Restore and verify GCC compatibility (#177)

* Declare intermediate targets as manual

Makes it easier to skip targets, such as those using FuzzedDataProvider
when using gcc as CC.

* Restore compatibility with gcc for replay engine

Using the weak attribute together with an explicitly undefined symbol
should still work on macOS, see:
https://stackoverflow.com/a/34983229/297261

* Update Jazzer for gcc compatibility

* Skip FuzzedDataProvider test with non-clang CC

* Run regression tests with GCC

* Run regression tests in CI on macOS

Excludes the tests in //examples/java, which require further fixes to
find libjvm.dylib.

* Make launchers compatible with macOS

Implements the missing readlink -f command in Python.

Author: fmeum

.github/workflows/bazel_test.yml

@@ -114,3 +114,26 @@ jobs:
           bazel test --verbose_failures --test_output=all \
               --build_tag_filters=fuzz-test --config=${{ matrix.config }} \
               //examples/java/...
+  regression_tests_gcc:
+    name: Regression tests (GCC)
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+      - name: Run regression tests with GCC
+        run: |
+          bazel test --action_env=CC=gcc --action_env=CXX=g++ \
+              --verbose_failures --test_output=all \
+              //examples/...
+  regression_tests_mac:
+    name: Regression tests (macOS)
+    runs-on: macos-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+      - name: Run regression tests on macOS
+        run: |
+          bazel test --verbose_failures --test_output=all \
+              -- //examples/... -//examples/java:all

BUILD

@@ -11,3 +11,8 @@
 # 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.
+
+config_setting(
+    name = "clang",
+    flag_values = {"@bazel_tools//tools/cpp:compiler": "clang"},
+)

examples/BUILD

@@ -58,6 +58,10 @@ cc_fuzz_test(
 cc_fuzz_test(
     name = "fuzzed_data_provider_fuzz_test",
     srcs = ["fuzzed_data_provider_fuzz_test.cc"],
+    target_compatible_with = select({
+        "//:clang": [],
+        "//conditions:default": ["@platforms//:incompatible"],
+    }),
 )
 
 cc_fuzz_test(

fuzzing/engines/honggfuzz_launcher.sh

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-command_line="$(readlink -f ${HONGGFUZZ_PATH})"
+command_line="$(python3 -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' ${HONGGFUZZ_PATH})"
 command_line+=("--workspace=${FUZZER_OUTPUT_ROOT}")
 
 if [[ -n "${FUZZER_SEED_CORPUS_DIR}" ]]; then

fuzzing/engines/jazzer_launcher.sh

@@ -16,7 +16,7 @@
 # engine. The launch configuration is supplied by the launcher script through
 # environment variables.
 
-command_line=("$(readlink -f ${FUZZER_BINARY})")
+command_line=("$(python3 -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' ${FUZZER_BINARY})")
 
 # libFuzzer flags (compatible with Jazzer).
 

fuzzing/engines/libfuzzer_launcher.sh

@@ -16,7 +16,7 @@
 # libFuzzer engine. The launch configuration is supplied by the launcher
 # script through environment variables.
 
-command_line=("$(readlink -f ${FUZZER_BINARY})")
+command_line=("$(python3 -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' ${FUZZER_BINARY})")
 
 # libFuzzer flags.
 

fuzzing/engines/replay_launcher.sh

@@ -16,7 +16,7 @@ if (( ! FUZZER_IS_REGRESSION )); then
     echo "NOTE: Non-regression mode is not supported by the replay engine."
 fi
 
-command_line=("$(readlink -f ${FUZZER_BINARY})")
+command_line=("$(python3 -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' ${FUZZER_BINARY})")
 if [[ -n "${FUZZER_SEED_CORPUS_DIR}" ]]; then
     command_line+=("${FUZZER_SEED_CORPUS_DIR}")
 fi

fuzzing/private/fuzz_test.bzl

@@ -174,6 +174,7 @@ def cc_fuzz_test(
     # instrumented configuration.
     raw_binary_name = name + "_raw_"
     binary_kwargs.setdefault("deps", []).append(engine)
+    binary_kwargs.setdefault("tags", []).append("manual")
     cc_binary(
         name = raw_binary_name,
         **binary_kwargs
@@ -251,6 +252,7 @@ def java_fuzz_test(
         "Jazzer-Fuzz-Target-Class: %s" % target_class,
     ]
     binary_kwargs.setdefault("deps", []).append(engine)
+    binary_kwargs.setdefault("tags", []).append("manual")
     native.java_binary(
         name = raw_target_name,
         srcs = srcs,
@@ -282,6 +284,7 @@ def java_fuzz_test(
             "@rules_fuzzing//fuzzing/private:use_oss_fuzz": "@rules_fuzzing//fuzzing/private:oss_fuzz_jazzer_sanitizer_options.sh",
             "//conditions:default": "@rules_fuzzing//fuzzing/private:local_jazzer_sanitizer_options.sh",
         }),
+        tags = ["manual"],
         target = raw_target_name,
         target_deploy_jar = raw_target_name + "_deploy.jar",
     )

fuzzing/private/java_utils.bzl

@@ -110,7 +110,7 @@ runfiles_export_envvars
 # Determine the path to load libjvm.so from, either relative to the location of
 # the java binary or to $JAVA_HOME, if set. On OSS-Fuzz, the path is provided in
 # JVM_LD_LIBRARY_PATH.
-JAVA_BIN=$(readlink -f "$(which java)")
+JAVA_BIN=$(python3 -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' "$(which java)")
 JAVA_HOME=${JAVA_HOME:-${JAVA_BIN%/bin/java}}
 # The location of libjvm.so relative to the JDK differs between JDK <= 8 and 9+.
 JVM_LD_LIBRARY_PATH=${JVM_LD_LIBRARY_PATH:-"$JAVA_HOME/lib/server:$JAVA_HOME/lib/amd64/server"}

fuzzing/replay/replay_main.cc

@@ -22,7 +22,7 @@
 
 extern "C" {
 int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size);
-int LLVMFuzzerInitialize(int* argc, char*** argv) __attribute__((weak_import));
+int LLVMFuzzerInitialize(int* argc, char*** argv) __attribute__((weak));
 }
 
 namespace {