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#!/bin/bash
# Copyright (c) 2012 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
# Saves the gdb index for a given binary and its shared library dependencies.
#
# This will run gdb index in parallel on a number of binaries using SIGUSR1
# as the communication mechanism to simulate a semaphore. Because of the
# nature of this technique, using "set -e" is very difficult. The SIGUSR1
# terminates a "wait" with an error which we need to interpret.
#
# When modifying this code, most of the real logic is in the index_one_file
# function. The rest is cleanup + sempahore plumbing.
function usage_exit {
echo "Usage: $0 [-f] [-r] [-n] <paths-to-binaries>..."
echo " -f forces replacement of an existing index."
echo " -r removes the index section."
echo " -n don't extract the dependencies of each binary with lld."
echo " e.g., $0 -n out/Debug/lib.unstripped/lib*"
echo
echo " Set TOOLCHAIN_PREFIX to use a non-default set of binutils."
exit 1
}
# Cleanup temp directory and ensure all child jobs are dead-dead.
function on_exit {
trap "" EXIT USR1 # Avoid reentrancy.
local jobs=$(jobs -p)
if [ -n "$jobs" ]; then
echo -n "Killing outstanding index jobs..."
kill -KILL $(jobs -p)
wait
echo "done"
fi
if [ -d "$directory" ]; then
echo -n "Removing temp directory $directory..."
rm -rf "$directory"
echo done
fi
}
# Add index to one binary.
function index_one_file {
local file=$1
local basename=$(basename "$file")
local should_index_this_file="${should_index}"
local readelf_out=$(${TOOLCHAIN_PREFIX}readelf -S "$file")
if [[ $readelf_out =~ "gdb_index" ]]; then
if $remove_index; then
${TOOLCHAIN_PREFIX}objcopy --remove-section .gdb_index "$file"
echo "Removed index from $basename."
else
echo "Skipped $basename -- already contains index."
should_index_this_file=false
fi
fi
if $should_index_this_file; then
local start=$(date +"%s%N")
echo "Adding index to $basename..."
${TOOLCHAIN_PREFIX}gdb -batch "$file" -ex "save gdb-index $directory" \
-ex "quit"
local index_file="$directory/$basename.gdb-index"
if [ -f "$index_file" ]; then
${TOOLCHAIN_PREFIX}objcopy --add-section .gdb_index="$index_file" \
--set-section-flags .gdb_index=readonly "$file" "$file"
local finish=$(date +"%s%N")
local elapsed=$(((finish - start) / 1000000))
echo " ...$basename indexed. [${elapsed}ms]"
else
echo " ...$basename unindexable."
fi
fi
}
# Functions that when combined, concurrently index all files in FILES_TO_INDEX
# array. The global FILES_TO_INDEX is declared in the main body of the script.
function async_index {
# Start a background subshell to run the index command.
{
index_one_file $1
kill -SIGUSR1 $$ # $$ resolves to the parent script.
exit 129 # See comment above wait loop at bottom.
} &
}
cur_file_num=0
function index_next {
if ((cur_file_num >= ${#files_to_index[@]})); then
return
fi
async_index "${files_to_index[cur_file_num]}"
((cur_file_num += 1)) || true
}
########
### Main body of the script.
remove_index=false
should_index=true
should_index_deps=true
files_to_index=()
while (($# > 0)); do
case "$1" in
-h)
usage_exit
;;
-f)
remove_index=true
;;
-r)
remove_index=true
should_index=false
;;
-n)
should_index_deps=false
;;
-*)
echo "Invalid option: $1" >&2
usage_exit
;;
*)
if [[ ! -f "$1" ]]; then
echo "Path $1 does not exist."
exit 1
fi
files_to_index+=("$1")
;;
esac
shift
done
if ((${#files_to_index[@]} == 0)); then
usage_exit
fi
dependencies=()
if $should_index_deps; then
for file in "${files_to_index[@]}"; do
# Append the shared library dependencies of this file that
# have the same dirname. The dirname is a signal that these
# shared libraries were part of the same build as the binary.
dependencies+=( \
$(ldd "$file" 2>/dev/null \
| grep $(dirname "$file") \
| sed "s/.*[ \t]\(.*\) (.*/\1/") \
)
done
fi
files_to_index+=("${dependencies[@]}")
# Ensure we cleanup on on exit.
trap on_exit EXIT INT
# We're good to go! Create temp directory for index files.
directory=$(mktemp -d)
echo "Made temp directory $directory."
# Start concurrent indexing.
trap index_next USR1
# 4 is an arbitrary default. When changing, remember we are likely IO bound
# so basing this off the number of cores is not sensible.
index_tasks=${INDEX_TASKS:-4}
for ((i = 0; i < index_tasks; i++)); do
index_next
done
# Do a wait loop. Bash waits that terminate due a trap have an exit
# code > 128. We also ensure that our subshell's "normal" exit occurs with
# an exit code > 128. This allows us to do consider a > 128 exit code as
# an indication that the loop should continue. Unfortunately, it also means
# we cannot use set -e since technically the "wait" is failing.
wait
while (($? > 128)); do
wait
done