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global variables and static initializers that log are not sound #368

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opened 2024-06-01 04:04:17 +00:00 by qyriad · 1 comment
qyriad commented 2024-06-01 04:04:17 +00:00
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Brought up in https://github.com/NixOS/nix/issues/10772, see also #306 and #359 for more context. -Wl,--whole-archive seems to work around the specific issue at hand, but the order of static initializers is undefined in C++, and lots of things assume nix::logger != nullptr and just dereference it willy nilly. In https://github.com/NixOS/nix/issues/10772 the global nix::evalSettings constructor calls getDefaultNixPath(), which ends up calling getStateDir(), which of course calls getHome(), which logs a warning if $HOME isn't owned by the current user.

This is fucked. We should not be doing any IO before main in the first place, and we should probably replace the raw pointer nix::logger with a smart pointer or something

Brought up in https://github.com/NixOS/nix/issues/10772, see also #306 and #359 for more context. `-Wl,--whole-archive` seems to work around the specific issue at hand, but the order of static initializers is undefined in C++, and lots of things assume `nix::logger != nullptr` and just dereference it willy nilly. In https://github.com/NixOS/nix/issues/10772 the global `nix::evalSettings` constructor calls `getDefaultNixPath()`, which ends up calling `getStateDir()`, which of course calls `getHome()`, which logs a warning if `$HOME` isn't owned by the current user. This is *fucked*. We should *not* be doing any IO before main in the first place, and we should probably replace the raw pointer `nix::logger` with a smart pointer or something
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jade commented 2025-03-17 00:01:48 +00:00
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This CL fixes the logger to not be broken during static destructors: https://gerrit.lix.systems/c/lix/+/2684

I am not sure if we can avoid those completely, but at least it is now kinda sorta sound.

This CL fixes the logger to not be broken during static destructors: https://gerrit.lix.systems/c/lix/+/2684 I am not sure if we can avoid those completely, but at least it is now kinda sorta sound.
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Reference: lix-project/lix#368
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