pacman/scripts/libmakepkg/tidy/strip.sh.in

#!/bin/bash
#
#   strip.sh - Strip debugging symbols from binary files
#
#   Copyright (c) 2007-2024 Pacman Development Team <pacman-dev@lists.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/>.
#

[[ -n "$LIBMAKEPKG_TIDY_STRIP_SH" ]] && return
LIBMAKEPKG_TIDY_STRIP_SH=1

MAKEPKG_LIBRARY=${MAKEPKG_LIBRARY:-'@libmakepkgdir@'}

source "$MAKEPKG_LIBRARY/util/message.sh"
source "$MAKEPKG_LIBRARY/util/option.sh"


packaging_options+=('strip' 'debug')
tidy_modify+=('tidy_strip')


build_id() {
	LANG=C readelf -n "$1" | sed -n '/Build ID/ { s/.*: //p; q; }'
}

source_files() {
	# This function does two things:
	#
	# 1) rewrites source file locations for packages not respecting prefix-
	#    map switches.  This ensures all source file references in debug
	#    info point to $dbgsrcdir.
	#
	# 2) outputs a list of files from the package source files to stdout
	#    while stripping the $dbgsrcdir prefix

	LANG=C debugedit --no-recompute-build-id \
		--base-dir "${srcdir}" \
		--dest-dir "${dbgsrcdir}" \
		--list-file /dev/stdout "$1" \
		| sort -zu | tr '\0' '\n'
}

package_source_files() {
	local binary=$1

	local file dest t
	while IFS= read -r t; do
		file="${srcdir}/${t}"
		dest="${dbgsrc}/${t}"
		mkdir -p "${dest%/*}"
		if [[ -f "$file" && ! -f "$dest" ]]; then
			cp -- "$file" "$dest" 2>/dev/null
		fi
	done < <(source_files "$binary")
}

safe_objcopy() {
	local binary=$1; shift
	local tempfile=$(mktemp "$binary.XXXXXX")
	objcopy "$@" "$binary" "$tempfile"
	cat "$tempfile" > "$binary"
	rm "$tempfile"
}

collect_debug_symbols() {
	local binary=$1; shift

	if check_option "debug" "y"; then
		local bid=$(build_id "$binary")

		# has this file already been stripped
		if [[ -n "$bid" ]]; then
			if [[ -f "$dbgdir/.build-id/${bid:0:2}/${bid:2}.debug" ]]; then
				return
			fi
		elif [[ -f "$dbgdir/$binary.debug" ]]; then
			return
		fi

		# copy source files to debug directory
		package_source_files "$binary"

		# copy debug symbols to debug directory
		mkdir -p "$dbgdir/${binary%/*}"

		# abandon processing files that are not a recognised format
		if ! objcopy --only-keep-debug "$binary" "$dbgdir/$binary.debug" 2>/dev/null; then
			return
		fi

		safe_objcopy "$binary" --remove-section=.gnu_debuglink
		safe_objcopy "$binary" --add-gnu-debuglink="$dbgdir/${binary#/}.debug"

		if [[ -n "$bid" ]]; then
			local target
			mkdir -p "$dbgdir/.build-id/${bid:0:2}"

			target="../../../../../${binary#./}"
			target="${target/..\/..\/usr\/lib\/}"
			target="${target/..\/usr\/}"
			ln -s "$target" "$dbgdir/.build-id/${bid:0:2}/${bid:2}"

			target="../../${binary#./}.debug"
			ln -s "$target" "$dbgdir/.build-id/${bid:0:2}/${bid:2}.debug"
		fi
	fi
}

safe_strip_file(){
	local binary=$1; shift
	local tempfile=$(mktemp "$binary.XXXXXX")
	if strip "$@" "$binary" -o "$tempfile"; then
		cat "$tempfile" > "$binary"
	fi
	rm -f "$tempfile"
}

safe_strip_lto() {
	local binary=$1;

	local tempfile=$(mktemp "$binary.XXXXXX")
	if strip -R .gnu.lto_* -R .gnu.debuglto_* -N __gnu_lto_v1 "$binary" -o "$tempfile"; then
		cat "$tempfile" > "$binary"
	fi
	rm -f "$tempfile"
}

process_file_stripping() {
	local binary="$1"
	local strip_flags

	# skip filepaths that cause stripping issues - ideally these should be temporary
	# guile-2.2
	[[ "$binary" =~ .*/guile/.*\.go$ ]] && return

	local STATICOBJ=0
	case "$(LC_ALL=C readelf -h "$binary" 2>/dev/null)" in
		*Type:*'DYN (Shared object file)'*) # Libraries (.so) or Relocatable binaries
			strip_flags="$STRIP_SHARED";;
		*Type:*'DYN (Position-Independent Executable file)'*) # Relocatable binaries
			strip_flags="$STRIP_SHARED";;
		*Type:*'EXEC (Executable file)'*) # Binaries
			if [[ "$(readelf -x .dynamic "$binary" 2>/dev/null)" ]]; then
				strip_flags="$STRIP_BINARIES"
			else
				strip_flags="$STRIP_STATIC"
			fi
			;;
		*Type:*'REL (Relocatable file)'*) # Libraries (.a) or objects
			if [[ $binary = *'.o' ]] || ar t "$binary" &>/dev/null; then
				strip_flags="$STRIP_STATIC"
				STATICOBJ=1
			elif [[ $binary = *'.ko' ]]; then # Kernel modules
				strip_flags="$STRIP_SHARED"
			else
				return
			fi
			;;
		*)
			return ;;
	esac
	(( ! STATICOBJ )) && collect_debug_symbols "$binary"
	safe_strip_file "$binary" ${strip_flags}
	(( STATICOBJ )) && safe_strip_lto "$binary"
}

tidy_strip() {
	if check_option "strip" "y"; then
		msg2 "$(gettext "Stripping unneeded symbols from binaries and libraries...")"
		# make sure library stripping variables are defined to prevent excess stripping
		[[ -z ${STRIP_SHARED+x} ]] && STRIP_SHARED="-S"
		[[ -z ${STRIP_STATIC+x} ]] && STRIP_STATIC="-S"

		if check_option "debug" "y"; then
			dbgdir="$pkgdirbase/$pkgbase-@DEBUGSUFFIX@/usr/lib/debug"
			dbgsrcdir="${DBGSRCDIR:-/usr/src/debug}/${pkgbase}"
			dbgsrc="$pkgdirbase/$pkgbase-@DEBUGSUFFIX@$dbgsrcdir"
			mkdir -p "$dbgdir" "$dbgsrc"
		fi

		_parallel_stripper() {
			# Inherit traps in subshell to perform cleanup after an interrupt
			set -E
			(
				local jobs binary

				while IFS= read -rd '' binary ; do
					# Be sure to keep the number of concurrently running processes less
					# than limit value to prevent an accidental fork bomb.
					jobs=($(jobs -p))
					(( ${#jobs[@]} >= $NPROC )) && wait -n "${jobs[@]}"

					process_file_stripping "$binary" &
				done < <(find . -type f -perm -u+w -links 1 -print0 2>/dev/null)

				# Wait for all jobs to complete
				wait
			)
			set +E
		}
		_parallel_stripper

		# hardlinks only need processed once, but need additional links in debug packages
		declare -A hardlinks
		while IFS= read -rd '' binary ; do
			if check_option "debug" "y"; then
				local inode="$(@INODECMD@ -- "$binary")"
				inode=${inode%% *}
				if [[ -z "${hardlinks[$inode]}" ]]; then
					hardlinks[$inode]="$binary"
				else
					if [[ -f "$dbgdir/${hardlinks[$inode]}.debug" ]]; then
						mkdir -p "$dbgdir/${binary%/*}"
						ln "$dbgdir/${hardlinks[$inode]}.debug" "$dbgdir/${binary}.debug"
						continue
					fi
				fi
			fi
			process_file_stripping "$binary"
		done < <(find . -type f -perm -u+w -links +1 -print0 2>/dev/null | LC_ALL=C sort -z)

	elif check_option "debug" "y"; then
		msg2 "$(gettext "Copying source files needed for debug symbols...")"

		dbgsrcdir="${DBGSRCDIR:-/usr/src/debug}/${pkgbase}"
		dbgsrc="$pkgdirbase/$pkgbase/$dbgsrcdir"
		mkdir -p "$dbgsrc"

		local binary
		find . -type f -perm -u+w -print0 2>/dev/null | while IFS= read -rd '' binary ; do
			package_source_files "$binary" 2>/dev/null
		done
	fi
}