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android / platform / system / libbase / d25dd2b
commitd25dd2b9851b7803d5ead5b8043c6cb6afdae034[log] [tgz]
authorElliott Hughes <enh@google.com>Thu Apr 03 12:38:14 2025 -0400
committerElliott Hughes <enh@google.com>Thu Apr 03 12:38:14 2025 -0400
treecb2b7ce6e7819566234883c9a3f7b28ee04fff13
parent094b64294f1e1f3cb9c6acda597df6f6383fcd9e [diff]
Avoid subtraction overflow in SplitByLogdChunks().

Passing a _tag_ (as opposed to a message) too long to fit in a single
log message is obviously a mistake. But it happened in the wild, and
caused Java code to die with a ubsan trap.

There's an argument that the point at which we call a tag "unreasonable"
should be no more than _half_ the buffer, but this corresponds more
closely with the lower-level liblog implementation which will happily
let you use every last byte on your tag.

Bug: https://issuetracker.google.com/400886840
Test: new test
Change-Id: I0a0980dcc75e87fc72cca9787aade5dfd554972d
2 files changed
tree: cb2b7ce6e7819566234883c9a3f7b28ee04fff13
  1. include/
  2. tidy/
  3. .clang-format ⇨ ../../build/soong/scripts/system-clang-format-2
  4. abi_compatibility.cpp
  5. Android.bp
  6. chrono_utils.cpp
  7. chrono_utils_test.cpp
  8. cmsg.cpp
  9. cmsg_test.cpp
  10. CPPLINT.cfg
  11. endian_test.cpp
  12. errors_test.cpp
  13. errors_unix.cpp
  14. errors_windows.cpp
  15. expected_test.cpp
  16. file.cpp
  17. file_benchmark.cpp
  18. file_test.cpp
  19. format_benchmark.cpp
  20. function_ref_benchmark.cpp
  21. function_ref_test.cpp
  22. hex.cpp
  23. hex_test.cpp
  24. logging.cpp
  25. logging_splitters.h
  26. logging_splitters_test.cpp
  27. logging_test.cpp
  28. macros_test.cpp
  29. mapped_file.cpp
  30. mapped_file_test.cpp
  31. no_destructor_test.cpp
  32. NOTICE
  33. OWNERS
  34. parsebool.cpp
  35. parsebool_test.cpp
  36. parsedouble_test.cpp
  37. parseint_test.cpp
  38. parsenetaddress.cpp
  39. parsenetaddress_fuzzer.cpp
  40. parsenetaddress_fuzzer.dict
  41. parsenetaddress_test.cpp
  42. posix_strerror_r.cpp
  43. PREUPLOAD.cfg
  44. process.cpp
  45. process_test.cpp
  46. properties.cpp
  47. properties_test.cpp
  48. README.md
  49. result.cpp
  50. result_test.cpp
  51. scopeguard_test.cpp
  52. stringprintf.cpp
  53. stringprintf_test.cpp
  54. strings.cpp
  55. strings_test.cpp
  56. test_main.cpp
  57. TEST_MAPPING
  58. test_utils.cpp
  59. test_utils_test.cpp
  60. threads.cpp
  61. utf8.cpp
  62. utf8_test.cpp
README.md

libbase

Who is this library for?

This library is a collection of convenience functions to make common tasks easier and less error-prone.

In this context, “error-prone” covers both “hard to do correctly” and “hard to do with good performance”, but as a general purpose library, libbase's primary focus is on making it easier to do things easily and correctly when a compromise has to be made between “simplest API” on the one hand and “fastest implementation” on the other. Though obviously the ideal is to have both.

Should my routine be added?

The intention is to cover the 80% use cases, not be all things to all users.

If you have a routine that‘s really useful in your project, congratulations. But that doesn’t mean it should be here rather than just in your project.

The question for libbase is “should everyone be doing this?”/“does this make everyone's code cleaner/safer?”. Historically we've considered the bar for inclusion to be “are there at least three unrelated projects that would be cleaned up by doing so”.

If your routine is actually something from a future C++ standard (that isn‘t yet in libc++), or it’s widely used in another library, that helps show that there's precedent. Being able to say “so-and-so has used this API for n years” is a good way to reduce concerns about API choices.

Any other restrictions?

Unlike most Android code, code in libbase has to build for Mac and Windows too.

Code here is also expected to have good test coverage.

By its nature, it‘s difficult to change libbase API. It’s often best to start using your routine just in your project, and let it “graduate” after you're certain that the API is solid.