1#!/bin/bash -e
2
3# Copyright 2017 Google Inc. All rights reserved.
4#
5# Licensed under the Apache License, Version 2.0 (the "License");
6# you may not use this file except in compliance with the License.
7# You may obtain a copy of the License at
8#
9#     http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS,
13# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14# See the License for the specific language governing permissions and
15# limitations under the License.
16
17# Script to handle the various ways soong may need to strip binaries
18# Inputs:
19#  Environment:
20#   CLANG_BIN: path to the clang bin directory
21#   CROSS_COMPILE: prefix added to readelf, objcopy tools
22#   XZ: path to the xz binary
23#  Arguments:
24#   -i ${file}: input file (required)
25#   -o ${file}: output file (required)
26#   -d ${file}: deps file (required)
27#   -k symbols: Symbols to keep (optional)
28#   --add-gnu-debuglink
29#   --keep-mini-debug-info
30#   --keep-symbols
31#   --keep-symbols-and-debug-frame
32#   --remove-build-id
33
34set -o pipefail
35
36OPTSTRING=d:i:o:k:-:
37
38usage() {
39    cat <<EOF
40Usage: strip.sh [options] -k symbols -i in-file -o out-file -d deps-file
41Options:
42        --add-gnu-debuglink             Add a gnu-debuglink section to out-file
43        --keep-mini-debug-info          Keep compressed debug info in out-file
44        --keep-symbols                  Keep symbols in out-file
45        --keep-symbols-and-debug-frame  Keep symbols and .debug_frame in out-file
46        --remove-build-id               Remove the gnu build-id section in out-file
47EOF
48    exit 1
49}
50
51do_strip() {
52    # GNU strip --strip-all does not strip .ARM.attributes,
53    # so we tell llvm-strip to keep it too.
54    "${CLANG_BIN}/llvm-strip" --strip-all --keep-section=.ARM.attributes "${infile}" -o "${outfile}.tmp"
55}
56
57do_strip_keep_symbols_and_debug_frame() {
58    REMOVE_SECTIONS=`"${CLANG_BIN}/llvm-readelf" -S "${infile}" | awk '/.debug_/ {if ($2 != ".debug_frame") {print "--remove-section " $2}}' | xargs`
59    "${CLANG_BIN}/llvm-objcopy" "${infile}" "${outfile}.tmp" ${REMOVE_SECTIONS}
60}
61
62do_strip_keep_symbols() {
63    REMOVE_SECTIONS=`"${CLANG_BIN}/llvm-readelf" -S "${infile}" | awk '/.debug_/ {print "--remove-section " $2}' | xargs`
64    "${CLANG_BIN}/llvm-objcopy" "${infile}" "${outfile}.tmp" ${REMOVE_SECTIONS}
65}
66
67do_strip_keep_symbol_list() {
68    echo "${symbols_to_keep}" | tr ',' '\n' > "${outfile}.symbolList"
69
70    KEEP_SYMBOLS="--strip-unneeded-symbol=* --keep-symbols="
71    KEEP_SYMBOLS+="${outfile}.symbolList"
72    "${CROSS_COMPILE}objcopy" -w "${infile}" "${outfile}.tmp" ${KEEP_SYMBOLS}
73}
74
75do_strip_keep_mini_debug_info() {
76    rm -f "${outfile}.dynsyms" "${outfile}.funcsyms" "${outfile}.keep_symbols" "${outfile}.debug" "${outfile}.mini_debuginfo" "${outfile}.mini_debuginfo.xz"
77    local fail=
78    "${CLANG_BIN}/llvm-strip" --strip-all --keep-section=.ARM.attributes --remove-section=.comment "${infile}" -o "${outfile}.tmp" || fail=true
79
80    if [ -z $fail ]; then
81        # Current prebult llvm-objcopy does not support --only-keep-debug flag,
82        # and cannot process object files that are produced with the flag. Use
83        # GNU objcopy instead for now. (b/141010852)
84        "${CROSS_COMPILE}objcopy" --only-keep-debug "${infile}" "${outfile}.debug"
85        "${CLANG_BIN}/llvm-nm" -D "${infile}" --format=posix --defined-only 2> /dev/null | awk '{ print $1 }' | sort >"${outfile}.dynsyms"
86        "${CLANG_BIN}/llvm-nm" "${infile}" --format=posix --defined-only | awk '{ if ($2 == "T" || $2 == "t" || $2 == "D") print $1 }' | sort > "${outfile}.funcsyms"
87        comm -13 "${outfile}.dynsyms" "${outfile}.funcsyms" > "${outfile}.keep_symbols"
88        echo >> "${outfile}.keep_symbols" # Ensure that the keep_symbols file is not empty.
89        "${CROSS_COMPILE}objcopy" --rename-section .debug_frame=saved_debug_frame "${outfile}.debug" "${outfile}.mini_debuginfo"
90        "${CROSS_COMPILE}objcopy" -S --remove-section .gdb_index --remove-section .comment --keep-symbols="${outfile}.keep_symbols" "${outfile}.mini_debuginfo"
91        "${CROSS_COMPILE}objcopy" --rename-section saved_debug_frame=.debug_frame "${outfile}.mini_debuginfo"
92        "${XZ}" "${outfile}.mini_debuginfo"
93
94        "${CLANG_BIN}/llvm-objcopy" --add-section .gnu_debugdata="${outfile}.mini_debuginfo.xz" "${outfile}.tmp"
95        rm -f "${outfile}.dynsyms" "${outfile}.funcsyms" "${outfile}.keep_symbols" "${outfile}.debug" "${outfile}.mini_debuginfo" "${outfile}.mini_debuginfo.xz"
96    else
97        cp -f "${infile}" "${outfile}.tmp"
98    fi
99}
100
101do_add_gnu_debuglink() {
102    "${CLANG_BIN}/llvm-objcopy" --add-gnu-debuglink="${infile}" "${outfile}.tmp"
103}
104
105do_remove_build_id() {
106    "${CLANG_BIN}/llvm-strip" --remove-section=.note.gnu.build-id "${outfile}.tmp" -o "${outfile}.tmp.no-build-id"
107    rm -f "${outfile}.tmp"
108    mv "${outfile}.tmp.no-build-id" "${outfile}.tmp"
109}
110
111while getopts $OPTSTRING opt; do
112    case "$opt" in
113        d) depsfile="${OPTARG}" ;;
114        i) infile="${OPTARG}" ;;
115        o) outfile="${OPTARG}" ;;
116        k) symbols_to_keep="${OPTARG}" ;;
117        -)
118            case "${OPTARG}" in
119                add-gnu-debuglink) add_gnu_debuglink=true ;;
120                keep-mini-debug-info) keep_mini_debug_info=true ;;
121                keep-symbols) keep_symbols=true ;;
122                keep-symbols-and-debug-frame) keep_symbols_and_debug_frame=true ;;
123                remove-build-id) remove_build_id=true ;;
124                *) echo "Unknown option --${OPTARG}"; usage ;;
125            esac;;
126        ?) usage ;;
127        *) echo "'${opt}' '${OPTARG}'"
128    esac
129done
130
131if [ -z "${infile}" ]; then
132    echo "-i argument is required"
133    usage
134fi
135
136if [ -z "${outfile}" ]; then
137    echo "-o argument is required"
138    usage
139fi
140
141if [ -z "${depsfile}" ]; then
142    echo "-d argument is required"
143    usage
144fi
145
146if [ ! -z "${keep_symbols}" -a ! -z "${keep_mini_debug_info}" ]; then
147    echo "--keep-symbols and --keep-mini-debug-info cannot be used together"
148    usage
149fi
150
151if [ ! -z "${keep_symbols}" -a ! -z "${keep_symbols_and_debug_frame}" ]; then
152    echo "--keep-symbols and --keep-symbols-and-debug-frame cannot be used together"
153    usage
154fi
155
156if [ ! -z "${keep_mini_debug_info}" -a ! -z "${keep_symbols_and_debug_frame}" ]; then
157    echo "--keep-symbols-mini-debug-info and --keep-symbols-and-debug-frame cannot be used together"
158    usage
159fi
160
161if [ ! -z "${symbols_to_keep}" -a ! -z "${keep_symbols}" ]; then
162    echo "--keep-symbols and -k cannot be used together"
163    usage
164fi
165
166if [ ! -z "${add_gnu_debuglink}" -a ! -z "${keep_mini_debug_info}" ]; then
167    echo "--add-gnu-debuglink cannot be used with --keep-mini-debug-info"
168    usage
169fi
170
171rm -f "${outfile}.tmp"
172
173if [ ! -z "${keep_symbols}" ]; then
174    do_strip_keep_symbols
175elif [ ! -z "${symbols_to_keep}" ]; then
176    do_strip_keep_symbol_list
177elif [ ! -z "${keep_mini_debug_info}" ]; then
178    do_strip_keep_mini_debug_info
179elif [ ! -z "${keep_symbols_and_debug_frame}" ]; then
180    do_strip_keep_symbols_and_debug_frame
181else
182    do_strip
183fi
184
185if [ ! -z "${add_gnu_debuglink}" ]; then
186    do_add_gnu_debuglink
187fi
188
189if [ ! -z "${remove_build_id}" ]; then
190    do_remove_build_id
191fi
192
193rm -f "${outfile}"
194mv "${outfile}.tmp" "${outfile}"
195
196cat <<EOF > "${depsfile}"
197${outfile}: \
198  ${infile} \
199  ${CROSS_COMPILE}objcopy \
200  ${CLANG_BIN}/llvm-nm \
201  ${CLANG_BIN}/llvm-objcopy \
202  ${CLANG_BIN}/llvm-readelf \
203  ${CLANG_BIN}/llvm-strip
204
205EOF
206