare -r myname='updpkgsums'
declare -r myver='@PACKAGE_VERSION@'

usage() {
	printf "%s (pacman) v%s\n" "${myname}" "${myver}"
	echo
	printf "%s will perform an in place update of the checksums in the\n" "${myname}"
	echo "path specified by [build file], defaulting to PKGBUILD in the current"
	echo "working directory."
	echo
	printf "Usage: %s [build file]\n" "${myname}"
	echo
	echo "    -h, --help        display this help message and exit"
	echo "    -V, --version     display version information and exit"
}

version() {
	printf "%s %s\n" "$myname" "$myver"
	echo 'Copyright (C) 2012-2013 Dave Reisner <dreisner@archlinux.org>'
}

case $1 in
	-h|--help) usage; exit ;;
	-V|--version) version; exit ;;
esac

buildfile=${1:-PKGBUILD}
if [[ ! -f $buildfile ]]; then
	printf "==> ERROR: %s not found or is not a file\n" "$buildfile"
	exit 1
fi

# Resolve any symlinks to avoid replacing the symlink with a file. But, we
# have to do this portably -- readlink's flags are inconsistent across OSes.
while [[ -L $buildfile ]]; do
	buildfile=$(readlink "$buildfile")
	if [[ $buildfile = */* ]]; then
		cd "${buildfile%/*}"
		buildfile=${buildfile##*/}
	fi
done

# cd into the directory with the build file. This avoids creating random src/
# directories scattered about the filesystem, and avoids cases where we might
# not be able to write in the $PWD.
if [[ $buildfile = */* ]]; then
	cd "${buildfile%/*}"
	buildfile=${buildfile##*/}
fi

# Check $PWD/ for permission to unlink the $buildfile and write a new one
if [[ ! -w . ]]; then
	printf "==> ERROR: No write permission in '%s'\n" "$PWD"
	exit 1
fi

{
	# Generate the new sums and try to unlink the file before writing stdin back
	# into it. This final precaution shouldn't fail based on the previous checks,
	# but it's better to be extra careful before unlinking files.
	newsums=$(makepkg -g -p "$buildfile") && rm -f "$buildfile" &&
	exec awk -v newsums="$newsums" '
	/^[[:blank:]]*(md|sha)[[:digit:]]+sums=/,/\)[[:blank:]]*(#.*)?$/ {
		if (!w) {
			print newsums
			w++
		}
		next
	}

	1
	END { if (!w) print newsums }
	' > "$buildfile"
} < "$buildfile"

# vim: set ts=2 sw=2 noet: