Sergei Golubchik 2233798c11 MDEV-40341 store read-only sysvars in a read-only segment ...

Protect all READ_ONLY sysvars from run-time changes.

Put them into a separate section and use my_virtual_mem_protect()
to make this section read-only before the server starts accepting
connections.

Verify that they're all protected in the sys_var constructor.

One exception: opt_noacl (--skip-grant-tables) can be changed
from 1 to 0 on FLUSH PRIVILEGES. Let's briefly drop the
protection for this 1->0 change. It can be needed only once
in a server lifetime and only if it was started with --skip-grant-tables

On shutdown the protection is removed, making variables writable
again because shutdown resets some of them during the cleanup

Assisted-By: Claude:claude-4.8-opus

2026-07-29 13:05:09 +02:00

20 KiB

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