# Copyright 2018 Google LLC

#

# 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.

# Add fuzz testing options to the current build.

option(FUZZING "Build for Fuzz Testing (local fuzzing and OSS Fuzz)" OFF)

# Assume OSS Fuzz if LIB_FUZZING_ENGINE environment variable is set. OSS Fuzz

# provides its required compiler-specific flags in CXXFLAGS, which are

# automatically added to CMAKE_CXX_FLAGS. For local fuzzing, multiple compile

# and linking flags must be set. These flags depend on the compiler version.

if(FUZZING AND NOT DEFINED ENV{LIB_FUZZING_ENGINE})

if(WIN32)

# Currently, libFuzzer cannot be built on Windows.

message(FATAL_ERROR "Fuzzing is currently not supported on Windows.")

endif()

# Address sanitizer must be enabled during fuzzing to detect memory errors.

if(NOT WITH_ASAN)

message(FATAL_ERROR "Fuzzing requires WITH_ASAN=ON to detect memory errors.")

endif()

# Set the flag to enable code coverage instrumentation. Fuzzing engines use

# code coverage as a metric to guide the fuzzing. We use the basic code

# coverage level (trace-pc). This flag has different values in Clang and GNU.

# Other values, such as trace-cmp, can be used to trace data flow. See the

# official documentation for the compiler flags.

if(CXX_CLANG)

# TODO(minafarid): Check the version of Clang. Clang versions >= 5.0 should

# have libFuzzer by default.

set(fuzzing_flags -fsanitize-coverage=trace-pc-guard)

elseif(CXX_GNU)

set(fuzzing_flags -fsanitize-coverage=trace-pc)

else()

message(FATAL_ERROR "Only Clang and GCC support fuzzing.")

endif()

foreach(flag ${fuzzing_flags})

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag}")

endforeach()

endif()