#!/bin/bash -u
# Copyright 2018 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.
#
################################################################################
cd $OUT

if (( $# > 0 )); then
  FUZZ_TARGETS="$@"
else
  FUZZ_TARGETS="$(find . -maxdepth 1 -type f -executable -printf '%P\n')"
fi

DUMPS_DIR="$OUT/dumps"
FUZZER_STATS_DIR="$OUT/fuzzer_stats"
LOGS_DIR="$OUT/logs"
REPORT_ROOT_DIR="$OUT/report"
REPORT_PLATFORM_DIR="$OUT/report/linux"

for directory in $DUMPS_DIR $FUZZER_STATS_DIR $LOGS_DIR $REPORT_ROOT_DIR \
                 $REPORT_PLATFORM_DIR; do
  rm -rf $directory
  mkdir -p $directory
done

PROFILE_FILE="$DUMPS_DIR/merged.profdata"
SUMMARY_FILE="$REPORT_PLATFORM_DIR/summary.json"

# Use path mapping, as $SRC directory from the builder is copied into $OUT/$SRC.
PATH_EQUIVALENCE_ARGS="-path-equivalence=/,$OUT"

# It's important to use $COVERAGE_EXTRA_ARGS as the last argument, because it
# can contain paths to source files / directories which are positional args.
LLVM_COV_COMMON_ARGS="$PATH_EQUIVALENCE_ARGS \
    -ignore-filename-regex=.*src/libfuzzer/.* $COVERAGE_EXTRA_ARGS"

# Timeout for running a single fuzz target.
TIMEOUT=1h

# This will be used by llvm-cov command to generate the actual report.
objects=""

# Number of CPUs available, this is needed for running tests in parallel.
NPROC=$(nproc)

function run_fuzz_target {
  local target=$1

  # '%1m' will produce separate dump files for every object. For example, if a
  # fuzz target loads a shared library, we will have dumps for both of them.
  local profraw_file="$DUMPS_DIR/$target.%1m.profraw"
  local profraw_file_mask="$DUMPS_DIR/$target.*.profraw"
  local profdata_file="$DUMPS_DIR/$target.profdata"
  local corpus_real="/corpus/${target}"

  # -merge=1 requires an output directory, create a dummy dir for that.
  local corpus_dummy="$OUT/dummy_corpus_dir_for_${target}"
  rm -rf $corpus_dummy && mkdir -p $corpus_dummy

  # Use -merge=1 instead of -runs=0 because merge is crash resistant and would
  # let to get coverage using all corpus files even if there are crash inputs.
  # Merge should not introduce any significant overhead compared to -runs=0,
  # because (A) corpuses are already minimized; (B) we do not use sancov, and so
  # libFuzzer always finishes merge with an empty output dir.
  # Use 100s timeout instead of 25s as code coverage builds can be very slow.
  local args="-merge=1 -timeout=100 -close_fd_mask=3 $corpus_dummy $corpus_real"

  export LLVM_PROFILE_FILE=$profraw_file
  timeout $TIMEOUT $OUT/$target $args &> $LOGS_DIR/$target.log
  if (( $? != 0 )); then
    echo "Error occured while running $target:"
    cat $LOGS_DIR/$target.log
  fi

  rm -rf $corpus_dummy

  if (( $(du -c $profraw_file_mask | tail -n 1 | cut -f 1) == 0 )); then
    # Skip fuzz targets that failed to produce profile dumps.
    return 0
  fi

  llvm-profdata merge -j=1 -sparse $profraw_file_mask -o $profdata_file

  # Delete unnecessary and (potentially) large .profraw files.
  rm $profraw_file_mask

  shared_libraries=$(coverage_helper shared_libs -build-dir=$OUT -object=$target)
  llvm-cov export -summary-only -instr-profile=$profdata_file -object=$target \
      $shared_libraries $LLVM_COV_COMMON_ARGS > $FUZZER_STATS_DIR/$target.json
}

# Run each fuzz target, generate raw coverage dumps.
for fuzz_target in $FUZZ_TARGETS; do
  # Continue if not a fuzz target.
  if [[ $FUZZING_ENGINE != "none" ]]; then
    grep "LLVMFuzzerTestOneInput" $fuzz_target > /dev/null 2>&1 || continue
  fi

  echo "Running $fuzz_target"
  run_fuzz_target $fuzz_target &

  if [[ -z $objects ]]; then
    # The first object needs to be passed without -object= flag.
    objects="$fuzz_target"
  else
    objects="$objects -object=$fuzz_target"
  fi

  # Do not spawn more processes than the number of CPUs available.
  n_child_proc=$(jobs -rp | wc -l)
  while [ "$n_child_proc" -eq "$NPROC" ]; do
    sleep 4
    n_child_proc=$(jobs -rp | wc -l)
  done
done

# Wait for background processes to finish.
wait

# From this point on the script does not tolerate any errors.
set -e

# Merge all dumps from the individual targets.
rm -f $PROFILE_FILE
llvm-profdata merge -sparse $DUMPS_DIR/*.profdata -o $PROFILE_FILE

# TODO(mmoroz): add script from Chromium for rendering directory view reports.
# The first path in $objects does not have -object= prefix (llvm-cov format).
shared_libraries=$(coverage_helper shared_libs -build-dir=$OUT -object=$objects)
objects="$objects $shared_libraries"

# It's important to use $LLVM_COV_COMMON_ARGS as the last argument due to
# positional arguments (SOURCES) that can be passed via $COVERAGE_EXTRA_ARGS.
LLVM_COV_ARGS="-instr-profile=$PROFILE_FILE $objects $LLVM_COV_COMMON_ARGS"

# Generate HTML report.
llvm-cov show -format=html -output-dir=$REPORT_ROOT_DIR \
    -Xdemangler c++filt -Xdemangler -n $LLVM_COV_ARGS

# Export coverage summary in JSON format.
llvm-cov export -summary-only $LLVM_COV_ARGS > $SUMMARY_FILE

# Post process HTML report.
coverage_helper -v post_process -src-root-dir=/ -summary-file=$SUMMARY_FILE \
    -output-dir=$REPORT_ROOT_DIR $PATH_EQUIVALENCE_ARGS

if [[ -n $HTTP_PORT ]]; then
  # Serve the report locally.
  echo "Serving the report on http://127.0.0.1:$HTTP_PORT/linux/index.html"
  cd $REPORT_ROOT_DIR
  python3 -m http.server $HTTP_PORT
fi