commit | 20b8b0791d8f29ce03ec84864f38467f0f9059b8 | [log] [tgz] |
---|---|---|
author | danakj <danakj@chromium.org> | Thu Jul 11 22:40:43 2024 |
committer | Copybara-Service <copybara-worker@google.com> | Thu Jul 11 22:46:58 2024 |
tree | f3b1e20f88aa9b9c90437957c05ceedad28a247d | |
parent | 605ed6d512fb195bea6d2b9af721ec9e49c98239 [diff] |
When moving elements around in circular_deque, use modulo arithmetic When we copy elements to make room for new ones, it's possible that we will copy from a range, or to a range, that cross the back of the underlying buffer and wrap around to the start. As we move things in reverse, when we subtract we're wrapping around to an invalid address instead of to the back of the buffer. Fix this by applying the capacity as the modulus. This OOB should have been caught by bounds checks in VectorBuffer but they were defeated by our unfortunately-very-likely foe: integer overflow. Move the UNSAFE_BUFFERS() to as_span() which does not do any arithmetic with arguments and implement subspan() through base::span which correctly handles overflow. R=dcheng@chromium.org Fuchsia-Binary-Size: PGO size artifacts Fixed: 352481077 Change-Id: I52e0e882b71eb54d791752a9dab6ddc110d60295 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5695465 Auto-Submit: danakj <danakj@chromium.org> Reviewed-by: Daniel Cheng <dcheng@chromium.org> Commit-Queue: danakj <danakj@chromium.org> Commit-Queue: Daniel Cheng <dcheng@chromium.org> Cr-Commit-Position: refs/heads/main@{#1326431} NOKEYCHECK=True GitOrigin-RevId: d5b80eac5288626bb63b0cfa8430cf02d7f13740
Contains a written down set of principles and other information on //base. Please add to it!
Chromium is a very mature project. Most things that are generally useful are already here and things not here aren't generally useful.
The bar for adding stuff to base is that it must have demonstrated wide applicability. Prefer to add things closer to where they're used (i.e. “not base”), and pull into base only when needed. In a project our size, sometimes even duplication is OK and inevitable.
Adding a new logging macro DPVELOG_NE
is not more clear than just writing the stuff you want to log in a regular logging statement, even if it makes your calling code longer. Just add it to your own code.
If the code in question does not need to be used inside base, but will have multiple consumers across the codebase, consider placing it in a new directory under components/ instead.
base is written for the Chromium project and is not intended to be used outside it. Using base outside of src.git is explicitly not supported, and base makes no guarantees about API (or even ABI) stability (like all other code in Chromium). New code that depends on base/ must be in src.git. Code that's not in src.git but pulled in through DEPS (for example, v8) cannot use base.
Owners are added when a contributor has shown the above qualifications and when they express interest. There isn't an upper bound on the number of OWNERS.
Since the primitives provided by //base are used very widely, it is important to ensure they scale to the necessary workloads and perform well under all supported platforms. The base_perftests
target is a suite of synthetic microbenchmarks that measure performance in various scenarios:
thread_local
, the implementation in //base, the POSIX/WinAPI directly)Regressions in these benchmarks can generally by caused by 1) operating system changes, 2) compiler version or flag changes or 3) changes in //base code itself.