1#!/bin/bash 2# Copyright (c) 2012 The Chromium Authors. All rights reserved. 3# Use of this source code is governed by a BSD-style license that can be 4# found in the LICENSE file. 5# 6# Saves the gdb index for a given binary and its shared library dependencies. 7# 8# This will run gdb index in parallel on a number of binaries using SIGUSR1 9# as the communication mechanism to simulate a semaphore. Because of the 10# nature of this technique, using "set -e" is very difficult. The SIGUSR1 11# terminates a "wait" with an error which we need to interpret. 12# 13# When modifying this code, most of the real logic is in the index_one_file 14# function. The rest is cleanup + sempahore plumbing. 15 16# Cleanup temp directory and ensure all child jobs are dead-dead. 17function on_exit { 18 trap "" EXIT USR1 # Avoid reentrancy. 19 20 local jobs=$(jobs -p) 21 if [ -n "$jobs" ]; then 22 echo -n "Killing outstanding index jobs..." 23 kill -KILL $(jobs -p) 24 wait 25 echo "done" 26 fi 27 28 if [ -f "$DIRECTORY" ]; then 29 echo -n "Removing temp directory $DIRECTORY..." 30 rm -rf $DIRECTORY 31 echo done 32 fi 33} 34 35# Add index to one binary. 36function index_one_file { 37 local file=$1 38 local basename=$(basename "$file") 39 40 local readelf_out=$(readelf -S "$file") 41 if [[ $readelf_out =~ "gdb_index" ]]; then 42 echo "Skipped $basename -- already contains index." 43 else 44 local start=$(date +"%s%N") 45 echo "Adding index to $basename..." 46 47 gdb -batch "$file" -ex "save gdb-index $DIRECTORY" -ex "quit" 48 local index_file="$DIRECTORY/$basename.gdb-index" 49 if [ -f "$index_file" ]; then 50 objcopy --add-section .gdb_index="$index_file" \ 51 --set-section-flags .gdb_index=readonly "$file" "$file" 52 local finish=$(date +"%s%N") 53 local elappsed=$(((finish - start)/1000000)) 54 echo " ...$basename indexed. [${elappsed}ms]" 55 else 56 echo " ...$basename unindexable." 57 fi 58 fi 59} 60 61# Functions that when combined, concurrently index all files in FILES_TO_INDEX 62# array. The global FILES_TO_INDEX is declared in the main body of the script. 63function async_index { 64 # Start a background subshell to run the index command. 65 { 66 index_one_file $1 67 kill -SIGUSR1 $$ # $$ resolves to the parent script. 68 exit 129 # See comment above wait loop at bottom. 69 } & 70} 71 72CUR_FILE_NUM=0 73function index_next { 74 if (( CUR_FILE_NUM >= ${#FILES_TO_INDEX[@]} )); then 75 return 76 fi 77 78 async_index "${FILES_TO_INDEX[CUR_FILE_NUM]}" 79 ((CUR_FILE_NUM += 1)) || true 80} 81 82 83######## 84### Main body of the script. 85 86if [[ ! $# == 1 ]]; then 87 echo "Usage: $0 path-to-binary" 88 exit 1 89fi 90 91FILENAME="$1" 92if [[ ! -f "$FILENAME" ]]; then 93 echo "Path $FILENAME does not exist." 94 exit 1 95fi 96 97# Ensure we cleanup on on exit. 98trap on_exit EXIT 99 100# We're good to go! Create temp directory for index files. 101DIRECTORY=$(mktemp -d) 102echo "Made temp directory $DIRECTORY." 103 104# Create array with the filename and all shared libraries that 105# have the same dirname. The dirname is a signal that these 106# shared libraries were part of the same build as the binary. 107declare -a FILES_TO_INDEX=($FILENAME 108 $(ldd "$FILENAME" 2>/dev/null \ 109 | grep $(dirname "$FILENAME") \ 110 | sed "s/.*[ \t]\(.*\) (.*/\1/") 111) 112 113# Start concurrent indexing. 114trap index_next USR1 115 116# 4 is an arbitrary default. When changing, remember we are likely IO bound 117# so basing this off the number of cores is not sensible. 118INDEX_TASKS=${INDEX_TASKS:-4} 119for ((i=0;i<${INDEX_TASKS};i++)); do 120 index_next 121done 122 123# Do a wait loop. Bash waits that terminate due a trap have an exit 124# code > 128. We also ensure that our subshell's "normal" exit occurs with 125# an exit code > 128. This allows us to do consider a > 128 exit code as 126# an indication that the loop should continue. Unfortunately, it also means 127# we cannot use set -e since technically the "wait" is failing. 128wait 129while (( $? > 128 )); do 130 wait 131done 132