# Copyright 2015 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

declare_args() {
  # Compile for Address Sanitizer to find memory bugs.
  is_asan = false

  # Compile for Leak Sanitizer to find leaks.
  is_lsan = false

  # Compile for Memory Sanitizer to find uninitialized reads.
  is_msan = false

  # Compile for Thread Sanitizer to find threading bugs.
  is_tsan = false

  # Compile for Undefined Behaviour Sanitizer to find various types of
  # undefined behaviour (excludes vptr checks).
  is_ubsan = false

  # Halt the program if a problem is detected.
  is_ubsan_no_recover = false

  # Compile for Undefined Behaviour Sanitizer's null pointer checks.
  is_ubsan_null = false

  # Compile for Undefined Behaviour Sanitizer's vptr checks.
  is_ubsan_vptr = false

  # Track where uninitialized memory originates from. From fastest to slowest:
  # 0 - no tracking, 1 - track only the initial allocation site, 2 - track the
  # chain of stores leading from allocation site to use site.
  msan_track_origins = 2

  # Use dynamic libraries instrumented by one of the sanitizers instead of the
  # standard system libraries. Set this flag to download prebuilt binaries from
  # GCS.
  use_prebuilt_instrumented_libraries = false

  # Enable building with SyzyAsan which can find certain types of memory
  # errors. Only works on Windows. See
  # https://github.com/google/syzygy/wiki/SyzyASanHowTo
  is_syzyasan = false

  # Compile with Control Flow Integrity to protect virtual calls and casts.
  # See http://clang.llvm.org/docs/ControlFlowIntegrity.html
  #
  # TODO(pcc): Remove this flag if/when CFI is enabled in official builds.
  is_cfi = false

  # Enable checks for bad casts: derived cast and unrelated cast.
  # TODO(krasin): remove this, when we're ready to add these checks by default.
  # https://crbug.com/626794
  use_cfi_cast = false

  # By default, Control Flow Integrity will crash the program if it detects a
  # violation. Set this to true to print detailed diagnostics instead.
  use_cfi_diag = false

  # Compile for fuzzing with LLVM LibFuzzer.
  # See http://www.chromium.org/developers/testing/libfuzzer
  use_libfuzzer = false

  # Compile for fuzzing with AFL.
  use_afl = false

  # Enables core ubsan security features. Will later be removed once it matches
  # is_ubsan.
  is_ubsan_security = false

  # Compile for fuzzing with Dr. Fuzz
  # See http://www.chromium.org/developers/testing/dr-fuzz
  use_drfuzz = false

  # Helper variable for testing builds with disabled libfuzzer.
  # Not for client use.
  disable_libfuzzer = false

  # Value for -fsanitize-coverage flag. Setting this causes
  # use_sanitizer_coverage to be enabled.
  # Default value when unset and use_afl=true:
  # trace-pc
  # Default value when unset and use_sanitizer_coverage=true:
  #     edge,indirect-calls,8bit-counters
  sanitizer_coverage_flags = ""
}

# Args that are in turn dependent on other args must be in a separate
# declare_args block. User overrides are only applied at the end of a
# declare_args block.
declare_args() {
  # Use libc++ (buildtools/third_party/libc++ and
  # buildtools/third_party/libc++abi) instead of stdlibc++ as standard library.
  # This is intended to be used for instrumented builds.
  use_custom_libcxx =
      (is_asan && is_linux && !is_chromeos) || is_tsan || is_msan || is_ubsan ||
      is_ubsan_security || use_libfuzzer || use_afl

  # Enable -fsanitize-coverage.
  use_sanitizer_coverage =
      use_libfuzzer || use_afl || sanitizer_coverage_flags != ""

  # Detect overflow/underflow for global objects.
  #
  # Android build relies on -Wl,--gc-sections removing unreachable code.
  # ASan instrumentation for globals inhibits this and results in a
  # library with unresolvable relocations.
  # TODO(eugenis): find a way to reenable this.
  #
  # Mac: http://crbug.com/352073
  asan_globals = !is_android && !is_mac
}

if (use_afl && sanitizer_coverage_flags == "") {
  sanitizer_coverage_flags = "trace-pc"
} else if (use_sanitizer_coverage && sanitizer_coverage_flags == "") {
  sanitizer_coverage_flags = "edge,indirect-calls,8bit-counters"
}

using_sanitizer = is_asan || is_lsan || is_tsan || is_msan || is_ubsan ||
                  is_ubsan_null || is_ubsan_vptr || is_ubsan_security

assert(!using_sanitizer || is_clang,
       "Sanitizers (is_*san) require setting is_clang = true in 'gn args'")

prebuilt_instrumented_libraries_available =
    is_msan && (msan_track_origins == 0 || msan_track_origins == 2)

# MSan only links Chrome properly in release builds (brettw -- 9/1/2015). The
# same is possibly true for the other non-ASan sanitizers. But regardless of
# whether it links, one would normally never run a sanitizer in debug mode.
# Running in debug mode probably indicates you forgot to set the "is_debug =
# false" flag in the build args. ASan seems to run fine in debug mode.
#
# If you find a use-case where you want to compile a sanitizer in debug mode
# and have verified it works, ask brettw and we can consider removing it from
# this condition. We may also be able to find another way to enable your case
# without having people accidentally get broken builds by compiling an
# unsupported or unadvisable configurations.
#
# For one-off testing, just comment this assertion out.
assert(!is_debug || !(is_msan || is_ubsan || is_ubsan_null || is_ubsan_vptr),
       "Sanitizers should generally be used in release (set is_debug=false).")