# Copyright 2019 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("$zx/public/gn/toolchain/environment.gni")

# Fuzzer environments: These add libFuzzer instrumentation and hooks. These
# hooks will be undefined in shared libraries, and provided by the compiler
# runtime, which itself has an implicit dependency on libzircon.
standard_environments(".fuzzer") {
  # Everything is compiled with the fuzzer instrumentation.
  # Each variant can add additional bug-detection instrumentation.
  configs = [
    "$zx/public/gn/config/instrumentation:fuzzer",
    {
      # libFuzzer can only be statically linked into each executable.
      # Instrumented shared library code has dangling references to runtime
      # symbols that will only be defined in the executable.
      shlib = true
      remove = [ "$zx_build_config:no_undefined_symbols" ]
    },
    {
      # We care more about accurate stack traces than binary size when fuzzing.
      remove = [ "$zx_build_config:default_icf" ]
    },
  ]
  implicit_deps = [
    {
      types = [ "executable" ]
      add = [ "$zx/public/gn/config/instrumentation:fuzzer_deps" ]
    },
  ]

  # Required by the above. See $zx/public/gn/config/instrumentation:fuzzer.
  tags = [ "sancov" ]

  toolchain_vars = {
    # Trailing dot will get "$variant/" appended to locate shared libraries.
    libprefix = "fuzzer."
  }
  variant_libprefix = true

  # Support all the sanitizers plus the baseline variant (i.e. a fuzzer
  # that only detects explicit failure reports in the code, or crashes).
  variant_selectors = standard_sanitizer_variants + standard_base_variants

  # GCC doesn't support the fuzzer config always added here, so prune
  # it from the baseline list.
  exclude_variant_tags = [ "gcc" ]

  # Set sanitizer options that we only want to apply for fuzzers.
  toolchain_args = {
    # Unless otherwise noted, these options are the defaults from ClusterFuzz.
    asan_default_options = string_join(":",
                                       [
                                         "alloc_dealloc_mismatch=0",
                                         "allocator_may_return_null=1",
                                         "check_malloc_usable_size=0",
                                         "detect_leaks=0",
                                         "detect_odr_violation=0",
                                         "malloc_context_size=128",
                                         "max_uar_stack_size_log=16",
                                         "print_scariness=1",
                                         "print_summary=1",
                                         "print_suppressions=0",
                                         "strict_memcmp=0",
                                         "symbolize=0",
                                       ])
  }
}