scripts/llvm-objcopy-wrapper

#!/bin/bash
# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (c) 2019, Linaro Limited
#
# This is a wrapper script to llvm-objcopy to add support for:
#  - The --pad-to argument
#  - Regular expressions in --only-section= and --remove-section
#  - Creating empty output files when no section match
#  - Allowing removal of sections that are referenced by some other sections
#    by default (--allow-broken-links).
#
# Depends on llvm-readelf.

args=("--allow-broken-links") # llvm-objcopy >= 9.0
only_section_re=()
remove_section_re=()
for arg in "$@"; do
	if [ "$pad_found" ]; then
		pad_addr="$arg"
		pad_found=
		continue
	fi
	case "$arg" in
		--pad-to)
			pad_found=1
			continue
			;;
		--only-section=*)
			re=$(echo "$arg" | sed s/--only-section=//)
			only_section_re+=("$re")
			continue
			;;
		--remove-section=*)
			re=$(echo "$arg" | sed s/--remove-section=//)
			remove_section_re+=("$re")
			continue
			;;
	esac
	args+=("$arg")
done

in="${@: -2:1}"
out="${@: -1:1}"
if [ ! -e "$in" ]; then
	in=$out # That is good enough for our use cases
fi

if [ '${only_section_re[@]}''${remove_section_re[@]}' ]; then
	sections=$(llvm-readelf -sections $in | grep ' *\[ *[0-9]*] [^ ]' | sed 's/ *\[ *[0-9]*] \(.[^ ]*\).*/\1/')
	for s in $sections; do
		for re in "${only_section_re[@]}"; do
			if [ "$(echo $s | grep -- $re)" != "" ]; then
				args+=("--only-section=$s")
				break
			fi
		done
		for re in "${remove_section_re[@]}"; do
			if [ "$(echo $s | grep -- $re)" != "" ]; then
				args+=("--remove-section=$s")
				break
			fi
		done
	done
fi

pad_sz=0
if [ "$pad_addr" ]; then

	# Find address and size of last PROGBITS section in input file
	addr_sz=$(llvm-readelf -sections $in | grep PROGBITS | sed 's/.*PROGBITS *\([^ ]*\) [^ ]* \([^ ]*\).*/\1 \2/' | sort -n | tail -1)
	read addr sz <<< "$addr_sz"

	# Now figure out the size of the padding. Can be 0.
	pad_sz=$(($pad_addr - 0x$addr - 0x$sz))
fi

# Run llvm-objcopy without "--pad-to <addr>" and with expanded
# --only-section/--remove-section
if [ "$VV" = 1 ]; then
	echo Running: llvm-objcopy "${args[@]}"
fi
llvm-objcopy "${args[@]}" || exit $?

# Pad with zeroes if necessary
if [ $pad_sz -gt 0 ]; then
	truncate -s +$pad_sz $out
fi