#!/system/bin/sh
# Copyright (C) 2018 The Android Open Source Project
#
# 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.
# Abort on any error

# Global configuration
FUZZER_BASES=( "/data/nativetest64/fuzzers" "/data/nativetest/fuzzers" )
WORK_BASE="/data/local/tmp/fuzz"
LAST_FUZZ="$WORK_BASE/last_session"

#------------------------------ HELPER FUNCTIONS ------------------------------
function die() {
    echo "$@" >&2
    exit 1
}

# Print the usage and exit.
# Optionally takes an extra string to print.
function usage() {
    die "\
Usage: $0 [-a artifacts_path] [-c corpus] [-e engine] [-l logname] [-n new_corpus] [-w workdir] fuzzer [-- fuzzer_option...]

Run a fuzzing session.

All of the information on the most recent session is symlinked at $LAST_FUZZ,
which points to the most recent session's working directory.

The working directory is standardized to contain the following directories (or symlinks,
if non-default options are provided):

    artifacts/      Crashing test cases and other fuzzer output
    corpus/         Input corpus
    corpus_new/     Mutated test cases which exercise coverage features not represented
                    in the input corpus.
    fuzz.log        Contents of stdout from the fuzzing session.

Arguments:
    fuzzer          Name of the fuzzer, e.g. cxa_demangle_fuzzer, or a full path to the fuzzer
    fuzzer_option   Fuzzer-specific arguments

Options:
    -a  Path where fuzzer artifacts (logs, timeouts, crashes) should be stored
        (Default: \$WORK/artifacts)

    -c  Path where input corpus is stored.  Must not be empty.
        (Default: \$WORK/corpus)

    -e  Fuzzer engine to use.  Defaults to libFuzzer.

    -l  Filename to use for the fuzzer log.
        (Default: fuzz.log)

    -n  Path to store new corpus elements
        (Default: \$WORK/corpus_new)

    -w  Work directory to use
        (Default: $WORK_BASE/\$FUZZER)

Examples:

    $ adb shell fuzz IOMX
    $ adb shell fuzz -e honggfuzz IOMX
    $ adb shell fuzz -w /sdcard        IOMX
    $ adb shell fuzz -c /sdcard/corpus IOMX
    $ adb shell fuzz /data/my_fuzzer -- --foo --bar
$@"
}

# Create a symlink from $1 ==> $2, if $2 is specified.
# Otherwise, ensure $1 exists and is a directory.
function symlink_or_create() {
    DIR=$1
    TARGET=$2
    if [ -n "$TARGET" ]; then
        if [ ! -d "$TARGET" ]; then
            die "Directory does not exist: $TARGET"
        fi
        rm -rf "$DIR"
        ln -sv "$TARGET" "$DIR"
    elif [ ! -d "$DIR" ]; then
        mkdir -p "$DIR"
    fi
}

# Ensure that there is "enough space" left on the device for
# the path provided.
function ensure_space() {
    FREE_SPACE=$(df $1 | tail -1 | awk '{print $4}')
    TEN_MEGABYTES=$((1024*10))

    if [ $FREE_SPACE -lt $TEN_MEGABYTES ]; then
        die "Not enough free space available at $(realpath $1):\n$(df -h $1)"
    fi
}

# Ensure that the provided directory is not empty.
function ensure_not_empty() {
    if [ "$(find -H $1 -type f | wc -l)" -eq "0" ]; then
        die "$1 is empty"
    fi
}

#--------------------------- CHECK SYSTEM VIABILITY ---------------------------
# Make sure ASAN and coverage work
if ! sanitizer-status asan cov &>/dev/null; then
    # repeat the command to show the output
    die "Sanitizer Checks Failed!\n$(sanitizer-status)"
fi

#------------------------------ CHECK ARGUMENTS -------------------------------
# Determine what fuzzer we want to run, and ensure that it's on the device
OPT_ARTIFACTS=""
OPT_CORPUS=""
OPT_CORPUS_NEW=""
OPT_ENGINE="libFuzzer"
OPT_LOG="fuzz.log"
OPT_WORKDIR=""

while getopts "a:c:e:l:n:w:" o; do
    case "${o}" in
        a) OPT_ARTIFACTS="${OPTARG}" ;;
        c) OPT_CORPUS="${OPTARG}" ;;
        e) OPT_ENGINE="${OPTARG}" ;;
        l) OPT_LOG="${OPTARG}" ;;
        n) OPT_CORPUS_NEW="${OPTARG}" ;;
        w) OPT_WORKDIR="${OPTARG}" ;;
        *) usage ;;
    esac
done

shift $((OPTIND-1))

if [ $# -lt 1 ]; then
    usage "\nMissing arguments: fuzzer"
fi

if [ -e $1 ]; then
    FUZZER_BIN="$1"
    FUZZER="$(basename $FUZZER_BIN)"
else
    FUZZER="${1%_fuzzer}"

    for FUZZER_BASE in "${FUZZER_BASES[@]}"; do
        FUZZER_BIN="${FUZZER_BASE}/${OPT_ENGINE}/${FUZZER}_fuzzer/${FUZZER}_fuzzer"
        [ -e "$FUZZER_BIN" ] && break
    done
fi

shift

if [ ! -e "$FUZZER_BIN" ]; then
    die "Invalid fuzzer path $FUZZER_BIN: File does not exist"
fi

#------------------------- CREATE DIRECTORY STRUCTURE -------------------------
# First set up the root work directory.
#
# This directory is the default location where the corpus/, corpus_new/, and
# artifacts/ directories will be created.
#
# We also create symlinks here if any of those options are provided, so that
# the same directory structure is always available, and any external utilities
# can easily find the last fuzzing session's data.
WORK_ROOT="$WORK_BASE/$FUZZER"
symlink_or_create "$WORK_ROOT"  "$OPT_WORKDIR"
WORK_ROOT="${OPT_WORKDIR:-$WORK_ROOT}"

# Change into the work root, in case any of the OPT_XXX paths are relative.
cd "$WORK_ROOT"

# Create the rest of the directory structure
ARTIFACTS="$WORK_ROOT/artifacts"
CORPUS="$WORK_ROOT/corpus"
CORPUS_NEW="$WORK_ROOT/corpus_new"

symlink_or_create "$ARTIFACTS"  "$OPT_ARTIFACTS"
symlink_or_create "$CORPUS"     "$OPT_CORPUS"
symlink_or_create "$CORPUS_NEW" "$OPT_CORPUS_NEW"

# Update the environment variables so that the "real" paths show up in
# the command invocation.
ARTIFACTS="${OPT_ARTIFACTS:-$ARTIFACTS}"
CORPUS="${OPT_CORPUS:-$CORPUS}"
CORPUS_NEW="${OPT_CORPUS_NEW:-$CORPUS_NEW}"

# Check the contents of the corpus aren't empty, this indicates a user error.
ensure_not_empty "$CORPUS"

# Ensure that there's room to grow the corpus / dump artifacts.
ensure_space "$CORPUS_NEW"
ensure_space "$ARTIFACTS"

#------------------------- UPDATE ENVIRONMENT OPTIONS -------------------------
# Set up the ASAN_OPTIONS for optimal everything
# Note that we are only appending options, so that we do not override the
# default-at-boot ASAN_OPTIONS (e.g include=/system/asan.options).

ASAN_OPTIONS+=:coverage=1
ASAN_OPTIONS+=:atexit=1
# ASAN_OPTIONS+=:verbosity=2
ASAN_OPTIONS+=:print_cmdline=1
ASAN_OPTIONS+=:print_stats=1
ASAN_OPTIONS+=:print_legend=1
ASAN_OPTIONS+=:print_scariness=1
ASAN_OPTIONS+=:log_path=/dev/null

export ASAN_OPTIONS="$ASAN_OPTIONS"
echo "ASAN_OPTIONS=$ASAN_OPTIONS"


#---------------------------- BUILD FUZZER COMMAND ----------------------------
# Based on the fuzzer engine selected, build up the command line.
case "${OPT_ENGINE}" in
    libFuzzer)
        # NOTE: We use '-jobs=-1' to get libFuzzer to fuzz forever.
        set -A FUZZ_CMD -- \
        "$FUZZER_BIN" \
            -artifact_prefix="$ARTIFACTS" \
            -print_coverage=1 \
            -detect_leaks=0 \
            -jobs=-1 \
            "$CORPUS_NEW" \
            "$CORPUS" \
            "$@"
        ;;
    honggfuzz)
        set -A FUZZ_CMD -- \
        honggfuzz \
            --persistent \
            --sanitizers \
            --tmout_sigvtalrm \
            --workspace "$ARTIFACTS" \
            --input "$CORPUS_NEW" \
            --covdir_new "$CORPUS_NEW" \
            -- "$FUZZER_BIN" "$@"
        ;;
    *)
        die "Unknown fuzzer engine $FUZZER_TYPE"
        ;;
esac

#--------------------------------- RUN FUZZER ---------------------------------
# Set up a symlink for the "last fuzz session" so that we can easily find it.
ln -svf "$WORK_ROOT" "$LAST_FUZZ"

# Change into the artifacts directory, so that anything
# the fuzzer emits to $PWD will also be captured.
cd "$ARTIFACTS"

echo "Running fuzzer: ${FUZZ_CMD[@]}"
echo "------------------------------"
${FUZZ_CMD[@]} | tee "${OPT_LOG}"