quick_exit is not _Exit / _exit

[frobtech]

Currently llvm-libc's actual OS-specific exit code is implemented as quick_exit, and _Exit and _exit call that. This is backwards. _Exit (C11 name) and _exit (POSIX name) are the underlying OS-specific thing (in Unix, the system call). quick_exit is the new C11 function that runs at_quick_exit hooks and then calls _Exit.

llvm-libc is missing at_quick_exit entirely.

[llvmbot]

@llvm/issue-subscribers-libc

Author: Roland McGrath (frobtech)

Currently llvm-libc's actual OS-specific exit code is implemented as `quick_exit`, and `_Exit` and `_exit` call that. This is backwards. `_Exit` (C11 name) and `_exit` (POSIX name) are the underlying OS-specific thing (in Unix, the system call). `quick_exit` is the new C11 function that runs `at_quick_exit` hooks and then calls `_Exit`.

llvm-libc is missing at_quick_exit entirely.

[michaelrj-google]

It seems like someone got confused about the names while implementing these functions. Here's the TODOs from what I can tell:

• rename the existing quick_exit (defined in /__support/OSUtils/quick_exit.h) to something else, and put it in the internal namespace.
  • The function __llvm_libc_quick_exit is forward declared in /__support/OSUtil/baremetal/quick_exit.cpp and intended to be provided by vendors. We should check with them before we rename the symbol (cc @petrhosek)
• add new entrypoints for quick_exit and at_quick_exit
  • See if the code for atexit can be shared with at_quick_exit

I'm assigning this bug to myself for the moment, but I will probably end up splitting this up into multiple smaller bugs.

[michaelrj-google]

The internal quick_exit function was renamed in patch #93620 and __llvm_libc_quick_exit is now __llvm_libc_exit, found in OSUtil/baremetal/exit.cpp

at_quick_exit will be added next, tracked by #94060

[michaelrj-google]

the internal exit function has been renamed, and both quick_exit and at_quick_exit have been added. Closing this as fixed.

Patches:
#93620
#94317