oss-fuzz/infra/base-images/base-builder/compile_afl

#!/bin/bash -eu
# Copyright 2016 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
################################################################################

# Temporarily disable randomization and enforce a safe and sane setup
export AFL_SKIP_OSSFUZZ=1
export AFL_LLVM_INSTRUMENT=CLASSIC

# In emergencies where afl++'s own compiler fails set this to "1":
export AFL_LLVM_MODE_WORKAROUND=0

# AFL++ setup
echo "Copying precompiled AFL++"

# Copy AFL++ tools necessary for fuzzing.
pushd $SRC/aflplusplus > /dev/null

cp -f libAFLDriver.a $LIB_FUZZING_ENGINE

# Some important projects include libraries, copy those even when they don't
# start with "afl-". Use "sort -u" to avoid a warning about duplicates.
ls afl-* *.txt *.a *.o *.so | sort -u | xargs cp -t $OUT
export CC="$SRC/aflplusplus/afl-clang-fast"
export CXX="$SRC/aflplusplus/afl-clang-fast++"

# Set sane AFL++ environment defaults:
# Be quiet, otherwise this can break some builds.
export AFL_QUIET=1
# No leak errors during builds.
export ASAN_OPTIONS="detect_leaks=0:symbolize=0:detect_odr_violation=0:abort_on_error=1"
# Do not abort on any problems (because this is during build where it is ok)
export AFL_IGNORE_PROBLEMS=1
# No complain on unknown AFL environment variables
export AFL_IGNORE_UNKNOWN_ENVS=1

# To analyze build failures and set specific AFL++ settings, set
# `export AFL_SKIP_OSSFUZZ=1`
# The 'env|grep' setup ensures we do not trigger the linter.
env | egrep -q '^AFL_SKIP_OSSFUZZ=' || {

  # The variables need to be set to "1" here - or before running this script.
  # AFL++ configuration options.
  export AFL_ENABLE_DICTIONARY=0
  export AFL_ENABLE_CMPLOG=1
  export AFL_LAF_CHANCE=5

  #
  # AFL++ compile option roulette. It is OK if they all happen together.
  #

  # 20% chance for CTX-2 coverage instrumentation (Caller conTeXt sensitive
  # edge coverage).
  test $(($RANDOM % 100)) -lt 20 && {
    export AFL_LLVM_INSTRUMENT=CLASSIC,CTX-2
    export AFL_ENABLE_CMPLOG=0
    # we increase the chance for LAF because we do not do CMPLOG with CTX
    export AFL_LAF_CHANCE=20
  }

  # 40% chance to create a dictionary.
  test $(($RANDOM % 100)) -lt 40 && {
    export AFL_ENABLE_DICTIONARY=1
  }

  # 60% chance to perform CMPLOG/REDQUEEN.
  rm -f "$OUT/afl_cmplog.txt"
  test "$AFL_ENABLE_CMPLOG" = "1" -a $(($RANDOM % 100)) -lt 60 && {
    export AFL_LLVM_CMPLOG=1
    touch "$OUT/afl_cmplog.txt"
  }

  # chance to perform COMPCOV/LAF_INTEL - if CMPLOG is not enabled.
  test $(($RANDOM % 100)) -lt $AFL_LAF_CHANCE -a "$AFL_ENABLE_CMPLOG" = "0" && {
    export AFL_LLVM_LAF_ALL=1
  }

  #
  # End of AFL++ compile option roulette
  #

  # Create a dictionary if one is wanted.
  test "$AFL_ENABLE_DICTIONARY" = "1" && {
    export AFL_LLVM_DICT2FILE="$OUT/afl++.dict"
  }

}

# In case afl-clang-fast ever breaks, this is a workaround:
test "$AFL_LLVM_MODE_WORKAROUND" = "1" && {
  export CC=clang
  export CXX=clang++
  WORKAROUND_FLAGS=-fsanitize-coverage=trace-pc-guard
  # We can still do CMPLOG light:
  test -e "$OUT/afl_cmplog.txt" && {
    WORKAROUND_FLAGS="$WORKAROUND_FLAGS",trace-cmp
  }
  export CFLAGS="$CFLAGS $WORKAROUND_FLAGS"
  export CXXFLAGS="$CXXFLAGS $WORKAROUND_FLAGS"
  unset AFL_LLVM_LAF_ALL
  unset AFL_LLVM_DICT2FILE
  unset AFL_ENABLE_DICTIONARY
  # We need to create a new fuzzer lib however.
  ar ru libAFLDrivernew.a afl-compiler-rt.o utils/aflpp_driver/aflpp_driver.o
  cp -f libAFLDrivernew.a $LIB_FUZZING_ENGINE
}

# Provide a way to document the AFL++ options used in this build:
echo
echo AFL++ target compilation setup:
env | egrep '^AFL_' | tee "$OUT/afl_options.txt"
echo

popd > /dev/null

echo " done."