Include implementation of musl's __lock/__unlock functions. NFC #16129
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kripken
reviewed
Jan 28, 2022
The functions `__lock` and `__unlock` are never called directly within musl but always via the `LOCK()` and `UNLOCK()` macros. They are implemented internally using an atomic integer along with the `__wake` and `__futexwait` internal function which emscripten already supports. Not to be confused with `__lockfile/__unlockfile` which are used to implement the `FLOCK()/FUNLOCK()` macros (which we already support and have enabled). In theory this could help remove data races and crashed within musl. In practice many of the uses of `LOCK/UNLOCK` are in places not compiled into emscripten. However I noticed at least these 3 that we do depend on and they do look useful/valid: - stdio/ofl.c: Open file lock used in fclose.c/fflush.c/__stdio_exit.c (We don't use __stdio_exit.c under emscripten) - random/srandom: Used as a mutex for the prng generator - dirent/rewinddir/seekdir: Used a mutex on an open directory handle
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CI appears to have some issues. GitHub marks some test suites as pending, but when I look at the details, the tests have already been completed successfully. |
kleisauke
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Jan 28, 2022
kripken
approved these changes
Jan 28, 2022
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The functions
__lockand__unlockare never called directly withinmusl but always via the
LOCK()andUNLOCK()macros.They are implemented internally using an atomic integer along with the
__wakeand__futexwaitinternal function which emscripten alreadysupports.
Not to be confused with
__lockfile/__unlockfilewhich are used toimplement the
FLOCK()/FUNLOCK()macros (which we already support andhave enabled).
In theory this could help remove data races and crashed within musl.
In practice many of the uses of
LOCK/UNLOCKare in places not compiledinto emscripten. However I noticed at least these 3 that we do depend
on and they do look useful/valid:
don't use __stdio_exit.c under emscripten)