src/tint/cmd/fuzz/ir/main_fuzz.cc

// Copyright 2024 The Dawn & Tint Authors
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#include <cstddef>
#include <span>

#include "src/tint/cmd/fuzz/common/init.h"
#include "src/tint/cmd/fuzz/ir/fuzz.h"
#include "src/tint/lang/core/ir/module.h"
#include "src/tint/lang/core/ir/validator/validate.h"
#include "src/utils/compiler.h"

#if TINT_BUILD_IR_BINARY

#include "src/tint/lang/core/ir/binary/decode.h"
#include "src/tint/utils/macros/defer.h"

TINT_BEGIN_DISABLE_PROTOBUF_WARNINGS();
#include "src/libfuzzer/libfuzzer_macro.h"
#include "src/tint/utils/protos/ir_fuzz/ir_fuzz.pb.h"
#include "testing/libfuzzer/proto/lpm_interface.h"
TINT_END_DISABLE_PROTOBUF_WARNINGS();

namespace {

tint::fuzz::ir::Options options;

}  // namespace

DEFINE_BINARY_PROTO_FUZZER(const tint::cmd::fuzz::ir::pb::Root& pb) {
    /// As the fuzzers are free to mutate the module, we need to deserialize a new module for each
    /// sub-fuzzer. Because the protobuf may error when deserializing and the module may be invalid,
    /// we early deserialize. If this fails, then we do not call Run().
    thread_local std::optional<tint::core::ir::Module> module;
    tint::core::ir::binary::DecoderOptions decoder_options{
        .strip_invalid_identifiers = options.strip_invalid_identifiers,
    };

    {
        auto decoded = tint::core::ir::binary::Decode(pb.module(), decoder_options);
        if (decoded != tint::Success) {
            return;  // Failed to decode
        }
        module = std::move(decoded.Move());
    }
    auto acquire_module = [&] {
        if (!module) {
            auto decoded = tint::core::ir::binary::Decode(pb.module(), decoder_options);
            TINT_ASSERT(decoded == tint::Success)
                << "module successfully decoded once, then failed a subsequent time\n"
                << decoded.Failure();

            module = std::move(decoded.Move());
        }

        auto out = std::move(module.value());
        module.reset();
        return out;
    };

    auto data = std::as_bytes(std::span(pb.data()));
    tint::fuzz::ir::Run(acquire_module, options, data);
}

// Explicitly specify the visibility to prevent the linker from stripping the function on macOS, as
// the LibFuzzer runtime uses dlsym() instead of calling the function directly.
extern "C" __attribute__((visibility("default"))) int LLVMFuzzerInitialize(int* argc,
                                                                           char*** argv) {
    return tint::fuzz::common::ParseFuzzerOptions(tint::fuzz::common::FuzzerType::kIR, argc, argv,
                                                  &options);
}

#endif