build: re-enable unsafe buffer checks

[ckerr]

Description of Change

Re-enable the unsafe-buffer checks that were disabled by 1e9acec in the 134.0.6988.0 Chromium roll (#45334).

Fixes #45411.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Maintainer Notes

I'd never poked around in Chromium's Clang plugins before, so in case I (or another maintainer) has to do it again: I tracked this down by patching tools/clang/plugins/UnsafeBuffersPlugin.cpp with these new log statements and then rebuilding clang by following these instructions. Then I used that build of Clang to rebuild Electron. To ensure the patched clang got used, I passed the --offline flag to reclient/rewrapper.

Warnings in net/cookies/parsed_cookie.cc:

../../net/cookies/parsed_cookie.cc:90:45: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
   90 |   for (; *it != end && **it != character; ++(*it)) {
      |                                             ^~~~~
../../net/cookies/parsed_cookie.cc:90:45: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:100:49: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  100 |   for (; *it != end && !CharIsA(**it, chars); ++(*it)) {
      |                                                 ^~~~~
../../net/cookies/parsed_cookie.cc:100:49: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:109:48: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  109 |   for (; *it != end && CharIsA(**it, chars); ++(*it)) {
      |                                                ^~~~~
../../net/cookies/parsed_cookie.cc:109:48: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:116:48: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  116 |   for (; *it != end && CharIsA(**it, chars); --(*it)) {
      |                                                ^~~~~
../../net/cookies/parsed_cookie.cc:116:48: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:308:13: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  308 |     end = s.begin() + term_pos;
      |           ~~^~~~~~~
../../net/cookies/parsed_cookie.cc:308:13: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:337:7: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  337 |     --(*it);                  // Go back before the token separator.
      |       ^~~~~
../../net/cookies/parsed_cookie.cc:337:7: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:341:7: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  341 |     ++(*it);
      |       ^~~~~
../../net/cookies/parsed_cookie.cc:341:7: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:371:7: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  371 |     --(*value_end);
      |       ^~~~~~~~~~~~
../../net/cookies/parsed_cookie.cc:371:7: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:375:7: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  375 |     ++(*value_end);
      |       ^~~~~~~~~~~~
../../net/cookies/parsed_cookie.cc:375:7: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:571:9: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  571 |       ++it;  // Skip past the '='.
      |         ^~
../../net/cookies/parsed_cookie.cc:571:9: note: See //docs/unsafe_buffers.md for help.
/home/charles/electron/gn/main/src/tools/clang/plugins/UnsafeBuffersPlugin.cpp:238 filename ../../net/cookies/parsed_cookie.cc
243 returning from cache: 1
../../net/cookies/parsed_cookie.cc:634:9: error: unsafe pointer arithmetic [-Werror,-Wunsafe-buffer-usage]
  634 |       ++it;
      |         ^~
../../net/cookies/parsed_cookie.cc:634:9: note: See //docs/unsafe_buffers.md for help.

Release Notes

Notes: none.

[deepak1556]

Thanks for re-enabling the warnings!

@ckerr can you help clarify why we have some directories in https://github.com/electron/electron/blob/main/electron_unsafe_buffers_paths.txt while they are no longer present in https://source.chromium.org/chromium/chromium/src/+/main:build/config/unsafe_buffers_paths.txt. For ex: net/ in this case https://chromium-review.googlesource.com/c/chromium/src/+/5563610, why did upstream consider the above file safe for unsafe buffer warnings ?

[ckerr]

@deepak1556 two different answers:

• From the perspective of our own txt file: IMO unsafe buffer warnings should only break our build if the warning in C++ code that we maintain, i.e. shell/. I left -net/ in our config so that warnings there won't break our build.

• Clearly there is code in net/cookies/parsed_cookie.cc that generates unsafe buffer warnings. But since Chromium builds & releases keep happening, that doesn't seem to be a blocker for them. So maybe they don't build with -Werror, or maybe they don't do production builds with buffer warnings enabled? Something odd is going on there.