Use std::equal instead of memcmp in file_buffer_unittest.cc

memcmp is impacted by a C language bug where it doesn't support empty
slices with null pointers. See
https://davidben.net/2024/01/15/empty-slices.html for details.

This is the cause of a UBSan regression in Chromium:
https://ci.chromium.org/ui/labs/p/chromium/inv/build-8747392691953287169/test/ninja%3A%2F%2Fthird_party%2Fperfetto%3Aperfetto_unittests%2FFileBuffer.ContiguousAccessAtOffset/variant/1ca38ed05f7bcb2c?resultIndex=0

Instead, use std::equal, which is not impacted by this C bug.

begin() and end() would be better, but TraceBlobView doesn't seem to
have begin() and end() methods. Instead I've used data() and data() +
size().

std::ranges::equal would be even better, but that would require C++20,
and I don't see other uses of std::ranges, so I'm guessing perfetto
doesn't yet assume a C++20 STL.

Bug: chromium:40248746
Change-Id: Ib4b7e90798ac822a179d64262965e61da498349c
1 file changed
tree: cb28343412eaf8f2d523b7a70d29a9466dee1965
  1. .github/
  2. bazel/
  3. build_overrides/
  4. buildtools/
  5. debian/
  6. docs/
  7. examples/
  8. gn/
  9. include/
  10. infra/
  11. protos/
  12. python/
  13. src/
  14. test/
  15. third_party/
  16. tools/
  17. ui/
  18. .clang-format
  19. .clang-tidy
  20. .git-blame-ignore-revs
  21. .gitattributes
  22. .gitignore
  23. .gn
  24. .style.yapf
  25. Android.bp
  26. Android.bp.extras
  27. BUILD
  28. BUILD.extras
  29. BUILD.gn
  30. CHANGELOG
  31. codereview.settings
  32. DIR_METADATA
  33. heapprofd.rc
  34. LICENSE
  35. meson.build
  36. METADATA
  37. MODULE_LICENSE_APACHE2
  38. OWNERS
  39. perfetto.rc
  40. PerfettoIntegrationTests.xml
  41. persistent_cfg.pbtxt
  42. PRESUBMIT.py
  43. README.chromium
  44. README.md
  45. TEST_MAPPING
  46. traced_perf.rc
  47. WATCHLISTS
  48. WORKSPACE
README.md

Perfetto - System profiling, app tracing and trace analysis

Perfetto is a production-grade open-source stack for performance instrumentation and trace analysis. It offers services and libraries and for recording system-level and app-level traces, native + java heap profiling, a library for analyzing traces using SQL and a web-based UI to visualize and explore multi-GB traces.

See https://perfetto.dev/docs or the /docs/ directory for documentation.