error: static assertion failed due to requirement 'always_false<unsigned char *>': => Type not supported yet

[thealberto]

Hi all,
I'm trying to port the example woff2 fuzzer to bazel. I have prepared the project so I can run simple tests but when I try to mimic the original LibFuzzer entry point I get an error.

This is the code

#include <stddef.h>
#include <stdint.h>
#include "fuzztest/fuzztest.h"
#include "gtest/gtest.h"

#include <woff2/decode.h>

void ConvertWOFF2ToTTF(uint8_t* data, int size) {
}
FUZZ_TEST(AlbertoFuzzTest, ConvertWOFF2ToTTF);

// Entry point for LibFuzzer.
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  std::string buf;
  woff2::WOFF2StringOut out(&buf);
  out.SetMaxSize(30 * 1024 * 1024);
  woff2::ConvertWOFF2ToTTF(data, size, &out);
  return 0;
}

This is the output when I run bazel run --config=fuzztest --copt=-I./include :alberto -- --fuzz=AlbertoFuzzTest.ConvertWOFF2ToTTF

In file included from external/com_google_fuzztest/fuzztest/fuzztest.h:24:
In file included from external/com_google_fuzztest/./fuzztest/domain.h:18:
In file included from external/com_google_fuzztest/./fuzztest/domain_core.h:48:
external/com_google_fuzztest/./fuzztest/internal/domains/arbitrary_impl.h:60:17: error: static assertion failed due to requirement 'always_false<unsigned char *>': => Type not supported yet. Consider filing an issue.
   60 |   static_assert(always_false<T>,
      |                 ^~~~~~~~~~~~~~~
external/com_google_fuzztest/./fuzztest/domain_core.h:398:10: note: in instantiation of template class 'fuzztest::internal::ArbitraryImpl<unsigned char *>' requested here
  398 |   return internal::ArbitraryImpl<T>{};
      |          ^
external/com_google_fuzztest/./fuzztest/internal/registration.h:65:20: note: in instantiation of function template specialization 'fuzztest::internal_no_adl::Arbitrary<unsigned char *>' requested here
   65 |     return TupleOf(Arbitrary<Args>()...);
      |                    ^
external/com_google_fuzztest/./fuzztest/internal/registry.h:84:66: note: in instantiation of member function 'fuzztest::internal::DefaultRegistrationBase<unsigned char *, int>::GetDomains' requested here
   84 |     return [target_function = reg.target_function_, domain = reg.GetDomains(),
      |                                                                  ^
external/com_google_fuzztest/./fuzztest/internal/registry.h:65:18: note: in instantiation of function template specialization 'fuzztest::internal::RegistrationToken::GetFuzzTestFuzzerFactory<fuzztest::internal::DefaultRegistrationBase<unsigned char *, int>, fuzztest::internal::NoFixture, void (*)(unsigned char *, int), void *>' requested here
   65 |                  GetFuzzTestFuzzerFactory(std::move(reg)));
      |                  ^
src/alberto.cc:11:1: note: in instantiation of function template specialization 'fuzztest::internal::RegistrationToken::operator=<fuzztest::internal::DefaultRegistrationBase<unsigned char *, int>, fuzztest::internal::NoFixture, void (*)(unsigned char *, int), void *>' requested here
   11 | FUZZ_TEST(AlbertoFuzzTest, ConvertWOFF2ToTTF);
      | ^
external/com_google_fuzztest/fuzztest/fuzztest.h:66:37: note: expanded from macro 'FUZZ_TEST'
   66 | #define FUZZ_TEST(suite_name, func) INTERNAL_FUZZ_TEST(suite_name, func)
      |                                     ^
external/com_google_fuzztest/./fuzztest/internal/registry.h:107:53: note: expanded from macro 'INTERNAL_FUZZ_TEST'
  107 |           ::fuzztest::internal::RegistrationToken{} =             \
      |                                                     ^
1 error generated.
Target //:alberto failed to build
Use --verbose_failures to see the command lines of failed build steps.
INFO: Elapsed time: 7.115s, Critical Path: 6.92s
INFO: 66 processes: 26 internal, 40 linux-sandbox.
ERROR: Build did NOT complete successfully
ERROR: Build failed. Not running target
➜  woff2 git:(ccbeb246d2)

Which type should I use instead? Any other way to fix it?

[racko]

How about the following?

void ConvertWOFF2ToTTF(const std::vector<std::uint8_t>& bytes) {
    const uint8_t* const data{bytes.data()};
    const int size{static_cast<int>(bytes.size())};
    // ...
}
FUZZ_TEST(AlbertoFuzzTest, ConvertWOFF2ToTTF);

[thealberto]

@racko

Thanks it worked!

INFO: Found 1 target...
Target //:alberto up-to-date:
  bazel-bin/alberto
INFO: Elapsed time: 3.321s, Critical Path: 3.27s
INFO: 3 processes: 1 internal, 2 linux-sandbox.
INFO: Build completed successfully, 3 total actions
INFO: Running command line: external/bazel_tools/tools/test/test-setup.sh ./alberto '--fuzz=AlbertoFuzzTest.ConvertWOFF2ToTTF'
exec ${PAGER:-/usr/bin/less} "$0" || exit 1
Executing tests from //:alberto
-----------------------------------------------------------------------------
[.] Sanitizer coverage enabled. Counter map size: 30385, Cmp map size: 262144
Note: Google Test filter = AlbertoFuzzTest.ConvertWOFF2ToTTF
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from AlbertoFuzzTest
[ RUN      ] AlbertoFuzzTest.ConvertWOFF2ToTTF
FUZZTEST_PRNG_SEED=tnaxpgtwGcTdechb4cT-MAbJTMn3j09oJQQ1jE_rR5Y
[*] Corpus size:     1 | Edges covered:    152 | Fuzzing time:        342.062us | Total runs:  1.00e+00 | Runs/secs:  2923 | Max stack usage:     2880
[*] Corpus size:     2 | Edges covered:    152 | Fuzzing time:        745.952us | Total runs:  3.00e+00 | Runs/secs:  4021 | Max stack usage:     2880
[*] Corpus size:     3 | Edges covered:    154 | Fuzzing time:        1.85638ms | Total runs:  3.50e+01 | Runs/secs: 18853 | Max stack usage:     2880
[*] Corpus size:     4 | Edges covered:    154 | Fuzzing time:       4.787332ms | Total runs:  3.90e+01 | Runs/secs:  8146 | Max stack usage:     2880
[*] Corpus size:     5 | Edges covered:    154 | Fuzzing time:        6.88421ms | Total runs:  4.20e+01 | Runs/secs:  6100 | Max stack usage:     2880

Is it worth to add an example in the docs?