update-checksums.sh

#!/bin/bash
# Author: Emil Lundberg <lundberg.emil@gmail.com>
#
# This script runs 'makepkg -g' on a copy of PKGBUILD where all if/elif/else/fi
# statements have been removed, and then uses sed to replace the old checksums
# in PKGBUILD with the new ones. The original PKGBUILD is backed up to
# PKGBUILD.bak.
#
# The script assumes that all checksums in the original PKGBUILD are strings of
# 32 or more hexadecimal characters ([0-9a-f], greedy), and that all such
# strings are checksums. 'SKIP' checksums are not updated.
#
# Note that since this script works by replacing checksum strings with new
# values, it only updates existing checksums. If a source file has no checksum
# specified, it will not be given one by this script.

if [[ $0 == '/bin/bash' ]]; then
	echo "It looks like you're sourcing this script."
	echo "Please execute it directly instead, lest it clutter your shell with variables."
	return 1
fi

grep -vE "^[[:space:]]*(if|elif|else|fi)" PKGBUILD > PKGBUILD.geninteg

# Compute the new checksums
newsums=( )
for l in $(makepkg -g -p PKGBUILD.geninteg | grep -oE "[0-9a-f]{32,}"); do
	newsums+=("$l")
done

rm PKGBUILD.geninteg

# Find the old checksums
oldsums=( )
for l in $(grep -oE "[0-9a-f]{32,}|SKIP" PKGBUILD); do
	oldsums+=("$l")
done

# Update the checksums in PKGBUILD
echo "Updating checksums..."
SCRIPT_NAME=$0.sed
for i in ${!oldsums[@]}; do
	if [ "${oldsums[i]}" == 'SKIP' ]; then
		echo 'SKIP > SKIP'
	else
		echo "${oldsums[i]} > ${newsums[i]}"
		echo "s/${oldsums[i]}/${newsums[i]}/" >> $SCRIPT_NAME
	fi
done

sed -i.bak -f $SCRIPT_NAME PKGBUILD && rm $SCRIPT_NAME

echo "Verifying correctness..."
makepkg --verifysource