build/gdb-add-index

   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.
  17 function 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.
  36 function index_one_file {
  37   local file=$1
  38   local basename=$(basename "$file")
  39   local should_index="${SHOULD_INDEX}"
  40
  41   local readelf_out=$(${TOOLCHAIN_PREFIX}readelf -S "$file")
  42   if [[ $readelf_out =~ "gdb_index" ]]; then
  43     if [ "${REMOVE_INDEX}" = 1 ]; then
  44       ${TOOLCHAIN_PREFIX}objcopy --remove-section .gdb_index "$file"
  45       echo "Removed index from $basename."
  46     else
  47       echo "Skipped $basename -- already contains index."
  48       should_index=0
  49     fi
  50   fi
  51
  52   if [ "${should_index}" = 1 ]; then
  53     local start=$(date +"%s%N")
  54     echo "Adding index to $basename..."
  55
  56     ${TOOLCHAIN_PREFIX}gdb -batch "$file" -ex "save gdb-index $DIRECTORY" \
  57       -ex "quit"
  58     local index_file="$DIRECTORY/$basename.gdb-index"
  59     if [ -f "$index_file" ]; then
  60       ${TOOLCHAIN_PREFIX}objcopy --add-section .gdb_index="$index_file" \
  61         --set-section-flags .gdb_index=readonly "$file" "$file"
  62       local finish=$(date +"%s%N")
  63       local elapsed=$(((finish - start)/1000000))
  64       echo "   ...$basename indexed. [${elapsed}ms]"
  65     else
  66       echo "   ...$basename unindexable."
  67     fi
  68   fi
  69 }
  70
  71 # Functions that when combined, concurrently index all files in FILES_TO_INDEX
  72 # array. The global FILES_TO_INDEX is declared in the main body of the script.
  73 function async_index {
  74   # Start a background subshell to run the index command.
  75   {
  76     index_one_file $1
  77     kill -SIGUSR1 $$  # $$ resolves to the parent script.
  78     exit 129  # See comment above wait loop at bottom.
  79   } &
  80 }
  81
  82 CUR_FILE_NUM=0
  83 function index_next {
  84   if (( CUR_FILE_NUM >= ${#FILES_TO_INDEX[@]} )); then
  85     return
  86   fi
  87
  88   async_index "${FILES_TO_INDEX[CUR_FILE_NUM]}"
  89   ((CUR_FILE_NUM += 1)) || true
  90 }
  91
  92
  93 ########
  94 ### Main body of the script.
  95
  96 REMOVE_INDEX=0
  97 SHOULD_INDEX=1
  98 while getopts ":f:r" opt; do
  99   case $opt in
 100     f)
 101       REMOVE_INDEX=1
 102       shift
 103       ;;
 104     r)
 105       REMOVE_INDEX=1
 106       SHOULD_INDEX=0
 107       shift
 108       ;;
 109     *)
 110       echo "Invalid option: -$OPTARG" >&2
 111       ;;
 112   esac
 113 done
 114
 115 if [[ ! $# == 1 ]]; then
 116   echo "Usage: $0 [-f] [-r] path-to-binary"
 117   echo "  -f forces replacement of an existing index."
 118   echo "  -r removes the index section."
 119   exit 1
 120 fi
 121
 122 FILENAME="$1"
 123 if [[ ! -f "$FILENAME" ]]; then
 124   echo "Path $FILENAME does not exist."
 125   exit 1
 126 fi
 127
 128 # Ensure we cleanup on on exit.
 129 trap on_exit EXIT
 130
 131 # We're good to go! Create temp directory for index files.
 132 DIRECTORY=$(mktemp -d)
 133 echo "Made temp directory $DIRECTORY."
 134
 135 # Create array with the filename and all shared libraries that
 136 # have the same dirname. The dirname is a signal that these
 137 # shared libraries were part of the same build as the binary.
 138 declare -a FILES_TO_INDEX=($FILENAME
 139  $(ldd "$FILENAME" 2>/dev/null \
 140   | grep $(dirname "$FILENAME") \
 141   | sed "s/.*[ \t]\(.*\) (.*/\1/")
 142 )
 143
 144 # Start concurrent indexing.
 145 trap index_next USR1
 146
 147 # 4 is an arbitrary default. When changing, remember we are likely IO bound
 148 # so basing this off the number of cores is not sensible.
 149 INDEX_TASKS=${INDEX_TASKS:-4}
 150 for ((i=0;i<${INDEX_TASKS};i++)); do
 151   index_next
 152 done
 153
 154 # Do a wait loop. Bash waits that terminate due a trap have an exit
 155 # code > 128. We also ensure that our subshell's "normal" exit occurs with
 156 # an exit code > 128. This allows us to do consider a > 128 exit code as
 157 # an indication that the loop should continue. Unfortunately, it also means
 158 # we cannot use set -e since technically the "wait" is failing.
 159 wait
 160 while (( $? > 128 )); do
 161   wait
 162 done